1 /*
   2  * Copyright (c) 2003, 2015, 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 package java.lang;
  27 
  28 import sun.misc.FloatingDecimal;
  29 import java.util.Arrays;
  30 import java.util.Spliterator;
  31 import java.util.stream.IntStream;
  32 import java.util.stream.StreamSupport;
  33 
  34 /**
  35  * A mutable sequence of characters.
  36  * <p>
  37  * Implements a modifiable string. At any point in time it contains some
  38  * particular sequence of characters, but the length and content of the
  39  * sequence can be changed through certain method calls.
  40  *
  41  * <p>Unless otherwise noted, passing a {@code null} argument to a constructor
  42  * or method in this class will cause a {@link NullPointerException} to be
  43  * thrown.
  44  *
  45  * @author      Michael McCloskey
  46  * @author      Martin Buchholz
  47  * @author      Ulf Zibis
  48  * @since       1.5
  49  */
  50 abstract class AbstractStringBuilder implements Appendable, CharSequence {
  51     /**
  52      * The value is used for character storage.
  53      */
  54     char[] value;
  55 
  56     /**
  57      * The count is the number of characters used.
  58      */
  59     int count;
  60 
  61     /**
  62      * This no-arg constructor is necessary for serialization of subclasses.
  63      */
  64     AbstractStringBuilder() {
  65     }
  66 
  67     /**
  68      * Creates an AbstractStringBuilder of the specified capacity.
  69      */
  70     AbstractStringBuilder(int capacity) {
  71         value = new char[capacity];
  72     }
  73 
  74     /**
  75      * Returns the length (character count).
  76      *
  77      * @return  the length of the sequence of characters currently
  78      *          represented by this object
  79      */
  80     @Override
  81     public int length() {
  82         return count;
  83     }
  84 
  85     /**
  86      * Returns the current capacity. The capacity is the amount of storage
  87      * available for newly inserted characters, beyond which an allocation
  88      * will occur.
  89      *
  90      * @return  the current capacity
  91      */
  92     public int capacity() {
  93         return value.length;
  94     }
  95 
  96     /**
  97      * Ensures that the capacity is at least equal to the specified minimum.
  98      * If the current capacity is less than the argument, then a new internal
  99      * array is allocated with greater capacity. The new capacity is the
 100      * larger of:
 101      * <ul>
 102      * <li>The {@code minimumCapacity} argument.
 103      * <li>Twice the old capacity, plus {@code 2}.
 104      * </ul>
 105      * If the {@code minimumCapacity} argument is nonpositive, this
 106      * method takes no action and simply returns.
 107      * Note that subsequent operations on this object can reduce the
 108      * actual capacity below that requested here.
 109      *
 110      * @param   minimumCapacity   the minimum desired capacity.
 111      */
 112     public void ensureCapacity(int minimumCapacity) {
 113         if (minimumCapacity > 0)
 114             ensureCapacityInternal(minimumCapacity);
 115     }
 116 
 117     /**
 118      * This method has the same contract as ensureCapacity, but is
 119      * never synchronized.
 120      */
 121     private void ensureCapacityInternal(int minimumCapacity) {
 122         // overflow-conscious code
 123         if (minimumCapacity - value.length > 0)
 124             expandCapacity(minimumCapacity);
 125     }
 126 
 127     /**
 128      * This implements the expansion semantics of ensureCapacity with no
 129      * size check or synchronization.
 130      */
 131     void expandCapacity(int minimumCapacity) {
 132         int newCapacity = value.length * 2 + 2;
 133         if (newCapacity - minimumCapacity < 0)
 134             newCapacity = minimumCapacity;
 135         if (newCapacity < 0) {
 136             if (minimumCapacity < 0) // overflow
 137                 throw new OutOfMemoryError();
 138             newCapacity = Integer.MAX_VALUE;
 139         }
 140         value = Arrays.copyOf(value, newCapacity);
 141     }
 142 
 143     /**
 144      * Attempts to reduce storage used for the character sequence.
 145      * If the buffer is larger than necessary to hold its current sequence of
 146      * characters, then it may be resized to become more space efficient.
 147      * Calling this method may, but is not required to, affect the value
 148      * returned by a subsequent call to the {@link #capacity()} method.
 149      */
 150     public void trimToSize() {
 151         if (count < value.length) {
 152             value = Arrays.copyOf(value, count);
 153         }
 154     }
 155 
 156     /**
 157      * Sets the length of the character sequence.
 158      * The sequence is changed to a new character sequence
 159      * whose length is specified by the argument. For every nonnegative
 160      * index <i>k</i> less than {@code newLength}, the character at
 161      * index <i>k</i> in the new character sequence is the same as the
 162      * character at index <i>k</i> in the old sequence if <i>k</i> is less
 163      * than the length of the old character sequence; otherwise, it is the
 164      * null character {@code '\u005Cu0000'}.
 165      *
 166      * In other words, if the {@code newLength} argument is less than
 167      * the current length, the length is changed to the specified length.
 168      * <p>
 169      * If the {@code newLength} argument is greater than or equal
 170      * to the current length, sufficient null characters
 171      * ({@code '\u005Cu0000'}) are appended so that
 172      * length becomes the {@code newLength} argument.
 173      * <p>
 174      * The {@code newLength} argument must be greater than or equal
 175      * to {@code 0}.
 176      *
 177      * @param      newLength   the new length
 178      * @throws     IndexOutOfBoundsException  if the
 179      *               {@code newLength} argument is negative.
 180      */
 181     public void setLength(int newLength) {
 182         if (newLength < 0)
 183             throw new StringIndexOutOfBoundsException(newLength);
 184         ensureCapacityInternal(newLength);
 185 
 186         if (count < newLength) {
 187             Arrays.fill(value, count, newLength, '\0');
 188         }
 189 
 190         count = newLength;
 191     }
 192 
 193     /**
 194      * Returns the {@code char} value in this sequence at the specified index.
 195      * The first {@code char} value is at index {@code 0}, the next at index
 196      * {@code 1}, and so on, as in array indexing.
 197      * <p>
 198      * The index argument must be greater than or equal to
 199      * {@code 0}, and less than the length of this sequence.
 200      *
 201      * <p>If the {@code char} value specified by the index is a
 202      * <a href="Character.html#unicode">surrogate</a>, the surrogate
 203      * value is returned.
 204      *
 205      * @param      index   the index of the desired {@code char} value.
 206      * @return     the {@code char} value at the specified index.
 207      * @throws     IndexOutOfBoundsException  if {@code index} is
 208      *             negative or greater than or equal to {@code length()}.
 209      */
 210     @Override
 211     public char charAt(int index) {
 212         if ((index < 0) || (index >= count))
 213             throw new StringIndexOutOfBoundsException(index);
 214         return value[index];
 215     }
 216 
 217     /**
 218      * Returns the character (Unicode code point) at the specified
 219      * index. The index refers to {@code char} values
 220      * (Unicode code units) and ranges from {@code 0} to
 221      * {@link #length()}{@code  - 1}.
 222      *
 223      * <p> If the {@code char} value specified at the given index
 224      * is in the high-surrogate range, the following index is less
 225      * than the length of this sequence, and the
 226      * {@code char} value at the following index is in the
 227      * low-surrogate range, then the supplementary code point
 228      * corresponding to this surrogate pair is returned. Otherwise,
 229      * the {@code char} value at the given index is returned.
 230      *
 231      * @param      index the index to the {@code char} values
 232      * @return     the code point value of the character at the
 233      *             {@code index}
 234      * @exception  IndexOutOfBoundsException  if the {@code index}
 235      *             argument is negative or not less than the length of this
 236      *             sequence.
 237      */
 238     public int codePointAt(int index) {
 239         if ((index < 0) || (index >= count)) {
 240             throw new StringIndexOutOfBoundsException(index);
 241         }
 242         return Character.codePointAtImpl(value, index, count);
 243     }
 244 
 245     /**
 246      * Returns the character (Unicode code point) before the specified
 247      * index. The index refers to {@code char} values
 248      * (Unicode code units) and ranges from {@code 1} to {@link
 249      * #length()}.
 250      *
 251      * <p> If the {@code char} value at {@code (index - 1)}
 252      * is in the low-surrogate range, {@code (index - 2)} is not
 253      * negative, and the {@code char} value at {@code (index -
 254      * 2)} is in the high-surrogate range, then the
 255      * supplementary code point value of the surrogate pair is
 256      * returned. If the {@code char} value at {@code index -
 257      * 1} is an unpaired low-surrogate or a high-surrogate, the
 258      * surrogate value is returned.
 259      *
 260      * @param     index the index following the code point that should be returned
 261      * @return    the Unicode code point value before the given index.
 262      * @exception IndexOutOfBoundsException if the {@code index}
 263      *            argument is less than 1 or greater than the length
 264      *            of this sequence.
 265      */
 266     public int codePointBefore(int index) {
 267         int i = index - 1;
 268         if ((i < 0) || (i >= count)) {
 269             throw new StringIndexOutOfBoundsException(index);
 270         }
 271         return Character.codePointBeforeImpl(value, index, 0);
 272     }
 273 
 274     /**
 275      * Returns the number of Unicode code points in the specified text
 276      * range of this sequence. The text range begins at the specified
 277      * {@code beginIndex} and extends to the {@code char} at
 278      * index {@code endIndex - 1}. Thus the length (in
 279      * {@code char}s) of the text range is
 280      * {@code endIndex-beginIndex}. Unpaired surrogates within
 281      * this sequence count as one code point each.
 282      *
 283      * @param beginIndex the index to the first {@code char} of
 284      * the text range.
 285      * @param endIndex the index after the last {@code char} of
 286      * the text range.
 287      * @return the number of Unicode code points in the specified text
 288      * range
 289      * @exception IndexOutOfBoundsException if the
 290      * {@code beginIndex} is negative, or {@code endIndex}
 291      * is larger than the length of this sequence, or
 292      * {@code beginIndex} is larger than {@code endIndex}.
 293      */
 294     public int codePointCount(int beginIndex, int endIndex) {
 295         if (beginIndex < 0 || endIndex > count || beginIndex > endIndex) {
 296             throw new IndexOutOfBoundsException();
 297         }
 298         return Character.codePointCountImpl(value, beginIndex, endIndex - beginIndex);
 299     }
 300 
 301     /**
 302      * Returns the index within this sequence that is offset from the
 303      * given {@code index} by {@code codePointOffset} code
 304      * points. Unpaired surrogates within the text range given by
 305      * {@code index} and {@code codePointOffset} count as
 306      * one code point each.
 307      *
 308      * @param index the index to be offset
 309      * @param codePointOffset the offset in code points
 310      * @return the index within this sequence
 311      * @exception IndexOutOfBoundsException if {@code index}
 312      *   is negative or larger then the length of this sequence,
 313      *   or if {@code codePointOffset} is positive and the subsequence
 314      *   starting with {@code index} has fewer than
 315      *   {@code codePointOffset} code points,
 316      *   or if {@code codePointOffset} is negative and the subsequence
 317      *   before {@code index} has fewer than the absolute value of
 318      *   {@code codePointOffset} code points.
 319      */
 320     public int offsetByCodePoints(int index, int codePointOffset) {
 321         if (index < 0 || index > count) {
 322             throw new IndexOutOfBoundsException();
 323         }
 324         return Character.offsetByCodePointsImpl(value, 0, count,
 325                                                 index, codePointOffset);
 326     }
 327 
 328     /**
 329      * Characters are copied from this sequence into the
 330      * destination character array {@code dst}. The first character to
 331      * be copied is at index {@code srcBegin}; the last character to
 332      * be copied is at index {@code srcEnd-1}. The total number of
 333      * characters to be copied is {@code srcEnd-srcBegin}. The
 334      * characters are copied into the subarray of {@code dst} starting
 335      * at index {@code dstBegin} and ending at index:
 336      * <pre>{@code
 337      * dstbegin + (srcEnd-srcBegin) - 1
 338      * }</pre>
 339      *
 340      * @param      srcBegin   start copying at this offset.
 341      * @param      srcEnd     stop copying at this offset.
 342      * @param      dst        the array to copy the data into.
 343      * @param      dstBegin   offset into {@code dst}.
 344      * @throws     IndexOutOfBoundsException  if any of the following is true:
 345      *             <ul>
 346      *             <li>{@code srcBegin} is negative
 347      *             <li>{@code dstBegin} is negative
 348      *             <li>the {@code srcBegin} argument is greater than
 349      *             the {@code srcEnd} argument.
 350      *             <li>{@code srcEnd} is greater than
 351      *             {@code this.length()}.
 352      *             <li>{@code dstBegin+srcEnd-srcBegin} is greater than
 353      *             {@code dst.length}
 354      *             </ul>
 355      */
 356     public void getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin)
 357     {
 358         if (srcBegin < 0)
 359             throw new StringIndexOutOfBoundsException(srcBegin);
 360         if ((srcEnd < 0) || (srcEnd > count))
 361             throw new StringIndexOutOfBoundsException(srcEnd);
 362         if (srcBegin > srcEnd)
 363             throw new StringIndexOutOfBoundsException("srcBegin > srcEnd");
 364         System.arraycopy(value, srcBegin, dst, dstBegin, srcEnd - srcBegin);
 365     }
 366 
 367     /**
 368      * The character at the specified index is set to {@code ch}. This
 369      * sequence is altered to represent a new character sequence that is
 370      * identical to the old character sequence, except that it contains the
 371      * character {@code ch} at position {@code index}.
 372      * <p>
 373      * The index argument must be greater than or equal to
 374      * {@code 0}, and less than the length of this sequence.
 375      *
 376      * @param      index   the index of the character to modify.
 377      * @param      ch      the new character.
 378      * @throws     IndexOutOfBoundsException  if {@code index} is
 379      *             negative or greater than or equal to {@code length()}.
 380      */
 381     public void setCharAt(int index, char ch) {
 382         if ((index < 0) || (index >= count))
 383             throw new StringIndexOutOfBoundsException(index);
 384         value[index] = ch;
 385     }
 386 
 387     /**
 388      * Appends the string representation of the {@code Object} argument.
 389      * <p>
 390      * The overall effect is exactly as if the argument were converted
 391      * to a string by the method {@link String#valueOf(Object)},
 392      * and the characters of that string were then
 393      * {@link #append(String) appended} to this character sequence.
 394      *
 395      * @param   obj   an {@code Object}.
 396      * @return  a reference to this object.
 397      */
 398     public AbstractStringBuilder append(Object obj) {
 399         return append(String.valueOf(obj));
 400     }
 401 
 402     /**
 403      * Appends the specified string to this character sequence.
 404      * <p>
 405      * The characters of the {@code String} argument are appended, in
 406      * order, increasing the length of this sequence by the length of the
 407      * argument. If {@code str} is {@code null}, then the four
 408      * characters {@code "null"} are appended.
 409      * <p>
 410      * Let <i>n</i> be the length of this character sequence just prior to
 411      * execution of the {@code append} method. Then the character at
 412      * index <i>k</i> in the new character sequence is equal to the character
 413      * at index <i>k</i> in the old character sequence, if <i>k</i> is less
 414      * than <i>n</i>; otherwise, it is equal to the character at index
 415      * <i>k-n</i> in the argument {@code str}.
 416      *
 417      * @param   str   a string.
 418      * @return  a reference to this object.
 419      */
 420     public AbstractStringBuilder append(String str) {
 421         if (str == null)
 422             return appendNull();
 423         int len = str.length();
 424         ensureCapacityInternal(count + len);
 425         str.getChars(0, len, value, count);
 426         count += len;
 427         return this;
 428     }
 429 
 430     // Documentation in subclasses because of synchro difference
 431     public AbstractStringBuilder append(StringBuffer sb) {
 432         if (sb == null)
 433             return appendNull();
 434         int len = sb.length();
 435         ensureCapacityInternal(count + len);
 436         sb.getChars(0, len, value, count);
 437         count += len;
 438         return this;
 439     }
 440 
 441     /**
 442      * @since 1.8
 443      */
 444     AbstractStringBuilder append(AbstractStringBuilder asb) {
 445         if (asb == null)
 446             return appendNull();
 447         int len = asb.length();
 448         ensureCapacityInternal(count + len);
 449         asb.getChars(0, len, value, count);
 450         count += len;
 451         return this;
 452     }
 453 
 454     // Documentation in subclasses because of synchro difference
 455     @Override
 456     public AbstractStringBuilder append(CharSequence s) {
 457         if (s == null)
 458             return appendNull();
 459         if (s instanceof String)
 460             return this.append((String)s);
 461         if (s instanceof AbstractStringBuilder)
 462             return this.append((AbstractStringBuilder)s);
 463 
 464         return this.append(s, 0, s.length());
 465     }
 466 
 467     private AbstractStringBuilder appendNull() {
 468         int c = count;
 469         ensureCapacityInternal(c + 4);
 470         final char[] value = this.value;
 471         value[c++] = 'n';
 472         value[c++] = 'u';
 473         value[c++] = 'l';
 474         value[c++] = 'l';
 475         count = c;
 476         return this;
 477     }
 478 
 479     /**
 480      * Appends a subsequence of the specified {@code CharSequence} to this
 481      * sequence.
 482      * <p>
 483      * Characters of the argument {@code s}, starting at
 484      * index {@code start}, are appended, in order, to the contents of
 485      * this sequence up to the (exclusive) index {@code end}. The length
 486      * of this sequence is increased by the value of {@code end - start}.
 487      * <p>
 488      * Let <i>n</i> be the length of this character sequence just prior to
 489      * execution of the {@code append} method. Then the character at
 490      * index <i>k</i> in this character sequence becomes equal to the
 491      * character at index <i>k</i> in this sequence, if <i>k</i> is less than
 492      * <i>n</i>; otherwise, it is equal to the character at index
 493      * <i>k+start-n</i> in the argument {@code s}.
 494      * <p>
 495      * If {@code s} is {@code null}, then this method appends
 496      * characters as if the s parameter was a sequence containing the four
 497      * characters {@code "null"}.
 498      *
 499      * @param   s the sequence to append.
 500      * @param   start   the starting index of the subsequence to be appended.
 501      * @param   end     the end index of the subsequence to be appended.
 502      * @return  a reference to this object.
 503      * @throws     IndexOutOfBoundsException if
 504      *             {@code start} is negative, or
 505      *             {@code start} is greater than {@code end} or
 506      *             {@code end} is greater than {@code s.length()}
 507      */
 508     @Override
 509     public AbstractStringBuilder append(CharSequence s, int start, int end) {
 510         if (s == null)
 511             s = "null";
 512         if ((start < 0) || (start > end) || (end > s.length()))
 513             throw new StringIndexOutOfBoundsException(
 514                 "start " + start + ", end " + end + ", s.length() "
 515                 + s.length());
 516         int len = end - start;
 517         ensureCapacityInternal(count + len);
 518         if (s instanceof String) {
 519             ((String)s).getChars(start, end, value, count);
 520         } else {
 521             for (int i = start, j = count; i < end; i++, j++)
 522                 value[j] = s.charAt(i);
 523         }
 524         count += len;
 525         return this;
 526     }
 527 
 528     /**
 529      * Appends the string representation of the {@code char} array
 530      * argument to this sequence.
 531      * <p>
 532      * The characters of the array argument are appended, in order, to
 533      * the contents of this sequence. The length of this sequence
 534      * increases by the length of the argument.
 535      * <p>
 536      * The overall effect is exactly as if the argument were converted
 537      * to a string by the method {@link String#valueOf(char[])},
 538      * and the characters of that string were then
 539      * {@link #append(String) appended} to this character sequence.
 540      *
 541      * @param   str   the characters to be appended.
 542      * @return  a reference to this object.
 543      */
 544     public AbstractStringBuilder append(char[] str) {
 545         int len = str.length;
 546         ensureCapacityInternal(count + len);
 547         System.arraycopy(str, 0, value, count, len);
 548         count += len;
 549         return this;
 550     }
 551 
 552     /**
 553      * Appends the string representation of a subarray of the
 554      * {@code char} array argument to this sequence.
 555      * <p>
 556      * Characters of the {@code char} array {@code str}, starting at
 557      * index {@code offset}, are appended, in order, to the contents
 558      * of this sequence. The length of this sequence increases
 559      * by the value of {@code len}.
 560      * <p>
 561      * The overall effect is exactly as if the arguments were converted
 562      * to a string by the method {@link String#valueOf(char[],int,int)},
 563      * and the characters of that string were then
 564      * {@link #append(String) appended} to this character sequence.
 565      *
 566      * @param   str      the characters to be appended.
 567      * @param   offset   the index of the first {@code char} to append.
 568      * @param   len      the number of {@code char}s to append.
 569      * @return  a reference to this object.
 570      * @throws IndexOutOfBoundsException
 571      *         if {@code offset < 0} or {@code len < 0}
 572      *         or {@code offset+len > str.length}
 573      */
 574     public AbstractStringBuilder append(char str[], int offset, int len) {
 575         if (len > 0)                // let arraycopy report AIOOBE for len < 0
 576             ensureCapacityInternal(count + len);
 577         System.arraycopy(str, offset, value, count, len);
 578         count += len;
 579         return this;
 580     }
 581 
 582     /**
 583      * Appends the string representation of the {@code boolean}
 584      * argument to the sequence.
 585      * <p>
 586      * The overall effect is exactly as if the argument were converted
 587      * to a string by the method {@link String#valueOf(boolean)},
 588      * and the characters of that string were then
 589      * {@link #append(String) appended} to this character sequence.
 590      *
 591      * @param   b   a {@code boolean}.
 592      * @return  a reference to this object.
 593      */
 594     public AbstractStringBuilder append(boolean b) {
 595         if (b) {
 596             ensureCapacityInternal(count + 4);
 597             value[count++] = 't';
 598             value[count++] = 'r';
 599             value[count++] = 'u';
 600             value[count++] = 'e';
 601         } else {
 602             ensureCapacityInternal(count + 5);
 603             value[count++] = 'f';
 604             value[count++] = 'a';
 605             value[count++] = 'l';
 606             value[count++] = 's';
 607             value[count++] = 'e';
 608         }
 609         return this;
 610     }
 611 
 612     /**
 613      * Appends the string representation of the {@code char}
 614      * argument to this sequence.
 615      * <p>
 616      * The argument is appended to the contents of this sequence.
 617      * The length of this sequence increases by {@code 1}.
 618      * <p>
 619      * The overall effect is exactly as if the argument were converted
 620      * to a string by the method {@link String#valueOf(char)},
 621      * and the character in that string were then
 622      * {@link #append(String) appended} to this character sequence.
 623      *
 624      * @param   c   a {@code char}.
 625      * @return  a reference to this object.
 626      */
 627     @Override
 628     public AbstractStringBuilder append(char c) {
 629         ensureCapacityInternal(count + 1);
 630         value[count++] = c;
 631         return this;
 632     }
 633 
 634     /**
 635      * Appends the string representation of the {@code int}
 636      * argument to this sequence.
 637      * <p>
 638      * The overall effect is exactly as if the argument were converted
 639      * to a string by the method {@link String#valueOf(int)},
 640      * and the characters of that string were then
 641      * {@link #append(String) appended} to this character sequence.
 642      *
 643      * @param   i   an {@code int}.
 644      * @return  a reference to this object.
 645      */
 646     public AbstractStringBuilder append(int i) {
 647         if (i == Integer.MIN_VALUE) {
 648             append("-2147483648");
 649             return this;
 650         }
 651         int appendedLength = (i < 0) ? Integer.stringSize(-i) + 1
 652                                      : Integer.stringSize(i);
 653         int spaceNeeded = count + appendedLength;
 654         ensureCapacityInternal(spaceNeeded);
 655         Integer.getChars(i, spaceNeeded, value);
 656         count = spaceNeeded;
 657         return this;
 658     }
 659 
 660     /**
 661      * Appends the string representation of the {@code long}
 662      * argument to this sequence.
 663      * <p>
 664      * The overall effect is exactly as if the argument were converted
 665      * to a string by the method {@link String#valueOf(long)},
 666      * and the characters of that string were then
 667      * {@link #append(String) appended} to this character sequence.
 668      *
 669      * @param   l   a {@code long}.
 670      * @return  a reference to this object.
 671      */
 672     public AbstractStringBuilder append(long l) {
 673         if (l == Long.MIN_VALUE) {
 674             append("-9223372036854775808");
 675             return this;
 676         }
 677         int appendedLength = (l < 0) ? Long.stringSize(-l) + 1
 678                                      : Long.stringSize(l);
 679         int spaceNeeded = count + appendedLength;
 680         ensureCapacityInternal(spaceNeeded);
 681         Long.getChars(l, spaceNeeded, value);
 682         count = spaceNeeded;
 683         return this;
 684     }
 685 
 686     /**
 687      * Appends the string representation of the {@code float}
 688      * argument to this sequence.
 689      * <p>
 690      * The overall effect is exactly as if the argument were converted
 691      * to a string by the method {@link String#valueOf(float)},
 692      * and the characters of that string were then
 693      * {@link #append(String) appended} to this character sequence.
 694      *
 695      * @param   f   a {@code float}.
 696      * @return  a reference to this object.
 697      */
 698     public AbstractStringBuilder append(float f) {
 699         FloatingDecimal.appendTo(f,this);
 700         return this;
 701     }
 702 
 703     /**
 704      * Appends the string representation of the {@code double}
 705      * argument to this sequence.
 706      * <p>
 707      * The overall effect is exactly as if the argument were converted
 708      * to a string by the method {@link String#valueOf(double)},
 709      * and the characters of that string were then
 710      * {@link #append(String) appended} to this character sequence.
 711      *
 712      * @param   d   a {@code double}.
 713      * @return  a reference to this object.
 714      */
 715     public AbstractStringBuilder append(double d) {
 716         FloatingDecimal.appendTo(d,this);
 717         return this;
 718     }
 719 
 720     /**
 721      * Removes the characters in a substring of this sequence.
 722      * The substring begins at the specified {@code start} and extends to
 723      * the character at index {@code end - 1} or to the end of the
 724      * sequence if no such character exists. If
 725      * {@code start} is equal to {@code end}, no changes are made.
 726      *
 727      * @param      start  The beginning index, inclusive.
 728      * @param      end    The ending index, exclusive.
 729      * @return     This object.
 730      * @throws     StringIndexOutOfBoundsException  if {@code start}
 731      *             is negative, greater than {@code length()}, or
 732      *             greater than {@code end}.
 733      */
 734     public AbstractStringBuilder delete(int start, int end) {
 735         if (start < 0)
 736             throw new StringIndexOutOfBoundsException(start);
 737         if (end > count)
 738             end = count;
 739         if (start > end)
 740             throw new StringIndexOutOfBoundsException();
 741         int len = end - start;
 742         if (len > 0) {
 743             System.arraycopy(value, start+len, value, start, count-end);
 744             count -= len;
 745         }
 746         return this;
 747     }
 748 
 749     /**
 750      * Appends the string representation of the {@code codePoint}
 751      * argument to this sequence.
 752      *
 753      * <p> The argument is appended to the contents of this sequence.
 754      * The length of this sequence increases by
 755      * {@link Character#charCount(int) Character.charCount(codePoint)}.
 756      *
 757      * <p> The overall effect is exactly as if the argument were
 758      * converted to a {@code char} array by the method
 759      * {@link Character#toChars(int)} and the character in that array
 760      * were then {@link #append(char[]) appended} to this character
 761      * sequence.
 762      *
 763      * @param   codePoint   a Unicode code point
 764      * @return  a reference to this object.
 765      * @exception IllegalArgumentException if the specified
 766      * {@code codePoint} isn't a valid Unicode code point
 767      */
 768     public AbstractStringBuilder appendCodePoint(int codePoint) {
 769         final int count = this.count;
 770 
 771         if (Character.isBmpCodePoint(codePoint)) {
 772             ensureCapacityInternal(count + 1);
 773             value[count] = (char) codePoint;
 774             this.count = count + 1;
 775         } else if (Character.isValidCodePoint(codePoint)) {
 776             ensureCapacityInternal(count + 2);
 777             Character.toSurrogates(codePoint, value, count);
 778             this.count = count + 2;
 779         } else {
 780             throw new IllegalArgumentException();
 781         }
 782         return this;
 783     }
 784 
 785     /**
 786      * Removes the {@code char} at the specified position in this
 787      * sequence. This sequence is shortened by one {@code char}.
 788      *
 789      * <p>Note: If the character at the given index is a supplementary
 790      * character, this method does not remove the entire character. If
 791      * correct handling of supplementary characters is required,
 792      * determine the number of {@code char}s to remove by calling
 793      * {@code Character.charCount(thisSequence.codePointAt(index))},
 794      * where {@code thisSequence} is this sequence.
 795      *
 796      * @param       index  Index of {@code char} to remove
 797      * @return      This object.
 798      * @throws      StringIndexOutOfBoundsException  if the {@code index}
 799      *              is negative or greater than or equal to
 800      *              {@code length()}.
 801      */
 802     public AbstractStringBuilder deleteCharAt(int index) {
 803         if ((index < 0) || (index >= count))
 804             throw new StringIndexOutOfBoundsException(index);
 805         System.arraycopy(value, index+1, value, index, count-index-1);
 806         count--;
 807         return this;
 808     }
 809 
 810     /**
 811      * Replaces the characters in a substring of this sequence
 812      * with characters in the specified {@code String}. The substring
 813      * begins at the specified {@code start} and extends to the character
 814      * at index {@code end - 1} or to the end of the
 815      * sequence if no such character exists. First the
 816      * characters in the substring are removed and then the specified
 817      * {@code String} is inserted at {@code start}. (This
 818      * sequence will be lengthened to accommodate the
 819      * specified String if necessary.)
 820      *
 821      * @param      start    The beginning index, inclusive.
 822      * @param      end      The ending index, exclusive.
 823      * @param      str   String that will replace previous contents.
 824      * @return     This object.
 825      * @throws     StringIndexOutOfBoundsException  if {@code start}
 826      *             is negative, greater than {@code length()}, or
 827      *             greater than {@code end}.
 828      */
 829     public AbstractStringBuilder replace(int start, int end, String str) {
 830         if (start < 0)
 831             throw new StringIndexOutOfBoundsException(start);
 832         if (start > count)
 833             throw new StringIndexOutOfBoundsException("start > length()");
 834         if (start > end)
 835             throw new StringIndexOutOfBoundsException("start > end");
 836 
 837         if (end > count)
 838             end = count;
 839         int len = str.length();
 840         int newCount = count + len - (end - start);
 841         ensureCapacityInternal(newCount);
 842 
 843         System.arraycopy(value, end, value, start + len, count - end);
 844         str.getChars(value, start);
 845         count = newCount;
 846         return this;
 847     }
 848 
 849     /**
 850      * Returns a new {@code String} that contains a subsequence of
 851      * characters currently contained in this character sequence. The
 852      * substring begins at the specified index and extends to the end of
 853      * this sequence.
 854      *
 855      * @param      start    The beginning index, inclusive.
 856      * @return     The new string.
 857      * @throws     StringIndexOutOfBoundsException  if {@code start} is
 858      *             less than zero, or greater than the length of this object.
 859      */
 860     public String substring(int start) {
 861         return substring(start, count);
 862     }
 863 
 864     /**
 865      * Returns a new character sequence that is a subsequence of this sequence.
 866      *
 867      * <p> An invocation of this method of the form
 868      *
 869      * <pre>{@code
 870      * sb.subSequence(begin,&nbsp;end)}</pre>
 871      *
 872      * behaves in exactly the same way as the invocation
 873      *
 874      * <pre>{@code
 875      * sb.substring(begin,&nbsp;end)}</pre>
 876      *
 877      * This method is provided so that this class can
 878      * implement the {@link CharSequence} interface.
 879      *
 880      * @param      start   the start index, inclusive.
 881      * @param      end     the end index, exclusive.
 882      * @return     the specified subsequence.
 883      *
 884      * @throws  IndexOutOfBoundsException
 885      *          if {@code start} or {@code end} are negative,
 886      *          if {@code end} is greater than {@code length()},
 887      *          or if {@code start} is greater than {@code end}
 888      * @spec JSR-51
 889      */
 890     @Override
 891     public CharSequence subSequence(int start, int end) {
 892         return substring(start, end);
 893     }
 894 
 895     /**
 896      * Returns a new {@code String} that contains a subsequence of
 897      * characters currently contained in this sequence. The
 898      * substring begins at the specified {@code start} and
 899      * extends to the character at index {@code end - 1}.
 900      *
 901      * @param      start    The beginning index, inclusive.
 902      * @param      end      The ending index, exclusive.
 903      * @return     The new string.
 904      * @throws     StringIndexOutOfBoundsException  if {@code start}
 905      *             or {@code end} are negative or greater than
 906      *             {@code length()}, or {@code start} is
 907      *             greater than {@code end}.
 908      */
 909     public String substring(int start, int end) {
 910         if (start < 0)
 911             throw new StringIndexOutOfBoundsException(start);
 912         if (end > count)
 913             throw new StringIndexOutOfBoundsException(end);
 914         if (start > end)
 915             throw new StringIndexOutOfBoundsException(end - start);
 916         return new String(value, start, end - start);
 917     }
 918 
 919     /**
 920      * Inserts the string representation of a subarray of the {@code str}
 921      * array argument into this sequence. The subarray begins at the
 922      * specified {@code offset} and extends {@code len} {@code char}s.
 923      * The characters of the subarray are inserted into this sequence at
 924      * the position indicated by {@code index}. The length of this
 925      * sequence increases by {@code len} {@code char}s.
 926      *
 927      * @param      index    position at which to insert subarray.
 928      * @param      str       A {@code char} array.
 929      * @param      offset   the index of the first {@code char} in subarray to
 930      *             be inserted.
 931      * @param      len      the number of {@code char}s in the subarray to
 932      *             be inserted.
 933      * @return     This object
 934      * @throws     StringIndexOutOfBoundsException  if {@code index}
 935      *             is negative or greater than {@code length()}, or
 936      *             {@code offset} or {@code len} are negative, or
 937      *             {@code (offset+len)} is greater than
 938      *             {@code str.length}.
 939      */
 940     public AbstractStringBuilder insert(int index, char[] str, int offset,
 941                                         int len)
 942     {
 943         if ((index < 0) || (index > length()))
 944             throw new StringIndexOutOfBoundsException(index);
 945         if ((offset < 0) || (len < 0) || (offset > str.length - len))
 946             throw new StringIndexOutOfBoundsException(
 947                 "offset " + offset + ", len " + len + ", str.length "
 948                 + str.length);
 949         ensureCapacityInternal(count + len);
 950         System.arraycopy(value, index, value, index + len, count - index);
 951         System.arraycopy(str, offset, value, index, len);
 952         count += len;
 953         return this;
 954     }
 955 
 956     /**
 957      * Inserts the string representation of the {@code Object}
 958      * argument into this character sequence.
 959      * <p>
 960      * The overall effect is exactly as if the second argument were
 961      * converted to a string by the method {@link String#valueOf(Object)},
 962      * and the characters of that string were then
 963      * {@link #insert(int,String) inserted} into this character
 964      * sequence at the indicated offset.
 965      * <p>
 966      * The {@code offset} argument must be greater than or equal to
 967      * {@code 0}, and less than or equal to the {@linkplain #length() length}
 968      * of this sequence.
 969      *
 970      * @param      offset   the offset.
 971      * @param      obj      an {@code Object}.
 972      * @return     a reference to this object.
 973      * @throws     StringIndexOutOfBoundsException  if the offset is invalid.
 974      */
 975     public AbstractStringBuilder insert(int offset, Object obj) {
 976         return insert(offset, String.valueOf(obj));
 977     }
 978 
 979     /**
 980      * Inserts the string into this character sequence.
 981      * <p>
 982      * The characters of the {@code String} argument are inserted, in
 983      * order, into this sequence at the indicated offset, moving up any
 984      * characters originally above that position and increasing the length
 985      * of this sequence by the length of the argument. If
 986      * {@code str} is {@code null}, then the four characters
 987      * {@code "null"} are inserted into this sequence.
 988      * <p>
 989      * The character at index <i>k</i> in the new character sequence is
 990      * equal to:
 991      * <ul>
 992      * <li>the character at index <i>k</i> in the old character sequence, if
 993      * <i>k</i> is less than {@code offset}
 994      * <li>the character at index <i>k</i>{@code -offset} in the
 995      * argument {@code str}, if <i>k</i> is not less than
 996      * {@code offset} but is less than {@code offset+str.length()}
 997      * <li>the character at index <i>k</i>{@code -str.length()} in the
 998      * old character sequence, if <i>k</i> is not less than
 999      * {@code offset+str.length()}
1000      * </ul><p>
1001      * The {@code offset} argument must be greater than or equal to
1002      * {@code 0}, and less than or equal to the {@linkplain #length() length}
1003      * of this sequence.
1004      *
1005      * @param      offset   the offset.
1006      * @param      str      a string.
1007      * @return     a reference to this object.
1008      * @throws     StringIndexOutOfBoundsException  if the offset is invalid.
1009      */
1010     public AbstractStringBuilder insert(int offset, String str) {
1011         if ((offset < 0) || (offset > length()))
1012             throw new StringIndexOutOfBoundsException(offset);
1013         if (str == null)
1014             str = "null";
1015         int len = str.length();
1016         ensureCapacityInternal(count + len);
1017         System.arraycopy(value, offset, value, offset + len, count - offset);
1018         str.getChars(value, offset);
1019         count += len;
1020         return this;
1021     }
1022 
1023     /**
1024      * Inserts the string representation of the {@code char} array
1025      * argument into this sequence.
1026      * <p>
1027      * The characters of the array argument are inserted into the
1028      * contents of this sequence at the position indicated by
1029      * {@code offset}. The length of this sequence increases by
1030      * the length of the argument.
1031      * <p>
1032      * The overall effect is exactly as if the second argument were
1033      * converted to a string by the method {@link String#valueOf(char[])},
1034      * and the characters of that string were then
1035      * {@link #insert(int,String) inserted} into this character
1036      * sequence at the indicated offset.
1037      * <p>
1038      * The {@code offset} argument must be greater than or equal to
1039      * {@code 0}, and less than or equal to the {@linkplain #length() length}
1040      * of this sequence.
1041      *
1042      * @param      offset   the offset.
1043      * @param      str      a character array.
1044      * @return     a reference to this object.
1045      * @throws     StringIndexOutOfBoundsException  if the offset is invalid.
1046      */
1047     public AbstractStringBuilder insert(int offset, char[] str) {
1048         if ((offset < 0) || (offset > length()))
1049             throw new StringIndexOutOfBoundsException(offset);
1050         int len = str.length;
1051         ensureCapacityInternal(count + len);
1052         System.arraycopy(value, offset, value, offset + len, count - offset);
1053         System.arraycopy(str, 0, value, offset, len);
1054         count += len;
1055         return this;
1056     }
1057 
1058     /**
1059      * Inserts the specified {@code CharSequence} into this sequence.
1060      * <p>
1061      * The characters of the {@code CharSequence} argument are inserted,
1062      * in order, into this sequence at the indicated offset, moving up
1063      * any characters originally above that position and increasing the length
1064      * of this sequence by the length of the argument s.
1065      * <p>
1066      * The result of this method is exactly the same as if it were an
1067      * invocation of this object's
1068      * {@link #insert(int,CharSequence,int,int) insert}(dstOffset, s, 0, s.length())
1069      * method.
1070      *
1071      * <p>If {@code s} is {@code null}, then the four characters
1072      * {@code "null"} are inserted into this sequence.
1073      *
1074      * @param      dstOffset   the offset.
1075      * @param      s the sequence to be inserted
1076      * @return     a reference to this object.
1077      * @throws     IndexOutOfBoundsException  if the offset is invalid.
1078      */
1079     public AbstractStringBuilder insert(int dstOffset, CharSequence s) {
1080         if (s == null)
1081             s = "null";
1082         if (s instanceof String)
1083             return this.insert(dstOffset, (String)s);
1084         return this.insert(dstOffset, s, 0, s.length());
1085     }
1086 
1087     /**
1088      * Inserts a subsequence of the specified {@code CharSequence} into
1089      * this sequence.
1090      * <p>
1091      * The subsequence of the argument {@code s} specified by
1092      * {@code start} and {@code end} are inserted,
1093      * in order, into this sequence at the specified destination offset, moving
1094      * up any characters originally above that position. The length of this
1095      * sequence is increased by {@code end - start}.
1096      * <p>
1097      * The character at index <i>k</i> in this sequence becomes equal to:
1098      * <ul>
1099      * <li>the character at index <i>k</i> in this sequence, if
1100      * <i>k</i> is less than {@code dstOffset}
1101      * <li>the character at index <i>k</i>{@code +start-dstOffset} in
1102      * the argument {@code s}, if <i>k</i> is greater than or equal to
1103      * {@code dstOffset} but is less than {@code dstOffset+end-start}
1104      * <li>the character at index <i>k</i>{@code -(end-start)} in this
1105      * sequence, if <i>k</i> is greater than or equal to
1106      * {@code dstOffset+end-start}
1107      * </ul><p>
1108      * The {@code dstOffset} argument must be greater than or equal to
1109      * {@code 0}, and less than or equal to the {@linkplain #length() length}
1110      * of this sequence.
1111      * <p>The start argument must be nonnegative, and not greater than
1112      * {@code end}.
1113      * <p>The end argument must be greater than or equal to
1114      * {@code start}, and less than or equal to the length of s.
1115      *
1116      * <p>If {@code s} is {@code null}, then this method inserts
1117      * characters as if the s parameter was a sequence containing the four
1118      * characters {@code "null"}.
1119      *
1120      * @param      dstOffset   the offset in this sequence.
1121      * @param      s       the sequence to be inserted.
1122      * @param      start   the starting index of the subsequence to be inserted.
1123      * @param      end     the end index of the subsequence to be inserted.
1124      * @return     a reference to this object.
1125      * @throws     IndexOutOfBoundsException  if {@code dstOffset}
1126      *             is negative or greater than {@code this.length()}, or
1127      *              {@code start} or {@code end} are negative, or
1128      *              {@code start} is greater than {@code end} or
1129      *              {@code end} is greater than {@code s.length()}
1130      */
1131      public AbstractStringBuilder insert(int dstOffset, CharSequence s,
1132                                          int start, int end) {
1133         if (s == null)
1134             s = "null";
1135         if ((dstOffset < 0) || (dstOffset > this.length()))
1136             throw new IndexOutOfBoundsException("dstOffset "+dstOffset);
1137         if ((start < 0) || (end < 0) || (start > end) || (end > s.length()))
1138             throw new IndexOutOfBoundsException(
1139                 "start " + start + ", end " + end + ", s.length() "
1140                 + s.length());
1141         int len = end - start;
1142         ensureCapacityInternal(count + len);
1143         System.arraycopy(value, dstOffset, value, dstOffset + len,
1144                          count - dstOffset);
1145         for (int i=start; i<end; i++)
1146             value[dstOffset++] = s.charAt(i);
1147         count += len;
1148         return this;
1149     }
1150 
1151     /**
1152      * Inserts the string representation of the {@code boolean}
1153      * argument into this sequence.
1154      * <p>
1155      * The overall effect is exactly as if the second argument were
1156      * converted to a string by the method {@link String#valueOf(boolean)},
1157      * and the characters of that string were then
1158      * {@link #insert(int,String) inserted} into this character
1159      * sequence at the indicated offset.
1160      * <p>
1161      * The {@code offset} argument must be greater than or equal to
1162      * {@code 0}, and less than or equal to the {@linkplain #length() length}
1163      * of this sequence.
1164      *
1165      * @param      offset   the offset.
1166      * @param      b        a {@code boolean}.
1167      * @return     a reference to this object.
1168      * @throws     StringIndexOutOfBoundsException  if the offset is invalid.
1169      */
1170     public AbstractStringBuilder insert(int offset, boolean b) {
1171         return insert(offset, String.valueOf(b));
1172     }
1173 
1174     /**
1175      * Inserts the string representation of the {@code char}
1176      * argument into this sequence.
1177      * <p>
1178      * The overall effect is exactly as if the second argument were
1179      * converted to a string by the method {@link String#valueOf(char)},
1180      * and the character in that string were then
1181      * {@link #insert(int,String) inserted} into this character
1182      * sequence at the indicated offset.
1183      * <p>
1184      * The {@code offset} argument must be greater than or equal to
1185      * {@code 0}, and less than or equal to the {@linkplain #length() length}
1186      * of this sequence.
1187      *
1188      * @param      offset   the offset.
1189      * @param      c        a {@code char}.
1190      * @return     a reference to this object.
1191      * @throws     IndexOutOfBoundsException  if the offset is invalid.
1192      */
1193     public AbstractStringBuilder insert(int offset, char c) {
1194         ensureCapacityInternal(count + 1);
1195         System.arraycopy(value, offset, value, offset + 1, count - offset);
1196         value[offset] = c;
1197         count += 1;
1198         return this;
1199     }
1200 
1201     /**
1202      * Inserts the string representation of the second {@code int}
1203      * argument into this sequence.
1204      * <p>
1205      * The overall effect is exactly as if the second argument were
1206      * converted to a string by the method {@link String#valueOf(int)},
1207      * and the characters of that string were then
1208      * {@link #insert(int,String) inserted} into this character
1209      * sequence at the indicated offset.
1210      * <p>
1211      * The {@code offset} argument must be greater than or equal to
1212      * {@code 0}, and less than or equal to the {@linkplain #length() length}
1213      * of this sequence.
1214      *
1215      * @param      offset   the offset.
1216      * @param      i        an {@code int}.
1217      * @return     a reference to this object.
1218      * @throws     StringIndexOutOfBoundsException  if the offset is invalid.
1219      */
1220     public AbstractStringBuilder insert(int offset, int i) {
1221         return insert(offset, String.valueOf(i));
1222     }
1223 
1224     /**
1225      * Inserts the string representation of the {@code long}
1226      * argument into this sequence.
1227      * <p>
1228      * The overall effect is exactly as if the second argument were
1229      * converted to a string by the method {@link String#valueOf(long)},
1230      * and the characters of that string were then
1231      * {@link #insert(int,String) inserted} into this character
1232      * sequence at the indicated offset.
1233      * <p>
1234      * The {@code offset} argument must be greater than or equal to
1235      * {@code 0}, and less than or equal to the {@linkplain #length() length}
1236      * of this sequence.
1237      *
1238      * @param      offset   the offset.
1239      * @param      l        a {@code long}.
1240      * @return     a reference to this object.
1241      * @throws     StringIndexOutOfBoundsException  if the offset is invalid.
1242      */
1243     public AbstractStringBuilder insert(int offset, long l) {
1244         return insert(offset, String.valueOf(l));
1245     }
1246 
1247     /**
1248      * Inserts the string representation of the {@code float}
1249      * argument into this sequence.
1250      * <p>
1251      * The overall effect is exactly as if the second argument were
1252      * converted to a string by the method {@link String#valueOf(float)},
1253      * and the characters of that string were then
1254      * {@link #insert(int,String) inserted} into this character
1255      * sequence at the indicated offset.
1256      * <p>
1257      * The {@code offset} argument must be greater than or equal to
1258      * {@code 0}, and less than or equal to the {@linkplain #length() length}
1259      * of this sequence.
1260      *
1261      * @param      offset   the offset.
1262      * @param      f        a {@code float}.
1263      * @return     a reference to this object.
1264      * @throws     StringIndexOutOfBoundsException  if the offset is invalid.
1265      */
1266     public AbstractStringBuilder insert(int offset, float f) {
1267         return insert(offset, String.valueOf(f));
1268     }
1269 
1270     /**
1271      * Inserts the string representation of the {@code double}
1272      * argument into this sequence.
1273      * <p>
1274      * The overall effect is exactly as if the second argument were
1275      * converted to a string by the method {@link String#valueOf(double)},
1276      * and the characters of that string were then
1277      * {@link #insert(int,String) inserted} into this character
1278      * sequence at the indicated offset.
1279      * <p>
1280      * The {@code offset} argument must be greater than or equal to
1281      * {@code 0}, and less than or equal to the {@linkplain #length() length}
1282      * of this sequence.
1283      *
1284      * @param      offset   the offset.
1285      * @param      d        a {@code double}.
1286      * @return     a reference to this object.
1287      * @throws     StringIndexOutOfBoundsException  if the offset is invalid.
1288      */
1289     public AbstractStringBuilder insert(int offset, double d) {
1290         return insert(offset, String.valueOf(d));
1291     }
1292 
1293     /**
1294      * Returns the index within this string of the first occurrence of the
1295      * specified substring.
1296      *
1297      * <p>The returned index is the smallest value {@code k} for which:
1298      * <pre>{@code
1299      * this.toString().startsWith(str, k)
1300      * }</pre>
1301      * If no such value of {@code k} exists, then {@code -1} is returned.
1302      *
1303      * @param   str   the substring to search for.
1304      * @return  the index of the first occurrence of the specified substring,
1305      *          or {@code -1} if there is no such occurrence.
1306      */
1307     public int indexOf(String str) {
1308         return indexOf(str, 0);
1309     }
1310 
1311     /**
1312      * Returns the index within this string of the first occurrence of the
1313      * specified substring, starting at the specified index.
1314      *
1315      * <p>The returned index is the smallest value {@code k} for which:
1316      * <pre>{@code
1317      *     k >= Math.min(fromIndex, this.length()) &&
1318      *                   this.toString().startsWith(str, k)
1319      * }</pre>
1320      * If no such value of {@code k} exists, then {@code -1} is returned.
1321      *
1322      * @param   str         the substring to search for.
1323      * @param   fromIndex   the index from which to start the search.
1324      * @return  the index of the first occurrence of the specified substring,
1325      *          starting at the specified index,
1326      *          or {@code -1} if there is no such occurrence.
1327      */
1328     public int indexOf(String str, int fromIndex) {
1329         return String.indexOf(value, 0, count, str, fromIndex);
1330     }
1331 
1332     /**
1333      * Returns the index within this string of the last occurrence of the
1334      * specified substring.  The last occurrence of the empty string "" is
1335      * considered to occur at the index value {@code this.length()}.
1336      *
1337      * <p>The returned index is the largest value {@code k} for which:
1338      * <pre>{@code
1339      * this.toString().startsWith(str, k)
1340      * }</pre>
1341      * If no such value of {@code k} exists, then {@code -1} is returned.
1342      *
1343      * @param   str   the substring to search for.
1344      * @return  the index of the last occurrence of the specified substring,
1345      *          or {@code -1} if there is no such occurrence.
1346      */
1347     public int lastIndexOf(String str) {
1348         return lastIndexOf(str, count);
1349     }
1350 
1351     /**
1352      * Returns the index within this string of the last occurrence of the
1353      * specified substring, searching backward starting at the specified index.
1354      *
1355      * <p>The returned index is the largest value {@code k} for which:
1356      * <pre>{@code
1357      *     k <= Math.min(fromIndex, this.length()) &&
1358      *                   this.toString().startsWith(str, k)
1359      * }</pre>
1360      * If no such value of {@code k} exists, then {@code -1} is returned.
1361      *
1362      * @param   str         the substring to search for.
1363      * @param   fromIndex   the index to start the search from.
1364      * @return  the index of the last occurrence of the specified substring,
1365      *          searching backward from the specified index,
1366      *          or {@code -1} if there is no such occurrence.
1367      */
1368     public int lastIndexOf(String str, int fromIndex) {
1369         return String.lastIndexOf(value, 0, count, str, fromIndex);
1370     }
1371 
1372     /**
1373      * Causes this character sequence to be replaced by the reverse of
1374      * the sequence. If there are any surrogate pairs included in the
1375      * sequence, these are treated as single characters for the
1376      * reverse operation. Thus, the order of the high-low surrogates
1377      * is never reversed.
1378      *
1379      * Let <i>n</i> be the character length of this character sequence
1380      * (not the length in {@code char} values) just prior to
1381      * execution of the {@code reverse} method. Then the
1382      * character at index <i>k</i> in the new character sequence is
1383      * equal to the character at index <i>n-k-1</i> in the old
1384      * character sequence.
1385      *
1386      * <p>Note that the reverse operation may result in producing
1387      * surrogate pairs that were unpaired low-surrogates and
1388      * high-surrogates before the operation. For example, reversing
1389      * "\u005CuDC00\u005CuD800" produces "\u005CuD800\u005CuDC00" which is
1390      * a valid surrogate pair.
1391      *
1392      * @return  a reference to this object.
1393      */
1394     public AbstractStringBuilder reverse() {
1395         boolean hasSurrogates = false;
1396         int n = count - 1;
1397         for (int j = (n-1) >> 1; j >= 0; j--) {
1398             int k = n - j;
1399             char cj = value[j];
1400             char ck = value[k];
1401             value[j] = ck;
1402             value[k] = cj;
1403             if (Character.isSurrogate(cj) ||
1404                 Character.isSurrogate(ck)) {
1405                 hasSurrogates = true;
1406             }
1407         }
1408         if (hasSurrogates) {
1409             reverseAllValidSurrogatePairs();
1410         }
1411         return this;
1412     }
1413 
1414     /** Outlined helper method for reverse() */
1415     private void reverseAllValidSurrogatePairs() {
1416         for (int i = 0; i < count - 1; i++) {
1417             char c2 = value[i];
1418             if (Character.isLowSurrogate(c2)) {
1419                 char c1 = value[i + 1];
1420                 if (Character.isHighSurrogate(c1)) {
1421                     value[i++] = c1;
1422                     value[i] = c2;
1423                 }
1424             }
1425         }
1426     }
1427 
1428     /**
1429      * Returns a string representing the data in this sequence.
1430      * A new {@code String} object is allocated and initialized to
1431      * contain the character sequence currently represented by this
1432      * object. This {@code String} is then returned. Subsequent
1433      * changes to this sequence do not affect the contents of the
1434      * {@code String}.
1435      *
1436      * @return  a string representation of this sequence of characters.
1437      */
1438     @Override
1439     public abstract String toString();
1440 
1441     /**
1442      * {@inheritDoc}
1443      * @since 1.9
1444      */
1445     @Override
1446     public IntStream chars() {
1447         // Reuse String-based spliterator. This requires a supplier to
1448         // capture the value and count when the terminal operation is executed
1449         return StreamSupport.intStream(
1450                 () -> new String.IntCharArraySpliterator(value, 0, count, 0),
1451                 Spliterator.ORDERED | Spliterator.SIZED | Spliterator.SUBSIZED,
1452                 false);
1453     }
1454 
1455     /**
1456      * {@inheritDoc}
1457      * @since 1.9
1458      */
1459     @Override
1460     public IntStream codePoints() {
1461         // Reuse String-based spliterator. This requires a supplier to
1462         // capture the value and count when the terminal operation is executed
1463         return StreamSupport.intStream(
1464                 () -> new String.CodePointsSpliterator(value, 0, count, 0),
1465                 Spliterator.ORDERED,
1466                 false);
1467     }
1468 
1469     /**
1470      * Needed by {@code String} for the contentEquals method.
1471      */
1472     final char[] getValue() {
1473         return value;
1474     }
1475 
1476 }