1 /* 2 * Copyright (c) 2005, Oracle and/or its affiliates. All rights reserved. 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 6 * under the terms of the GNU General Public License version 2 only, as 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 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 /* 27 ******************************************************************************* 28 * (C) Copyright IBM Corp. 1996-2005 - All Rights Reserved * 29 * * 30 * The original version of this source code and documentation is copyrighted * 31 * and owned by IBM, These materials are provided under terms of a License * 32 * Agreement between IBM and Sun. This technology is protected by multiple * 33 * US and International patents. This notice and attribution to IBM may not * 34 * to removed. * 35 ******************************************************************************* 36 */ 37 38 /* 39 ********************************************************************** 40 * Author: Alan Liu 41 * Created: September 23 2003 42 * Since: ICU 2.8 43 ********************************************************************** 44 */ 45 46 package sun.text.normalizer; 47 48 import java.text.ParsePosition; 49 50 /** 51 * An iterator that returns 32-bit code points. This class is deliberately 52 * <em>not</em> related to any of the JDK or ICU4J character iterator classes 53 * in order to minimize complexity. 54 * @author Alan Liu 55 * @since ICU 2.8 56 */ 57 @SuppressWarnings("deprecation") 58 public class RuleCharacterIterator { 59 60 // TODO: Ideas for later. (Do not implement if not needed, lest the 61 // code coverage numbers go down due to unused methods.) 62 // 1. Add a copy constructor, equals() method, clone() method. 63 // 2. Rather than return DONE, throw an exception if the end 64 // is reached -- this is an alternate usage model, probably not useful. 65 // 3. Return isEscaped from next(). If this happens, 66 // don't keep an isEscaped member variable. 67 68 /** 69 * Text being iterated. 70 */ 71 private String text; 72 73 /** 74 * Position of iterator. 75 */ 76 private ParsePosition pos; 77 78 /** 79 * Symbol table used to parse and dereference variables. May be null. 80 */ 81 private SymbolTable sym; 82 83 /** 84 * Current variable expansion, or null if none. 85 */ 86 private char[] buf; 87 88 /** 89 * Position within buf[]. Meaningless if buf == null. 90 */ 91 private int bufPos; 92 93 /** 94 * Flag indicating whether the last character was parsed from an escape. 95 */ 96 private boolean isEscaped; 97 98 /** 99 * Value returned when there are no more characters to iterate. 100 */ 101 public static final int DONE = -1; 102 103 /** 104 * Bitmask option to enable parsing of variable names. 105 * If {@code (options & PARSE_VARIABLES) != 0}, 106 * then an embedded variable will be expanded to 107 * its value. Variables are parsed using the SymbolTable API. 108 */ 109 public static final int PARSE_VARIABLES = 1; 110 111 /** 112 * Bitmask option to enable parsing of escape sequences. 113 * If {@code (options & PARSE_ESCAPES) != 0}, 114 * then an embedded escape sequence will be expanded 115 * to its value. Escapes are parsed using Utility.unescapeAt(). 116 */ 117 public static final int PARSE_ESCAPES = 2; 118 119 /** 120 * Bitmask option to enable skipping of whitespace. 121 * If {@code (options & SKIP_WHITESPACE) != 0}, 122 * then whitespace characters will be silently 123 * skipped, as if they were not present in the input. Whitespace 124 * characters are defined by UCharacterProperty.isRuleWhiteSpace(). 125 */ 126 public static final int SKIP_WHITESPACE = 4; 127 128 /** 129 * Constructs an iterator over the given text, starting at the given 130 * position. 131 * @param text the text to be iterated 132 * @param sym the symbol table, or null if there is none. If sym is null, 133 * then variables will not be deferenced, even if the PARSE_VARIABLES 134 * option is set. 135 * @param pos upon input, the index of the next character to return. If a 136 * variable has been dereferenced, then pos will <em>not</em> increment as 137 * characters of the variable value are iterated. 138 */ 139 public RuleCharacterIterator(String text, SymbolTable sym, 140 ParsePosition pos) { 141 if (text == null || pos.getIndex() > text.length()) { 142 throw new IllegalArgumentException(); 143 } 144 this.text = text; 145 this.sym = sym; 146 this.pos = pos; 147 buf = null; 148 } 149 150 /** 151 * Returns true if this iterator has no more characters to return. 152 */ 153 public boolean atEnd() { 154 return buf == null && pos.getIndex() == text.length(); 155 } 156 157 /** 158 * Returns the next character using the given options, or DONE if there 159 * are no more characters, and advance the position to the next 160 * character. 161 * @param options one or more of the following options, bitwise-OR-ed 162 * together: PARSE_VARIABLES, PARSE_ESCAPES, SKIP_WHITESPACE. 163 * @return the current 32-bit code point, or DONE 164 */ 165 public int next(int options) { 166 int c = DONE; 167 isEscaped = false; 168 169 for (;;) { 170 c = _current(); 171 _advance(UTF16.getCharCount(c)); 172 173 if (c == SymbolTable.SYMBOL_REF && buf == null && 174 (options & PARSE_VARIABLES) != 0 && sym != null) { 175 String name = sym.parseReference(text, pos, text.length()); 176 // If name == null there was an isolated SYMBOL_REF; 177 // return it. Caller must be prepared for this. 178 if (name == null) { 179 break; 180 } 181 bufPos = 0; 182 buf = sym.lookup(name); 183 if (buf == null) { 184 throw new IllegalArgumentException( 185 "Undefined variable: " + name); 186 } 187 // Handle empty variable value 188 if (buf.length == 0) { 189 buf = null; 190 } 191 continue; 192 } 193 194 if ((options & SKIP_WHITESPACE) != 0 && 195 UCharacterProperty.isRuleWhiteSpace(c)) { 196 continue; 197 } 198 199 if (c == '\\' && (options & PARSE_ESCAPES) != 0) { 200 int offset[] = new int[] { 0 }; 201 c = Utility.unescapeAt(lookahead(), offset); 202 jumpahead(offset[0]); 203 isEscaped = true; 204 if (c < 0) { 205 throw new IllegalArgumentException("Invalid escape"); 206 } 207 } 208 209 break; 210 } 211 212 return c; 213 } 214 215 /** 216 * Returns true if the last character returned by next() was 217 * escaped. This will only be the case if the option passed in to 218 * next() included PARSE_ESCAPED and the next character was an 219 * escape sequence. 220 */ 221 public boolean isEscaped() { 222 return isEscaped; 223 } 224 225 /** 226 * Returns true if this iterator is currently within a variable expansion. 227 */ 228 public boolean inVariable() { 229 return buf != null; 230 } 231 232 /** 233 * Returns an object which, when later passed to setPos(), will 234 * restore this iterator's position. Usage idiom: 235 * 236 * RuleCharacterIterator iterator = ...; 237 * Object pos = iterator.getPos(null); // allocate position object 238 * for (;;) { 239 * pos = iterator.getPos(pos); // reuse position object 240 * int c = iterator.next(...); 241 * ... 242 * } 243 * iterator.setPos(pos); 244 * 245 * @param p a position object previously returned by getPos(), 246 * or null. If not null, it will be updated and returned. If 247 * null, a new position object will be allocated and returned. 248 * @return a position object which may be passed to setPos(), 249 * either `p,' or if `p' == null, a newly-allocated object 250 */ 251 public Object getPos(Object p) { 252 if (p == null) { 253 return new Object[] {buf, new int[] {pos.getIndex(), bufPos}}; 254 } 255 Object[] a = (Object[]) p; 256 a[0] = buf; 257 int[] v = (int[]) a[1]; 258 v[0] = pos.getIndex(); 259 v[1] = bufPos; 260 return p; 261 } 262 263 /** 264 * Restores this iterator to the position it had when getPos() 265 * returned the given object. 266 * @param p a position object previously returned by getPos() 267 */ 268 public void setPos(Object p) { 269 Object[] a = (Object[]) p; 270 buf = (char[]) a[0]; 271 int[] v = (int[]) a[1]; 272 pos.setIndex(v[0]); 273 bufPos = v[1]; 274 } 275 276 /** 277 * Skips ahead past any ignored characters, as indicated by the given 278 * options. This is useful in conjunction with the lookahead() method. 279 * 280 * Currently, this only has an effect for SKIP_WHITESPACE. 281 * @param options one or more of the following options, bitwise-OR-ed 282 * together: PARSE_VARIABLES, PARSE_ESCAPES, SKIP_WHITESPACE. 283 */ 284 public void skipIgnored(int options) { 285 if ((options & SKIP_WHITESPACE) != 0) { 286 for (;;) { 287 int a = _current(); 288 if (!UCharacterProperty.isRuleWhiteSpace(a)) break; 289 _advance(UTF16.getCharCount(a)); 290 } 291 } 292 } 293 294 /** 295 * Returns a string containing the remainder of the characters to be 296 * returned by this iterator, without any option processing. If the 297 * iterator is currently within a variable expansion, this will only 298 * extend to the end of the variable expansion. This method is provided 299 * so that iterators may interoperate with string-based APIs. The typical 300 * sequence of calls is to call skipIgnored(), then call lookahead(), then 301 * parse the string returned by lookahead(), then call jumpahead() to 302 * resynchronize the iterator. 303 * @return a string containing the characters to be returned by future 304 * calls to next() 305 */ 306 public String lookahead() { 307 if (buf != null) { 308 return new String(buf, bufPos, buf.length - bufPos); 309 } else { 310 return text.substring(pos.getIndex()); 311 } 312 } 313 314 /** 315 * Advances the position by the given number of 16-bit code units. 316 * This is useful in conjunction with the lookahead() method. 317 * @param count the number of 16-bit code units to jump over 318 */ 319 public void jumpahead(int count) { 320 if (count < 0) { 321 throw new IllegalArgumentException(); 322 } 323 if (buf != null) { 324 bufPos += count; 325 if (bufPos > buf.length) { 326 throw new IllegalArgumentException(); 327 } 328 if (bufPos == buf.length) { 329 buf = null; 330 } 331 } else { 332 int i = pos.getIndex() + count; 333 pos.setIndex(i); 334 if (i > text.length()) { 335 throw new IllegalArgumentException(); 336 } 337 } 338 } 339 340 /** 341 * Returns the current 32-bit code point without parsing escapes, parsing 342 * variables, or skipping whitespace. 343 * @return the current 32-bit code point 344 */ 345 private int _current() { 346 if (buf != null) { 347 return UTF16.charAt(buf, 0, buf.length, bufPos); 348 } else { 349 int i = pos.getIndex(); 350 return (i < text.length()) ? UTF16.charAt(text, i) : DONE; 351 } 352 } 353 354 /** 355 * Advances the position by the given amount. 356 * @param count the number of 16-bit code units to advance past 357 */ 358 private void _advance(int count) { 359 if (buf != null) { 360 bufPos += count; 361 if (bufPos == buf.length) { 362 buf = null; 363 } 364 } else { 365 pos.setIndex(pos.getIndex() + count); 366 if (pos.getIndex() > text.length()) { 367 pos.setIndex(text.length()); 368 } 369 } 370 } 371 }