rev 12318 : [mq]: 8131034-Cleanup-in-j.u.regex.Pattern.quote

   1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
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   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
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  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
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  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
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  25 
  26 package java.util.regex;
  27 
  28 import java.text.Normalizer;
  29 import java.util.Locale;
  30 import java.util.Iterator;
  31 import java.util.Map;
  32 import java.util.ArrayList;
  33 import java.util.HashMap;
  34 import java.util.Arrays;
  35 import java.util.NoSuchElementException;
  36 import java.util.Spliterator;
  37 import java.util.Spliterators;
  38 import java.util.function.Predicate;
  39 import java.util.stream.Stream;
  40 import java.util.stream.StreamSupport;
  41 
  42 
  43 /**
  44  * A compiled representation of a regular expression.
  45  *
  46  * <p> A regular expression, specified as a string, must first be compiled into
  47  * an instance of this class.  The resulting pattern can then be used to create
  48  * a {@link Matcher} object that can match arbitrary {@linkplain
  49  * java.lang.CharSequence character sequences} against the regular
  50  * expression.  All of the state involved in performing a match resides in the
  51  * matcher, so many matchers can share the same pattern.
  52  *
  53  * <p> A typical invocation sequence is thus
  54  *
  55  * <blockquote><pre>
  56  * Pattern p = Pattern.{@link #compile compile}("a*b");
  57  * Matcher m = p.{@link #matcher matcher}("aaaaab");
  58  * boolean b = m.{@link Matcher#matches matches}();</pre></blockquote>
  59  *
  60  * <p> A {@link #matches matches} method is defined by this class as a
  61  * convenience for when a regular expression is used just once.  This method
  62  * compiles an expression and matches an input sequence against it in a single
  63  * invocation.  The statement
  64  *
  65  * <blockquote><pre>
  66  * boolean b = Pattern.matches("a*b", "aaaaab");</pre></blockquote>
  67  *
  68  * is equivalent to the three statements above, though for repeated matches it
  69  * is less efficient since it does not allow the compiled pattern to be reused.
  70  *
  71  * <p> Instances of this class are immutable and are safe for use by multiple
  72  * concurrent threads.  Instances of the {@link Matcher} class are not safe for
  73  * such use.
  74  *
  75  *
  76  * <h3><a name="sum">Summary of regular-expression constructs</a></h3>
  77  *
  78  * <table border="0" cellpadding="1" cellspacing="0"
  79  *  summary="Regular expression constructs, and what they match">
  80  *
  81  * <tr align="left">
  82  * <th align="left" id="construct">Construct</th>
  83  * <th align="left" id="matches">Matches</th>
  84  * </tr>
  85  *
  86  * <tr><th>&nbsp;</th></tr>
  87  * <tr align="left"><th colspan="2" id="characters">Characters</th></tr>
  88  *
  89  * <tr><td valign="top" headers="construct characters"><i>x</i></td>
  90  *     <td headers="matches">The character <i>x</i></td></tr>
  91  * <tr><td valign="top" headers="construct characters"><tt>\\</tt></td>
  92  *     <td headers="matches">The backslash character</td></tr>
  93  * <tr><td valign="top" headers="construct characters"><tt>\0</tt><i>n</i></td>
  94  *     <td headers="matches">The character with octal value <tt>0</tt><i>n</i>
  95  *         (0&nbsp;<tt>&lt;=</tt>&nbsp;<i>n</i>&nbsp;<tt>&lt;=</tt>&nbsp;7)</td></tr>
  96  * <tr><td valign="top" headers="construct characters"><tt>\0</tt><i>nn</i></td>
  97  *     <td headers="matches">The character with octal value <tt>0</tt><i>nn</i>
  98  *         (0&nbsp;<tt>&lt;=</tt>&nbsp;<i>n</i>&nbsp;<tt>&lt;=</tt>&nbsp;7)</td></tr>
  99  * <tr><td valign="top" headers="construct characters"><tt>\0</tt><i>mnn</i></td>
 100  *     <td headers="matches">The character with octal value <tt>0</tt><i>mnn</i>
 101  *         (0&nbsp;<tt>&lt;=</tt>&nbsp;<i>m</i>&nbsp;<tt>&lt;=</tt>&nbsp;3,
 102  *         0&nbsp;<tt>&lt;=</tt>&nbsp;<i>n</i>&nbsp;<tt>&lt;=</tt>&nbsp;7)</td></tr>
 103  * <tr><td valign="top" headers="construct characters"><tt>\x</tt><i>hh</i></td>
 104  *     <td headers="matches">The character with hexadecimal&nbsp;value&nbsp;<tt>0x</tt><i>hh</i></td></tr>
 105  * <tr><td valign="top" headers="construct characters"><tt>\u</tt><i>hhhh</i></td>
 106  *     <td headers="matches">The character with hexadecimal&nbsp;value&nbsp;<tt>0x</tt><i>hhhh</i></td></tr>
 107  * <tr><td valign="top" headers="construct characters"><tt>\x</tt><i>{h...h}</i></td>
 108  *     <td headers="matches">The character with hexadecimal&nbsp;value&nbsp;<tt>0x</tt><i>h...h</i>
 109  *         ({@link java.lang.Character#MIN_CODE_POINT Character.MIN_CODE_POINT}
 110  *         &nbsp;&lt;=&nbsp;<tt>0x</tt><i>h...h</i>&nbsp;&lt;=&nbsp;
 111  *          {@link java.lang.Character#MAX_CODE_POINT Character.MAX_CODE_POINT})</td></tr>
 112  * <tr><td valign="top" headers="matches"><tt>\t</tt></td>
 113  *     <td headers="matches">The tab character (<tt>'\u0009'</tt>)</td></tr>
 114  * <tr><td valign="top" headers="construct characters"><tt>\n</tt></td>
 115  *     <td headers="matches">The newline (line feed) character (<tt>'\u000A'</tt>)</td></tr>
 116  * <tr><td valign="top" headers="construct characters"><tt>\r</tt></td>
 117  *     <td headers="matches">The carriage-return character (<tt>'\u000D'</tt>)</td></tr>
 118  * <tr><td valign="top" headers="construct characters"><tt>\f</tt></td>
 119  *     <td headers="matches">The form-feed character (<tt>'\u000C'</tt>)</td></tr>
 120  * <tr><td valign="top" headers="construct characters"><tt>\a</tt></td>
 121  *     <td headers="matches">The alert (bell) character (<tt>'\u0007'</tt>)</td></tr>
 122  * <tr><td valign="top" headers="construct characters"><tt>\e</tt></td>
 123  *     <td headers="matches">The escape character (<tt>'\u001B'</tt>)</td></tr>
 124  * <tr><td valign="top" headers="construct characters"><tt>\c</tt><i>x</i></td>
 125  *     <td headers="matches">The control character corresponding to <i>x</i></td></tr>
 126  *
 127  * <tr><th>&nbsp;</th></tr>
 128  * <tr align="left"><th colspan="2" id="classes">Character classes</th></tr>
 129  *
 130  * <tr><td valign="top" headers="construct classes">{@code [abc]}</td>
 131  *     <td headers="matches">{@code a}, {@code b}, or {@code c} (simple class)</td></tr>
 132  * <tr><td valign="top" headers="construct classes">{@code [^abc]}</td>
 133  *     <td headers="matches">Any character except {@code a}, {@code b}, or {@code c} (negation)</td></tr>
 134  * <tr><td valign="top" headers="construct classes">{@code [a-zA-Z]}</td>
 135  *     <td headers="matches">{@code a} through {@code z}
 136  *         or {@code A} through {@code Z}, inclusive (range)</td></tr>
 137  * <tr><td valign="top" headers="construct classes">{@code [a-d[m-p]]}</td>
 138  *     <td headers="matches">{@code a} through {@code d},
 139  *      or {@code m} through {@code p}: {@code [a-dm-p]} (union)</td></tr>
 140  * <tr><td valign="top" headers="construct classes">{@code [a-z&&[def]]}</td>
 141  *     <td headers="matches">{@code d}, {@code e}, or {@code f} (intersection)</tr>
 142  * <tr><td valign="top" headers="construct classes">{@code [a-z&&[^bc]]}</td>
 143  *     <td headers="matches">{@code a} through {@code z},
 144  *         except for {@code b} and {@code c}: {@code [ad-z]} (subtraction)</td></tr>
 145  * <tr><td valign="top" headers="construct classes">{@code [a-z&&[^m-p]]}</td>
 146  *     <td headers="matches">{@code a} through {@code z},
 147  *          and not {@code m} through {@code p}: {@code [a-lq-z]}(subtraction)</td></tr>
 148  * <tr><th>&nbsp;</th></tr>
 149  *
 150  * <tr align="left"><th colspan="2" id="predef">Predefined character classes</th></tr>
 151  *
 152  * <tr><td valign="top" headers="construct predef"><tt>.</tt></td>
 153  *     <td headers="matches">Any character (may or may not match <a href="#lt">line terminators</a>)</td></tr>
 154  * <tr><td valign="top" headers="construct predef"><tt>\d</tt></td>
 155  *     <td headers="matches">A digit: <tt>[0-9]</tt></td></tr>
 156  * <tr><td valign="top" headers="construct predef"><tt>\D</tt></td>
 157  *     <td headers="matches">A non-digit: <tt>[^0-9]</tt></td></tr>
 158  * <tr><td valign="top" headers="construct predef"><tt>\h</tt></td>
 159  *     <td headers="matches">A horizontal whitespace character:
 160  *     <tt>[ \t\xA0\u1680\u180e\u2000-\u200a\u202f\u205f\u3000]</tt></td></tr>
 161  * <tr><td valign="top" headers="construct predef"><tt>\H</tt></td>
 162  *     <td headers="matches">A non-horizontal whitespace character: <tt>[^\h]</tt></td></tr>
 163  * <tr><td valign="top" headers="construct predef"><tt>\s</tt></td>
 164  *     <td headers="matches">A whitespace character: <tt>[ \t\n\x0B\f\r]</tt></td></tr>
 165  * <tr><td valign="top" headers="construct predef"><tt>\S</tt></td>
 166  *     <td headers="matches">A non-whitespace character: <tt>[^\s]</tt></td></tr>
 167  * <tr><td valign="top" headers="construct predef"><tt>\v</tt></td>
 168  *     <td headers="matches">A vertical whitespace character: <tt>[\n\x0B\f\r\x85\u2028\u2029]</tt>
 169  *     </td></tr>
 170  * <tr><td valign="top" headers="construct predef"><tt>\V</tt></td>
 171  *     <td headers="matches">A non-vertical whitespace character: <tt>[^\v]</tt></td></tr>
 172  * <tr><td valign="top" headers="construct predef"><tt>\w</tt></td>
 173  *     <td headers="matches">A word character: <tt>[a-zA-Z_0-9]</tt></td></tr>
 174  * <tr><td valign="top" headers="construct predef"><tt>\W</tt></td>
 175  *     <td headers="matches">A non-word character: <tt>[^\w]</tt></td></tr>
 176  * <tr><th>&nbsp;</th></tr>
 177  * <tr align="left"><th colspan="2" id="posix"><b>POSIX character classes (US-ASCII only)</b></th></tr>
 178  *
 179  * <tr><td valign="top" headers="construct posix">{@code \p{Lower}}</td>
 180  *     <td headers="matches">A lower-case alphabetic character: {@code [a-z]}</td></tr>
 181  * <tr><td valign="top" headers="construct posix">{@code \p{Upper}}</td>
 182  *     <td headers="matches">An upper-case alphabetic character:{@code [A-Z]}</td></tr>
 183  * <tr><td valign="top" headers="construct posix">{@code \p{ASCII}}</td>
 184  *     <td headers="matches">All ASCII:{@code [\x00-\x7F]}</td></tr>
 185  * <tr><td valign="top" headers="construct posix">{@code \p{Alpha}}</td>
 186  *     <td headers="matches">An alphabetic character:{@code [\p{Lower}\p{Upper}]}</td></tr>
 187  * <tr><td valign="top" headers="construct posix">{@code \p{Digit}}</td>
 188  *     <td headers="matches">A decimal digit: {@code [0-9]}</td></tr>
 189  * <tr><td valign="top" headers="construct posix">{@code \p{Alnum}}</td>
 190  *     <td headers="matches">An alphanumeric character:{@code [\p{Alpha}\p{Digit}]}</td></tr>
 191  * <tr><td valign="top" headers="construct posix">{@code \p{Punct}}</td>
 192  *     <td headers="matches">Punctuation: One of {@code !"#$%&'()*+,-./:;<=>?@[\]^_`{|}~}</td></tr>
 193  *     <!-- {@code [\!"#\$%&'\(\)\*\+,\-\./:;\<=\>\?@\[\\\]\^_`\{\|\}~]}
 194  *          {@code [\X21-\X2F\X31-\X40\X5B-\X60\X7B-\X7E]} -->
 195  * <tr><td valign="top" headers="construct posix">{@code \p{Graph}}</td>
 196  *     <td headers="matches">A visible character: {@code [\p{Alnum}\p{Punct}]}</td></tr>
 197  * <tr><td valign="top" headers="construct posix">{@code \p{Print}}</td>
 198  *     <td headers="matches">A printable character: {@code [\p{Graph}\x20]}</td></tr>
 199  * <tr><td valign="top" headers="construct posix">{@code \p{Blank}}</td>
 200  *     <td headers="matches">A space or a tab: {@code [ \t]}</td></tr>
 201  * <tr><td valign="top" headers="construct posix">{@code \p{Cntrl}}</td>
 202  *     <td headers="matches">A control character: {@code [\x00-\x1F\x7F]}</td></tr>
 203  * <tr><td valign="top" headers="construct posix">{@code \p{XDigit}}</td>
 204  *     <td headers="matches">A hexadecimal digit: {@code [0-9a-fA-F]}</td></tr>
 205  * <tr><td valign="top" headers="construct posix">{@code \p{Space}}</td>
 206  *     <td headers="matches">A whitespace character: {@code [ \t\n\x0B\f\r]}</td></tr>
 207  *
 208  * <tr><th>&nbsp;</th></tr>
 209  * <tr align="left"><th colspan="2">java.lang.Character classes (simple <a href="#jcc">java character type</a>)</th></tr>
 210  *
 211  * <tr><td valign="top"><tt>\p{javaLowerCase}</tt></td>
 212  *     <td>Equivalent to java.lang.Character.isLowerCase()</td></tr>
 213  * <tr><td valign="top"><tt>\p{javaUpperCase}</tt></td>
 214  *     <td>Equivalent to java.lang.Character.isUpperCase()</td></tr>
 215  * <tr><td valign="top"><tt>\p{javaWhitespace}</tt></td>
 216  *     <td>Equivalent to java.lang.Character.isWhitespace()</td></tr>
 217  * <tr><td valign="top"><tt>\p{javaMirrored}</tt></td>
 218  *     <td>Equivalent to java.lang.Character.isMirrored()</td></tr>
 219  *
 220  * <tr><th>&nbsp;</th></tr>
 221  * <tr align="left"><th colspan="2" id="unicode">Classes for Unicode scripts, blocks, categories and binary properties</th></tr>
 222  * <tr><td valign="top" headers="construct unicode">{@code \p{IsLatin}}</td>
 223  *     <td headers="matches">A Latin&nbsp;script character (<a href="#usc">script</a>)</td></tr>
 224  * <tr><td valign="top" headers="construct unicode">{@code \p{InGreek}}</td>
 225  *     <td headers="matches">A character in the Greek&nbsp;block (<a href="#ubc">block</a>)</td></tr>
 226  * <tr><td valign="top" headers="construct unicode">{@code \p{Lu}}</td>
 227  *     <td headers="matches">An uppercase letter (<a href="#ucc">category</a>)</td></tr>
 228  * <tr><td valign="top" headers="construct unicode">{@code \p{IsAlphabetic}}</td>
 229  *     <td headers="matches">An alphabetic character (<a href="#ubpc">binary property</a>)</td></tr>
 230  * <tr><td valign="top" headers="construct unicode">{@code \p{Sc}}</td>
 231  *     <td headers="matches">A currency symbol</td></tr>
 232  * <tr><td valign="top" headers="construct unicode">{@code \P{InGreek}}</td>
 233  *     <td headers="matches">Any character except one in the Greek block (negation)</td></tr>
 234  * <tr><td valign="top" headers="construct unicode">{@code [\p{L}&&[^\p{Lu}]]}</td>
 235  *     <td headers="matches">Any letter except an uppercase letter (subtraction)</td></tr>
 236  *
 237  * <tr><th>&nbsp;</th></tr>
 238  * <tr align="left"><th colspan="2" id="bounds">Boundary matchers</th></tr>
 239  *
 240  * <tr><td valign="top" headers="construct bounds"><tt>^</tt></td>
 241  *     <td headers="matches">The beginning of a line</td></tr>
 242  * <tr><td valign="top" headers="construct bounds"><tt>$</tt></td>
 243  *     <td headers="matches">The end of a line</td></tr>
 244  * <tr><td valign="top" headers="construct bounds"><tt>\b</tt></td>
 245  *     <td headers="matches">A word boundary</td></tr>
 246  * <tr><td valign="top" headers="construct bounds"><tt>\B</tt></td>
 247  *     <td headers="matches">A non-word boundary</td></tr>
 248  * <tr><td valign="top" headers="construct bounds"><tt>\A</tt></td>
 249  *     <td headers="matches">The beginning of the input</td></tr>
 250  * <tr><td valign="top" headers="construct bounds"><tt>\G</tt></td>
 251  *     <td headers="matches">The end of the previous match</td></tr>
 252  * <tr><td valign="top" headers="construct bounds"><tt>\Z</tt></td>
 253  *     <td headers="matches">The end of the input but for the final
 254  *         <a href="#lt">terminator</a>, if&nbsp;any</td></tr>
 255  * <tr><td valign="top" headers="construct bounds"><tt>\z</tt></td>
 256  *     <td headers="matches">The end of the input</td></tr>
 257  *
 258  * <tr><th>&nbsp;</th></tr>
 259  * <tr align="left"><th colspan="2" id="lineending">Linebreak matcher</th></tr>
 260  * <tr><td valign="top" headers="construct lineending"><tt>\R</tt></td>
 261  *     <td headers="matches">Any Unicode linebreak sequence, is equivalent to
 262  *     <tt>\u000D\u000A|[\u000A\u000B\u000C\u000D\u0085\u2028\u2029]
 263  *     </tt></td></tr>
 264  *
 265  * <tr><th>&nbsp;</th></tr>
 266  * <tr align="left"><th colspan="2" id="greedy">Greedy quantifiers</th></tr>
 267  *
 268  * <tr><td valign="top" headers="construct greedy"><i>X</i><tt>?</tt></td>
 269  *     <td headers="matches"><i>X</i>, once or not at all</td></tr>
 270  * <tr><td valign="top" headers="construct greedy"><i>X</i><tt>*</tt></td>
 271  *     <td headers="matches"><i>X</i>, zero or more times</td></tr>
 272  * <tr><td valign="top" headers="construct greedy"><i>X</i><tt>+</tt></td>
 273  *     <td headers="matches"><i>X</i>, one or more times</td></tr>
 274  * <tr><td valign="top" headers="construct greedy"><i>X</i><tt>{</tt><i>n</i><tt>}</tt></td>
 275  *     <td headers="matches"><i>X</i>, exactly <i>n</i> times</td></tr>
 276  * <tr><td valign="top" headers="construct greedy"><i>X</i><tt>{</tt><i>n</i><tt>,}</tt></td>
 277  *     <td headers="matches"><i>X</i>, at least <i>n</i> times</td></tr>
 278  * <tr><td valign="top" headers="construct greedy"><i>X</i><tt>{</tt><i>n</i><tt>,</tt><i>m</i><tt>}</tt></td>
 279  *     <td headers="matches"><i>X</i>, at least <i>n</i> but not more than <i>m</i> times</td></tr>
 280  *
 281  * <tr><th>&nbsp;</th></tr>
 282  * <tr align="left"><th colspan="2" id="reluc">Reluctant quantifiers</th></tr>
 283  *
 284  * <tr><td valign="top" headers="construct reluc"><i>X</i><tt>??</tt></td>
 285  *     <td headers="matches"><i>X</i>, once or not at all</td></tr>
 286  * <tr><td valign="top" headers="construct reluc"><i>X</i><tt>*?</tt></td>
 287  *     <td headers="matches"><i>X</i>, zero or more times</td></tr>
 288  * <tr><td valign="top" headers="construct reluc"><i>X</i><tt>+?</tt></td>
 289  *     <td headers="matches"><i>X</i>, one or more times</td></tr>
 290  * <tr><td valign="top" headers="construct reluc"><i>X</i><tt>{</tt><i>n</i><tt>}?</tt></td>
 291  *     <td headers="matches"><i>X</i>, exactly <i>n</i> times</td></tr>
 292  * <tr><td valign="top" headers="construct reluc"><i>X</i><tt>{</tt><i>n</i><tt>,}?</tt></td>
 293  *     <td headers="matches"><i>X</i>, at least <i>n</i> times</td></tr>
 294  * <tr><td valign="top" headers="construct reluc"><i>X</i><tt>{</tt><i>n</i><tt>,</tt><i>m</i><tt>}?</tt></td>
 295  *     <td headers="matches"><i>X</i>, at least <i>n</i> but not more than <i>m</i> times</td></tr>
 296  *
 297  * <tr><th>&nbsp;</th></tr>
 298  * <tr align="left"><th colspan="2" id="poss">Possessive quantifiers</th></tr>
 299  *
 300  * <tr><td valign="top" headers="construct poss"><i>X</i><tt>?+</tt></td>
 301  *     <td headers="matches"><i>X</i>, once or not at all</td></tr>
 302  * <tr><td valign="top" headers="construct poss"><i>X</i><tt>*+</tt></td>
 303  *     <td headers="matches"><i>X</i>, zero or more times</td></tr>
 304  * <tr><td valign="top" headers="construct poss"><i>X</i><tt>++</tt></td>
 305  *     <td headers="matches"><i>X</i>, one or more times</td></tr>
 306  * <tr><td valign="top" headers="construct poss"><i>X</i><tt>{</tt><i>n</i><tt>}+</tt></td>
 307  *     <td headers="matches"><i>X</i>, exactly <i>n</i> times</td></tr>
 308  * <tr><td valign="top" headers="construct poss"><i>X</i><tt>{</tt><i>n</i><tt>,}+</tt></td>
 309  *     <td headers="matches"><i>X</i>, at least <i>n</i> times</td></tr>
 310  * <tr><td valign="top" headers="construct poss"><i>X</i><tt>{</tt><i>n</i><tt>,</tt><i>m</i><tt>}+</tt></td>
 311  *     <td headers="matches"><i>X</i>, at least <i>n</i> but not more than <i>m</i> times</td></tr>
 312  *
 313  * <tr><th>&nbsp;</th></tr>
 314  * <tr align="left"><th colspan="2" id="logical">Logical operators</th></tr>
 315  *
 316  * <tr><td valign="top" headers="construct logical"><i>XY</i></td>
 317  *     <td headers="matches"><i>X</i> followed by <i>Y</i></td></tr>
 318  * <tr><td valign="top" headers="construct logical"><i>X</i><tt>|</tt><i>Y</i></td>
 319  *     <td headers="matches">Either <i>X</i> or <i>Y</i></td></tr>
 320  * <tr><td valign="top" headers="construct logical"><tt>(</tt><i>X</i><tt>)</tt></td>
 321  *     <td headers="matches">X, as a <a href="#cg">capturing group</a></td></tr>
 322  *
 323  * <tr><th>&nbsp;</th></tr>
 324  * <tr align="left"><th colspan="2" id="backref">Back references</th></tr>
 325  *
 326  * <tr><td valign="bottom" headers="construct backref"><tt>\</tt><i>n</i></td>
 327  *     <td valign="bottom" headers="matches">Whatever the <i>n</i><sup>th</sup>
 328  *     <a href="#cg">capturing group</a> matched</td></tr>
 329  *
 330  * <tr><td valign="bottom" headers="construct backref"><tt>\</tt><i>k</i>&lt;<i>name</i>&gt;</td>
 331  *     <td valign="bottom" headers="matches">Whatever the
 332  *     <a href="#groupname">named-capturing group</a> "name" matched</td></tr>
 333  *
 334  * <tr><th>&nbsp;</th></tr>
 335  * <tr align="left"><th colspan="2" id="quot">Quotation</th></tr>
 336  *
 337  * <tr><td valign="top" headers="construct quot"><tt>\</tt></td>
 338  *     <td headers="matches">Nothing, but quotes the following character</td></tr>
 339  * <tr><td valign="top" headers="construct quot"><tt>\Q</tt></td>
 340  *     <td headers="matches">Nothing, but quotes all characters until <tt>\E</tt></td></tr>
 341  * <tr><td valign="top" headers="construct quot"><tt>\E</tt></td>
 342  *     <td headers="matches">Nothing, but ends quoting started by <tt>\Q</tt></td></tr>
 343  *     <!-- Metachars: !$()*+.<>?[\]^{|} -->
 344  *
 345  * <tr><th>&nbsp;</th></tr>
 346  * <tr align="left"><th colspan="2" id="special">Special constructs (named-capturing and non-capturing)</th></tr>
 347  *
 348  * <tr><td valign="top" headers="construct special"><tt>(?&lt;<a href="#groupname">name</a>&gt;</tt><i>X</i><tt>)</tt></td>
 349  *     <td headers="matches"><i>X</i>, as a named-capturing group</td></tr>
 350  * <tr><td valign="top" headers="construct special"><tt>(?:</tt><i>X</i><tt>)</tt></td>
 351  *     <td headers="matches"><i>X</i>, as a non-capturing group</td></tr>
 352  * <tr><td valign="top" headers="construct special"><tt>(?idmsuxU-idmsuxU)&nbsp;</tt></td>
 353  *     <td headers="matches">Nothing, but turns match flags <a href="#CASE_INSENSITIVE">i</a>
 354  * <a href="#UNIX_LINES">d</a> <a href="#MULTILINE">m</a> <a href="#DOTALL">s</a>
 355  * <a href="#UNICODE_CASE">u</a> <a href="#COMMENTS">x</a> <a href="#UNICODE_CHARACTER_CLASS">U</a>
 356  * on - off</td></tr>
 357  * <tr><td valign="top" headers="construct special"><tt>(?idmsux-idmsux:</tt><i>X</i><tt>)</tt>&nbsp;&nbsp;</td>
 358  *     <td headers="matches"><i>X</i>, as a <a href="#cg">non-capturing group</a> with the
 359  *         given flags <a href="#CASE_INSENSITIVE">i</a> <a href="#UNIX_LINES">d</a>
 360  * <a href="#MULTILINE">m</a> <a href="#DOTALL">s</a> <a href="#UNICODE_CASE">u</a >
 361  * <a href="#COMMENTS">x</a> on - off</td></tr>
 362  * <tr><td valign="top" headers="construct special"><tt>(?=</tt><i>X</i><tt>)</tt></td>
 363  *     <td headers="matches"><i>X</i>, via zero-width positive lookahead</td></tr>
 364  * <tr><td valign="top" headers="construct special"><tt>(?!</tt><i>X</i><tt>)</tt></td>
 365  *     <td headers="matches"><i>X</i>, via zero-width negative lookahead</td></tr>
 366  * <tr><td valign="top" headers="construct special"><tt>(?&lt;=</tt><i>X</i><tt>)</tt></td>
 367  *     <td headers="matches"><i>X</i>, via zero-width positive lookbehind</td></tr>
 368  * <tr><td valign="top" headers="construct special"><tt>(?&lt;!</tt><i>X</i><tt>)</tt></td>
 369  *     <td headers="matches"><i>X</i>, via zero-width negative lookbehind</td></tr>
 370  * <tr><td valign="top" headers="construct special"><tt>(?&gt;</tt><i>X</i><tt>)</tt></td>
 371  *     <td headers="matches"><i>X</i>, as an independent, non-capturing group</td></tr>
 372  *
 373  * </table>
 374  *
 375  * <hr>
 376  *
 377  *
 378  * <h3><a name="bs">Backslashes, escapes, and quoting</a></h3>
 379  *
 380  * <p> The backslash character (<tt>'\'</tt>) serves to introduce escaped
 381  * constructs, as defined in the table above, as well as to quote characters
 382  * that otherwise would be interpreted as unescaped constructs.  Thus the
 383  * expression <tt>\\</tt> matches a single backslash and <tt>\{</tt> matches a
 384  * left brace.
 385  *
 386  * <p> It is an error to use a backslash prior to any alphabetic character that
 387  * does not denote an escaped construct; these are reserved for future
 388  * extensions to the regular-expression language.  A backslash may be used
 389  * prior to a non-alphabetic character regardless of whether that character is
 390  * part of an unescaped construct.
 391  *
 392  * <p> Backslashes within string literals in Java source code are interpreted
 393  * as required by
 394  * <cite>The Java&trade; Language Specification</cite>
 395  * as either Unicode escapes (section 3.3) or other character escapes (section 3.10.6)
 396  * It is therefore necessary to double backslashes in string
 397  * literals that represent regular expressions to protect them from
 398  * interpretation by the Java bytecode compiler.  The string literal
 399  * <tt>"\b"</tt>, for example, matches a single backspace character when
 400  * interpreted as a regular expression, while <tt>"\\b"</tt> matches a
 401  * word boundary.  The string literal <tt>"\(hello\)"</tt> is illegal
 402  * and leads to a compile-time error; in order to match the string
 403  * <tt>(hello)</tt> the string literal <tt>"\\(hello\\)"</tt>
 404  * must be used.
 405  *
 406  * <h3><a name="cc">Character Classes</a></h3>
 407  *
 408  *    <p> Character classes may appear within other character classes, and
 409  *    may be composed by the union operator (implicit) and the intersection
 410  *    operator (<tt>&amp;&amp;</tt>).
 411  *    The union operator denotes a class that contains every character that is
 412  *    in at least one of its operand classes.  The intersection operator
 413  *    denotes a class that contains every character that is in both of its
 414  *    operand classes.
 415  *
 416  *    <p> The precedence of character-class operators is as follows, from
 417  *    highest to lowest:
 418  *
 419  *    <blockquote><table border="0" cellpadding="1" cellspacing="0"
 420  *                 summary="Precedence of character class operators.">
 421  *      <tr><th>1&nbsp;&nbsp;&nbsp;&nbsp;</th>
 422  *        <td>Literal escape&nbsp;&nbsp;&nbsp;&nbsp;</td>
 423  *        <td><tt>\x</tt></td></tr>
 424  *     <tr><th>2&nbsp;&nbsp;&nbsp;&nbsp;</th>
 425  *        <td>Grouping</td>
 426  *        <td><tt>[...]</tt></td></tr>
 427  *     <tr><th>3&nbsp;&nbsp;&nbsp;&nbsp;</th>
 428  *        <td>Range</td>
 429  *        <td><tt>a-z</tt></td></tr>
 430  *      <tr><th>4&nbsp;&nbsp;&nbsp;&nbsp;</th>
 431  *        <td>Union</td>
 432  *        <td><tt>[a-e][i-u]</tt></td></tr>
 433  *      <tr><th>5&nbsp;&nbsp;&nbsp;&nbsp;</th>
 434  *        <td>Intersection</td>
 435  *        <td>{@code [a-z&&[aeiou]]}</td></tr>
 436  *    </table></blockquote>
 437  *
 438  *    <p> Note that a different set of metacharacters are in effect inside
 439  *    a character class than outside a character class. For instance, the
 440  *    regular expression <tt>.</tt> loses its special meaning inside a
 441  *    character class, while the expression <tt>-</tt> becomes a range
 442  *    forming metacharacter.
 443  *
 444  * <h3><a name="lt">Line terminators</a></h3>
 445  *
 446  * <p> A <i>line terminator</i> is a one- or two-character sequence that marks
 447  * the end of a line of the input character sequence.  The following are
 448  * recognized as line terminators:
 449  *
 450  * <ul>
 451  *
 452  *   <li> A newline (line feed) character&nbsp;(<tt>'\n'</tt>),
 453  *
 454  *   <li> A carriage-return character followed immediately by a newline
 455  *   character&nbsp;(<tt>"\r\n"</tt>),
 456  *
 457  *   <li> A standalone carriage-return character&nbsp;(<tt>'\r'</tt>),
 458  *
 459  *   <li> A next-line character&nbsp;(<tt>'\u0085'</tt>),
 460  *
 461  *   <li> A line-separator character&nbsp;(<tt>'\u2028'</tt>), or
 462  *
 463  *   <li> A paragraph-separator character&nbsp;(<tt>'\u2029</tt>).
 464  *
 465  * </ul>
 466  * <p>If {@link #UNIX_LINES} mode is activated, then the only line terminators
 467  * recognized are newline characters.
 468  *
 469  * <p> The regular expression <tt>.</tt> matches any character except a line
 470  * terminator unless the {@link #DOTALL} flag is specified.
 471  *
 472  * <p> By default, the regular expressions <tt>^</tt> and <tt>$</tt> ignore
 473  * line terminators and only match at the beginning and the end, respectively,
 474  * of the entire input sequence. If {@link #MULTILINE} mode is activated then
 475  * <tt>^</tt> matches at the beginning of input and after any line terminator
 476  * except at the end of input. When in {@link #MULTILINE} mode <tt>$</tt>
 477  * matches just before a line terminator or the end of the input sequence.
 478  *
 479  * <h3><a name="cg">Groups and capturing</a></h3>
 480  *
 481  * <h4><a name="gnumber">Group number</a></h4>
 482  * <p> Capturing groups are numbered by counting their opening parentheses from
 483  * left to right.  In the expression <tt>((A)(B(C)))</tt>, for example, there
 484  * are four such groups: </p>
 485  *
 486  * <blockquote><table cellpadding=1 cellspacing=0 summary="Capturing group numberings">
 487  * <tr><th>1&nbsp;&nbsp;&nbsp;&nbsp;</th>
 488  *     <td><tt>((A)(B(C)))</tt></td></tr>
 489  * <tr><th>2&nbsp;&nbsp;&nbsp;&nbsp;</th>
 490  *     <td><tt>(A)</tt></td></tr>
 491  * <tr><th>3&nbsp;&nbsp;&nbsp;&nbsp;</th>
 492  *     <td><tt>(B(C))</tt></td></tr>
 493  * <tr><th>4&nbsp;&nbsp;&nbsp;&nbsp;</th>
 494  *     <td><tt>(C)</tt></td></tr>
 495  * </table></blockquote>
 496  *
 497  * <p> Group zero always stands for the entire expression.
 498  *
 499  * <p> Capturing groups are so named because, during a match, each subsequence
 500  * of the input sequence that matches such a group is saved.  The captured
 501  * subsequence may be used later in the expression, via a back reference, and
 502  * may also be retrieved from the matcher once the match operation is complete.
 503  *
 504  * <h4><a name="groupname">Group name</a></h4>
 505  * <p>A capturing group can also be assigned a "name", a <tt>named-capturing group</tt>,
 506  * and then be back-referenced later by the "name". Group names are composed of
 507  * the following characters. The first character must be a <tt>letter</tt>.
 508  *
 509  * <ul>
 510  *   <li> The uppercase letters <tt>'A'</tt> through <tt>'Z'</tt>
 511  *        (<tt>'\u0041'</tt>&nbsp;through&nbsp;<tt>'\u005a'</tt>),
 512  *   <li> The lowercase letters <tt>'a'</tt> through <tt>'z'</tt>
 513  *        (<tt>'\u0061'</tt>&nbsp;through&nbsp;<tt>'\u007a'</tt>),
 514  *   <li> The digits <tt>'0'</tt> through <tt>'9'</tt>
 515  *        (<tt>'\u0030'</tt>&nbsp;through&nbsp;<tt>'\u0039'</tt>),
 516  * </ul>
 517  *
 518  * <p> A <tt>named-capturing group</tt> is still numbered as described in
 519  * <a href="#gnumber">Group number</a>.
 520  *
 521  * <p> The captured input associated with a group is always the subsequence
 522  * that the group most recently matched.  If a group is evaluated a second time
 523  * because of quantification then its previously-captured value, if any, will
 524  * be retained if the second evaluation fails.  Matching the string
 525  * <tt>"aba"</tt> against the expression <tt>(a(b)?)+</tt>, for example, leaves
 526  * group two set to <tt>"b"</tt>.  All captured input is discarded at the
 527  * beginning of each match.
 528  *
 529  * <p> Groups beginning with <tt>(?</tt> are either pure, <i>non-capturing</i> groups
 530  * that do not capture text and do not count towards the group total, or
 531  * <i>named-capturing</i> group.
 532  *
 533  * <h3> Unicode support </h3>
 534  *
 535  * <p> This class is in conformance with Level 1 of <a
 536  * href="http://www.unicode.org/reports/tr18/"><i>Unicode Technical
 537  * Standard #18: Unicode Regular Expression</i></a>, plus RL2.1
 538  * Canonical Equivalents.
 539  * <p>
 540  * <b>Unicode escape sequences</b> such as <tt>\u2014</tt> in Java source code
 541  * are processed as described in section 3.3 of
 542  * <cite>The Java&trade; Language Specification</cite>.
 543  * Such escape sequences are also implemented directly by the regular-expression
 544  * parser so that Unicode escapes can be used in expressions that are read from
 545  * files or from the keyboard.  Thus the strings <tt>"\u2014"</tt> and
 546  * <tt>"\\u2014"</tt>, while not equal, compile into the same pattern, which
 547  * matches the character with hexadecimal value <tt>0x2014</tt>.
 548  * <p>
 549  * A Unicode character can also be represented in a regular-expression by
 550  * using its <b>Hex notation</b>(hexadecimal code point value) directly as described in construct
 551  * <tt>\x{...}</tt>, for example a supplementary character U+2011F
 552  * can be specified as <tt>\x{2011F}</tt>, instead of two consecutive
 553  * Unicode escape sequences of the surrogate pair
 554  * <tt>\uD840</tt><tt>\uDD1F</tt>.
 555  * <p>
 556  * Unicode scripts, blocks, categories and binary properties are written with
 557  * the <tt>\p</tt> and <tt>\P</tt> constructs as in Perl.
 558  * <tt>\p{</tt><i>prop</i><tt>}</tt> matches if
 559  * the input has the property <i>prop</i>, while <tt>\P{</tt><i>prop</i><tt>}</tt>
 560  * does not match if the input has that property.
 561  * <p>
 562  * Scripts, blocks, categories and binary properties can be used both inside
 563  * and outside of a character class.
 564  *
 565  * <p>
 566  * <b><a name="usc">Scripts</a></b> are specified either with the prefix {@code Is}, as in
 567  * {@code IsHiragana}, or by using  the {@code script} keyword (or its short
 568  * form {@code sc}) as in {@code script=Hiragana} or {@code sc=Hiragana}.
 569  * <p>
 570  * The script names supported by <code>Pattern</code> are the valid script names
 571  * accepted and defined by
 572  * {@link java.lang.Character.UnicodeScript#forName(String) UnicodeScript.forName}.
 573  *
 574  * <p>
 575  * <b><a name="ubc">Blocks</a></b> are specified with the prefix {@code In}, as in
 576  * {@code InMongolian}, or by using the keyword {@code block} (or its short
 577  * form {@code blk}) as in {@code block=Mongolian} or {@code blk=Mongolian}.
 578  * <p>
 579  * The block names supported by <code>Pattern</code> are the valid block names
 580  * accepted and defined by
 581  * {@link java.lang.Character.UnicodeBlock#forName(String) UnicodeBlock.forName}.
 582  * <p>
 583  *
 584  * <b><a name="ucc">Categories</a></b> may be specified with the optional prefix {@code Is}:
 585  * Both {@code \p{L}} and {@code \p{IsL}} denote the category of Unicode
 586  * letters. Same as scripts and blocks, categories can also be specified
 587  * by using the keyword {@code general_category} (or its short form
 588  * {@code gc}) as in {@code general_category=Lu} or {@code gc=Lu}.
 589  * <p>
 590  * The supported categories are those of
 591  * <a href="http://www.unicode.org/unicode/standard/standard.html">
 592  * <i>The Unicode Standard</i></a> in the version specified by the
 593  * {@link java.lang.Character Character} class. The category names are those
 594  * defined in the Standard, both normative and informative.
 595  * <p>
 596  *
 597  * <b><a name="ubpc">Binary properties</a></b> are specified with the prefix {@code Is}, as in
 598  * {@code IsAlphabetic}. The supported binary properties by <code>Pattern</code>
 599  * are
 600  * <ul>
 601  *   <li> Alphabetic
 602  *   <li> Ideographic
 603  *   <li> Letter
 604  *   <li> Lowercase
 605  *   <li> Uppercase
 606  *   <li> Titlecase
 607  *   <li> Punctuation
 608  *   <Li> Control
 609  *   <li> White_Space
 610  *   <li> Digit
 611  *   <li> Hex_Digit
 612  *   <li> Join_Control
 613  *   <li> Noncharacter_Code_Point
 614  *   <li> Assigned
 615  * </ul>
 616  * <p>
 617  * The following <b>Predefined Character classes</b> and <b>POSIX character classes</b>
 618  * are in conformance with the recommendation of <i>Annex C: Compatibility Properties</i>
 619  * of <a href="http://www.unicode.org/reports/tr18/"><i>Unicode Regular Expression
 620  * </i></a>, when {@link #UNICODE_CHARACTER_CLASS} flag is specified.
 621  *
 622  * <table border="0" cellpadding="1" cellspacing="0"
 623  *  summary="predefined and posix character classes in Unicode mode">
 624  * <tr align="left">
 625  * <th align="left" id="predef_classes">Classes</th>
 626  * <th align="left" id="predef_matches">Matches</th>
 627  *</tr>
 628  * <tr><td><tt>\p{Lower}</tt></td>
 629  *     <td>A lowercase character:<tt>\p{IsLowercase}</tt></td></tr>
 630  * <tr><td><tt>\p{Upper}</tt></td>
 631  *     <td>An uppercase character:<tt>\p{IsUppercase}</tt></td></tr>
 632  * <tr><td><tt>\p{ASCII}</tt></td>
 633  *     <td>All ASCII:<tt>[\x00-\x7F]</tt></td></tr>
 634  * <tr><td><tt>\p{Alpha}</tt></td>
 635  *     <td>An alphabetic character:<tt>\p{IsAlphabetic}</tt></td></tr>
 636  * <tr><td><tt>\p{Digit}</tt></td>
 637  *     <td>A decimal digit character:<tt>p{IsDigit}</tt></td></tr>
 638  * <tr><td><tt>\p{Alnum}</tt></td>
 639  *     <td>An alphanumeric character:<tt>[\p{IsAlphabetic}\p{IsDigit}]</tt></td></tr>
 640  * <tr><td><tt>\p{Punct}</tt></td>
 641  *     <td>A punctuation character:<tt>p{IsPunctuation}</tt></td></tr>
 642  * <tr><td><tt>\p{Graph}</tt></td>
 643  *     <td>A visible character: <tt>[^\p{IsWhite_Space}\p{gc=Cc}\p{gc=Cs}\p{gc=Cn}]</tt></td></tr>
 644  * <tr><td><tt>\p{Print}</tt></td>
 645  *     <td>A printable character: {@code [\p{Graph}\p{Blank}&&[^\p{Cntrl}]]}</td></tr>
 646  * <tr><td><tt>\p{Blank}</tt></td>
 647  *     <td>A space or a tab: {@code [\p{IsWhite_Space}&&[^\p{gc=Zl}\p{gc=Zp}\x0a\x0b\x0c\x0d\x85]]}</td></tr>
 648  * <tr><td><tt>\p{Cntrl}</tt></td>
 649  *     <td>A control character: <tt>\p{gc=Cc}</tt></td></tr>
 650  * <tr><td><tt>\p{XDigit}</tt></td>
 651  *     <td>A hexadecimal digit: <tt>[\p{gc=Nd}\p{IsHex_Digit}]</tt></td></tr>
 652  * <tr><td><tt>\p{Space}</tt></td>
 653  *     <td>A whitespace character:<tt>\p{IsWhite_Space}</tt></td></tr>
 654  * <tr><td><tt>\d</tt></td>
 655  *     <td>A digit: <tt>\p{IsDigit}</tt></td></tr>
 656  * <tr><td><tt>\D</tt></td>
 657  *     <td>A non-digit: <tt>[^\d]</tt></td></tr>
 658  * <tr><td><tt>\s</tt></td>
 659  *     <td>A whitespace character: <tt>\p{IsWhite_Space}</tt></td></tr>
 660  * <tr><td><tt>\S</tt></td>
 661  *     <td>A non-whitespace character: <tt>[^\s]</tt></td></tr>
 662  * <tr><td><tt>\w</tt></td>
 663  *     <td>A word character: <tt>[\p{Alpha}\p{gc=Mn}\p{gc=Me}\p{gc=Mc}\p{Digit}\p{gc=Pc}\p{IsJoin_Control}]</tt></td></tr>
 664  * <tr><td><tt>\W</tt></td>
 665  *     <td>A non-word character: <tt>[^\w]</tt></td></tr>
 666  * </table>
 667  * <p>
 668  * <a name="jcc">
 669  * Categories that behave like the java.lang.Character
 670  * boolean is<i>methodname</i> methods (except for the deprecated ones) are
 671  * available through the same <tt>\p{</tt><i>prop</i><tt>}</tt> syntax where
 672  * the specified property has the name <tt>java<i>methodname</i></tt></a>.
 673  *
 674  * <h3> Comparison to Perl 5 </h3>
 675  *
 676  * <p>The <code>Pattern</code> engine performs traditional NFA-based matching
 677  * with ordered alternation as occurs in Perl 5.
 678  *
 679  * <p> Perl constructs not supported by this class: </p>
 680  *
 681  * <ul>
 682  *    <li><p> Predefined character classes (Unicode character)
 683  *    <p><tt>\X&nbsp;&nbsp;&nbsp;&nbsp;</tt>Match Unicode
 684  *    <a href="http://www.unicode.org/reports/tr18/#Default_Grapheme_Clusters">
 685  *    <i>extended grapheme cluster</i></a>
 686  *    </p></li>
 687  *
 688  *    <li><p> The backreference constructs, <tt>\g{</tt><i>n</i><tt>}</tt> for
 689  *    the <i>n</i><sup>th</sup><a href="#cg">capturing group</a> and
 690  *    <tt>\g{</tt><i>name</i><tt>}</tt> for
 691  *    <a href="#groupname">named-capturing group</a>.
 692  *    </p></li>
 693  *
 694  *    <li><p> The named character construct, <tt>\N{</tt><i>name</i><tt>}</tt>
 695  *    for a Unicode character by its name.
 696  *    </p></li>
 697  *
 698  *    <li><p> The conditional constructs
 699  *    <tt>(?(</tt><i>condition</i><tt>)</tt><i>X</i><tt>)</tt> and
 700  *    <tt>(?(</tt><i>condition</i><tt>)</tt><i>X</i><tt>|</tt><i>Y</i><tt>)</tt>,
 701  *    </p></li>
 702  *
 703  *    <li><p> The embedded code constructs <tt>(?{</tt><i>code</i><tt>})</tt>
 704  *    and <tt>(??{</tt><i>code</i><tt>})</tt>,</p></li>
 705  *
 706  *    <li><p> The embedded comment syntax <tt>(?#comment)</tt>, and </p></li>
 707  *
 708  *    <li><p> The preprocessing operations <tt>\l</tt> <tt>\u</tt>,
 709  *    <tt>\L</tt>, and <tt>\U</tt>.  </p></li>
 710  *
 711  * </ul>
 712  *
 713  * <p> Constructs supported by this class but not by Perl: </p>
 714  *
 715  * <ul>
 716  *
 717  *    <li><p> Character-class union and intersection as described
 718  *    <a href="#cc">above</a>.</p></li>
 719  *
 720  * </ul>
 721  *
 722  * <p> Notable differences from Perl: </p>
 723  *
 724  * <ul>
 725  *
 726  *    <li><p> In Perl, <tt>\1</tt> through <tt>\9</tt> are always interpreted
 727  *    as back references; a backslash-escaped number greater than <tt>9</tt> is
 728  *    treated as a back reference if at least that many subexpressions exist,
 729  *    otherwise it is interpreted, if possible, as an octal escape.  In this
 730  *    class octal escapes must always begin with a zero. In this class,
 731  *    <tt>\1</tt> through <tt>\9</tt> are always interpreted as back
 732  *    references, and a larger number is accepted as a back reference if at
 733  *    least that many subexpressions exist at that point in the regular
 734  *    expression, otherwise the parser will drop digits until the number is
 735  *    smaller or equal to the existing number of groups or it is one digit.
 736  *    </p></li>
 737  *
 738  *    <li><p> Perl uses the <tt>g</tt> flag to request a match that resumes
 739  *    where the last match left off.  This functionality is provided implicitly
 740  *    by the {@link Matcher} class: Repeated invocations of the {@link
 741  *    Matcher#find find} method will resume where the last match left off,
 742  *    unless the matcher is reset.  </p></li>
 743  *
 744  *    <li><p> In Perl, embedded flags at the top level of an expression affect
 745  *    the whole expression.  In this class, embedded flags always take effect
 746  *    at the point at which they appear, whether they are at the top level or
 747  *    within a group; in the latter case, flags are restored at the end of the
 748  *    group just as in Perl.  </p></li>
 749  *
 750  * </ul>
 751  *
 752  *
 753  * <p> For a more precise description of the behavior of regular expression
 754  * constructs, please see <a href="http://www.oreilly.com/catalog/regex3/">
 755  * <i>Mastering Regular Expressions, 3nd Edition</i>, Jeffrey E. F. Friedl,
 756  * O'Reilly and Associates, 2006.</a>
 757  * </p>
 758  *
 759  * @see java.lang.String#split(String, int)
 760  * @see java.lang.String#split(String)
 761  *
 762  * @author      Mike McCloskey
 763  * @author      Mark Reinhold
 764  * @author      JSR-51 Expert Group
 765  * @since       1.4
 766  * @spec        JSR-51
 767  */
 768 
 769 public final class Pattern
 770     implements java.io.Serializable
 771 {
 772 
 773     /**
 774      * Regular expression modifier values.  Instead of being passed as
 775      * arguments, they can also be passed as inline modifiers.
 776      * For example, the following statements have the same effect.
 777      * <pre>
 778      * RegExp r1 = RegExp.compile("abc", Pattern.I|Pattern.M);
 779      * RegExp r2 = RegExp.compile("(?im)abc", 0);
 780      * </pre>
 781      *
 782      * The flags are duplicated so that the familiar Perl match flag
 783      * names are available.
 784      */
 785 
 786     /**
 787      * Enables Unix lines mode.
 788      *
 789      * <p> In this mode, only the <tt>'\n'</tt> line terminator is recognized
 790      * in the behavior of <tt>.</tt>, <tt>^</tt>, and <tt>$</tt>.
 791      *
 792      * <p> Unix lines mode can also be enabled via the embedded flag
 793      * expression&nbsp;<tt>(?d)</tt>.
 794      */
 795     public static final int UNIX_LINES = 0x01;
 796 
 797     /**
 798      * Enables case-insensitive matching.
 799      *
 800      * <p> By default, case-insensitive matching assumes that only characters
 801      * in the US-ASCII charset are being matched.  Unicode-aware
 802      * case-insensitive matching can be enabled by specifying the {@link
 803      * #UNICODE_CASE} flag in conjunction with this flag.
 804      *
 805      * <p> Case-insensitive matching can also be enabled via the embedded flag
 806      * expression&nbsp;<tt>(?i)</tt>.
 807      *
 808      * <p> Specifying this flag may impose a slight performance penalty.  </p>
 809      */
 810     public static final int CASE_INSENSITIVE = 0x02;
 811 
 812     /**
 813      * Permits whitespace and comments in pattern.
 814      *
 815      * <p> In this mode, whitespace is ignored, and embedded comments starting
 816      * with <tt>#</tt> are ignored until the end of a line.
 817      *
 818      * <p> Comments mode can also be enabled via the embedded flag
 819      * expression&nbsp;<tt>(?x)</tt>.
 820      */
 821     public static final int COMMENTS = 0x04;
 822 
 823     /**
 824      * Enables multiline mode.
 825      *
 826      * <p> In multiline mode the expressions <tt>^</tt> and <tt>$</tt> match
 827      * just after or just before, respectively, a line terminator or the end of
 828      * the input sequence.  By default these expressions only match at the
 829      * beginning and the end of the entire input sequence.
 830      *
 831      * <p> Multiline mode can also be enabled via the embedded flag
 832      * expression&nbsp;<tt>(?m)</tt>.  </p>
 833      */
 834     public static final int MULTILINE = 0x08;
 835 
 836     /**
 837      * Enables literal parsing of the pattern.
 838      *
 839      * <p> When this flag is specified then the input string that specifies
 840      * the pattern is treated as a sequence of literal characters.
 841      * Metacharacters or escape sequences in the input sequence will be
 842      * given no special meaning.
 843      *
 844      * <p>The flags CASE_INSENSITIVE and UNICODE_CASE retain their impact on
 845      * matching when used in conjunction with this flag. The other flags
 846      * become superfluous.
 847      *
 848      * <p> There is no embedded flag character for enabling literal parsing.
 849      * @since 1.5
 850      */
 851     public static final int LITERAL = 0x10;
 852 
 853     /**
 854      * Enables dotall mode.
 855      *
 856      * <p> In dotall mode, the expression <tt>.</tt> matches any character,
 857      * including a line terminator.  By default this expression does not match
 858      * line terminators.
 859      *
 860      * <p> Dotall mode can also be enabled via the embedded flag
 861      * expression&nbsp;<tt>(?s)</tt>.  (The <tt>s</tt> is a mnemonic for
 862      * "single-line" mode, which is what this is called in Perl.)  </p>
 863      */
 864     public static final int DOTALL = 0x20;
 865 
 866     /**
 867      * Enables Unicode-aware case folding.
 868      *
 869      * <p> When this flag is specified then case-insensitive matching, when
 870      * enabled by the {@link #CASE_INSENSITIVE} flag, is done in a manner
 871      * consistent with the Unicode Standard.  By default, case-insensitive
 872      * matching assumes that only characters in the US-ASCII charset are being
 873      * matched.
 874      *
 875      * <p> Unicode-aware case folding can also be enabled via the embedded flag
 876      * expression&nbsp;<tt>(?u)</tt>.
 877      *
 878      * <p> Specifying this flag may impose a performance penalty.  </p>
 879      */
 880     public static final int UNICODE_CASE = 0x40;
 881 
 882     /**
 883      * Enables canonical equivalence.
 884      *
 885      * <p> When this flag is specified then two characters will be considered
 886      * to match if, and only if, their full canonical decompositions match.
 887      * The expression <tt>"a\u030A"</tt>, for example, will match the
 888      * string <tt>"\u00E5"</tt> when this flag is specified.  By default,
 889      * matching does not take canonical equivalence into account.
 890      *
 891      * <p> There is no embedded flag character for enabling canonical
 892      * equivalence.
 893      *
 894      * <p> Specifying this flag may impose a performance penalty.  </p>
 895      */
 896     public static final int CANON_EQ = 0x80;
 897 
 898     /**
 899      * Enables the Unicode version of <i>Predefined character classes</i> and
 900      * <i>POSIX character classes</i>.
 901      *
 902      * <p> When this flag is specified then the (US-ASCII only)
 903      * <i>Predefined character classes</i> and <i>POSIX character classes</i>
 904      * are in conformance with
 905      * <a href="http://www.unicode.org/reports/tr18/"><i>Unicode Technical
 906      * Standard #18: Unicode Regular Expression</i></a>
 907      * <i>Annex C: Compatibility Properties</i>.
 908      * <p>
 909      * The UNICODE_CHARACTER_CLASS mode can also be enabled via the embedded
 910      * flag expression&nbsp;<tt>(?U)</tt>.
 911      * <p>
 912      * The flag implies UNICODE_CASE, that is, it enables Unicode-aware case
 913      * folding.
 914      * <p>
 915      * Specifying this flag may impose a performance penalty.  </p>
 916      * @since 1.7
 917      */
 918     public static final int UNICODE_CHARACTER_CLASS = 0x100;
 919 
 920     /**
 921      * Contains all possible flags for compile(regex, flags).
 922      */
 923     private static final int ALL_FLAGS = CASE_INSENSITIVE | MULTILINE |
 924             DOTALL | UNICODE_CASE | CANON_EQ | UNIX_LINES | LITERAL |
 925             UNICODE_CHARACTER_CLASS | COMMENTS;
 926 
 927     /* Pattern has only two serialized components: The pattern string
 928      * and the flags, which are all that is needed to recompile the pattern
 929      * when it is deserialized.
 930      */
 931 
 932     /** use serialVersionUID from Merlin b59 for interoperability */
 933     private static final long serialVersionUID = 5073258162644648461L;
 934 
 935     /**
 936      * The original regular-expression pattern string.
 937      *
 938      * @serial
 939      */
 940     private String pattern;
 941 
 942     /**
 943      * The original pattern flags.
 944      *
 945      * @serial
 946      */
 947     private int flags;
 948 
 949     /**
 950      * Boolean indicating this Pattern is compiled; this is necessary in order
 951      * to lazily compile deserialized Patterns.
 952      */
 953     private transient volatile boolean compiled = false;
 954 
 955     /**
 956      * The normalized pattern string.
 957      */
 958     private transient String normalizedPattern;
 959 
 960     /**
 961      * The starting point of state machine for the find operation.  This allows
 962      * a match to start anywhere in the input.
 963      */
 964     transient Node root;
 965 
 966     /**
 967      * The root of object tree for a match operation.  The pattern is matched
 968      * at the beginning.  This may include a find that uses BnM or a First
 969      * node.
 970      */
 971     transient Node matchRoot;
 972 
 973     /**
 974      * Temporary storage used by parsing pattern slice.
 975      */
 976     transient int[] buffer;
 977 
 978     /**
 979      * Map the "name" of the "named capturing group" to its group id
 980      * node.
 981      */
 982     transient volatile Map<String, Integer> namedGroups;
 983 
 984     /**
 985      * Temporary storage used while parsing group references.
 986      */
 987     transient GroupHead[] groupNodes;
 988 
 989     /**
 990      * Temporary null terminated code point array used by pattern compiling.
 991      */
 992     private transient int[] temp;
 993 
 994     /**
 995      * The number of capturing groups in this Pattern. Used by matchers to
 996      * allocate storage needed to perform a match.
 997      */
 998     transient int capturingGroupCount;
 999 
1000     /**
1001      * The local variable count used by parsing tree. Used by matchers to
1002      * allocate storage needed to perform a match.
1003      */
1004     transient int localCount;
1005 
1006     /**
1007      * Index into the pattern string that keeps track of how much has been
1008      * parsed.
1009      */
1010     private transient int cursor;
1011 
1012     /**
1013      * Holds the length of the pattern string.
1014      */
1015     private transient int patternLength;
1016 
1017     /**
1018      * If the Start node might possibly match supplementary characters.
1019      * It is set to true during compiling if
1020      * (1) There is supplementary char in pattern, or
1021      * (2) There is complement node of Category or Block
1022      */
1023     private transient boolean hasSupplementary;
1024 
1025     /**
1026      * Compiles the given regular expression into a pattern.
1027      *
1028      * @param  regex
1029      *         The expression to be compiled
1030      * @return the given regular expression compiled into a pattern
1031      * @throws  PatternSyntaxException
1032      *          If the expression's syntax is invalid
1033      */
1034     public static Pattern compile(String regex) {
1035         return new Pattern(regex, 0);
1036     }
1037 
1038     /**
1039      * Compiles the given regular expression into a pattern with the given
1040      * flags.
1041      *
1042      * @param  regex
1043      *         The expression to be compiled
1044      *
1045      * @param  flags
1046      *         Match flags, a bit mask that may include
1047      *         {@link #CASE_INSENSITIVE}, {@link #MULTILINE}, {@link #DOTALL},
1048      *         {@link #UNICODE_CASE}, {@link #CANON_EQ}, {@link #UNIX_LINES},
1049      *         {@link #LITERAL}, {@link #UNICODE_CHARACTER_CLASS}
1050      *         and {@link #COMMENTS}
1051      *
1052      * @return the given regular expression compiled into a pattern with the given flags
1053      * @throws  IllegalArgumentException
1054      *          If bit values other than those corresponding to the defined
1055      *          match flags are set in <tt>flags</tt>
1056      *
1057      * @throws  PatternSyntaxException
1058      *          If the expression's syntax is invalid
1059      */
1060     public static Pattern compile(String regex, int flags) {
1061         return new Pattern(regex, flags);
1062     }
1063 
1064     /**
1065      * Returns the regular expression from which this pattern was compiled.
1066      *
1067      * @return  The source of this pattern
1068      */
1069     public String pattern() {
1070         return pattern;
1071     }
1072 
1073     /**
1074      * <p>Returns the string representation of this pattern. This
1075      * is the regular expression from which this pattern was
1076      * compiled.</p>
1077      *
1078      * @return  The string representation of this pattern
1079      * @since 1.5
1080      */
1081     public String toString() {
1082         return pattern;
1083     }
1084 
1085     /**
1086      * Creates a matcher that will match the given input against this pattern.
1087      *
1088      * @param  input
1089      *         The character sequence to be matched
1090      *
1091      * @return  A new matcher for this pattern
1092      */
1093     public Matcher matcher(CharSequence input) {
1094         if (!compiled) {
1095             synchronized(this) {
1096                 if (!compiled)
1097                     compile();
1098             }
1099         }
1100         Matcher m = new Matcher(this, input);
1101         return m;
1102     }
1103 
1104     /**
1105      * Returns this pattern's match flags.
1106      *
1107      * @return  The match flags specified when this pattern was compiled
1108      */
1109     public int flags() {
1110         return flags;
1111     }
1112 
1113     /**
1114      * Compiles the given regular expression and attempts to match the given
1115      * input against it.
1116      *
1117      * <p> An invocation of this convenience method of the form
1118      *
1119      * <blockquote><pre>
1120      * Pattern.matches(regex, input);</pre></blockquote>
1121      *
1122      * behaves in exactly the same way as the expression
1123      *
1124      * <blockquote><pre>
1125      * Pattern.compile(regex).matcher(input).matches()</pre></blockquote>
1126      *
1127      * <p> If a pattern is to be used multiple times, compiling it once and reusing
1128      * it will be more efficient than invoking this method each time.  </p>
1129      *
1130      * @param  regex
1131      *         The expression to be compiled
1132      *
1133      * @param  input
1134      *         The character sequence to be matched
1135      * @return whether or not the regular expression matches on the input
1136      * @throws  PatternSyntaxException
1137      *          If the expression's syntax is invalid
1138      */
1139     public static boolean matches(String regex, CharSequence input) {
1140         Pattern p = Pattern.compile(regex);
1141         Matcher m = p.matcher(input);
1142         return m.matches();
1143     }
1144 
1145     /**
1146      * Splits the given input sequence around matches of this pattern.
1147      *
1148      * <p> The array returned by this method contains each substring of the
1149      * input sequence that is terminated by another subsequence that matches
1150      * this pattern or is terminated by the end of the input sequence.  The
1151      * substrings in the array are in the order in which they occur in the
1152      * input. If this pattern does not match any subsequence of the input then
1153      * the resulting array has just one element, namely the input sequence in
1154      * string form.
1155      *
1156      * <p> When there is a positive-width match at the beginning of the input
1157      * sequence then an empty leading substring is included at the beginning
1158      * of the resulting array. A zero-width match at the beginning however
1159      * never produces such empty leading substring.
1160      *
1161      * <p> The <tt>limit</tt> parameter controls the number of times the
1162      * pattern is applied and therefore affects the length of the resulting
1163      * array.  If the limit <i>n</i> is greater than zero then the pattern
1164      * will be applied at most <i>n</i>&nbsp;-&nbsp;1 times, the array's
1165      * length will be no greater than <i>n</i>, and the array's last entry
1166      * will contain all input beyond the last matched delimiter.  If <i>n</i>
1167      * is non-positive then the pattern will be applied as many times as
1168      * possible and the array can have any length.  If <i>n</i> is zero then
1169      * the pattern will be applied as many times as possible, the array can
1170      * have any length, and trailing empty strings will be discarded.
1171      *
1172      * <p> The input <tt>"boo:and:foo"</tt>, for example, yields the following
1173      * results with these parameters:
1174      *
1175      * <blockquote><table cellpadding=1 cellspacing=0
1176      *              summary="Split examples showing regex, limit, and result">
1177      * <tr><th align="left"><i>Regex&nbsp;&nbsp;&nbsp;&nbsp;</i></th>
1178      *     <th align="left"><i>Limit&nbsp;&nbsp;&nbsp;&nbsp;</i></th>
1179      *     <th align="left"><i>Result&nbsp;&nbsp;&nbsp;&nbsp;</i></th></tr>
1180      * <tr><td align=center>:</td>
1181      *     <td align=center>2</td>
1182      *     <td><tt>{ "boo", "and:foo" }</tt></td></tr>
1183      * <tr><td align=center>:</td>
1184      *     <td align=center>5</td>
1185      *     <td><tt>{ "boo", "and", "foo" }</tt></td></tr>
1186      * <tr><td align=center>:</td>
1187      *     <td align=center>-2</td>
1188      *     <td><tt>{ "boo", "and", "foo" }</tt></td></tr>
1189      * <tr><td align=center>o</td>
1190      *     <td align=center>5</td>
1191      *     <td><tt>{ "b", "", ":and:f", "", "" }</tt></td></tr>
1192      * <tr><td align=center>o</td>
1193      *     <td align=center>-2</td>
1194      *     <td><tt>{ "b", "", ":and:f", "", "" }</tt></td></tr>
1195      * <tr><td align=center>o</td>
1196      *     <td align=center>0</td>
1197      *     <td><tt>{ "b", "", ":and:f" }</tt></td></tr>
1198      * </table></blockquote>
1199      *
1200      * @param  input
1201      *         The character sequence to be split
1202      *
1203      * @param  limit
1204      *         The result threshold, as described above
1205      *
1206      * @return  The array of strings computed by splitting the input
1207      *          around matches of this pattern
1208      */
1209     public String[] split(CharSequence input, int limit) {
1210         int index = 0;
1211         boolean matchLimited = limit > 0;
1212         ArrayList<String> matchList = new ArrayList<>();
1213         Matcher m = matcher(input);
1214 
1215         // Add segments before each match found
1216         while(m.find()) {
1217             if (!matchLimited || matchList.size() < limit - 1) {
1218                 if (index == 0 && index == m.start() && m.start() == m.end()) {
1219                     // no empty leading substring included for zero-width match
1220                     // at the beginning of the input char sequence.
1221                     continue;
1222                 }
1223                 String match = input.subSequence(index, m.start()).toString();
1224                 matchList.add(match);
1225                 index = m.end();
1226             } else if (matchList.size() == limit - 1) { // last one
1227                 String match = input.subSequence(index,
1228                                                  input.length()).toString();
1229                 matchList.add(match);
1230                 index = m.end();
1231             }
1232         }
1233 
1234         // If no match was found, return this
1235         if (index == 0)
1236             return new String[] {input.toString()};
1237 
1238         // Add remaining segment
1239         if (!matchLimited || matchList.size() < limit)
1240             matchList.add(input.subSequence(index, input.length()).toString());
1241 
1242         // Construct result
1243         int resultSize = matchList.size();
1244         if (limit == 0)
1245             while (resultSize > 0 && matchList.get(resultSize-1).equals(""))
1246                 resultSize--;
1247         String[] result = new String[resultSize];
1248         return matchList.subList(0, resultSize).toArray(result);
1249     }
1250 
1251     /**
1252      * Splits the given input sequence around matches of this pattern.
1253      *
1254      * <p> This method works as if by invoking the two-argument {@link
1255      * #split(java.lang.CharSequence, int) split} method with the given input
1256      * sequence and a limit argument of zero.  Trailing empty strings are
1257      * therefore not included in the resulting array. </p>
1258      *
1259      * <p> The input <tt>"boo:and:foo"</tt>, for example, yields the following
1260      * results with these expressions:
1261      *
1262      * <blockquote><table cellpadding=1 cellspacing=0
1263      *              summary="Split examples showing regex and result">
1264      * <tr><th align="left"><i>Regex&nbsp;&nbsp;&nbsp;&nbsp;</i></th>
1265      *     <th align="left"><i>Result</i></th></tr>
1266      * <tr><td align=center>:</td>
1267      *     <td><tt>{ "boo", "and", "foo" }</tt></td></tr>
1268      * <tr><td align=center>o</td>
1269      *     <td><tt>{ "b", "", ":and:f" }</tt></td></tr>
1270      * </table></blockquote>
1271      *
1272      *
1273      * @param  input
1274      *         The character sequence to be split
1275      *
1276      * @return  The array of strings computed by splitting the input
1277      *          around matches of this pattern
1278      */
1279     public String[] split(CharSequence input) {
1280         return split(input, 0);
1281     }
1282 
1283     /**
1284      * Returns a literal pattern <code>String</code> for the specified
1285      * <code>String</code>.
1286      *
1287      * <p>This method produces a <code>String</code> that can be used to
1288      * create a <code>Pattern</code> that would match the string
1289      * <code>s</code> as if it were a literal pattern.</p> Metacharacters
1290      * or escape sequences in the input sequence will be given no special
1291      * meaning.
1292      *
1293      * @param  s The string to be literalized
1294      * @return  A literal string replacement
1295      * @since 1.5
1296      */
1297     public static String quote(String s) {
1298         int slashEIndex = s.indexOf("\\E");
1299         if (slashEIndex == -1)
1300             return "\\Q" + s + "\\E";
1301 
1302         int lenHint = s.length();
1303         lenHint = (lenHint < Integer.MAX_VALUE - 8 - lenHint) ?
1304                 (lenHint << 1) : (Integer.MAX_VALUE - 8);
1305 
1306         StringBuilder sb = new StringBuilder(lenHint);
1307         sb.append("\\Q");

1308         int current = 0;
1309         do {
1310             sb.append(s, current, slashEIndex)
1311                     .append("\\E\\\\E\\Q");
1312             current = slashEIndex + 2;
1313         } while ((slashEIndex = s.indexOf("\\E", current)) != -1);
1314 
1315         return sb.append(s, current, s.length())
1316                 .append("\\E")
1317                 .toString();
1318     }
1319 
1320     /**
1321      * Recompile the Pattern instance from a stream.  The original pattern
1322      * string is read in and the object tree is recompiled from it.
1323      */
1324     private void readObject(java.io.ObjectInputStream s)
1325         throws java.io.IOException, ClassNotFoundException {
1326 
1327         // Read in all fields
1328         s.defaultReadObject();
1329 
1330         // Initialize counts
1331         capturingGroupCount = 1;
1332         localCount = 0;
1333 
1334         // if length > 0, the Pattern is lazily compiled
1335         compiled = false;
1336         if (pattern.length() == 0) {
1337             root = new Start(lastAccept);
1338             matchRoot = lastAccept;
1339             compiled = true;
1340         }
1341     }
1342 
1343     /**
1344      * This private constructor is used to create all Patterns. The pattern
1345      * string and match flags are all that is needed to completely describe
1346      * a Pattern. An empty pattern string results in an object tree with
1347      * only a Start node and a LastNode node.
1348      */
1349     private Pattern(String p, int f) {
1350         if ((f & ~ALL_FLAGS) != 0) {
1351             throw new IllegalArgumentException("Unknown flag 0x"
1352                                                + Integer.toHexString(f));
1353         }
1354         pattern = p;
1355         flags = f;
1356 
1357         // to use UNICODE_CASE if UNICODE_CHARACTER_CLASS present
1358         if ((flags & UNICODE_CHARACTER_CLASS) != 0)
1359             flags |= UNICODE_CASE;
1360 
1361         // Reset group index count
1362         capturingGroupCount = 1;
1363         localCount = 0;
1364 
1365         if (pattern.length() > 0) {
1366             compile();
1367         } else {
1368             root = new Start(lastAccept);
1369             matchRoot = lastAccept;
1370         }
1371     }
1372 
1373     /**
1374      * The pattern is converted to normalized form and then a pure group
1375      * is constructed to match canonical equivalences of the characters.
1376      */
1377     private void normalize() {
1378         boolean inCharClass = false;
1379         int lastCodePoint = -1;
1380 
1381         // Convert pattern into normalized form
1382         normalizedPattern = Normalizer.normalize(pattern, Normalizer.Form.NFD);
1383         patternLength = normalizedPattern.length();
1384 
1385         // Modify pattern to match canonical equivalences
1386         StringBuilder newPattern = new StringBuilder(patternLength);
1387         for(int i=0; i<patternLength; ) {
1388             int c = normalizedPattern.codePointAt(i);
1389             StringBuilder sequenceBuffer;
1390             if ((Character.getType(c) == Character.NON_SPACING_MARK)
1391                 && (lastCodePoint != -1)) {
1392                 sequenceBuffer = new StringBuilder();
1393                 sequenceBuffer.appendCodePoint(lastCodePoint);
1394                 sequenceBuffer.appendCodePoint(c);
1395                 while(Character.getType(c) == Character.NON_SPACING_MARK) {
1396                     i += Character.charCount(c);
1397                     if (i >= patternLength)
1398                         break;
1399                     c = normalizedPattern.codePointAt(i);
1400                     sequenceBuffer.appendCodePoint(c);
1401                 }
1402                 String ea = produceEquivalentAlternation(
1403                                                sequenceBuffer.toString());
1404                 newPattern.setLength(newPattern.length()-Character.charCount(lastCodePoint));
1405                 newPattern.append("(?:").append(ea).append(")");
1406             } else if (c == '[' && lastCodePoint != '\\') {
1407                 i = normalizeCharClass(newPattern, i);
1408             } else {
1409                 newPattern.appendCodePoint(c);
1410             }
1411             lastCodePoint = c;
1412             i += Character.charCount(c);
1413         }
1414         normalizedPattern = newPattern.toString();
1415     }
1416 
1417     /**
1418      * Complete the character class being parsed and add a set
1419      * of alternations to it that will match the canonical equivalences
1420      * of the characters within the class.
1421      */
1422     private int normalizeCharClass(StringBuilder newPattern, int i) {
1423         StringBuilder charClass = new StringBuilder();
1424         StringBuilder eq = null;
1425         int lastCodePoint = -1;
1426         String result;
1427 
1428         i++;
1429         charClass.append("[");
1430         while(true) {
1431             int c = normalizedPattern.codePointAt(i);
1432             StringBuilder sequenceBuffer;
1433 
1434             if (c == ']' && lastCodePoint != '\\') {
1435                 charClass.append((char)c);
1436                 break;
1437             } else if (Character.getType(c) == Character.NON_SPACING_MARK) {
1438                 sequenceBuffer = new StringBuilder();
1439                 sequenceBuffer.appendCodePoint(lastCodePoint);
1440                 while(Character.getType(c) == Character.NON_SPACING_MARK) {
1441                     sequenceBuffer.appendCodePoint(c);
1442                     i += Character.charCount(c);
1443                     if (i >= normalizedPattern.length())
1444                         break;
1445                     c = normalizedPattern.codePointAt(i);
1446                 }
1447                 String ea = produceEquivalentAlternation(
1448                                                   sequenceBuffer.toString());
1449 
1450                 charClass.setLength(charClass.length()-Character.charCount(lastCodePoint));
1451                 if (eq == null)
1452                     eq = new StringBuilder();
1453                 eq.append('|');
1454                 eq.append(ea);
1455             } else {
1456                 charClass.appendCodePoint(c);
1457                 i++;
1458             }
1459             if (i == normalizedPattern.length())
1460                 throw error("Unclosed character class");
1461             lastCodePoint = c;
1462         }
1463 
1464         if (eq != null) {
1465             result = "(?:"+charClass.toString()+eq.toString()+")";
1466         } else {
1467             result = charClass.toString();
1468         }
1469 
1470         newPattern.append(result);
1471         return i;
1472     }
1473 
1474     /**
1475      * Given a specific sequence composed of a regular character and
1476      * combining marks that follow it, produce the alternation that will
1477      * match all canonical equivalences of that sequence.
1478      */
1479     private String produceEquivalentAlternation(String source) {
1480         int len = countChars(source, 0, 1);
1481         if (source.length() == len)
1482             // source has one character.
1483             return source;
1484 
1485         String base = source.substring(0,len);
1486         String combiningMarks = source.substring(len);
1487 
1488         String[] perms = producePermutations(combiningMarks);
1489         StringBuilder result = new StringBuilder(source);
1490 
1491         // Add combined permutations
1492         for(int x=0; x<perms.length; x++) {
1493             String next = base + perms[x];
1494             if (x>0)
1495                 result.append("|"+next);
1496             next = composeOneStep(next);
1497             if (next != null)
1498                 result.append("|"+produceEquivalentAlternation(next));
1499         }
1500         return result.toString();
1501     }
1502 
1503     /**
1504      * Returns an array of strings that have all the possible
1505      * permutations of the characters in the input string.
1506      * This is used to get a list of all possible orderings
1507      * of a set of combining marks. Note that some of the permutations
1508      * are invalid because of combining class collisions, and these
1509      * possibilities must be removed because they are not canonically
1510      * equivalent.
1511      */
1512     private String[] producePermutations(String input) {
1513         if (input.length() == countChars(input, 0, 1))
1514             return new String[] {input};
1515 
1516         if (input.length() == countChars(input, 0, 2)) {
1517             int c0 = Character.codePointAt(input, 0);
1518             int c1 = Character.codePointAt(input, Character.charCount(c0));
1519             if (getClass(c1) == getClass(c0)) {
1520                 return new String[] {input};
1521             }
1522             String[] result = new String[2];
1523             result[0] = input;
1524             StringBuilder sb = new StringBuilder(2);
1525             sb.appendCodePoint(c1);
1526             sb.appendCodePoint(c0);
1527             result[1] = sb.toString();
1528             return result;
1529         }
1530 
1531         int length = 1;
1532         int nCodePoints = countCodePoints(input);
1533         for(int x=1; x<nCodePoints; x++)
1534             length = length * (x+1);
1535 
1536         String[] temp = new String[length];
1537 
1538         int combClass[] = new int[nCodePoints];
1539         for(int x=0, i=0; x<nCodePoints; x++) {
1540             int c = Character.codePointAt(input, i);
1541             combClass[x] = getClass(c);
1542             i +=  Character.charCount(c);
1543         }
1544 
1545         // For each char, take it out and add the permutations
1546         // of the remaining chars
1547         int index = 0;
1548         int len;
1549         // offset maintains the index in code units.
1550 loop:   for(int x=0, offset=0; x<nCodePoints; x++, offset+=len) {
1551             len = countChars(input, offset, 1);
1552             boolean skip = false;
1553             for(int y=x-1; y>=0; y--) {
1554                 if (combClass[y] == combClass[x]) {
1555                     continue loop;
1556                 }
1557             }
1558             StringBuilder sb = new StringBuilder(input);
1559             String otherChars = sb.delete(offset, offset+len).toString();
1560             String[] subResult = producePermutations(otherChars);
1561 
1562             String prefix = input.substring(offset, offset+len);
1563             for (String sre : subResult)
1564                 temp[index++] = prefix + sre;
1565         }
1566         String[] result = new String[index];
1567         for (int x=0; x<index; x++)
1568             result[x] = temp[x];
1569         return result;
1570     }
1571 
1572     private int getClass(int c) {
1573         return sun.text.Normalizer.getCombiningClass(c);
1574     }
1575 
1576     /**
1577      * Attempts to compose input by combining the first character
1578      * with the first combining mark following it. Returns a String
1579      * that is the composition of the leading character with its first
1580      * combining mark followed by the remaining combining marks. Returns
1581      * null if the first two characters cannot be further composed.
1582      */
1583     private String composeOneStep(String input) {
1584         int len = countChars(input, 0, 2);
1585         String firstTwoCharacters = input.substring(0, len);
1586         String result = Normalizer.normalize(firstTwoCharacters, Normalizer.Form.NFC);
1587 
1588         if (result.equals(firstTwoCharacters))
1589             return null;
1590         else {
1591             String remainder = input.substring(len);
1592             return result + remainder;
1593         }
1594     }
1595 
1596     /**
1597      * Preprocess any \Q...\E sequences in `temp', meta-quoting them.
1598      * See the description of `quotemeta' in perlfunc(1).
1599      */
1600     private void RemoveQEQuoting() {
1601         final int pLen = patternLength;
1602         int i = 0;
1603         while (i < pLen-1) {
1604             if (temp[i] != '\\')
1605                 i += 1;
1606             else if (temp[i + 1] != 'Q')
1607                 i += 2;
1608             else
1609                 break;
1610         }
1611         if (i >= pLen - 1)    // No \Q sequence found
1612             return;
1613         int j = i;
1614         i += 2;
1615         int[] newtemp = new int[j + 3*(pLen-i) + 2];
1616         System.arraycopy(temp, 0, newtemp, 0, j);
1617 
1618         boolean inQuote = true;
1619         boolean beginQuote = true;
1620         while (i < pLen) {
1621             int c = temp[i++];
1622             if (!ASCII.isAscii(c) || ASCII.isAlpha(c)) {
1623                 newtemp[j++] = c;
1624             } else if (ASCII.isDigit(c)) {
1625                 if (beginQuote) {
1626                     /*
1627                      * A unicode escape \[0xu] could be before this quote,
1628                      * and we don't want this numeric char to processed as
1629                      * part of the escape.
1630                      */
1631                     newtemp[j++] = '\\';
1632                     newtemp[j++] = 'x';
1633                     newtemp[j++] = '3';
1634                 }
1635                 newtemp[j++] = c;
1636             } else if (c != '\\') {
1637                 if (inQuote) newtemp[j++] = '\\';
1638                 newtemp[j++] = c;
1639             } else if (inQuote) {
1640                 if (temp[i] == 'E') {
1641                     i++;
1642                     inQuote = false;
1643                 } else {
1644                     newtemp[j++] = '\\';
1645                     newtemp[j++] = '\\';
1646                 }
1647             } else {
1648                 if (temp[i] == 'Q') {
1649                     i++;
1650                     inQuote = true;
1651                     beginQuote = true;
1652                     continue;
1653                 } else {
1654                     newtemp[j++] = c;
1655                     if (i != pLen)
1656                         newtemp[j++] = temp[i++];
1657                 }
1658             }
1659 
1660             beginQuote = false;
1661         }
1662 
1663         patternLength = j;
1664         temp = Arrays.copyOf(newtemp, j + 2); // double zero termination
1665     }
1666 
1667     /**
1668      * Copies regular expression to an int array and invokes the parsing
1669      * of the expression which will create the object tree.
1670      */
1671     private void compile() {
1672         // Handle canonical equivalences
1673         if (has(CANON_EQ) && !has(LITERAL)) {
1674             normalize();
1675         } else {
1676             normalizedPattern = pattern;
1677         }
1678         patternLength = normalizedPattern.length();
1679 
1680         // Copy pattern to int array for convenience
1681         // Use double zero to terminate pattern
1682         temp = new int[patternLength + 2];
1683 
1684         hasSupplementary = false;
1685         int c, count = 0;
1686         // Convert all chars into code points
1687         for (int x = 0; x < patternLength; x += Character.charCount(c)) {
1688             c = normalizedPattern.codePointAt(x);
1689             if (isSupplementary(c)) {
1690                 hasSupplementary = true;
1691             }
1692             temp[count++] = c;
1693         }
1694 
1695         patternLength = count;   // patternLength now in code points
1696 
1697         if (! has(LITERAL))
1698             RemoveQEQuoting();
1699 
1700         // Allocate all temporary objects here.
1701         buffer = new int[32];
1702         groupNodes = new GroupHead[10];
1703         namedGroups = null;
1704 
1705         if (has(LITERAL)) {
1706             // Literal pattern handling
1707             matchRoot = newSlice(temp, patternLength, hasSupplementary);
1708             matchRoot.next = lastAccept;
1709         } else {
1710             // Start recursive descent parsing
1711             matchRoot = expr(lastAccept);
1712             // Check extra pattern characters
1713             if (patternLength != cursor) {
1714                 if (peek() == ')') {
1715                     throw error("Unmatched closing ')'");
1716                 } else {
1717                     throw error("Unexpected internal error");
1718                 }
1719             }
1720         }
1721 
1722         // Peephole optimization
1723         if (matchRoot instanceof Slice) {
1724             root = BnM.optimize(matchRoot);
1725             if (root == matchRoot) {
1726                 root = hasSupplementary ? new StartS(matchRoot) : new Start(matchRoot);
1727             }
1728         } else if (matchRoot instanceof Begin || matchRoot instanceof First) {
1729             root = matchRoot;
1730         } else {
1731             root = hasSupplementary ? new StartS(matchRoot) : new Start(matchRoot);
1732         }
1733 
1734         // Release temporary storage
1735         temp = null;
1736         buffer = null;
1737         groupNodes = null;
1738         patternLength = 0;
1739         compiled = true;
1740     }
1741 
1742     Map<String, Integer> namedGroups() {
1743         if (namedGroups == null)
1744             namedGroups = new HashMap<>(2);
1745         return namedGroups;
1746     }
1747 
1748     /**
1749      * Used to print out a subtree of the Pattern to help with debugging.
1750      */
1751     private static void printObjectTree(Node node) {
1752         while(node != null) {
1753             if (node instanceof Prolog) {
1754                 System.out.println(node);
1755                 printObjectTree(((Prolog)node).loop);
1756                 System.out.println("**** end contents prolog loop");
1757             } else if (node instanceof Loop) {
1758                 System.out.println(node);
1759                 printObjectTree(((Loop)node).body);
1760                 System.out.println("**** end contents Loop body");
1761             } else if (node instanceof Curly) {
1762                 System.out.println(node);
1763                 printObjectTree(((Curly)node).atom);
1764                 System.out.println("**** end contents Curly body");
1765             } else if (node instanceof GroupCurly) {
1766                 System.out.println(node);
1767                 printObjectTree(((GroupCurly)node).atom);
1768                 System.out.println("**** end contents GroupCurly body");
1769             } else if (node instanceof GroupTail) {
1770                 System.out.println(node);
1771                 System.out.println("Tail next is "+node.next);
1772                 return;
1773             } else {
1774                 System.out.println(node);
1775             }
1776             node = node.next;
1777             if (node != null)
1778                 System.out.println("->next:");
1779             if (node == Pattern.accept) {
1780                 System.out.println("Accept Node");
1781                 node = null;
1782             }
1783        }
1784     }
1785 
1786     /**
1787      * Used to accumulate information about a subtree of the object graph
1788      * so that optimizations can be applied to the subtree.
1789      */
1790     static final class TreeInfo {
1791         int minLength;
1792         int maxLength;
1793         boolean maxValid;
1794         boolean deterministic;
1795 
1796         TreeInfo() {
1797             reset();
1798         }
1799         void reset() {
1800             minLength = 0;
1801             maxLength = 0;
1802             maxValid = true;
1803             deterministic = true;
1804         }
1805     }
1806 
1807     /*
1808      * The following private methods are mainly used to improve the
1809      * readability of the code. In order to let the Java compiler easily
1810      * inline them, we should not put many assertions or error checks in them.
1811      */
1812 
1813     /**
1814      * Indicates whether a particular flag is set or not.
1815      */
1816     private boolean has(int f) {
1817         return (flags & f) != 0;
1818     }
1819 
1820     /**
1821      * Match next character, signal error if failed.
1822      */
1823     private void accept(int ch, String s) {
1824         int testChar = temp[cursor++];
1825         if (has(COMMENTS))
1826             testChar = parsePastWhitespace(testChar);
1827         if (ch != testChar) {
1828             throw error(s);
1829         }
1830     }
1831 
1832     /**
1833      * Mark the end of pattern with a specific character.
1834      */
1835     private void mark(int c) {
1836         temp[patternLength] = c;
1837     }
1838 
1839     /**
1840      * Peek the next character, and do not advance the cursor.
1841      */
1842     private int peek() {
1843         int ch = temp[cursor];
1844         if (has(COMMENTS))
1845             ch = peekPastWhitespace(ch);
1846         return ch;
1847     }
1848 
1849     /**
1850      * Read the next character, and advance the cursor by one.
1851      */
1852     private int read() {
1853         int ch = temp[cursor++];
1854         if (has(COMMENTS))
1855             ch = parsePastWhitespace(ch);
1856         return ch;
1857     }
1858 
1859     /**
1860      * Read the next character, and advance the cursor by one,
1861      * ignoring the COMMENTS setting
1862      */
1863     private int readEscaped() {
1864         int ch = temp[cursor++];
1865         return ch;
1866     }
1867 
1868     /**
1869      * Advance the cursor by one, and peek the next character.
1870      */
1871     private int next() {
1872         int ch = temp[++cursor];
1873         if (has(COMMENTS))
1874             ch = peekPastWhitespace(ch);
1875         return ch;
1876     }
1877 
1878     /**
1879      * Advance the cursor by one, and peek the next character,
1880      * ignoring the COMMENTS setting
1881      */
1882     private int nextEscaped() {
1883         int ch = temp[++cursor];
1884         return ch;
1885     }
1886 
1887     /**
1888      * If in xmode peek past whitespace and comments.
1889      */
1890     private int peekPastWhitespace(int ch) {
1891         while (ASCII.isSpace(ch) || ch == '#') {
1892             while (ASCII.isSpace(ch))
1893                 ch = temp[++cursor];
1894             if (ch == '#') {
1895                 ch = peekPastLine();
1896             }
1897         }
1898         return ch;
1899     }
1900 
1901     /**
1902      * If in xmode parse past whitespace and comments.
1903      */
1904     private int parsePastWhitespace(int ch) {
1905         while (ASCII.isSpace(ch) || ch == '#') {
1906             while (ASCII.isSpace(ch))
1907                 ch = temp[cursor++];
1908             if (ch == '#')
1909                 ch = parsePastLine();
1910         }
1911         return ch;
1912     }
1913 
1914     /**
1915      * xmode parse past comment to end of line.
1916      */
1917     private int parsePastLine() {
1918         int ch = temp[cursor++];
1919         while (ch != 0 && !isLineSeparator(ch))
1920             ch = temp[cursor++];
1921         return ch;
1922     }
1923 
1924     /**
1925      * xmode peek past comment to end of line.
1926      */
1927     private int peekPastLine() {
1928         int ch = temp[++cursor];
1929         while (ch != 0 && !isLineSeparator(ch))
1930             ch = temp[++cursor];
1931         return ch;
1932     }
1933 
1934     /**
1935      * Determines if character is a line separator in the current mode
1936      */
1937     private boolean isLineSeparator(int ch) {
1938         if (has(UNIX_LINES)) {
1939             return ch == '\n';
1940         } else {
1941             return (ch == '\n' ||
1942                     ch == '\r' ||
1943                     (ch|1) == '\u2029' ||
1944                     ch == '\u0085');
1945         }
1946     }
1947 
1948     /**
1949      * Read the character after the next one, and advance the cursor by two.
1950      */
1951     private int skip() {
1952         int i = cursor;
1953         int ch = temp[i+1];
1954         cursor = i + 2;
1955         return ch;
1956     }
1957 
1958     /**
1959      * Unread one next character, and retreat cursor by one.
1960      */
1961     private void unread() {
1962         cursor--;
1963     }
1964 
1965     /**
1966      * Internal method used for handling all syntax errors. The pattern is
1967      * displayed with a pointer to aid in locating the syntax error.
1968      */
1969     private PatternSyntaxException error(String s) {
1970         return new PatternSyntaxException(s, normalizedPattern,  cursor - 1);
1971     }
1972 
1973     /**
1974      * Determines if there is any supplementary character or unpaired
1975      * surrogate in the specified range.
1976      */
1977     private boolean findSupplementary(int start, int end) {
1978         for (int i = start; i < end; i++) {
1979             if (isSupplementary(temp[i]))
1980                 return true;
1981         }
1982         return false;
1983     }
1984 
1985     /**
1986      * Determines if the specified code point is a supplementary
1987      * character or unpaired surrogate.
1988      */
1989     private static final boolean isSupplementary(int ch) {
1990         return ch >= Character.MIN_SUPPLEMENTARY_CODE_POINT ||
1991                Character.isSurrogate((char)ch);
1992     }
1993 
1994     /**
1995      *  The following methods handle the main parsing. They are sorted
1996      *  according to their precedence order, the lowest one first.
1997      */
1998 
1999     /**
2000      * The expression is parsed with branch nodes added for alternations.
2001      * This may be called recursively to parse sub expressions that may
2002      * contain alternations.
2003      */
2004     private Node expr(Node end) {
2005         Node prev = null;
2006         Node firstTail = null;
2007         Branch branch = null;
2008         Node branchConn = null;
2009 
2010         for (;;) {
2011             Node node = sequence(end);
2012             Node nodeTail = root;      //double return
2013             if (prev == null) {
2014                 prev = node;
2015                 firstTail = nodeTail;
2016             } else {
2017                 // Branch
2018                 if (branchConn == null) {
2019                     branchConn = new BranchConn();
2020                     branchConn.next = end;
2021                 }
2022                 if (node == end) {
2023                     // if the node returned from sequence() is "end"
2024                     // we have an empty expr, set a null atom into
2025                     // the branch to indicate to go "next" directly.
2026                     node = null;
2027                 } else {
2028                     // the "tail.next" of each atom goes to branchConn
2029                     nodeTail.next = branchConn;
2030                 }
2031                 if (prev == branch) {
2032                     branch.add(node);
2033                 } else {
2034                     if (prev == end) {
2035                         prev = null;
2036                     } else {
2037                         // replace the "end" with "branchConn" at its tail.next
2038                         // when put the "prev" into the branch as the first atom.
2039                         firstTail.next = branchConn;
2040                     }
2041                     prev = branch = new Branch(prev, node, branchConn);
2042                 }
2043             }
2044             if (peek() != '|') {
2045                 return prev;
2046             }
2047             next();
2048         }
2049     }
2050 
2051     @SuppressWarnings("fallthrough")
2052     /**
2053      * Parsing of sequences between alternations.
2054      */
2055     private Node sequence(Node end) {
2056         Node head = null;
2057         Node tail = null;
2058         Node node = null;
2059     LOOP:
2060         for (;;) {
2061             int ch = peek();
2062             switch (ch) {
2063             case '(':
2064                 // Because group handles its own closure,
2065                 // we need to treat it differently
2066                 node = group0();
2067                 // Check for comment or flag group
2068                 if (node == null)
2069                     continue;
2070                 if (head == null)
2071                     head = node;
2072                 else
2073                     tail.next = node;
2074                 // Double return: Tail was returned in root
2075                 tail = root;
2076                 continue;
2077             case '[':
2078                 node = clazz(true);
2079                 break;
2080             case '\\':
2081                 ch = nextEscaped();
2082                 if (ch == 'p' || ch == 'P') {
2083                     boolean oneLetter = true;
2084                     boolean comp = (ch == 'P');
2085                     ch = next(); // Consume { if present
2086                     if (ch != '{') {
2087                         unread();
2088                     } else {
2089                         oneLetter = false;
2090                     }
2091                     node = family(oneLetter, comp);
2092                 } else {
2093                     unread();
2094                     node = atom();
2095                 }
2096                 break;
2097             case '^':
2098                 next();
2099                 if (has(MULTILINE)) {
2100                     if (has(UNIX_LINES))
2101                         node = new UnixCaret();
2102                     else
2103                         node = new Caret();
2104                 } else {
2105                     node = new Begin();
2106                 }
2107                 break;
2108             case '$':
2109                 next();
2110                 if (has(UNIX_LINES))
2111                     node = new UnixDollar(has(MULTILINE));
2112                 else
2113                     node = new Dollar(has(MULTILINE));
2114                 break;
2115             case '.':
2116                 next();
2117                 if (has(DOTALL)) {
2118                     node = new All();
2119                 } else {
2120                     if (has(UNIX_LINES))
2121                         node = new UnixDot();
2122                     else {
2123                         node = new Dot();
2124                     }
2125                 }
2126                 break;
2127             case '|':
2128             case ')':
2129                 break LOOP;
2130             case ']': // Now interpreting dangling ] and } as literals
2131             case '}':
2132                 node = atom();
2133                 break;
2134             case '?':
2135             case '*':
2136             case '+':
2137                 next();
2138                 throw error("Dangling meta character '" + ((char)ch) + "'");
2139             case 0:
2140                 if (cursor >= patternLength) {
2141                     break LOOP;
2142                 }
2143                 // Fall through
2144             default:
2145                 node = atom();
2146                 break;
2147             }
2148 
2149             node = closure(node);
2150 
2151             if (head == null) {
2152                 head = tail = node;
2153             } else {
2154                 tail.next = node;
2155                 tail = node;
2156             }
2157         }
2158         if (head == null) {
2159             return end;
2160         }
2161         tail.next = end;
2162         root = tail;      //double return
2163         return head;
2164     }
2165 
2166     @SuppressWarnings("fallthrough")
2167     /**
2168      * Parse and add a new Single or Slice.
2169      */
2170     private Node atom() {
2171         int first = 0;
2172         int prev = -1;
2173         boolean hasSupplementary = false;
2174         int ch = peek();
2175         for (;;) {
2176             switch (ch) {
2177             case '*':
2178             case '+':
2179             case '?':
2180             case '{':
2181                 if (first > 1) {
2182                     cursor = prev;    // Unwind one character
2183                     first--;
2184                 }
2185                 break;
2186             case '$':
2187             case '.':
2188             case '^':
2189             case '(':
2190             case '[':
2191             case '|':
2192             case ')':
2193                 break;
2194             case '\\':
2195                 ch = nextEscaped();
2196                 if (ch == 'p' || ch == 'P') { // Property
2197                     if (first > 0) { // Slice is waiting; handle it first
2198                         unread();
2199                         break;
2200                     } else { // No slice; just return the family node
2201                         boolean comp = (ch == 'P');
2202                         boolean oneLetter = true;
2203                         ch = next(); // Consume { if present
2204                         if (ch != '{')
2205                             unread();
2206                         else
2207                             oneLetter = false;
2208                         return family(oneLetter, comp);
2209                     }
2210                 }
2211                 unread();
2212                 prev = cursor;
2213                 ch = escape(false, first == 0, false);
2214                 if (ch >= 0) {
2215                     append(ch, first);
2216                     first++;
2217                     if (isSupplementary(ch)) {
2218                         hasSupplementary = true;
2219                     }
2220                     ch = peek();
2221                     continue;
2222                 } else if (first == 0) {
2223                     return root;
2224                 }
2225                 // Unwind meta escape sequence
2226                 cursor = prev;
2227                 break;
2228             case 0:
2229                 if (cursor >= patternLength) {
2230                     break;
2231                 }
2232                 // Fall through
2233             default:
2234                 prev = cursor;
2235                 append(ch, first);
2236                 first++;
2237                 if (isSupplementary(ch)) {
2238                     hasSupplementary = true;
2239                 }
2240                 ch = next();
2241                 continue;
2242             }
2243             break;
2244         }
2245         if (first == 1) {
2246             return newSingle(buffer[0]);
2247         } else {
2248             return newSlice(buffer, first, hasSupplementary);
2249         }
2250     }
2251 
2252     private void append(int ch, int len) {
2253         if (len >= buffer.length) {
2254             int[] tmp = new int[len+len];
2255             System.arraycopy(buffer, 0, tmp, 0, len);
2256             buffer = tmp;
2257         }
2258         buffer[len] = ch;
2259     }
2260 
2261     /**
2262      * Parses a backref greedily, taking as many numbers as it
2263      * can. The first digit is always treated as a backref, but
2264      * multi digit numbers are only treated as a backref if at
2265      * least that many backrefs exist at this point in the regex.
2266      */
2267     private Node ref(int refNum) {
2268         boolean done = false;
2269         while(!done) {
2270             int ch = peek();
2271             switch(ch) {
2272             case '0':
2273             case '1':
2274             case '2':
2275             case '3':
2276             case '4':
2277             case '5':
2278             case '6':
2279             case '7':
2280             case '8':
2281             case '9':
2282                 int newRefNum = (refNum * 10) + (ch - '0');
2283                 // Add another number if it doesn't make a group
2284                 // that doesn't exist
2285                 if (capturingGroupCount - 1 < newRefNum) {
2286                     done = true;
2287                     break;
2288                 }
2289                 refNum = newRefNum;
2290                 read();
2291                 break;
2292             default:
2293                 done = true;
2294                 break;
2295             }
2296         }
2297         if (has(CASE_INSENSITIVE))
2298             return new CIBackRef(refNum, has(UNICODE_CASE));
2299         else
2300             return new BackRef(refNum);
2301     }
2302 
2303     /**
2304      * Parses an escape sequence to determine the actual value that needs
2305      * to be matched.
2306      * If -1 is returned and create was true a new object was added to the tree
2307      * to handle the escape sequence.
2308      * If the returned value is greater than zero, it is the value that
2309      * matches the escape sequence.
2310      */
2311     private int escape(boolean inclass, boolean create, boolean isrange) {
2312         int ch = skip();
2313         switch (ch) {
2314         case '0':
2315             return o();
2316         case '1':
2317         case '2':
2318         case '3':
2319         case '4':
2320         case '5':
2321         case '6':
2322         case '7':
2323         case '8':
2324         case '9':
2325             if (inclass) break;
2326             if (create) {
2327                 root = ref((ch - '0'));
2328             }
2329             return -1;
2330         case 'A':
2331             if (inclass) break;
2332             if (create) root = new Begin();
2333             return -1;
2334         case 'B':
2335             if (inclass) break;
2336             if (create) root = new Bound(Bound.NONE, has(UNICODE_CHARACTER_CLASS));
2337             return -1;
2338         case 'C':
2339             break;
2340         case 'D':
2341             if (create) root = has(UNICODE_CHARACTER_CLASS)
2342                                ? new Utype(UnicodeProp.DIGIT).complement()
2343                                : new Ctype(ASCII.DIGIT).complement();
2344             return -1;
2345         case 'E':
2346         case 'F':
2347             break;
2348         case 'G':
2349             if (inclass) break;
2350             if (create) root = new LastMatch();
2351             return -1;
2352         case 'H':
2353             if (create) root = new HorizWS().complement();
2354             return -1;
2355         case 'I':
2356         case 'J':
2357         case 'K':
2358         case 'L':
2359         case 'M':
2360         case 'N':
2361         case 'O':
2362         case 'P':
2363         case 'Q':
2364             break;
2365         case 'R':
2366             if (inclass) break;
2367             if (create) root = new LineEnding();
2368             return -1;
2369         case 'S':
2370             if (create) root = has(UNICODE_CHARACTER_CLASS)
2371                                ? new Utype(UnicodeProp.WHITE_SPACE).complement()
2372                                : new Ctype(ASCII.SPACE).complement();
2373             return -1;
2374         case 'T':
2375         case 'U':
2376             break;
2377         case 'V':
2378             if (create) root = new VertWS().complement();
2379             return -1;
2380         case 'W':
2381             if (create) root = has(UNICODE_CHARACTER_CLASS)
2382                                ? new Utype(UnicodeProp.WORD).complement()
2383                                : new Ctype(ASCII.WORD).complement();
2384             return -1;
2385         case 'X':
2386         case 'Y':
2387             break;
2388         case 'Z':
2389             if (inclass) break;
2390             if (create) {
2391                 if (has(UNIX_LINES))
2392                     root = new UnixDollar(false);
2393                 else
2394                     root = new Dollar(false);
2395             }
2396             return -1;
2397         case 'a':
2398             return '\007';
2399         case 'b':
2400             if (inclass) break;
2401             if (create) root = new Bound(Bound.BOTH, has(UNICODE_CHARACTER_CLASS));
2402             return -1;
2403         case 'c':
2404             return c();
2405         case 'd':
2406             if (create) root = has(UNICODE_CHARACTER_CLASS)
2407                                ? new Utype(UnicodeProp.DIGIT)
2408                                : new Ctype(ASCII.DIGIT);
2409             return -1;
2410         case 'e':
2411             return '\033';
2412         case 'f':
2413             return '\f';
2414         case 'g':
2415             break;
2416         case 'h':
2417             if (create) root = new HorizWS();
2418             return -1;
2419         case 'i':
2420         case 'j':
2421             break;
2422         case 'k':
2423             if (inclass)
2424                 break;
2425             if (read() != '<')
2426                 throw error("\\k is not followed by '<' for named capturing group");
2427             String name = groupname(read());
2428             if (!namedGroups().containsKey(name))
2429                 throw error("(named capturing group <"+ name+"> does not exit");
2430             if (create) {
2431                 if (has(CASE_INSENSITIVE))
2432                     root = new CIBackRef(namedGroups().get(name), has(UNICODE_CASE));
2433                 else
2434                     root = new BackRef(namedGroups().get(name));
2435             }
2436             return -1;
2437         case 'l':
2438         case 'm':
2439             break;
2440         case 'n':
2441             return '\n';
2442         case 'o':
2443         case 'p':
2444         case 'q':
2445             break;
2446         case 'r':
2447             return '\r';
2448         case 's':
2449             if (create) root = has(UNICODE_CHARACTER_CLASS)
2450                                ? new Utype(UnicodeProp.WHITE_SPACE)
2451                                : new Ctype(ASCII.SPACE);
2452             return -1;
2453         case 't':
2454             return '\t';
2455         case 'u':
2456             return u();
2457         case 'v':
2458             // '\v' was implemented as VT/0x0B in releases < 1.8 (though
2459             // undocumented). In JDK8 '\v' is specified as a predefined
2460             // character class for all vertical whitespace characters.
2461             // So [-1, root=VertWS node] pair is returned (instead of a
2462             // single 0x0B). This breaks the range if '\v' is used as
2463             // the start or end value, such as [\v-...] or [...-\v], in
2464             // which a single definite value (0x0B) is expected. For
2465             // compatibility concern '\013'/0x0B is returned if isrange.
2466             if (isrange)
2467                 return '\013';
2468             if (create) root = new VertWS();
2469             return -1;
2470         case 'w':
2471             if (create) root = has(UNICODE_CHARACTER_CLASS)
2472                                ? new Utype(UnicodeProp.WORD)
2473                                : new Ctype(ASCII.WORD);
2474             return -1;
2475         case 'x':
2476             return x();
2477         case 'y':
2478             break;
2479         case 'z':
2480             if (inclass) break;
2481             if (create) root = new End();
2482             return -1;
2483         default:
2484             return ch;
2485         }
2486         throw error("Illegal/unsupported escape sequence");
2487     }
2488 
2489     /**
2490      * Parse a character class, and return the node that matches it.
2491      *
2492      * Consumes a ] on the way out if consume is true. Usually consume
2493      * is true except for the case of [abc&&def] where def is a separate
2494      * right hand node with "understood" brackets.
2495      */
2496     private CharProperty clazz(boolean consume) {
2497         CharProperty prev = null;
2498         CharProperty node = null;
2499         BitClass bits = new BitClass();
2500         boolean include = true;
2501         boolean firstInClass = true;
2502         int ch = next();
2503         for (;;) {
2504             switch (ch) {
2505                 case '^':
2506                     // Negates if first char in a class, otherwise literal
2507                     if (firstInClass) {
2508                         if (temp[cursor-1] != '[')
2509                             break;
2510                         ch = next();
2511                         include = !include;
2512                         continue;
2513                     } else {
2514                         // ^ not first in class, treat as literal
2515                         break;
2516                     }
2517                 case '[':
2518                     firstInClass = false;
2519                     node = clazz(true);
2520                     if (prev == null)
2521                         prev = node;
2522                     else
2523                         prev = union(prev, node);
2524                     ch = peek();
2525                     continue;
2526                 case '&':
2527                     firstInClass = false;
2528                     ch = next();
2529                     if (ch == '&') {
2530                         ch = next();
2531                         CharProperty rightNode = null;
2532                         while (ch != ']' && ch != '&') {
2533                             if (ch == '[') {
2534                                 if (rightNode == null)
2535                                     rightNode = clazz(true);
2536                                 else
2537                                     rightNode = union(rightNode, clazz(true));
2538                             } else { // abc&&def
2539                                 unread();
2540                                 rightNode = clazz(false);
2541                             }
2542                             ch = peek();
2543                         }
2544                         if (rightNode != null)
2545                             node = rightNode;
2546                         if (prev == null) {
2547                             if (rightNode == null)
2548                                 throw error("Bad class syntax");
2549                             else
2550                                 prev = rightNode;
2551                         } else {
2552                             prev = intersection(prev, node);
2553                         }
2554                     } else {
2555                         // treat as a literal &
2556                         unread();
2557                         break;
2558                     }
2559                     continue;
2560                 case 0:
2561                     firstInClass = false;
2562                     if (cursor >= patternLength)
2563                         throw error("Unclosed character class");
2564                     break;
2565                 case ']':
2566                     firstInClass = false;
2567                     if (prev != null) {
2568                         if (consume)
2569                             next();
2570                         return prev;
2571                     }
2572                     break;
2573                 default:
2574                     firstInClass = false;
2575                     break;
2576             }
2577             node = range(bits);
2578             if (include) {
2579                 if (prev == null) {
2580                     prev = node;
2581                 } else {
2582                     if (prev != node)
2583                         prev = union(prev, node);
2584                 }
2585             } else {
2586                 if (prev == null) {
2587                     prev = node.complement();
2588                 } else {
2589                     if (prev != node)
2590                         prev = setDifference(prev, node);
2591                 }
2592             }
2593             ch = peek();
2594         }
2595     }
2596 
2597     private CharProperty bitsOrSingle(BitClass bits, int ch) {
2598         /* Bits can only handle codepoints in [u+0000-u+00ff] range.
2599            Use "single" node instead of bits when dealing with unicode
2600            case folding for codepoints listed below.
2601            (1)Uppercase out of range: u+00ff, u+00b5
2602               toUpperCase(u+00ff) -> u+0178
2603               toUpperCase(u+00b5) -> u+039c
2604            (2)LatinSmallLetterLongS u+17f
2605               toUpperCase(u+017f) -> u+0053
2606            (3)LatinSmallLetterDotlessI u+131
2607               toUpperCase(u+0131) -> u+0049
2608            (4)LatinCapitalLetterIWithDotAbove u+0130
2609               toLowerCase(u+0130) -> u+0069
2610            (5)KelvinSign u+212a
2611               toLowerCase(u+212a) ==> u+006B
2612            (6)AngstromSign u+212b
2613               toLowerCase(u+212b) ==> u+00e5
2614         */
2615         int d;
2616         if (ch < 256 &&
2617             !(has(CASE_INSENSITIVE) && has(UNICODE_CASE) &&
2618               (ch == 0xff || ch == 0xb5 ||
2619                ch == 0x49 || ch == 0x69 ||  //I and i
2620                ch == 0x53 || ch == 0x73 ||  //S and s
2621                ch == 0x4b || ch == 0x6b ||  //K and k
2622                ch == 0xc5 || ch == 0xe5)))  //A+ring
2623             return bits.add(ch, flags());
2624         return newSingle(ch);
2625     }
2626 
2627     /**
2628      * Parse a single character or a character range in a character class
2629      * and return its representative node.
2630      */
2631     private CharProperty range(BitClass bits) {
2632         int ch = peek();
2633         if (ch == '\\') {
2634             ch = nextEscaped();
2635             if (ch == 'p' || ch == 'P') { // A property
2636                 boolean comp = (ch == 'P');
2637                 boolean oneLetter = true;
2638                 // Consume { if present
2639                 ch = next();
2640                 if (ch != '{')
2641                     unread();
2642                 else
2643                     oneLetter = false;
2644                 return family(oneLetter, comp);
2645             } else { // ordinary escape
2646                 boolean isrange = temp[cursor+1] == '-';
2647                 unread();
2648                 ch = escape(true, true, isrange);
2649                 if (ch == -1)
2650                     return (CharProperty) root;
2651             }
2652         } else {
2653             next();
2654         }
2655         if (ch >= 0) {
2656             if (peek() == '-') {
2657                 int endRange = temp[cursor+1];
2658                 if (endRange == '[') {
2659                     return bitsOrSingle(bits, ch);
2660                 }
2661                 if (endRange != ']') {
2662                     next();
2663                     int m = peek();
2664                     if (m == '\\') {
2665                         m = escape(true, false, true);
2666                     } else {
2667                         next();
2668                     }
2669                     if (m < ch) {
2670                         throw error("Illegal character range");
2671                     }
2672                     if (has(CASE_INSENSITIVE))
2673                         return caseInsensitiveRangeFor(ch, m);
2674                     else
2675                         return rangeFor(ch, m);
2676                 }
2677             }
2678             return bitsOrSingle(bits, ch);
2679         }
2680         throw error("Unexpected character '"+((char)ch)+"'");
2681     }
2682 
2683     /**
2684      * Parses a Unicode character family and returns its representative node.
2685      */
2686     private CharProperty family(boolean singleLetter,
2687                                 boolean maybeComplement)
2688     {
2689         next();
2690         String name;
2691         CharProperty node = null;
2692 
2693         if (singleLetter) {
2694             int c = temp[cursor];
2695             if (!Character.isSupplementaryCodePoint(c)) {
2696                 name = String.valueOf((char)c);
2697             } else {
2698                 name = new String(temp, cursor, 1);
2699             }
2700             read();
2701         } else {
2702             int i = cursor;
2703             mark('}');
2704             while(read() != '}') {
2705             }
2706             mark('\000');
2707             int j = cursor;
2708             if (j > patternLength)
2709                 throw error("Unclosed character family");
2710             if (i + 1 >= j)
2711                 throw error("Empty character family");
2712             name = new String(temp, i, j-i-1);
2713         }
2714 
2715         int i = name.indexOf('=');
2716         if (i != -1) {
2717             // property construct \p{name=value}
2718             String value = name.substring(i + 1);
2719             name = name.substring(0, i).toLowerCase(Locale.ENGLISH);
2720             switch (name) {
2721                 case "sc":
2722                 case "script":
2723                     node = unicodeScriptPropertyFor(value);
2724                     break;
2725                 case "blk":
2726                 case "block":
2727                     node = unicodeBlockPropertyFor(value);
2728                     break;
2729                 case "gc":
2730                 case "general_category":
2731                     node = charPropertyNodeFor(value);
2732                     break;
2733                 default:
2734                     throw error("Unknown Unicode property {name=<" + name + ">, "
2735                                 + "value=<" + value + ">}");
2736             }
2737         } else {
2738             if (name.startsWith("In")) {
2739                 // \p{inBlockName}
2740                 node = unicodeBlockPropertyFor(name.substring(2));
2741             } else if (name.startsWith("Is")) {
2742                 // \p{isGeneralCategory} and \p{isScriptName}
2743                 name = name.substring(2);
2744                 UnicodeProp uprop = UnicodeProp.forName(name);
2745                 if (uprop != null)
2746                     node = new Utype(uprop);
2747                 if (node == null)
2748                     node = CharPropertyNames.charPropertyFor(name);
2749                 if (node == null)
2750                     node = unicodeScriptPropertyFor(name);
2751             } else {
2752                 if (has(UNICODE_CHARACTER_CLASS)) {
2753                     UnicodeProp uprop = UnicodeProp.forPOSIXName(name);
2754                     if (uprop != null)
2755                         node = new Utype(uprop);
2756                 }
2757                 if (node == null)
2758                     node = charPropertyNodeFor(name);
2759             }
2760         }
2761         if (maybeComplement) {
2762             if (node instanceof Category || node instanceof Block)
2763                 hasSupplementary = true;
2764             node = node.complement();
2765         }
2766         return node;
2767     }
2768 
2769 
2770     /**
2771      * Returns a CharProperty matching all characters belong to
2772      * a UnicodeScript.
2773      */
2774     private CharProperty unicodeScriptPropertyFor(String name) {
2775         final Character.UnicodeScript script;
2776         try {
2777             script = Character.UnicodeScript.forName(name);
2778         } catch (IllegalArgumentException iae) {
2779             throw error("Unknown character script name {" + name + "}");
2780         }
2781         return new Script(script);
2782     }
2783 
2784     /**
2785      * Returns a CharProperty matching all characters in a UnicodeBlock.
2786      */
2787     private CharProperty unicodeBlockPropertyFor(String name) {
2788         final Character.UnicodeBlock block;
2789         try {
2790             block = Character.UnicodeBlock.forName(name);
2791         } catch (IllegalArgumentException iae) {
2792             throw error("Unknown character block name {" + name + "}");
2793         }
2794         return new Block(block);
2795     }
2796 
2797     /**
2798      * Returns a CharProperty matching all characters in a named property.
2799      */
2800     private CharProperty charPropertyNodeFor(String name) {
2801         CharProperty p = CharPropertyNames.charPropertyFor(name);
2802         if (p == null)
2803             throw error("Unknown character property name {" + name + "}");
2804         return p;
2805     }
2806 
2807     /**
2808      * Parses and returns the name of a "named capturing group", the trailing
2809      * ">" is consumed after parsing.
2810      */
2811     private String groupname(int ch) {
2812         StringBuilder sb = new StringBuilder();
2813         sb.append(Character.toChars(ch));
2814         while (ASCII.isLower(ch=read()) || ASCII.isUpper(ch) ||
2815                ASCII.isDigit(ch)) {
2816             sb.append(Character.toChars(ch));
2817         }
2818         if (sb.length() == 0)
2819             throw error("named capturing group has 0 length name");
2820         if (ch != '>')
2821             throw error("named capturing group is missing trailing '>'");
2822         return sb.toString();
2823     }
2824 
2825     /**
2826      * Parses a group and returns the head node of a set of nodes that process
2827      * the group. Sometimes a double return system is used where the tail is
2828      * returned in root.
2829      */
2830     private Node group0() {
2831         boolean capturingGroup = false;
2832         Node head = null;
2833         Node tail = null;
2834         int save = flags;
2835         root = null;
2836         int ch = next();
2837         if (ch == '?') {
2838             ch = skip();
2839             switch (ch) {
2840             case ':':   //  (?:xxx) pure group
2841                 head = createGroup(true);
2842                 tail = root;
2843                 head.next = expr(tail);
2844                 break;
2845             case '=':   // (?=xxx) and (?!xxx) lookahead
2846             case '!':
2847                 head = createGroup(true);
2848                 tail = root;
2849                 head.next = expr(tail);
2850                 if (ch == '=') {
2851                     head = tail = new Pos(head);
2852                 } else {
2853                     head = tail = new Neg(head);
2854                 }
2855                 break;
2856             case '>':   // (?>xxx)  independent group
2857                 head = createGroup(true);
2858                 tail = root;
2859                 head.next = expr(tail);
2860                 head = tail = new Ques(head, INDEPENDENT);
2861                 break;
2862             case '<':   // (?<xxx)  look behind
2863                 ch = read();
2864                 if (ASCII.isLower(ch) || ASCII.isUpper(ch)) {
2865                     // named captured group
2866                     String name = groupname(ch);
2867                     if (namedGroups().containsKey(name))
2868                         throw error("Named capturing group <" + name
2869                                     + "> is already defined");
2870                     capturingGroup = true;
2871                     head = createGroup(false);
2872                     tail = root;
2873                     namedGroups().put(name, capturingGroupCount-1);
2874                     head.next = expr(tail);
2875                     break;
2876                 }
2877                 int start = cursor;
2878                 head = createGroup(true);
2879                 tail = root;
2880                 head.next = expr(tail);
2881                 tail.next = lookbehindEnd;
2882                 TreeInfo info = new TreeInfo();
2883                 head.study(info);
2884                 if (info.maxValid == false) {
2885                     throw error("Look-behind group does not have "
2886                                 + "an obvious maximum length");
2887                 }
2888                 boolean hasSupplementary = findSupplementary(start, patternLength);
2889                 if (ch == '=') {
2890                     head = tail = (hasSupplementary ?
2891                                    new BehindS(head, info.maxLength,
2892                                                info.minLength) :
2893                                    new Behind(head, info.maxLength,
2894                                               info.minLength));
2895                 } else if (ch == '!') {
2896                     head = tail = (hasSupplementary ?
2897                                    new NotBehindS(head, info.maxLength,
2898                                                   info.minLength) :
2899                                    new NotBehind(head, info.maxLength,
2900                                                  info.minLength));
2901                 } else {
2902                     throw error("Unknown look-behind group");
2903                 }
2904                 break;
2905             case '$':
2906             case '@':
2907                 throw error("Unknown group type");
2908             default:    // (?xxx:) inlined match flags
2909                 unread();
2910                 addFlag();
2911                 ch = read();
2912                 if (ch == ')') {
2913                     return null;    // Inline modifier only
2914                 }
2915                 if (ch != ':') {
2916                     throw error("Unknown inline modifier");
2917                 }
2918                 head = createGroup(true);
2919                 tail = root;
2920                 head.next = expr(tail);
2921                 break;
2922             }
2923         } else { // (xxx) a regular group
2924             capturingGroup = true;
2925             head = createGroup(false);
2926             tail = root;
2927             head.next = expr(tail);
2928         }
2929 
2930         accept(')', "Unclosed group");
2931         flags = save;
2932 
2933         // Check for quantifiers
2934         Node node = closure(head);
2935         if (node == head) { // No closure
2936             root = tail;
2937             return node;    // Dual return
2938         }
2939         if (head == tail) { // Zero length assertion
2940             root = node;
2941             return node;    // Dual return
2942         }
2943 
2944         if (node instanceof Ques) {
2945             Ques ques = (Ques) node;
2946             if (ques.type == POSSESSIVE) {
2947                 root = node;
2948                 return node;
2949             }
2950             tail.next = new BranchConn();
2951             tail = tail.next;
2952             if (ques.type == GREEDY) {
2953                 head = new Branch(head, null, tail);
2954             } else { // Reluctant quantifier
2955                 head = new Branch(null, head, tail);
2956             }
2957             root = tail;
2958             return head;
2959         } else if (node instanceof Curly) {
2960             Curly curly = (Curly) node;
2961             if (curly.type == POSSESSIVE) {
2962                 root = node;
2963                 return node;
2964             }
2965             // Discover if the group is deterministic
2966             TreeInfo info = new TreeInfo();
2967             if (head.study(info)) { // Deterministic
2968                 GroupTail temp = (GroupTail) tail;
2969                 head = root = new GroupCurly(head.next, curly.cmin,
2970                                    curly.cmax, curly.type,
2971                                    ((GroupTail)tail).localIndex,
2972                                    ((GroupTail)tail).groupIndex,
2973                                              capturingGroup);
2974                 return head;
2975             } else { // Non-deterministic
2976                 int temp = ((GroupHead) head).localIndex;
2977                 Loop loop;
2978                 if (curly.type == GREEDY)
2979                     loop = new Loop(this.localCount, temp);
2980                 else  // Reluctant Curly
2981                     loop = new LazyLoop(this.localCount, temp);
2982                 Prolog prolog = new Prolog(loop);
2983                 this.localCount += 1;
2984                 loop.cmin = curly.cmin;
2985                 loop.cmax = curly.cmax;
2986                 loop.body = head;
2987                 tail.next = loop;
2988                 root = loop;
2989                 return prolog; // Dual return
2990             }
2991         }
2992         throw error("Internal logic error");
2993     }
2994 
2995     /**
2996      * Create group head and tail nodes using double return. If the group is
2997      * created with anonymous true then it is a pure group and should not
2998      * affect group counting.
2999      */
3000     private Node createGroup(boolean anonymous) {
3001         int localIndex = localCount++;
3002         int groupIndex = 0;
3003         if (!anonymous)
3004             groupIndex = capturingGroupCount++;
3005         GroupHead head = new GroupHead(localIndex);
3006         root = new GroupTail(localIndex, groupIndex);
3007         if (!anonymous && groupIndex < 10)
3008             groupNodes[groupIndex] = head;
3009         return head;
3010     }
3011 
3012     @SuppressWarnings("fallthrough")
3013     /**
3014      * Parses inlined match flags and set them appropriately.
3015      */
3016     private void addFlag() {
3017         int ch = peek();
3018         for (;;) {
3019             switch (ch) {
3020             case 'i':
3021                 flags |= CASE_INSENSITIVE;
3022                 break;
3023             case 'm':
3024                 flags |= MULTILINE;
3025                 break;
3026             case 's':
3027                 flags |= DOTALL;
3028                 break;
3029             case 'd':
3030                 flags |= UNIX_LINES;
3031                 break;
3032             case 'u':
3033                 flags |= UNICODE_CASE;
3034                 break;
3035             case 'c':
3036                 flags |= CANON_EQ;
3037                 break;
3038             case 'x':
3039                 flags |= COMMENTS;
3040                 break;
3041             case 'U':
3042                 flags |= (UNICODE_CHARACTER_CLASS | UNICODE_CASE);
3043                 break;
3044             case '-': // subFlag then fall through
3045                 ch = next();
3046                 subFlag();
3047             default:
3048                 return;
3049             }
3050             ch = next();
3051         }
3052     }
3053 
3054     @SuppressWarnings("fallthrough")
3055     /**
3056      * Parses the second part of inlined match flags and turns off
3057      * flags appropriately.
3058      */
3059     private void subFlag() {
3060         int ch = peek();
3061         for (;;) {
3062             switch (ch) {
3063             case 'i':
3064                 flags &= ~CASE_INSENSITIVE;
3065                 break;
3066             case 'm':
3067                 flags &= ~MULTILINE;
3068                 break;
3069             case 's':
3070                 flags &= ~DOTALL;
3071                 break;
3072             case 'd':
3073                 flags &= ~UNIX_LINES;
3074                 break;
3075             case 'u':
3076                 flags &= ~UNICODE_CASE;
3077                 break;
3078             case 'c':
3079                 flags &= ~CANON_EQ;
3080                 break;
3081             case 'x':
3082                 flags &= ~COMMENTS;
3083                 break;
3084             case 'U':
3085                 flags &= ~(UNICODE_CHARACTER_CLASS | UNICODE_CASE);
3086             default:
3087                 return;
3088             }
3089             ch = next();
3090         }
3091     }
3092 
3093     static final int MAX_REPS   = 0x7FFFFFFF;
3094 
3095     static final int GREEDY     = 0;
3096 
3097     static final int LAZY       = 1;
3098 
3099     static final int POSSESSIVE = 2;
3100 
3101     static final int INDEPENDENT = 3;
3102 
3103     /**
3104      * Processes repetition. If the next character peeked is a quantifier
3105      * then new nodes must be appended to handle the repetition.
3106      * Prev could be a single or a group, so it could be a chain of nodes.
3107      */
3108     private Node closure(Node prev) {
3109         Node atom;
3110         int ch = peek();
3111         switch (ch) {
3112         case '?':
3113             ch = next();
3114             if (ch == '?') {
3115                 next();
3116                 return new Ques(prev, LAZY);
3117             } else if (ch == '+') {
3118                 next();
3119                 return new Ques(prev, POSSESSIVE);
3120             }
3121             return new Ques(prev, GREEDY);
3122         case '*':
3123             ch = next();
3124             if (ch == '?') {
3125                 next();
3126                 return new Curly(prev, 0, MAX_REPS, LAZY);
3127             } else if (ch == '+') {
3128                 next();
3129                 return new Curly(prev, 0, MAX_REPS, POSSESSIVE);
3130             }
3131             return new Curly(prev, 0, MAX_REPS, GREEDY);
3132         case '+':
3133             ch = next();
3134             if (ch == '?') {
3135                 next();
3136                 return new Curly(prev, 1, MAX_REPS, LAZY);
3137             } else if (ch == '+') {
3138                 next();
3139                 return new Curly(prev, 1, MAX_REPS, POSSESSIVE);
3140             }
3141             return new Curly(prev, 1, MAX_REPS, GREEDY);
3142         case '{':
3143             ch = temp[cursor+1];
3144             if (ASCII.isDigit(ch)) {
3145                 skip();
3146                 int cmin = 0;
3147                 do {
3148                     cmin = cmin * 10 + (ch - '0');
3149                 } while (ASCII.isDigit(ch = read()));
3150                 int cmax = cmin;
3151                 if (ch == ',') {
3152                     ch = read();
3153                     cmax = MAX_REPS;
3154                     if (ch != '}') {
3155                         cmax = 0;
3156                         while (ASCII.isDigit(ch)) {
3157                             cmax = cmax * 10 + (ch - '0');
3158                             ch = read();
3159                         }
3160                     }
3161                 }
3162                 if (ch != '}')
3163                     throw error("Unclosed counted closure");
3164                 if (((cmin) | (cmax) | (cmax - cmin)) < 0)
3165                     throw error("Illegal repetition range");
3166                 Curly curly;
3167                 ch = peek();
3168                 if (ch == '?') {
3169                     next();
3170                     curly = new Curly(prev, cmin, cmax, LAZY);
3171                 } else if (ch == '+') {
3172                     next();
3173                     curly = new Curly(prev, cmin, cmax, POSSESSIVE);
3174                 } else {
3175                     curly = new Curly(prev, cmin, cmax, GREEDY);
3176                 }
3177                 return curly;
3178             } else {
3179                 throw error("Illegal repetition");
3180             }
3181         default:
3182             return prev;
3183         }
3184     }
3185 
3186     /**
3187      *  Utility method for parsing control escape sequences.
3188      */
3189     private int c() {
3190         if (cursor < patternLength) {
3191             return read() ^ 64;
3192         }
3193         throw error("Illegal control escape sequence");
3194     }
3195 
3196     /**
3197      *  Utility method for parsing octal escape sequences.
3198      */
3199     private int o() {
3200         int n = read();
3201         if (((n-'0')|('7'-n)) >= 0) {
3202             int m = read();
3203             if (((m-'0')|('7'-m)) >= 0) {
3204                 int o = read();
3205                 if ((((o-'0')|('7'-o)) >= 0) && (((n-'0')|('3'-n)) >= 0)) {
3206                     return (n - '0') * 64 + (m - '0') * 8 + (o - '0');
3207                 }
3208                 unread();
3209                 return (n - '0') * 8 + (m - '0');
3210             }
3211             unread();
3212             return (n - '0');
3213         }
3214         throw error("Illegal octal escape sequence");
3215     }
3216 
3217     /**
3218      *  Utility method for parsing hexadecimal escape sequences.
3219      */
3220     private int x() {
3221         int n = read();
3222         if (ASCII.isHexDigit(n)) {
3223             int m = read();
3224             if (ASCII.isHexDigit(m)) {
3225                 return ASCII.toDigit(n) * 16 + ASCII.toDigit(m);
3226             }
3227         } else if (n == '{' && ASCII.isHexDigit(peek())) {
3228             int ch = 0;
3229             while (ASCII.isHexDigit(n = read())) {
3230                 ch = (ch << 4) + ASCII.toDigit(n);
3231                 if (ch > Character.MAX_CODE_POINT)
3232                     throw error("Hexadecimal codepoint is too big");
3233             }
3234             if (n != '}')
3235                 throw error("Unclosed hexadecimal escape sequence");
3236             return ch;
3237         }
3238         throw error("Illegal hexadecimal escape sequence");
3239     }
3240 
3241     /**
3242      *  Utility method for parsing unicode escape sequences.
3243      */
3244     private int cursor() {
3245         return cursor;
3246     }
3247 
3248     private void setcursor(int pos) {
3249         cursor = pos;
3250     }
3251 
3252     private int uxxxx() {
3253         int n = 0;
3254         for (int i = 0; i < 4; i++) {
3255             int ch = read();
3256             if (!ASCII.isHexDigit(ch)) {
3257                 throw error("Illegal Unicode escape sequence");
3258             }
3259             n = n * 16 + ASCII.toDigit(ch);
3260         }
3261         return n;
3262     }
3263 
3264     private int u() {
3265         int n = uxxxx();
3266         if (Character.isHighSurrogate((char)n)) {
3267             int cur = cursor();
3268             if (read() == '\\' && read() == 'u') {
3269                 int n2 = uxxxx();
3270                 if (Character.isLowSurrogate((char)n2))
3271                     return Character.toCodePoint((char)n, (char)n2);
3272             }
3273             setcursor(cur);
3274         }
3275         return n;
3276     }
3277 
3278     //
3279     // Utility methods for code point support
3280     //
3281 
3282     private static final int countChars(CharSequence seq, int index,
3283                                         int lengthInCodePoints) {
3284         // optimization
3285         if (lengthInCodePoints == 1 && !Character.isHighSurrogate(seq.charAt(index))) {
3286             assert (index >= 0 && index < seq.length());
3287             return 1;
3288         }
3289         int length = seq.length();
3290         int x = index;
3291         if (lengthInCodePoints >= 0) {
3292             assert (index >= 0 && index < length);
3293             for (int i = 0; x < length && i < lengthInCodePoints; i++) {
3294                 if (Character.isHighSurrogate(seq.charAt(x++))) {
3295                     if (x < length && Character.isLowSurrogate(seq.charAt(x))) {
3296                         x++;
3297                     }
3298                 }
3299             }
3300             return x - index;
3301         }
3302 
3303         assert (index >= 0 && index <= length);
3304         if (index == 0) {
3305             return 0;
3306         }
3307         int len = -lengthInCodePoints;
3308         for (int i = 0; x > 0 && i < len; i++) {
3309             if (Character.isLowSurrogate(seq.charAt(--x))) {
3310                 if (x > 0 && Character.isHighSurrogate(seq.charAt(x-1))) {
3311                     x--;
3312                 }
3313             }
3314         }
3315         return index - x;
3316     }
3317 
3318     private static final int countCodePoints(CharSequence seq) {
3319         int length = seq.length();
3320         int n = 0;
3321         for (int i = 0; i < length; ) {
3322             n++;
3323             if (Character.isHighSurrogate(seq.charAt(i++))) {
3324                 if (i < length && Character.isLowSurrogate(seq.charAt(i))) {
3325                     i++;
3326                 }
3327             }
3328         }
3329         return n;
3330     }
3331 
3332     /**
3333      *  Creates a bit vector for matching Latin-1 values. A normal BitClass
3334      *  never matches values above Latin-1, and a complemented BitClass always
3335      *  matches values above Latin-1.
3336      */
3337     private static final class BitClass extends BmpCharProperty {
3338         final boolean[] bits;
3339         BitClass() { bits = new boolean[256]; }
3340         private BitClass(boolean[] bits) { this.bits = bits; }
3341         BitClass add(int c, int flags) {
3342             assert c >= 0 && c <= 255;
3343             if ((flags & CASE_INSENSITIVE) != 0) {
3344                 if (ASCII.isAscii(c)) {
3345                     bits[ASCII.toUpper(c)] = true;
3346                     bits[ASCII.toLower(c)] = true;
3347                 } else if ((flags & UNICODE_CASE) != 0) {
3348                     bits[Character.toLowerCase(c)] = true;
3349                     bits[Character.toUpperCase(c)] = true;
3350                 }
3351             }
3352             bits[c] = true;
3353             return this;
3354         }
3355         boolean isSatisfiedBy(int ch) {
3356             return ch < 256 && bits[ch];
3357         }
3358     }
3359 
3360     /**
3361      *  Returns a suitably optimized, single character matcher.
3362      */
3363     private CharProperty newSingle(final int ch) {
3364         if (has(CASE_INSENSITIVE)) {
3365             int lower, upper;
3366             if (has(UNICODE_CASE)) {
3367                 upper = Character.toUpperCase(ch);
3368                 lower = Character.toLowerCase(upper);
3369                 if (upper != lower)
3370                     return new SingleU(lower);
3371             } else if (ASCII.isAscii(ch)) {
3372                 lower = ASCII.toLower(ch);
3373                 upper = ASCII.toUpper(ch);
3374                 if (lower != upper)
3375                     return new SingleI(lower, upper);
3376             }
3377         }
3378         if (isSupplementary(ch))
3379             return new SingleS(ch);    // Match a given Unicode character
3380         return new Single(ch);         // Match a given BMP character
3381     }
3382 
3383     /**
3384      *  Utility method for creating a string slice matcher.
3385      */
3386     private Node newSlice(int[] buf, int count, boolean hasSupplementary) {
3387         int[] tmp = new int[count];
3388         if (has(CASE_INSENSITIVE)) {
3389             if (has(UNICODE_CASE)) {
3390                 for (int i = 0; i < count; i++) {
3391                     tmp[i] = Character.toLowerCase(
3392                                  Character.toUpperCase(buf[i]));
3393                 }
3394                 return hasSupplementary? new SliceUS(tmp) : new SliceU(tmp);
3395             }
3396             for (int i = 0; i < count; i++) {
3397                 tmp[i] = ASCII.toLower(buf[i]);
3398             }
3399             return hasSupplementary? new SliceIS(tmp) : new SliceI(tmp);
3400         }
3401         for (int i = 0; i < count; i++) {
3402             tmp[i] = buf[i];
3403         }
3404         return hasSupplementary ? new SliceS(tmp) : new Slice(tmp);
3405     }
3406 
3407     /**
3408      * The following classes are the building components of the object
3409      * tree that represents a compiled regular expression. The object tree
3410      * is made of individual elements that handle constructs in the Pattern.
3411      * Each type of object knows how to match its equivalent construct with
3412      * the match() method.
3413      */
3414 
3415     /**
3416      * Base class for all node classes. Subclasses should override the match()
3417      * method as appropriate. This class is an accepting node, so its match()
3418      * always returns true.
3419      */
3420     static class Node extends Object {
3421         Node next;
3422         Node() {
3423             next = Pattern.accept;
3424         }
3425         /**
3426          * This method implements the classic accept node.
3427          */
3428         boolean match(Matcher matcher, int i, CharSequence seq) {
3429             matcher.last = i;
3430             matcher.groups[0] = matcher.first;
3431             matcher.groups[1] = matcher.last;
3432             return true;
3433         }
3434         /**
3435          * This method is good for all zero length assertions.
3436          */
3437         boolean study(TreeInfo info) {
3438             if (next != null) {
3439                 return next.study(info);
3440             } else {
3441                 return info.deterministic;
3442             }
3443         }
3444     }
3445 
3446     static class LastNode extends Node {
3447         /**
3448          * This method implements the classic accept node with
3449          * the addition of a check to see if the match occurred
3450          * using all of the input.
3451          */
3452         boolean match(Matcher matcher, int i, CharSequence seq) {
3453             if (matcher.acceptMode == Matcher.ENDANCHOR && i != matcher.to)
3454                 return false;
3455             matcher.last = i;
3456             matcher.groups[0] = matcher.first;
3457             matcher.groups[1] = matcher.last;
3458             return true;
3459         }
3460     }
3461 
3462     /**
3463      * Used for REs that can start anywhere within the input string.
3464      * This basically tries to match repeatedly at each spot in the
3465      * input string, moving forward after each try. An anchored search
3466      * or a BnM will bypass this node completely.
3467      */
3468     static class Start extends Node {
3469         int minLength;
3470         Start(Node node) {
3471             this.next = node;
3472             TreeInfo info = new TreeInfo();
3473             next.study(info);
3474             minLength = info.minLength;
3475         }
3476         boolean match(Matcher matcher, int i, CharSequence seq) {
3477             if (i > matcher.to - minLength) {
3478                 matcher.hitEnd = true;
3479                 return false;
3480             }
3481             int guard = matcher.to - minLength;
3482             for (; i <= guard; i++) {
3483                 if (next.match(matcher, i, seq)) {
3484                     matcher.first = i;
3485                     matcher.groups[0] = matcher.first;
3486                     matcher.groups[1] = matcher.last;
3487                     return true;
3488                 }
3489             }
3490             matcher.hitEnd = true;
3491             return false;
3492         }
3493         boolean study(TreeInfo info) {
3494             next.study(info);
3495             info.maxValid = false;
3496             info.deterministic = false;
3497             return false;
3498         }
3499     }
3500 
3501     /*
3502      * StartS supports supplementary characters, including unpaired surrogates.
3503      */
3504     static final class StartS extends Start {
3505         StartS(Node node) {
3506             super(node);
3507         }
3508         boolean match(Matcher matcher, int i, CharSequence seq) {
3509             if (i > matcher.to - minLength) {
3510                 matcher.hitEnd = true;
3511                 return false;
3512             }
3513             int guard = matcher.to - minLength;
3514             while (i <= guard) {
3515                 //if ((ret = next.match(matcher, i, seq)) || i == guard)
3516                 if (next.match(matcher, i, seq)) {
3517                     matcher.first = i;
3518                     matcher.groups[0] = matcher.first;
3519                     matcher.groups[1] = matcher.last;
3520                     return true;
3521                 }
3522                 if (i == guard)
3523                     break;
3524                 // Optimization to move to the next character. This is
3525                 // faster than countChars(seq, i, 1).
3526                 if (Character.isHighSurrogate(seq.charAt(i++))) {
3527                     if (i < seq.length() &&
3528                         Character.isLowSurrogate(seq.charAt(i))) {
3529                         i++;
3530                     }
3531                 }
3532             }
3533             matcher.hitEnd = true;
3534             return false;
3535         }
3536     }
3537 
3538     /**
3539      * Node to anchor at the beginning of input. This object implements the
3540      * match for a \A sequence, and the caret anchor will use this if not in
3541      * multiline mode.
3542      */
3543     static final class Begin extends Node {
3544         boolean match(Matcher matcher, int i, CharSequence seq) {
3545             int fromIndex = (matcher.anchoringBounds) ?
3546                 matcher.from : 0;
3547             if (i == fromIndex && next.match(matcher, i, seq)) {
3548                 matcher.first = i;
3549                 matcher.groups[0] = i;
3550                 matcher.groups[1] = matcher.last;
3551                 return true;
3552             } else {
3553                 return false;
3554             }
3555         }
3556     }
3557 
3558     /**
3559      * Node to anchor at the end of input. This is the absolute end, so this
3560      * should not match at the last newline before the end as $ will.
3561      */
3562     static final class End extends Node {
3563         boolean match(Matcher matcher, int i, CharSequence seq) {
3564             int endIndex = (matcher.anchoringBounds) ?
3565                 matcher.to : matcher.getTextLength();
3566             if (i == endIndex) {
3567                 matcher.hitEnd = true;
3568                 return next.match(matcher, i, seq);
3569             }
3570             return false;
3571         }
3572     }
3573 
3574     /**
3575      * Node to anchor at the beginning of a line. This is essentially the
3576      * object to match for the multiline ^.
3577      */
3578     static final class Caret extends Node {
3579         boolean match(Matcher matcher, int i, CharSequence seq) {
3580             int startIndex = matcher.from;
3581             int endIndex = matcher.to;
3582             if (!matcher.anchoringBounds) {
3583                 startIndex = 0;
3584                 endIndex = matcher.getTextLength();
3585             }
3586             // Perl does not match ^ at end of input even after newline
3587             if (i == endIndex) {
3588                 matcher.hitEnd = true;
3589                 return false;
3590             }
3591             if (i > startIndex) {
3592                 char ch = seq.charAt(i-1);
3593                 if (ch != '\n' && ch != '\r'
3594                     && (ch|1) != '\u2029'
3595                     && ch != '\u0085' ) {
3596                     return false;
3597                 }
3598                 // Should treat /r/n as one newline
3599                 if (ch == '\r' && seq.charAt(i) == '\n')
3600                     return false;
3601             }
3602             return next.match(matcher, i, seq);
3603         }
3604     }
3605 
3606     /**
3607      * Node to anchor at the beginning of a line when in unixdot mode.
3608      */
3609     static final class UnixCaret extends Node {
3610         boolean match(Matcher matcher, int i, CharSequence seq) {
3611             int startIndex = matcher.from;
3612             int endIndex = matcher.to;
3613             if (!matcher.anchoringBounds) {
3614                 startIndex = 0;
3615                 endIndex = matcher.getTextLength();
3616             }
3617             // Perl does not match ^ at end of input even after newline
3618             if (i == endIndex) {
3619                 matcher.hitEnd = true;
3620                 return false;
3621             }
3622             if (i > startIndex) {
3623                 char ch = seq.charAt(i-1);
3624                 if (ch != '\n') {
3625                     return false;
3626                 }
3627             }
3628             return next.match(matcher, i, seq);
3629         }
3630     }
3631 
3632     /**
3633      * Node to match the location where the last match ended.
3634      * This is used for the \G construct.
3635      */
3636     static final class LastMatch extends Node {
3637         boolean match(Matcher matcher, int i, CharSequence seq) {
3638             if (i != matcher.oldLast)
3639                 return false;
3640             return next.match(matcher, i, seq);
3641         }
3642     }
3643 
3644     /**
3645      * Node to anchor at the end of a line or the end of input based on the
3646      * multiline mode.
3647      *
3648      * When not in multiline mode, the $ can only match at the very end
3649      * of the input, unless the input ends in a line terminator in which
3650      * it matches right before the last line terminator.
3651      *
3652      * Note that \r\n is considered an atomic line terminator.
3653      *
3654      * Like ^ the $ operator matches at a position, it does not match the
3655      * line terminators themselves.
3656      */
3657     static final class Dollar extends Node {
3658         boolean multiline;
3659         Dollar(boolean mul) {
3660             multiline = mul;
3661         }
3662         boolean match(Matcher matcher, int i, CharSequence seq) {
3663             int endIndex = (matcher.anchoringBounds) ?
3664                 matcher.to : matcher.getTextLength();
3665             if (!multiline) {
3666                 if (i < endIndex - 2)
3667                     return false;
3668                 if (i == endIndex - 2) {
3669                     char ch = seq.charAt(i);
3670                     if (ch != '\r')
3671                         return false;
3672                     ch = seq.charAt(i + 1);
3673                     if (ch != '\n')
3674                         return false;
3675                 }
3676             }
3677             // Matches before any line terminator; also matches at the
3678             // end of input
3679             // Before line terminator:
3680             // If multiline, we match here no matter what
3681             // If not multiline, fall through so that the end
3682             // is marked as hit; this must be a /r/n or a /n
3683             // at the very end so the end was hit; more input
3684             // could make this not match here
3685             if (i < endIndex) {
3686                 char ch = seq.charAt(i);
3687                  if (ch == '\n') {
3688                      // No match between \r\n
3689                      if (i > 0 && seq.charAt(i-1) == '\r')
3690                          return false;
3691                      if (multiline)
3692                          return next.match(matcher, i, seq);
3693                  } else if (ch == '\r' || ch == '\u0085' ||
3694                             (ch|1) == '\u2029') {
3695                      if (multiline)
3696                          return next.match(matcher, i, seq);
3697                  } else { // No line terminator, no match
3698                      return false;
3699                  }
3700             }
3701             // Matched at current end so hit end
3702             matcher.hitEnd = true;
3703             // If a $ matches because of end of input, then more input
3704             // could cause it to fail!
3705             matcher.requireEnd = true;
3706             return next.match(matcher, i, seq);
3707         }
3708         boolean study(TreeInfo info) {
3709             next.study(info);
3710             return info.deterministic;
3711         }
3712     }
3713 
3714     /**
3715      * Node to anchor at the end of a line or the end of input based on the
3716      * multiline mode when in unix lines mode.
3717      */
3718     static final class UnixDollar extends Node {
3719         boolean multiline;
3720         UnixDollar(boolean mul) {
3721             multiline = mul;
3722         }
3723         boolean match(Matcher matcher, int i, CharSequence seq) {
3724             int endIndex = (matcher.anchoringBounds) ?
3725                 matcher.to : matcher.getTextLength();
3726             if (i < endIndex) {
3727                 char ch = seq.charAt(i);
3728                 if (ch == '\n') {
3729                     // If not multiline, then only possible to
3730                     // match at very end or one before end
3731                     if (multiline == false && i != endIndex - 1)
3732                         return false;
3733                     // If multiline return next.match without setting
3734                     // matcher.hitEnd
3735                     if (multiline)
3736                         return next.match(matcher, i, seq);
3737                 } else {
3738                     return false;
3739                 }
3740             }
3741             // Matching because at the end or 1 before the end;
3742             // more input could change this so set hitEnd
3743             matcher.hitEnd = true;
3744             // If a $ matches because of end of input, then more input
3745             // could cause it to fail!
3746             matcher.requireEnd = true;
3747             return next.match(matcher, i, seq);
3748         }
3749         boolean study(TreeInfo info) {
3750             next.study(info);
3751             return info.deterministic;
3752         }
3753     }
3754 
3755     /**
3756      * Node class that matches a Unicode line ending '\R'
3757      */
3758     static final class LineEnding extends Node {
3759         boolean match(Matcher matcher, int i, CharSequence seq) {
3760             // (u+000Du+000A|[u+000Au+000Bu+000Cu+000Du+0085u+2028u+2029])
3761             if (i < matcher.to) {
3762                 int ch = seq.charAt(i);
3763                 if (ch == 0x0A || ch == 0x0B || ch == 0x0C ||
3764                     ch == 0x85 || ch == 0x2028 || ch == 0x2029)
3765                     return next.match(matcher, i + 1, seq);
3766                 if (ch == 0x0D) {
3767                     i++;
3768                     if (i < matcher.to && seq.charAt(i) == 0x0A)
3769                         i++;
3770                     return next.match(matcher, i, seq);
3771                 }
3772             } else {
3773                 matcher.hitEnd = true;
3774             }
3775             return false;
3776         }
3777         boolean study(TreeInfo info) {
3778             info.minLength++;
3779             info.maxLength += 2;
3780             return next.study(info);
3781         }
3782     }
3783 
3784     /**
3785      * Abstract node class to match one character satisfying some
3786      * boolean property.
3787      */
3788     private static abstract class CharProperty extends Node {
3789         abstract boolean isSatisfiedBy(int ch);
3790         CharProperty complement() {
3791             return new CharProperty() {
3792                     boolean isSatisfiedBy(int ch) {
3793                         return ! CharProperty.this.isSatisfiedBy(ch);}};
3794         }
3795         boolean match(Matcher matcher, int i, CharSequence seq) {
3796             if (i < matcher.to) {
3797                 int ch = Character.codePointAt(seq, i);
3798                 return isSatisfiedBy(ch)
3799                     && next.match(matcher, i+Character.charCount(ch), seq);
3800             } else {
3801                 matcher.hitEnd = true;
3802                 return false;
3803             }
3804         }
3805         boolean study(TreeInfo info) {
3806             info.minLength++;
3807             info.maxLength++;
3808             return next.study(info);
3809         }
3810     }
3811 
3812     /**
3813      * Optimized version of CharProperty that works only for
3814      * properties never satisfied by Supplementary characters.
3815      */
3816     private static abstract class BmpCharProperty extends CharProperty {
3817         boolean match(Matcher matcher, int i, CharSequence seq) {
3818             if (i < matcher.to) {
3819                 return isSatisfiedBy(seq.charAt(i))
3820                     && next.match(matcher, i+1, seq);
3821             } else {
3822                 matcher.hitEnd = true;
3823                 return false;
3824             }
3825         }
3826     }
3827 
3828     /**
3829      * Node class that matches a Supplementary Unicode character
3830      */
3831     static final class SingleS extends CharProperty {
3832         final int c;
3833         SingleS(int c) { this.c = c; }
3834         boolean isSatisfiedBy(int ch) {
3835             return ch == c;
3836         }
3837     }
3838 
3839     /**
3840      * Optimization -- matches a given BMP character
3841      */
3842     static final class Single extends BmpCharProperty {
3843         final int c;
3844         Single(int c) { this.c = c; }
3845         boolean isSatisfiedBy(int ch) {
3846             return ch == c;
3847         }
3848     }
3849 
3850     /**
3851      * Case insensitive matches a given BMP character
3852      */
3853     static final class SingleI extends BmpCharProperty {
3854         final int lower;
3855         final int upper;
3856         SingleI(int lower, int upper) {
3857             this.lower = lower;
3858             this.upper = upper;
3859         }
3860         boolean isSatisfiedBy(int ch) {
3861             return ch == lower || ch == upper;
3862         }
3863     }
3864 
3865     /**
3866      * Unicode case insensitive matches a given Unicode character
3867      */
3868     static final class SingleU extends CharProperty {
3869         final int lower;
3870         SingleU(int lower) {
3871             this.lower = lower;
3872         }
3873         boolean isSatisfiedBy(int ch) {
3874             return lower == ch ||
3875                 lower == Character.toLowerCase(Character.toUpperCase(ch));
3876         }
3877     }
3878 
3879     /**
3880      * Node class that matches a Unicode block.
3881      */
3882     static final class Block extends CharProperty {
3883         final Character.UnicodeBlock block;
3884         Block(Character.UnicodeBlock block) {
3885             this.block = block;
3886         }
3887         boolean isSatisfiedBy(int ch) {
3888             return block == Character.UnicodeBlock.of(ch);
3889         }
3890     }
3891 
3892     /**
3893      * Node class that matches a Unicode script
3894      */
3895     static final class Script extends CharProperty {
3896         final Character.UnicodeScript script;
3897         Script(Character.UnicodeScript script) {
3898             this.script = script;
3899         }
3900         boolean isSatisfiedBy(int ch) {
3901             return script == Character.UnicodeScript.of(ch);
3902         }
3903     }
3904 
3905     /**
3906      * Node class that matches a Unicode category.
3907      */
3908     static final class Category extends CharProperty {
3909         final int typeMask;
3910         Category(int typeMask) { this.typeMask = typeMask; }
3911         boolean isSatisfiedBy(int ch) {
3912             return (typeMask & (1 << Character.getType(ch))) != 0;
3913         }
3914     }
3915 
3916     /**
3917      * Node class that matches a Unicode "type"
3918      */
3919     static final class Utype extends CharProperty {
3920         final UnicodeProp uprop;
3921         Utype(UnicodeProp uprop) { this.uprop = uprop; }
3922         boolean isSatisfiedBy(int ch) {
3923             return uprop.is(ch);
3924         }
3925     }
3926 
3927     /**
3928      * Node class that matches a POSIX type.
3929      */
3930     static final class Ctype extends BmpCharProperty {
3931         final int ctype;
3932         Ctype(int ctype) { this.ctype = ctype; }
3933         boolean isSatisfiedBy(int ch) {
3934             return ch < 128 && ASCII.isType(ch, ctype);
3935         }
3936     }
3937 
3938     /**
3939      * Node class that matches a Perl vertical whitespace
3940      */
3941     static final class VertWS extends BmpCharProperty {
3942         boolean isSatisfiedBy(int cp) {
3943             return (cp >= 0x0A && cp <= 0x0D) ||
3944                    cp == 0x85 || cp == 0x2028 || cp == 0x2029;
3945         }
3946     }
3947 
3948     /**
3949      * Node class that matches a Perl horizontal whitespace
3950      */
3951     static final class HorizWS extends BmpCharProperty {
3952         boolean isSatisfiedBy(int cp) {
3953             return cp == 0x09 || cp == 0x20 || cp == 0xa0 ||
3954                    cp == 0x1680 || cp == 0x180e ||
3955                    cp >= 0x2000 && cp <= 0x200a ||
3956                    cp == 0x202f || cp == 0x205f || cp == 0x3000;
3957         }
3958     }
3959 
3960     /**
3961      * Base class for all Slice nodes
3962      */
3963     static class SliceNode extends Node {
3964         int[] buffer;
3965         SliceNode(int[] buf) {
3966             buffer = buf;
3967         }
3968         boolean study(TreeInfo info) {
3969             info.minLength += buffer.length;
3970             info.maxLength += buffer.length;
3971             return next.study(info);
3972         }
3973     }
3974 
3975     /**
3976      * Node class for a case sensitive/BMP-only sequence of literal
3977      * characters.
3978      */
3979     static class Slice extends SliceNode {
3980         Slice(int[] buf) {
3981             super(buf);
3982         }
3983         boolean match(Matcher matcher, int i, CharSequence seq) {
3984             int[] buf = buffer;
3985             int len = buf.length;
3986             for (int j=0; j<len; j++) {
3987                 if ((i+j) >= matcher.to) {
3988                     matcher.hitEnd = true;
3989                     return false;
3990                 }
3991                 if (buf[j] != seq.charAt(i+j))
3992                     return false;
3993             }
3994             return next.match(matcher, i+len, seq);
3995         }
3996     }
3997 
3998     /**
3999      * Node class for a case_insensitive/BMP-only sequence of literal
4000      * characters.
4001      */
4002     static class SliceI extends SliceNode {
4003         SliceI(int[] buf) {
4004             super(buf);
4005         }
4006         boolean match(Matcher matcher, int i, CharSequence seq) {
4007             int[] buf = buffer;
4008             int len = buf.length;
4009             for (int j=0; j<len; j++) {
4010                 if ((i+j) >= matcher.to) {
4011                     matcher.hitEnd = true;
4012                     return false;
4013                 }
4014                 int c = seq.charAt(i+j);
4015                 if (buf[j] != c &&
4016                     buf[j] != ASCII.toLower(c))
4017                     return false;
4018             }
4019             return next.match(matcher, i+len, seq);
4020         }
4021     }
4022 
4023     /**
4024      * Node class for a unicode_case_insensitive/BMP-only sequence of
4025      * literal characters. Uses unicode case folding.
4026      */
4027     static final class SliceU extends SliceNode {
4028         SliceU(int[] buf) {
4029             super(buf);
4030         }
4031         boolean match(Matcher matcher, int i, CharSequence seq) {
4032             int[] buf = buffer;
4033             int len = buf.length;
4034             for (int j=0; j<len; j++) {
4035                 if ((i+j) >= matcher.to) {
4036                     matcher.hitEnd = true;
4037                     return false;
4038                 }
4039                 int c = seq.charAt(i+j);
4040                 if (buf[j] != c &&
4041                     buf[j] != Character.toLowerCase(Character.toUpperCase(c)))
4042                     return false;
4043             }
4044             return next.match(matcher, i+len, seq);
4045         }
4046     }
4047 
4048     /**
4049      * Node class for a case sensitive sequence of literal characters
4050      * including supplementary characters.
4051      */
4052     static final class SliceS extends Slice {
4053         SliceS(int[] buf) {
4054             super(buf);
4055         }
4056         boolean match(Matcher matcher, int i, CharSequence seq) {
4057             int[] buf = buffer;
4058             int x = i;
4059             for (int j = 0; j < buf.length; j++) {
4060                 if (x >= matcher.to) {
4061                     matcher.hitEnd = true;
4062                     return false;
4063                 }
4064                 int c = Character.codePointAt(seq, x);
4065                 if (buf[j] != c)
4066                     return false;
4067                 x += Character.charCount(c);
4068                 if (x > matcher.to) {
4069                     matcher.hitEnd = true;
4070                     return false;
4071                 }
4072             }
4073             return next.match(matcher, x, seq);
4074         }
4075     }
4076 
4077     /**
4078      * Node class for a case insensitive sequence of literal characters
4079      * including supplementary characters.
4080      */
4081     static class SliceIS extends SliceNode {
4082         SliceIS(int[] buf) {
4083             super(buf);
4084         }
4085         int toLower(int c) {
4086             return ASCII.toLower(c);
4087         }
4088         boolean match(Matcher matcher, int i, CharSequence seq) {
4089             int[] buf = buffer;
4090             int x = i;
4091             for (int j = 0; j < buf.length; j++) {
4092                 if (x >= matcher.to) {
4093                     matcher.hitEnd = true;
4094                     return false;
4095                 }
4096                 int c = Character.codePointAt(seq, x);
4097                 if (buf[j] != c && buf[j] != toLower(c))
4098                     return false;
4099                 x += Character.charCount(c);
4100                 if (x > matcher.to) {
4101                     matcher.hitEnd = true;
4102                     return false;
4103                 }
4104             }
4105             return next.match(matcher, x, seq);
4106         }
4107     }
4108 
4109     /**
4110      * Node class for a case insensitive sequence of literal characters.
4111      * Uses unicode case folding.
4112      */
4113     static final class SliceUS extends SliceIS {
4114         SliceUS(int[] buf) {
4115             super(buf);
4116         }
4117         int toLower(int c) {
4118             return Character.toLowerCase(Character.toUpperCase(c));
4119         }
4120     }
4121 
4122     private static boolean inRange(int lower, int ch, int upper) {
4123         return lower <= ch && ch <= upper;
4124     }
4125 
4126     /**
4127      * Returns node for matching characters within an explicit value range.
4128      */
4129     private static CharProperty rangeFor(final int lower,
4130                                          final int upper) {
4131         return new CharProperty() {
4132                 boolean isSatisfiedBy(int ch) {
4133                     return inRange(lower, ch, upper);}};
4134     }
4135 
4136     /**
4137      * Returns node for matching characters within an explicit value
4138      * range in a case insensitive manner.
4139      */
4140     private CharProperty caseInsensitiveRangeFor(final int lower,
4141                                                  final int upper) {
4142         if (has(UNICODE_CASE))
4143             return new CharProperty() {
4144                 boolean isSatisfiedBy(int ch) {
4145                     if (inRange(lower, ch, upper))
4146                         return true;
4147                     int up = Character.toUpperCase(ch);
4148                     return inRange(lower, up, upper) ||
4149                            inRange(lower, Character.toLowerCase(up), upper);}};
4150         return new CharProperty() {
4151             boolean isSatisfiedBy(int ch) {
4152                 return inRange(lower, ch, upper) ||
4153                     ASCII.isAscii(ch) &&
4154                         (inRange(lower, ASCII.toUpper(ch), upper) ||
4155                          inRange(lower, ASCII.toLower(ch), upper));
4156             }};
4157     }
4158 
4159     /**
4160      * Implements the Unicode category ALL and the dot metacharacter when
4161      * in dotall mode.
4162      */
4163     static final class All extends CharProperty {
4164         boolean isSatisfiedBy(int ch) {
4165             return true;
4166         }
4167     }
4168 
4169     /**
4170      * Node class for the dot metacharacter when dotall is not enabled.
4171      */
4172     static final class Dot extends CharProperty {
4173         boolean isSatisfiedBy(int ch) {
4174             return (ch != '\n' && ch != '\r'
4175                     && (ch|1) != '\u2029'
4176                     && ch != '\u0085');
4177         }
4178     }
4179 
4180     /**
4181      * Node class for the dot metacharacter when dotall is not enabled
4182      * but UNIX_LINES is enabled.
4183      */
4184     static final class UnixDot extends CharProperty {
4185         boolean isSatisfiedBy(int ch) {
4186             return ch != '\n';
4187         }
4188     }
4189 
4190     /**
4191      * The 0 or 1 quantifier. This one class implements all three types.
4192      */
4193     static final class Ques extends Node {
4194         Node atom;
4195         int type;
4196         Ques(Node node, int type) {
4197             this.atom = node;
4198             this.type = type;
4199         }
4200         boolean match(Matcher matcher, int i, CharSequence seq) {
4201             switch (type) {
4202             case GREEDY:
4203                 return (atom.match(matcher, i, seq) && next.match(matcher, matcher.last, seq))
4204                     || next.match(matcher, i, seq);
4205             case LAZY:
4206                 return next.match(matcher, i, seq)
4207                     || (atom.match(matcher, i, seq) && next.match(matcher, matcher.last, seq));
4208             case POSSESSIVE:
4209                 if (atom.match(matcher, i, seq)) i = matcher.last;
4210                 return next.match(matcher, i, seq);
4211             default:
4212                 return atom.match(matcher, i, seq) && next.match(matcher, matcher.last, seq);
4213             }
4214         }
4215         boolean study(TreeInfo info) {
4216             if (type != INDEPENDENT) {
4217                 int minL = info.minLength;
4218                 atom.study(info);
4219                 info.minLength = minL;
4220                 info.deterministic = false;
4221                 return next.study(info);
4222             } else {
4223                 atom.study(info);
4224                 return next.study(info);
4225             }
4226         }
4227     }
4228 
4229     /**
4230      * Handles the curly-brace style repetition with a specified minimum and
4231      * maximum occurrences. The * quantifier is handled as a special case.
4232      * This class handles the three types.
4233      */
4234     static final class Curly extends Node {
4235         Node atom;
4236         int type;
4237         int cmin;
4238         int cmax;
4239 
4240         Curly(Node node, int cmin, int cmax, int type) {
4241             this.atom = node;
4242             this.type = type;
4243             this.cmin = cmin;
4244             this.cmax = cmax;
4245         }
4246         boolean match(Matcher matcher, int i, CharSequence seq) {
4247             int j;
4248             for (j = 0; j < cmin; j++) {
4249                 if (atom.match(matcher, i, seq)) {
4250                     i = matcher.last;
4251                     continue;
4252                 }
4253                 return false;
4254             }
4255             if (type == GREEDY)
4256                 return match0(matcher, i, j, seq);
4257             else if (type == LAZY)
4258                 return match1(matcher, i, j, seq);
4259             else
4260                 return match2(matcher, i, j, seq);
4261         }
4262         // Greedy match.
4263         // i is the index to start matching at
4264         // j is the number of atoms that have matched
4265         boolean match0(Matcher matcher, int i, int j, CharSequence seq) {
4266             if (j >= cmax) {
4267                 // We have matched the maximum... continue with the rest of
4268                 // the regular expression
4269                 return next.match(matcher, i, seq);
4270             }
4271             int backLimit = j;
4272             while (atom.match(matcher, i, seq)) {
4273                 // k is the length of this match
4274                 int k = matcher.last - i;
4275                 if (k == 0) // Zero length match
4276                     break;
4277                 // Move up index and number matched
4278                 i = matcher.last;
4279                 j++;
4280                 // We are greedy so match as many as we can
4281                 while (j < cmax) {
4282                     if (!atom.match(matcher, i, seq))
4283                         break;
4284                     if (i + k != matcher.last) {
4285                         if (match0(matcher, matcher.last, j+1, seq))
4286                             return true;
4287                         break;
4288                     }
4289                     i += k;
4290                     j++;
4291                 }
4292                 // Handle backing off if match fails
4293                 while (j >= backLimit) {
4294                    if (next.match(matcher, i, seq))
4295                         return true;
4296                     i -= k;
4297                     j--;
4298                 }
4299                 return false;
4300             }
4301             return next.match(matcher, i, seq);
4302         }
4303         // Reluctant match. At this point, the minimum has been satisfied.
4304         // i is the index to start matching at
4305         // j is the number of atoms that have matched
4306         boolean match1(Matcher matcher, int i, int j, CharSequence seq) {
4307             for (;;) {
4308                 // Try finishing match without consuming any more
4309                 if (next.match(matcher, i, seq))
4310                     return true;
4311                 // At the maximum, no match found
4312                 if (j >= cmax)
4313                     return false;
4314                 // Okay, must try one more atom
4315                 if (!atom.match(matcher, i, seq))
4316                     return false;
4317                 // If we haven't moved forward then must break out
4318                 if (i == matcher.last)
4319                     return false;
4320                 // Move up index and number matched
4321                 i = matcher.last;
4322                 j++;
4323             }
4324         }
4325         boolean match2(Matcher matcher, int i, int j, CharSequence seq) {
4326             for (; j < cmax; j++) {
4327                 if (!atom.match(matcher, i, seq))
4328                     break;
4329                 if (i == matcher.last)
4330                     break;
4331                 i = matcher.last;
4332             }
4333             return next.match(matcher, i, seq);
4334         }
4335         boolean study(TreeInfo info) {
4336             // Save original info
4337             int minL = info.minLength;
4338             int maxL = info.maxLength;
4339             boolean maxV = info.maxValid;
4340             boolean detm = info.deterministic;
4341             info.reset();
4342 
4343             atom.study(info);
4344 
4345             int temp = info.minLength * cmin + minL;
4346             if (temp < minL) {
4347                 temp = 0xFFFFFFF; // arbitrary large number
4348             }
4349             info.minLength = temp;
4350 
4351             if (maxV & info.maxValid) {
4352                 temp = info.maxLength * cmax + maxL;
4353                 info.maxLength = temp;
4354                 if (temp < maxL) {
4355                     info.maxValid = false;
4356                 }
4357             } else {
4358                 info.maxValid = false;
4359             }
4360 
4361             if (info.deterministic && cmin == cmax)
4362                 info.deterministic = detm;
4363             else
4364                 info.deterministic = false;
4365             return next.study(info);
4366         }
4367     }
4368 
4369     /**
4370      * Handles the curly-brace style repetition with a specified minimum and
4371      * maximum occurrences in deterministic cases. This is an iterative
4372      * optimization over the Prolog and Loop system which would handle this
4373      * in a recursive way. The * quantifier is handled as a special case.
4374      * If capture is true then this class saves group settings and ensures
4375      * that groups are unset when backing off of a group match.
4376      */
4377     static final class GroupCurly extends Node {
4378         Node atom;
4379         int type;
4380         int cmin;
4381         int cmax;
4382         int localIndex;
4383         int groupIndex;
4384         boolean capture;
4385 
4386         GroupCurly(Node node, int cmin, int cmax, int type, int local,
4387                    int group, boolean capture) {
4388             this.atom = node;
4389             this.type = type;
4390             this.cmin = cmin;
4391             this.cmax = cmax;
4392             this.localIndex = local;
4393             this.groupIndex = group;
4394             this.capture = capture;
4395         }
4396         boolean match(Matcher matcher, int i, CharSequence seq) {
4397             int[] groups = matcher.groups;
4398             int[] locals = matcher.locals;
4399             int save0 = locals[localIndex];
4400             int save1 = 0;
4401             int save2 = 0;
4402 
4403             if (capture) {
4404                 save1 = groups[groupIndex];
4405                 save2 = groups[groupIndex+1];
4406             }
4407 
4408             // Notify GroupTail there is no need to setup group info
4409             // because it will be set here
4410             locals[localIndex] = -1;
4411 
4412             boolean ret = true;
4413             for (int j = 0; j < cmin; j++) {
4414                 if (atom.match(matcher, i, seq)) {
4415                     if (capture) {
4416                         groups[groupIndex] = i;
4417                         groups[groupIndex+1] = matcher.last;
4418                     }
4419                     i = matcher.last;
4420                 } else {
4421                     ret = false;
4422                     break;
4423                 }
4424             }
4425             if (ret) {
4426                 if (type == GREEDY) {
4427                     ret = match0(matcher, i, cmin, seq);
4428                 } else if (type == LAZY) {
4429                     ret = match1(matcher, i, cmin, seq);
4430                 } else {
4431                     ret = match2(matcher, i, cmin, seq);
4432                 }
4433             }
4434             if (!ret) {
4435                 locals[localIndex] = save0;
4436                 if (capture) {
4437                     groups[groupIndex] = save1;
4438                     groups[groupIndex+1] = save2;
4439                 }
4440             }
4441             return ret;
4442         }
4443         // Aggressive group match
4444         boolean match0(Matcher matcher, int i, int j, CharSequence seq) {
4445             // don't back off passing the starting "j"
4446             int min = j;
4447             int[] groups = matcher.groups;
4448             int save0 = 0;
4449             int save1 = 0;
4450             if (capture) {
4451                 save0 = groups[groupIndex];
4452                 save1 = groups[groupIndex+1];
4453             }
4454             for (;;) {
4455                 if (j >= cmax)
4456                     break;
4457                 if (!atom.match(matcher, i, seq))
4458                     break;
4459                 int k = matcher.last - i;
4460                 if (k <= 0) {
4461                     if (capture) {
4462                         groups[groupIndex] = i;
4463                         groups[groupIndex+1] = i + k;
4464                     }
4465                     i = i + k;
4466                     break;
4467                 }
4468                 for (;;) {
4469                     if (capture) {
4470                         groups[groupIndex] = i;
4471                         groups[groupIndex+1] = i + k;
4472                     }
4473                     i = i + k;
4474                     if (++j >= cmax)
4475                         break;
4476                     if (!atom.match(matcher, i, seq))
4477                         break;
4478                     if (i + k != matcher.last) {
4479                         if (match0(matcher, i, j, seq))
4480                             return true;
4481                         break;
4482                     }
4483                 }
4484                 while (j > min) {
4485                     if (next.match(matcher, i, seq)) {
4486                         if (capture) {
4487                             groups[groupIndex+1] = i;
4488                             groups[groupIndex] = i - k;
4489                         }
4490                         return true;
4491                     }
4492                     // backing off
4493                     i = i - k;
4494                     if (capture) {
4495                         groups[groupIndex+1] = i;
4496                         groups[groupIndex] = i - k;
4497                     }
4498                     j--;
4499 
4500                 }
4501                 break;
4502             }
4503             if (capture) {
4504                 groups[groupIndex] = save0;
4505                 groups[groupIndex+1] = save1;
4506             }
4507             return next.match(matcher, i, seq);
4508         }
4509         // Reluctant matching
4510         boolean match1(Matcher matcher, int i, int j, CharSequence seq) {
4511             for (;;) {
4512                 if (next.match(matcher, i, seq))
4513                     return true;
4514                 if (j >= cmax)
4515                     return false;
4516                 if (!atom.match(matcher, i, seq))
4517                     return false;
4518                 if (i == matcher.last)
4519                     return false;
4520                 if (capture) {
4521                     matcher.groups[groupIndex] = i;
4522                     matcher.groups[groupIndex+1] = matcher.last;
4523                 }
4524                 i = matcher.last;
4525                 j++;
4526             }
4527         }
4528         // Possessive matching
4529         boolean match2(Matcher matcher, int i, int j, CharSequence seq) {
4530             for (; j < cmax; j++) {
4531                 if (!atom.match(matcher, i, seq)) {
4532                     break;
4533                 }
4534                 if (capture) {
4535                     matcher.groups[groupIndex] = i;
4536                     matcher.groups[groupIndex+1] = matcher.last;
4537                 }
4538                 if (i == matcher.last) {
4539                     break;
4540                 }
4541                 i = matcher.last;
4542             }
4543             return next.match(matcher, i, seq);
4544         }
4545         boolean study(TreeInfo info) {
4546             // Save original info
4547             int minL = info.minLength;
4548             int maxL = info.maxLength;
4549             boolean maxV = info.maxValid;
4550             boolean detm = info.deterministic;
4551             info.reset();
4552 
4553             atom.study(info);
4554 
4555             int temp = info.minLength * cmin + minL;
4556             if (temp < minL) {
4557                 temp = 0xFFFFFFF; // Arbitrary large number
4558             }
4559             info.minLength = temp;
4560 
4561             if (maxV & info.maxValid) {
4562                 temp = info.maxLength * cmax + maxL;
4563                 info.maxLength = temp;
4564                 if (temp < maxL) {
4565                     info.maxValid = false;
4566                 }
4567             } else {
4568                 info.maxValid = false;
4569             }
4570 
4571             if (info.deterministic && cmin == cmax) {
4572                 info.deterministic = detm;
4573             } else {
4574                 info.deterministic = false;
4575             }
4576             return next.study(info);
4577         }
4578     }
4579 
4580     /**
4581      * A Guard node at the end of each atom node in a Branch. It
4582      * serves the purpose of chaining the "match" operation to
4583      * "next" but not the "study", so we can collect the TreeInfo
4584      * of each atom node without including the TreeInfo of the
4585      * "next".
4586      */
4587     static final class BranchConn extends Node {
4588         BranchConn() {};
4589         boolean match(Matcher matcher, int i, CharSequence seq) {
4590             return next.match(matcher, i, seq);
4591         }
4592         boolean study(TreeInfo info) {
4593             return info.deterministic;
4594         }
4595     }
4596 
4597     /**
4598      * Handles the branching of alternations. Note this is also used for
4599      * the ? quantifier to branch between the case where it matches once
4600      * and where it does not occur.
4601      */
4602     static final class Branch extends Node {
4603         Node[] atoms = new Node[2];
4604         int size = 2;
4605         Node conn;
4606         Branch(Node first, Node second, Node branchConn) {
4607             conn = branchConn;
4608             atoms[0] = first;
4609             atoms[1] = second;
4610         }
4611 
4612         void add(Node node) {
4613             if (size >= atoms.length) {
4614                 Node[] tmp = new Node[atoms.length*2];
4615                 System.arraycopy(atoms, 0, tmp, 0, atoms.length);
4616                 atoms = tmp;
4617             }
4618             atoms[size++] = node;
4619         }
4620 
4621         boolean match(Matcher matcher, int i, CharSequence seq) {
4622             for (int n = 0; n < size; n++) {
4623                 if (atoms[n] == null) {
4624                     if (conn.next.match(matcher, i, seq))
4625                         return true;
4626                 } else if (atoms[n].match(matcher, i, seq)) {
4627                     return true;
4628                 }
4629             }
4630             return false;
4631         }
4632 
4633         boolean study(TreeInfo info) {
4634             int minL = info.minLength;
4635             int maxL = info.maxLength;
4636             boolean maxV = info.maxValid;
4637 
4638             int minL2 = Integer.MAX_VALUE; //arbitrary large enough num
4639             int maxL2 = -1;
4640             for (int n = 0; n < size; n++) {
4641                 info.reset();
4642                 if (atoms[n] != null)
4643                     atoms[n].study(info);
4644                 minL2 = Math.min(minL2, info.minLength);
4645                 maxL2 = Math.max(maxL2, info.maxLength);
4646                 maxV = (maxV & info.maxValid);
4647             }
4648 
4649             minL += minL2;
4650             maxL += maxL2;
4651 
4652             info.reset();
4653             conn.next.study(info);
4654 
4655             info.minLength += minL;
4656             info.maxLength += maxL;
4657             info.maxValid &= maxV;
4658             info.deterministic = false;
4659             return false;
4660         }
4661     }
4662 
4663     /**
4664      * The GroupHead saves the location where the group begins in the locals
4665      * and restores them when the match is done.
4666      *
4667      * The matchRef is used when a reference to this group is accessed later
4668      * in the expression. The locals will have a negative value in them to
4669      * indicate that we do not want to unset the group if the reference
4670      * doesn't match.
4671      */
4672     static final class GroupHead extends Node {
4673         int localIndex;
4674         GroupHead(int localCount) {
4675             localIndex = localCount;
4676         }
4677         boolean match(Matcher matcher, int i, CharSequence seq) {
4678             int save = matcher.locals[localIndex];
4679             matcher.locals[localIndex] = i;
4680             boolean ret = next.match(matcher, i, seq);
4681             matcher.locals[localIndex] = save;
4682             return ret;
4683         }
4684         boolean matchRef(Matcher matcher, int i, CharSequence seq) {
4685             int save = matcher.locals[localIndex];
4686             matcher.locals[localIndex] = ~i; // HACK
4687             boolean ret = next.match(matcher, i, seq);
4688             matcher.locals[localIndex] = save;
4689             return ret;
4690         }
4691     }
4692 
4693     /**
4694      * Recursive reference to a group in the regular expression. It calls
4695      * matchRef because if the reference fails to match we would not unset
4696      * the group.
4697      */
4698     static final class GroupRef extends Node {
4699         GroupHead head;
4700         GroupRef(GroupHead head) {
4701             this.head = head;
4702         }
4703         boolean match(Matcher matcher, int i, CharSequence seq) {
4704             return head.matchRef(matcher, i, seq)
4705                 && next.match(matcher, matcher.last, seq);
4706         }
4707         boolean study(TreeInfo info) {
4708             info.maxValid = false;
4709             info.deterministic = false;
4710             return next.study(info);
4711         }
4712     }
4713 
4714     /**
4715      * The GroupTail handles the setting of group beginning and ending
4716      * locations when groups are successfully matched. It must also be able to
4717      * unset groups that have to be backed off of.
4718      *
4719      * The GroupTail node is also used when a previous group is referenced,
4720      * and in that case no group information needs to be set.
4721      */
4722     static final class GroupTail extends Node {
4723         int localIndex;
4724         int groupIndex;
4725         GroupTail(int localCount, int groupCount) {
4726             localIndex = localCount;
4727             groupIndex = groupCount + groupCount;
4728         }
4729         boolean match(Matcher matcher, int i, CharSequence seq) {
4730             int tmp = matcher.locals[localIndex];
4731             if (tmp >= 0) { // This is the normal group case.
4732                 // Save the group so we can unset it if it
4733                 // backs off of a match.
4734                 int groupStart = matcher.groups[groupIndex];
4735                 int groupEnd = matcher.groups[groupIndex+1];
4736 
4737                 matcher.groups[groupIndex] = tmp;
4738                 matcher.groups[groupIndex+1] = i;
4739                 if (next.match(matcher, i, seq)) {
4740                     return true;
4741                 }
4742                 matcher.groups[groupIndex] = groupStart;
4743                 matcher.groups[groupIndex+1] = groupEnd;
4744                 return false;
4745             } else {
4746                 // This is a group reference case. We don't need to save any
4747                 // group info because it isn't really a group.
4748                 matcher.last = i;
4749                 return true;
4750             }
4751         }
4752     }
4753 
4754     /**
4755      * This sets up a loop to handle a recursive quantifier structure.
4756      */
4757     static final class Prolog extends Node {
4758         Loop loop;
4759         Prolog(Loop loop) {
4760             this.loop = loop;
4761         }
4762         boolean match(Matcher matcher, int i, CharSequence seq) {
4763             return loop.matchInit(matcher, i, seq);
4764         }
4765         boolean study(TreeInfo info) {
4766             return loop.study(info);
4767         }
4768     }
4769 
4770     /**
4771      * Handles the repetition count for a greedy Curly. The matchInit
4772      * is called from the Prolog to save the index of where the group
4773      * beginning is stored. A zero length group check occurs in the
4774      * normal match but is skipped in the matchInit.
4775      */
4776     static class Loop extends Node {
4777         Node body;
4778         int countIndex; // local count index in matcher locals
4779         int beginIndex; // group beginning index
4780         int cmin, cmax;
4781         Loop(int countIndex, int beginIndex) {
4782             this.countIndex = countIndex;
4783             this.beginIndex = beginIndex;
4784         }
4785         boolean match(Matcher matcher, int i, CharSequence seq) {
4786             // Avoid infinite loop in zero-length case.
4787             if (i > matcher.locals[beginIndex]) {
4788                 int count = matcher.locals[countIndex];
4789 
4790                 // This block is for before we reach the minimum
4791                 // iterations required for the loop to match
4792                 if (count < cmin) {
4793                     matcher.locals[countIndex] = count + 1;
4794                     boolean b = body.match(matcher, i, seq);
4795                     // If match failed we must backtrack, so
4796                     // the loop count should NOT be incremented
4797                     if (!b)
4798                         matcher.locals[countIndex] = count;
4799                     // Return success or failure since we are under
4800                     // minimum
4801                     return b;
4802                 }
4803                 // This block is for after we have the minimum
4804                 // iterations required for the loop to match
4805                 if (count < cmax) {
4806                     matcher.locals[countIndex] = count + 1;
4807                     boolean b = body.match(matcher, i, seq);
4808                     // If match failed we must backtrack, so
4809                     // the loop count should NOT be incremented
4810                     if (!b)
4811                         matcher.locals[countIndex] = count;
4812                     else
4813                         return true;
4814                 }
4815             }
4816             return next.match(matcher, i, seq);
4817         }
4818         boolean matchInit(Matcher matcher, int i, CharSequence seq) {
4819             int save = matcher.locals[countIndex];
4820             boolean ret = false;
4821             if (0 < cmin) {
4822                 matcher.locals[countIndex] = 1;
4823                 ret = body.match(matcher, i, seq);
4824             } else if (0 < cmax) {
4825                 matcher.locals[countIndex] = 1;
4826                 ret = body.match(matcher, i, seq);
4827                 if (ret == false)
4828                     ret = next.match(matcher, i, seq);
4829             } else {
4830                 ret = next.match(matcher, i, seq);
4831             }
4832             matcher.locals[countIndex] = save;
4833             return ret;
4834         }
4835         boolean study(TreeInfo info) {
4836             info.maxValid = false;
4837             info.deterministic = false;
4838             return false;
4839         }
4840     }
4841 
4842     /**
4843      * Handles the repetition count for a reluctant Curly. The matchInit
4844      * is called from the Prolog to save the index of where the group
4845      * beginning is stored. A zero length group check occurs in the
4846      * normal match but is skipped in the matchInit.
4847      */
4848     static final class LazyLoop extends Loop {
4849         LazyLoop(int countIndex, int beginIndex) {
4850             super(countIndex, beginIndex);
4851         }
4852         boolean match(Matcher matcher, int i, CharSequence seq) {
4853             // Check for zero length group
4854             if (i > matcher.locals[beginIndex]) {
4855                 int count = matcher.locals[countIndex];
4856                 if (count < cmin) {
4857                     matcher.locals[countIndex] = count + 1;
4858                     boolean result = body.match(matcher, i, seq);
4859                     // If match failed we must backtrack, so
4860                     // the loop count should NOT be incremented
4861                     if (!result)
4862                         matcher.locals[countIndex] = count;
4863                     return result;
4864                 }
4865                 if (next.match(matcher, i, seq))
4866                     return true;
4867                 if (count < cmax) {
4868                     matcher.locals[countIndex] = count + 1;
4869                     boolean result = body.match(matcher, i, seq);
4870                     // If match failed we must backtrack, so
4871                     // the loop count should NOT be incremented
4872                     if (!result)
4873                         matcher.locals[countIndex] = count;
4874                     return result;
4875                 }
4876                 return false;
4877             }
4878             return next.match(matcher, i, seq);
4879         }
4880         boolean matchInit(Matcher matcher, int i, CharSequence seq) {
4881             int save = matcher.locals[countIndex];
4882             boolean ret = false;
4883             if (0 < cmin) {
4884                 matcher.locals[countIndex] = 1;
4885                 ret = body.match(matcher, i, seq);
4886             } else if (next.match(matcher, i, seq)) {
4887                 ret = true;
4888             } else if (0 < cmax) {
4889                 matcher.locals[countIndex] = 1;
4890                 ret = body.match(matcher, i, seq);
4891             }
4892             matcher.locals[countIndex] = save;
4893             return ret;
4894         }
4895         boolean study(TreeInfo info) {
4896             info.maxValid = false;
4897             info.deterministic = false;
4898             return false;
4899         }
4900     }
4901 
4902     /**
4903      * Refers to a group in the regular expression. Attempts to match
4904      * whatever the group referred to last matched.
4905      */
4906     static class BackRef extends Node {
4907         int groupIndex;
4908         BackRef(int groupCount) {
4909             super();
4910             groupIndex = groupCount + groupCount;
4911         }
4912         boolean match(Matcher matcher, int i, CharSequence seq) {
4913             int j = matcher.groups[groupIndex];
4914             int k = matcher.groups[groupIndex+1];
4915 
4916             int groupSize = k - j;
4917             // If the referenced group didn't match, neither can this
4918             if (j < 0)
4919                 return false;
4920 
4921             // If there isn't enough input left no match
4922             if (i + groupSize > matcher.to) {
4923                 matcher.hitEnd = true;
4924                 return false;
4925             }
4926             // Check each new char to make sure it matches what the group
4927             // referenced matched last time around
4928             for (int index=0; index<groupSize; index++)
4929                 if (seq.charAt(i+index) != seq.charAt(j+index))
4930                     return false;
4931 
4932             return next.match(matcher, i+groupSize, seq);
4933         }
4934         boolean study(TreeInfo info) {
4935             info.maxValid = false;
4936             return next.study(info);
4937         }
4938     }
4939 
4940     static class CIBackRef extends Node {
4941         int groupIndex;
4942         boolean doUnicodeCase;
4943         CIBackRef(int groupCount, boolean doUnicodeCase) {
4944             super();
4945             groupIndex = groupCount + groupCount;
4946             this.doUnicodeCase = doUnicodeCase;
4947         }
4948         boolean match(Matcher matcher, int i, CharSequence seq) {
4949             int j = matcher.groups[groupIndex];
4950             int k = matcher.groups[groupIndex+1];
4951 
4952             int groupSize = k - j;
4953 
4954             // If the referenced group didn't match, neither can this
4955             if (j < 0)
4956                 return false;
4957 
4958             // If there isn't enough input left no match
4959             if (i + groupSize > matcher.to) {
4960                 matcher.hitEnd = true;
4961                 return false;
4962             }
4963 
4964             // Check each new char to make sure it matches what the group
4965             // referenced matched last time around
4966             int x = i;
4967             for (int index=0; index<groupSize; index++) {
4968                 int c1 = Character.codePointAt(seq, x);
4969                 int c2 = Character.codePointAt(seq, j);
4970                 if (c1 != c2) {
4971                     if (doUnicodeCase) {
4972                         int cc1 = Character.toUpperCase(c1);
4973                         int cc2 = Character.toUpperCase(c2);
4974                         if (cc1 != cc2 &&
4975                             Character.toLowerCase(cc1) !=
4976                             Character.toLowerCase(cc2))
4977                             return false;
4978                     } else {
4979                         if (ASCII.toLower(c1) != ASCII.toLower(c2))
4980                             return false;
4981                     }
4982                 }
4983                 x += Character.charCount(c1);
4984                 j += Character.charCount(c2);
4985             }
4986 
4987             return next.match(matcher, i+groupSize, seq);
4988         }
4989         boolean study(TreeInfo info) {
4990             info.maxValid = false;
4991             return next.study(info);
4992         }
4993     }
4994 
4995     /**
4996      * Searches until the next instance of its atom. This is useful for
4997      * finding the atom efficiently without passing an instance of it
4998      * (greedy problem) and without a lot of wasted search time (reluctant
4999      * problem).
5000      */
5001     static final class First extends Node {
5002         Node atom;
5003         First(Node node) {
5004             this.atom = BnM.optimize(node);
5005         }
5006         boolean match(Matcher matcher, int i, CharSequence seq) {
5007             if (atom instanceof BnM) {
5008                 return atom.match(matcher, i, seq)
5009                     && next.match(matcher, matcher.last, seq);
5010             }
5011             for (;;) {
5012                 if (i > matcher.to) {
5013                     matcher.hitEnd = true;
5014                     return false;
5015                 }
5016                 if (atom.match(matcher, i, seq)) {
5017                     return next.match(matcher, matcher.last, seq);
5018                 }
5019                 i += countChars(seq, i, 1);
5020                 matcher.first++;
5021             }
5022         }
5023         boolean study(TreeInfo info) {
5024             atom.study(info);
5025             info.maxValid = false;
5026             info.deterministic = false;
5027             return next.study(info);
5028         }
5029     }
5030 
5031     static final class Conditional extends Node {
5032         Node cond, yes, not;
5033         Conditional(Node cond, Node yes, Node not) {
5034             this.cond = cond;
5035             this.yes = yes;
5036             this.not = not;
5037         }
5038         boolean match(Matcher matcher, int i, CharSequence seq) {
5039             if (cond.match(matcher, i, seq)) {
5040                 return yes.match(matcher, i, seq);
5041             } else {
5042                 return not.match(matcher, i, seq);
5043             }
5044         }
5045         boolean study(TreeInfo info) {
5046             int minL = info.minLength;
5047             int maxL = info.maxLength;
5048             boolean maxV = info.maxValid;
5049             info.reset();
5050             yes.study(info);
5051 
5052             int minL2 = info.minLength;
5053             int maxL2 = info.maxLength;
5054             boolean maxV2 = info.maxValid;
5055             info.reset();
5056             not.study(info);
5057 
5058             info.minLength = minL + Math.min(minL2, info.minLength);
5059             info.maxLength = maxL + Math.max(maxL2, info.maxLength);
5060             info.maxValid = (maxV & maxV2 & info.maxValid);
5061             info.deterministic = false;
5062             return next.study(info);
5063         }
5064     }
5065 
5066     /**
5067      * Zero width positive lookahead.
5068      */
5069     static final class Pos extends Node {
5070         Node cond;
5071         Pos(Node cond) {
5072             this.cond = cond;
5073         }
5074         boolean match(Matcher matcher, int i, CharSequence seq) {
5075             int savedTo = matcher.to;
5076             boolean conditionMatched = false;
5077 
5078             // Relax transparent region boundaries for lookahead
5079             if (matcher.transparentBounds)
5080                 matcher.to = matcher.getTextLength();
5081             try {
5082                 conditionMatched = cond.match(matcher, i, seq);
5083             } finally {
5084                 // Reinstate region boundaries
5085                 matcher.to = savedTo;
5086             }
5087             return conditionMatched && next.match(matcher, i, seq);
5088         }
5089     }
5090 
5091     /**
5092      * Zero width negative lookahead.
5093      */
5094     static final class Neg extends Node {
5095         Node cond;
5096         Neg(Node cond) {
5097             this.cond = cond;
5098         }
5099         boolean match(Matcher matcher, int i, CharSequence seq) {
5100             int savedTo = matcher.to;
5101             boolean conditionMatched = false;
5102 
5103             // Relax transparent region boundaries for lookahead
5104             if (matcher.transparentBounds)
5105                 matcher.to = matcher.getTextLength();
5106             try {
5107                 if (i < matcher.to) {
5108                     conditionMatched = !cond.match(matcher, i, seq);
5109                 } else {
5110                     // If a negative lookahead succeeds then more input
5111                     // could cause it to fail!
5112                     matcher.requireEnd = true;
5113                     conditionMatched = !cond.match(matcher, i, seq);
5114                 }
5115             } finally {
5116                 // Reinstate region boundaries
5117                 matcher.to = savedTo;
5118             }
5119             return conditionMatched && next.match(matcher, i, seq);
5120         }
5121     }
5122 
5123     /**
5124      * For use with lookbehinds; matches the position where the lookbehind
5125      * was encountered.
5126      */
5127     static Node lookbehindEnd = new Node() {
5128         boolean match(Matcher matcher, int i, CharSequence seq) {
5129             return i == matcher.lookbehindTo;
5130         }
5131     };
5132 
5133     /**
5134      * Zero width positive lookbehind.
5135      */
5136     static class Behind extends Node {
5137         Node cond;
5138         int rmax, rmin;
5139         Behind(Node cond, int rmax, int rmin) {
5140             this.cond = cond;
5141             this.rmax = rmax;
5142             this.rmin = rmin;
5143         }
5144 
5145         boolean match(Matcher matcher, int i, CharSequence seq) {
5146             int savedFrom = matcher.from;
5147             boolean conditionMatched = false;
5148             int startIndex = (!matcher.transparentBounds) ?
5149                              matcher.from : 0;
5150             int from = Math.max(i - rmax, startIndex);
5151             // Set end boundary
5152             int savedLBT = matcher.lookbehindTo;
5153             matcher.lookbehindTo = i;
5154             // Relax transparent region boundaries for lookbehind
5155             if (matcher.transparentBounds)
5156                 matcher.from = 0;
5157             for (int j = i - rmin; !conditionMatched && j >= from; j--) {
5158                 conditionMatched = cond.match(matcher, j, seq);
5159             }
5160             matcher.from = savedFrom;
5161             matcher.lookbehindTo = savedLBT;
5162             return conditionMatched && next.match(matcher, i, seq);
5163         }
5164     }
5165 
5166     /**
5167      * Zero width positive lookbehind, including supplementary
5168      * characters or unpaired surrogates.
5169      */
5170     static final class BehindS extends Behind {
5171         BehindS(Node cond, int rmax, int rmin) {
5172             super(cond, rmax, rmin);
5173         }
5174         boolean match(Matcher matcher, int i, CharSequence seq) {
5175             int rmaxChars = countChars(seq, i, -rmax);
5176             int rminChars = countChars(seq, i, -rmin);
5177             int savedFrom = matcher.from;
5178             int startIndex = (!matcher.transparentBounds) ?
5179                              matcher.from : 0;
5180             boolean conditionMatched = false;
5181             int from = Math.max(i - rmaxChars, startIndex);
5182             // Set end boundary
5183             int savedLBT = matcher.lookbehindTo;
5184             matcher.lookbehindTo = i;
5185             // Relax transparent region boundaries for lookbehind
5186             if (matcher.transparentBounds)
5187                 matcher.from = 0;
5188 
5189             for (int j = i - rminChars;
5190                  !conditionMatched && j >= from;
5191                  j -= j>from ? countChars(seq, j, -1) : 1) {
5192                 conditionMatched = cond.match(matcher, j, seq);
5193             }
5194             matcher.from = savedFrom;
5195             matcher.lookbehindTo = savedLBT;
5196             return conditionMatched && next.match(matcher, i, seq);
5197         }
5198     }
5199 
5200     /**
5201      * Zero width negative lookbehind.
5202      */
5203     static class NotBehind extends Node {
5204         Node cond;
5205         int rmax, rmin;
5206         NotBehind(Node cond, int rmax, int rmin) {
5207             this.cond = cond;
5208             this.rmax = rmax;
5209             this.rmin = rmin;
5210         }
5211 
5212         boolean match(Matcher matcher, int i, CharSequence seq) {
5213             int savedLBT = matcher.lookbehindTo;
5214             int savedFrom = matcher.from;
5215             boolean conditionMatched = false;
5216             int startIndex = (!matcher.transparentBounds) ?
5217                              matcher.from : 0;
5218             int from = Math.max(i - rmax, startIndex);
5219             matcher.lookbehindTo = i;
5220             // Relax transparent region boundaries for lookbehind
5221             if (matcher.transparentBounds)
5222                 matcher.from = 0;
5223             for (int j = i - rmin; !conditionMatched && j >= from; j--) {
5224                 conditionMatched = cond.match(matcher, j, seq);
5225             }
5226             // Reinstate region boundaries
5227             matcher.from = savedFrom;
5228             matcher.lookbehindTo = savedLBT;
5229             return !conditionMatched && next.match(matcher, i, seq);
5230         }
5231     }
5232 
5233     /**
5234      * Zero width negative lookbehind, including supplementary
5235      * characters or unpaired surrogates.
5236      */
5237     static final class NotBehindS extends NotBehind {
5238         NotBehindS(Node cond, int rmax, int rmin) {
5239             super(cond, rmax, rmin);
5240         }
5241         boolean match(Matcher matcher, int i, CharSequence seq) {
5242             int rmaxChars = countChars(seq, i, -rmax);
5243             int rminChars = countChars(seq, i, -rmin);
5244             int savedFrom = matcher.from;
5245             int savedLBT = matcher.lookbehindTo;
5246             boolean conditionMatched = false;
5247             int startIndex = (!matcher.transparentBounds) ?
5248                              matcher.from : 0;
5249             int from = Math.max(i - rmaxChars, startIndex);
5250             matcher.lookbehindTo = i;
5251             // Relax transparent region boundaries for lookbehind
5252             if (matcher.transparentBounds)
5253                 matcher.from = 0;
5254             for (int j = i - rminChars;
5255                  !conditionMatched && j >= from;
5256                  j -= j>from ? countChars(seq, j, -1) : 1) {
5257                 conditionMatched = cond.match(matcher, j, seq);
5258             }
5259             //Reinstate region boundaries
5260             matcher.from = savedFrom;
5261             matcher.lookbehindTo = savedLBT;
5262             return !conditionMatched && next.match(matcher, i, seq);
5263         }
5264     }
5265 
5266     /**
5267      * Returns the set union of two CharProperty nodes.
5268      */
5269     private static CharProperty union(final CharProperty lhs,
5270                                       final CharProperty rhs) {
5271         return new CharProperty() {
5272                 boolean isSatisfiedBy(int ch) {
5273                     return lhs.isSatisfiedBy(ch) || rhs.isSatisfiedBy(ch);}};
5274     }
5275 
5276     /**
5277      * Returns the set intersection of two CharProperty nodes.
5278      */
5279     private static CharProperty intersection(final CharProperty lhs,
5280                                              final CharProperty rhs) {
5281         return new CharProperty() {
5282                 boolean isSatisfiedBy(int ch) {
5283                     return lhs.isSatisfiedBy(ch) && rhs.isSatisfiedBy(ch);}};
5284     }
5285 
5286     /**
5287      * Returns the set difference of two CharProperty nodes.
5288      */
5289     private static CharProperty setDifference(final CharProperty lhs,
5290                                               final CharProperty rhs) {
5291         return new CharProperty() {
5292                 boolean isSatisfiedBy(int ch) {
5293                     return ! rhs.isSatisfiedBy(ch) && lhs.isSatisfiedBy(ch);}};
5294     }
5295 
5296     /**
5297      * Handles word boundaries. Includes a field to allow this one class to
5298      * deal with the different types of word boundaries we can match. The word
5299      * characters include underscores, letters, and digits. Non spacing marks
5300      * can are also part of a word if they have a base character, otherwise
5301      * they are ignored for purposes of finding word boundaries.
5302      */
5303     static final class Bound extends Node {
5304         static int LEFT = 0x1;
5305         static int RIGHT= 0x2;
5306         static int BOTH = 0x3;
5307         static int NONE = 0x4;
5308         int type;
5309         boolean useUWORD;
5310         Bound(int n, boolean useUWORD) {
5311             type = n;
5312             this.useUWORD = useUWORD;
5313         }
5314 
5315         boolean isWord(int ch) {
5316             return useUWORD ? UnicodeProp.WORD.is(ch)
5317                             : (ch == '_' || Character.isLetterOrDigit(ch));
5318         }
5319 
5320         int check(Matcher matcher, int i, CharSequence seq) {
5321             int ch;
5322             boolean left = false;
5323             int startIndex = matcher.from;
5324             int endIndex = matcher.to;
5325             if (matcher.transparentBounds) {
5326                 startIndex = 0;
5327                 endIndex = matcher.getTextLength();
5328             }
5329             if (i > startIndex) {
5330                 ch = Character.codePointBefore(seq, i);
5331                 left = (isWord(ch) ||
5332                     ((Character.getType(ch) == Character.NON_SPACING_MARK)
5333                      && hasBaseCharacter(matcher, i-1, seq)));
5334             }
5335             boolean right = false;
5336             if (i < endIndex) {
5337                 ch = Character.codePointAt(seq, i);
5338                 right = (isWord(ch) ||
5339                     ((Character.getType(ch) == Character.NON_SPACING_MARK)
5340                      && hasBaseCharacter(matcher, i, seq)));
5341             } else {
5342                 // Tried to access char past the end
5343                 matcher.hitEnd = true;
5344                 // The addition of another char could wreck a boundary
5345                 matcher.requireEnd = true;
5346             }
5347             return ((left ^ right) ? (right ? LEFT : RIGHT) : NONE);
5348         }
5349         boolean match(Matcher matcher, int i, CharSequence seq) {
5350             return (check(matcher, i, seq) & type) > 0
5351                 && next.match(matcher, i, seq);
5352         }
5353     }
5354 
5355     /**
5356      * Non spacing marks only count as word characters in bounds calculations
5357      * if they have a base character.
5358      */
5359     private static boolean hasBaseCharacter(Matcher matcher, int i,
5360                                             CharSequence seq)
5361     {
5362         int start = (!matcher.transparentBounds) ?
5363             matcher.from : 0;
5364         for (int x=i; x >= start; x--) {
5365             int ch = Character.codePointAt(seq, x);
5366             if (Character.isLetterOrDigit(ch))
5367                 return true;
5368             if (Character.getType(ch) == Character.NON_SPACING_MARK)
5369                 continue;
5370             return false;
5371         }
5372         return false;
5373     }
5374 
5375     /**
5376      * Attempts to match a slice in the input using the Boyer-Moore string
5377      * matching algorithm. The algorithm is based on the idea that the
5378      * pattern can be shifted farther ahead in the search text if it is
5379      * matched right to left.
5380      * <p>
5381      * The pattern is compared to the input one character at a time, from
5382      * the rightmost character in the pattern to the left. If the characters
5383      * all match the pattern has been found. If a character does not match,
5384      * the pattern is shifted right a distance that is the maximum of two
5385      * functions, the bad character shift and the good suffix shift. This
5386      * shift moves the attempted match position through the input more
5387      * quickly than a naive one position at a time check.
5388      * <p>
5389      * The bad character shift is based on the character from the text that
5390      * did not match. If the character does not appear in the pattern, the
5391      * pattern can be shifted completely beyond the bad character. If the
5392      * character does occur in the pattern, the pattern can be shifted to
5393      * line the pattern up with the next occurrence of that character.
5394      * <p>
5395      * The good suffix shift is based on the idea that some subset on the right
5396      * side of the pattern has matched. When a bad character is found, the
5397      * pattern can be shifted right by the pattern length if the subset does
5398      * not occur again in pattern, or by the amount of distance to the
5399      * next occurrence of the subset in the pattern.
5400      *
5401      * Boyer-Moore search methods adapted from code by Amy Yu.
5402      */
5403     static class BnM extends Node {
5404         int[] buffer;
5405         int[] lastOcc;
5406         int[] optoSft;
5407 
5408         /**
5409          * Pre calculates arrays needed to generate the bad character
5410          * shift and the good suffix shift. Only the last seven bits
5411          * are used to see if chars match; This keeps the tables small
5412          * and covers the heavily used ASCII range, but occasionally
5413          * results in an aliased match for the bad character shift.
5414          */
5415         static Node optimize(Node node) {
5416             if (!(node instanceof Slice)) {
5417                 return node;
5418             }
5419 
5420             int[] src = ((Slice) node).buffer;
5421             int patternLength = src.length;
5422             // The BM algorithm requires a bit of overhead;
5423             // If the pattern is short don't use it, since
5424             // a shift larger than the pattern length cannot
5425             // be used anyway.
5426             if (patternLength < 4) {
5427                 return node;
5428             }
5429             int i, j, k;
5430             int[] lastOcc = new int[128];
5431             int[] optoSft = new int[patternLength];
5432             // Precalculate part of the bad character shift
5433             // It is a table for where in the pattern each
5434             // lower 7-bit value occurs
5435             for (i = 0; i < patternLength; i++) {
5436                 lastOcc[src[i]&0x7F] = i + 1;
5437             }
5438             // Precalculate the good suffix shift
5439             // i is the shift amount being considered
5440 NEXT:       for (i = patternLength; i > 0; i--) {
5441                 // j is the beginning index of suffix being considered
5442                 for (j = patternLength - 1; j >= i; j--) {
5443                     // Testing for good suffix
5444                     if (src[j] == src[j-i]) {
5445                         // src[j..len] is a good suffix
5446                         optoSft[j-1] = i;
5447                     } else {
5448                         // No match. The array has already been
5449                         // filled up with correct values before.
5450                         continue NEXT;
5451                     }
5452                 }
5453                 // This fills up the remaining of optoSft
5454                 // any suffix can not have larger shift amount
5455                 // then its sub-suffix. Why???
5456                 while (j > 0) {
5457                     optoSft[--j] = i;
5458                 }
5459             }
5460             // Set the guard value because of unicode compression
5461             optoSft[patternLength-1] = 1;
5462             if (node instanceof SliceS)
5463                 return new BnMS(src, lastOcc, optoSft, node.next);
5464             return new BnM(src, lastOcc, optoSft, node.next);
5465         }
5466         BnM(int[] src, int[] lastOcc, int[] optoSft, Node next) {
5467             this.buffer = src;
5468             this.lastOcc = lastOcc;
5469             this.optoSft = optoSft;
5470             this.next = next;
5471         }
5472         boolean match(Matcher matcher, int i, CharSequence seq) {
5473             int[] src = buffer;
5474             int patternLength = src.length;
5475             int last = matcher.to - patternLength;
5476 
5477             // Loop over all possible match positions in text
5478 NEXT:       while (i <= last) {
5479                 // Loop over pattern from right to left
5480                 for (int j = patternLength - 1; j >= 0; j--) {
5481                     int ch = seq.charAt(i+j);
5482                     if (ch != src[j]) {
5483                         // Shift search to the right by the maximum of the
5484                         // bad character shift and the good suffix shift
5485                         i += Math.max(j + 1 - lastOcc[ch&0x7F], optoSft[j]);
5486                         continue NEXT;
5487                     }
5488                 }
5489                 // Entire pattern matched starting at i
5490                 matcher.first = i;
5491                 boolean ret = next.match(matcher, i + patternLength, seq);
5492                 if (ret) {
5493                     matcher.first = i;
5494                     matcher.groups[0] = matcher.first;
5495                     matcher.groups[1] = matcher.last;
5496                     return true;
5497                 }
5498                 i++;
5499             }
5500             // BnM is only used as the leading node in the unanchored case,
5501             // and it replaced its Start() which always searches to the end
5502             // if it doesn't find what it's looking for, so hitEnd is true.
5503             matcher.hitEnd = true;
5504             return false;
5505         }
5506         boolean study(TreeInfo info) {
5507             info.minLength += buffer.length;
5508             info.maxValid = false;
5509             return next.study(info);
5510         }
5511     }
5512 
5513     /**
5514      * Supplementary support version of BnM(). Unpaired surrogates are
5515      * also handled by this class.
5516      */
5517     static final class BnMS extends BnM {
5518         int lengthInChars;
5519 
5520         BnMS(int[] src, int[] lastOcc, int[] optoSft, Node next) {
5521             super(src, lastOcc, optoSft, next);
5522             for (int cp : buffer) {
5523                 lengthInChars += Character.charCount(cp);
5524             }
5525         }
5526         boolean match(Matcher matcher, int i, CharSequence seq) {
5527             int[] src = buffer;
5528             int patternLength = src.length;
5529             int last = matcher.to - lengthInChars;
5530 
5531             // Loop over all possible match positions in text
5532 NEXT:       while (i <= last) {
5533                 // Loop over pattern from right to left
5534                 int ch;
5535                 for (int j = countChars(seq, i, patternLength), x = patternLength - 1;
5536                      j > 0; j -= Character.charCount(ch), x--) {
5537                     ch = Character.codePointBefore(seq, i+j);
5538                     if (ch != src[x]) {
5539                         // Shift search to the right by the maximum of the
5540                         // bad character shift and the good suffix shift
5541                         int n = Math.max(x + 1 - lastOcc[ch&0x7F], optoSft[x]);
5542                         i += countChars(seq, i, n);
5543                         continue NEXT;
5544                     }
5545                 }
5546                 // Entire pattern matched starting at i
5547                 matcher.first = i;
5548                 boolean ret = next.match(matcher, i + lengthInChars, seq);
5549                 if (ret) {
5550                     matcher.first = i;
5551                     matcher.groups[0] = matcher.first;
5552                     matcher.groups[1] = matcher.last;
5553                     return true;
5554                 }
5555                 i += countChars(seq, i, 1);
5556             }
5557             matcher.hitEnd = true;
5558             return false;
5559         }
5560     }
5561 
5562 ///////////////////////////////////////////////////////////////////////////////
5563 ///////////////////////////////////////////////////////////////////////////////
5564 
5565     /**
5566      *  This must be the very first initializer.
5567      */
5568     static Node accept = new Node();
5569 
5570     static Node lastAccept = new LastNode();
5571 
5572     private static class CharPropertyNames {
5573 
5574         static CharProperty charPropertyFor(String name) {
5575             CharPropertyFactory m = map.get(name);
5576             return m == null ? null : m.make();
5577         }
5578 
5579         private static abstract class CharPropertyFactory {
5580             abstract CharProperty make();
5581         }
5582 
5583         private static void defCategory(String name,
5584                                         final int typeMask) {
5585             map.put(name, new CharPropertyFactory() {
5586                     CharProperty make() { return new Category(typeMask);}});
5587         }
5588 
5589         private static void defRange(String name,
5590                                      final int lower, final int upper) {
5591             map.put(name, new CharPropertyFactory() {
5592                     CharProperty make() { return rangeFor(lower, upper);}});
5593         }
5594 
5595         private static void defCtype(String name,
5596                                      final int ctype) {
5597             map.put(name, new CharPropertyFactory() {
5598                     CharProperty make() { return new Ctype(ctype);}});
5599         }
5600 
5601         private static abstract class CloneableProperty
5602             extends CharProperty implements Cloneable
5603         {
5604             public CloneableProperty clone() {
5605                 try {
5606                     return (CloneableProperty) super.clone();
5607                 } catch (CloneNotSupportedException e) {
5608                     throw new AssertionError(e);
5609                 }
5610             }
5611         }
5612 
5613         private static void defClone(String name,
5614                                      final CloneableProperty p) {
5615             map.put(name, new CharPropertyFactory() {
5616                     CharProperty make() { return p.clone();}});
5617         }
5618 
5619         private static final HashMap<String, CharPropertyFactory> map
5620             = new HashMap<>();
5621 
5622         static {
5623             // Unicode character property aliases, defined in
5624             // http://www.unicode.org/Public/UNIDATA/PropertyValueAliases.txt
5625             defCategory("Cn", 1<<Character.UNASSIGNED);
5626             defCategory("Lu", 1<<Character.UPPERCASE_LETTER);
5627             defCategory("Ll", 1<<Character.LOWERCASE_LETTER);
5628             defCategory("Lt", 1<<Character.TITLECASE_LETTER);
5629             defCategory("Lm", 1<<Character.MODIFIER_LETTER);
5630             defCategory("Lo", 1<<Character.OTHER_LETTER);
5631             defCategory("Mn", 1<<Character.NON_SPACING_MARK);
5632             defCategory("Me", 1<<Character.ENCLOSING_MARK);
5633             defCategory("Mc", 1<<Character.COMBINING_SPACING_MARK);
5634             defCategory("Nd", 1<<Character.DECIMAL_DIGIT_NUMBER);
5635             defCategory("Nl", 1<<Character.LETTER_NUMBER);
5636             defCategory("No", 1<<Character.OTHER_NUMBER);
5637             defCategory("Zs", 1<<Character.SPACE_SEPARATOR);
5638             defCategory("Zl", 1<<Character.LINE_SEPARATOR);
5639             defCategory("Zp", 1<<Character.PARAGRAPH_SEPARATOR);
5640             defCategory("Cc", 1<<Character.CONTROL);
5641             defCategory("Cf", 1<<Character.FORMAT);
5642             defCategory("Co", 1<<Character.PRIVATE_USE);
5643             defCategory("Cs", 1<<Character.SURROGATE);
5644             defCategory("Pd", 1<<Character.DASH_PUNCTUATION);
5645             defCategory("Ps", 1<<Character.START_PUNCTUATION);
5646             defCategory("Pe", 1<<Character.END_PUNCTUATION);
5647             defCategory("Pc", 1<<Character.CONNECTOR_PUNCTUATION);
5648             defCategory("Po", 1<<Character.OTHER_PUNCTUATION);
5649             defCategory("Sm", 1<<Character.MATH_SYMBOL);
5650             defCategory("Sc", 1<<Character.CURRENCY_SYMBOL);
5651             defCategory("Sk", 1<<Character.MODIFIER_SYMBOL);
5652             defCategory("So", 1<<Character.OTHER_SYMBOL);
5653             defCategory("Pi", 1<<Character.INITIAL_QUOTE_PUNCTUATION);
5654             defCategory("Pf", 1<<Character.FINAL_QUOTE_PUNCTUATION);
5655             defCategory("L", ((1<<Character.UPPERCASE_LETTER) |
5656                               (1<<Character.LOWERCASE_LETTER) |
5657                               (1<<Character.TITLECASE_LETTER) |
5658                               (1<<Character.MODIFIER_LETTER)  |
5659                               (1<<Character.OTHER_LETTER)));
5660             defCategory("M", ((1<<Character.NON_SPACING_MARK) |
5661                               (1<<Character.ENCLOSING_MARK)   |
5662                               (1<<Character.COMBINING_SPACING_MARK)));
5663             defCategory("N", ((1<<Character.DECIMAL_DIGIT_NUMBER) |
5664                               (1<<Character.LETTER_NUMBER)        |
5665                               (1<<Character.OTHER_NUMBER)));
5666             defCategory("Z", ((1<<Character.SPACE_SEPARATOR) |
5667                               (1<<Character.LINE_SEPARATOR)  |
5668                               (1<<Character.PARAGRAPH_SEPARATOR)));
5669             defCategory("C", ((1<<Character.CONTROL)     |
5670                               (1<<Character.FORMAT)      |
5671                               (1<<Character.PRIVATE_USE) |
5672                               (1<<Character.SURROGATE))); // Other
5673             defCategory("P", ((1<<Character.DASH_PUNCTUATION)      |
5674                               (1<<Character.START_PUNCTUATION)     |
5675                               (1<<Character.END_PUNCTUATION)       |
5676                               (1<<Character.CONNECTOR_PUNCTUATION) |
5677                               (1<<Character.OTHER_PUNCTUATION)     |
5678                               (1<<Character.INITIAL_QUOTE_PUNCTUATION) |
5679                               (1<<Character.FINAL_QUOTE_PUNCTUATION)));
5680             defCategory("S", ((1<<Character.MATH_SYMBOL)     |
5681                               (1<<Character.CURRENCY_SYMBOL) |
5682                               (1<<Character.MODIFIER_SYMBOL) |
5683                               (1<<Character.OTHER_SYMBOL)));
5684             defCategory("LC", ((1<<Character.UPPERCASE_LETTER) |
5685                                (1<<Character.LOWERCASE_LETTER) |
5686                                (1<<Character.TITLECASE_LETTER)));
5687             defCategory("LD", ((1<<Character.UPPERCASE_LETTER) |
5688                                (1<<Character.LOWERCASE_LETTER) |
5689                                (1<<Character.TITLECASE_LETTER) |
5690                                (1<<Character.MODIFIER_LETTER)  |
5691                                (1<<Character.OTHER_LETTER)     |
5692                                (1<<Character.DECIMAL_DIGIT_NUMBER)));
5693             defRange("L1", 0x00, 0xFF); // Latin-1
5694             map.put("all", new CharPropertyFactory() {
5695                     CharProperty make() { return new All(); }});
5696 
5697             // Posix regular expression character classes, defined in
5698             // http://www.unix.org/onlinepubs/009695399/basedefs/xbd_chap09.html
5699             defRange("ASCII", 0x00, 0x7F);   // ASCII
5700             defCtype("Alnum", ASCII.ALNUM);  // Alphanumeric characters
5701             defCtype("Alpha", ASCII.ALPHA);  // Alphabetic characters
5702             defCtype("Blank", ASCII.BLANK);  // Space and tab characters
5703             defCtype("Cntrl", ASCII.CNTRL);  // Control characters
5704             defRange("Digit", '0', '9');     // Numeric characters
5705             defCtype("Graph", ASCII.GRAPH);  // printable and visible
5706             defRange("Lower", 'a', 'z');     // Lower-case alphabetic
5707             defRange("Print", 0x20, 0x7E);   // Printable characters
5708             defCtype("Punct", ASCII.PUNCT);  // Punctuation characters
5709             defCtype("Space", ASCII.SPACE);  // Space characters
5710             defRange("Upper", 'A', 'Z');     // Upper-case alphabetic
5711             defCtype("XDigit",ASCII.XDIGIT); // hexadecimal digits
5712 
5713             // Java character properties, defined by methods in Character.java
5714             defClone("javaLowerCase", new CloneableProperty() {
5715                 boolean isSatisfiedBy(int ch) {
5716                     return Character.isLowerCase(ch);}});
5717             defClone("javaUpperCase", new CloneableProperty() {
5718                 boolean isSatisfiedBy(int ch) {
5719                     return Character.isUpperCase(ch);}});
5720             defClone("javaAlphabetic", new CloneableProperty() {
5721                 boolean isSatisfiedBy(int ch) {
5722                     return Character.isAlphabetic(ch);}});
5723             defClone("javaIdeographic", new CloneableProperty() {
5724                 boolean isSatisfiedBy(int ch) {
5725                     return Character.isIdeographic(ch);}});
5726             defClone("javaTitleCase", new CloneableProperty() {
5727                 boolean isSatisfiedBy(int ch) {
5728                     return Character.isTitleCase(ch);}});
5729             defClone("javaDigit", new CloneableProperty() {
5730                 boolean isSatisfiedBy(int ch) {
5731                     return Character.isDigit(ch);}});
5732             defClone("javaDefined", new CloneableProperty() {
5733                 boolean isSatisfiedBy(int ch) {
5734                     return Character.isDefined(ch);}});
5735             defClone("javaLetter", new CloneableProperty() {
5736                 boolean isSatisfiedBy(int ch) {
5737                     return Character.isLetter(ch);}});
5738             defClone("javaLetterOrDigit", new CloneableProperty() {
5739                 boolean isSatisfiedBy(int ch) {
5740                     return Character.isLetterOrDigit(ch);}});
5741             defClone("javaJavaIdentifierStart", new CloneableProperty() {
5742                 boolean isSatisfiedBy(int ch) {
5743                     return Character.isJavaIdentifierStart(ch);}});
5744             defClone("javaJavaIdentifierPart", new CloneableProperty() {
5745                 boolean isSatisfiedBy(int ch) {
5746                     return Character.isJavaIdentifierPart(ch);}});
5747             defClone("javaUnicodeIdentifierStart", new CloneableProperty() {
5748                 boolean isSatisfiedBy(int ch) {
5749                     return Character.isUnicodeIdentifierStart(ch);}});
5750             defClone("javaUnicodeIdentifierPart", new CloneableProperty() {
5751                 boolean isSatisfiedBy(int ch) {
5752                     return Character.isUnicodeIdentifierPart(ch);}});
5753             defClone("javaIdentifierIgnorable", new CloneableProperty() {
5754                 boolean isSatisfiedBy(int ch) {
5755                     return Character.isIdentifierIgnorable(ch);}});
5756             defClone("javaSpaceChar", new CloneableProperty() {
5757                 boolean isSatisfiedBy(int ch) {
5758                     return Character.isSpaceChar(ch);}});
5759             defClone("javaWhitespace", new CloneableProperty() {
5760                 boolean isSatisfiedBy(int ch) {
5761                     return Character.isWhitespace(ch);}});
5762             defClone("javaISOControl", new CloneableProperty() {
5763                 boolean isSatisfiedBy(int ch) {
5764                     return Character.isISOControl(ch);}});
5765             defClone("javaMirrored", new CloneableProperty() {
5766                 boolean isSatisfiedBy(int ch) {
5767                     return Character.isMirrored(ch);}});
5768         }
5769     }
5770 
5771     /**
5772      * Creates a predicate which can be used to match a string.
5773      *
5774      * @return  The predicate which can be used for matching on a string
5775      * @since   1.8
5776      */
5777     public Predicate<String> asPredicate() {
5778         return s -> matcher(s).find();
5779     }
5780 
5781     /**
5782      * Creates a stream from the given input sequence around matches of this
5783      * pattern.
5784      *
5785      * <p> The stream returned by this method contains each substring of the
5786      * input sequence that is terminated by another subsequence that matches
5787      * this pattern or is terminated by the end of the input sequence.  The
5788      * substrings in the stream are in the order in which they occur in the
5789      * input. Trailing empty strings will be discarded and not encountered in
5790      * the stream.
5791      *
5792      * <p> If this pattern does not match any subsequence of the input then
5793      * the resulting stream has just one element, namely the input sequence in
5794      * string form.
5795      *
5796      * <p> When there is a positive-width match at the beginning of the input
5797      * sequence then an empty leading substring is included at the beginning
5798      * of the stream. A zero-width match at the beginning however never produces
5799      * such empty leading substring.
5800      *
5801      * <p> If the input sequence is mutable, it must remain constant during the
5802      * execution of the terminal stream operation.  Otherwise, the result of the
5803      * terminal stream operation is undefined.
5804      *
5805      * @param   input
5806      *          The character sequence to be split
5807      *
5808      * @return  The stream of strings computed by splitting the input
5809      *          around matches of this pattern
5810      * @see     #split(CharSequence)
5811      * @since   1.8
5812      */
5813     public Stream<String> splitAsStream(final CharSequence input) {
5814         class MatcherIterator implements Iterator<String> {
5815             private final Matcher matcher;
5816             // The start position of the next sub-sequence of input
5817             // when current == input.length there are no more elements
5818             private int current;
5819             // null if the next element, if any, needs to obtained
5820             private String nextElement;
5821             // > 0 if there are N next empty elements
5822             private int emptyElementCount;
5823 
5824             MatcherIterator() {
5825                 this.matcher = matcher(input);
5826                 // If the input is an empty string then the result can only be a
5827                 // stream of the input.  Induce that by setting the empty
5828                 // element count to 1
5829                 this.emptyElementCount = input.length() == 0 ? 1 : 0;
5830             }
5831 
5832             public String next() {
5833                 if (!hasNext())
5834                     throw new NoSuchElementException();
5835 
5836                 if (emptyElementCount == 0) {
5837                     String n = nextElement;
5838                     nextElement = null;
5839                     return n;
5840                 } else {
5841                     emptyElementCount--;
5842                     return "";
5843                 }
5844             }
5845 
5846             public boolean hasNext() {
5847                 if (nextElement != null || emptyElementCount > 0)
5848                     return true;
5849 
5850                 if (current == input.length())
5851                     return false;
5852 
5853                 // Consume the next matching element
5854                 // Count sequence of matching empty elements
5855                 while (matcher.find()) {
5856                     nextElement = input.subSequence(current, matcher.start()).toString();
5857                     current = matcher.end();
5858                     if (!nextElement.isEmpty()) {
5859                         return true;
5860                     } else if (current > 0) { // no empty leading substring for zero-width
5861                                               // match at the beginning of the input
5862                         emptyElementCount++;
5863                     }
5864                 }
5865 
5866                 // Consume last matching element
5867                 nextElement = input.subSequence(current, input.length()).toString();
5868                 current = input.length();
5869                 if (!nextElement.isEmpty()) {
5870                     return true;
5871                 } else {
5872                     // Ignore a terminal sequence of matching empty elements
5873                     emptyElementCount = 0;
5874                     nextElement = null;
5875                     return false;
5876                 }
5877             }
5878         }
5879         return StreamSupport.stream(Spliterators.spliteratorUnknownSize(
5880                 new MatcherIterator(), Spliterator.ORDERED | Spliterator.NONNULL), false);
5881     }
5882 }
--- EOF ---