mcs/class/corlib/System.Text/StringBuilder.cs

   1 // -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*-
   2 //
   3 // System.Text.StringBuilder
   4 //
   5 // Authors:
   6 //   Marcin Szczepanski (marcins@zipworld.com.au)
   7 //   Paolo Molaro (lupus@ximian.com)
   8 //   Patrik Torstensson
   9 //
  10 // NOTE: In the case the buffer is only filled by 50% a new string
  11 //       will be returned by ToString() is cached in the '_cached_str'
  12 //               cache_string will also control if a string has been handed out
  13 //               to via ToString(). If you are chaning the code make sure that
  14 //               if you modify the string data set the cache_string to null.
  15 //
  16
  17 //
  18 // Copyright (C) 2004 Novell, Inc (http://www.novell.com)
  19 // Copyright 2011 Xamarin Inc
  20 //
  21 // Permission is hereby granted, free of charge, to any person obtaining
  22 // a copy of this software and associated documentation files (the
  23 // "Software"), to deal in the Software without restriction, including
  24 // without limitation the rights to use, copy, modify, merge, publish,
  25 // distribute, sublicense, and/or sell copies of the Software, and to
  26 // permit persons to whom the Software is furnished to do so, subject to
  27 // the following conditions:
  28 //
  29 // The above copyright notice and this permission notice shall be
  30 // included in all copies or substantial portions of the Software.
  31 //
  32 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  33 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  34 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  35 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  36 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  37 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  38 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  39 //
  40 using System.Runtime.Serialization;
  41 using System.Runtime.CompilerServices;
  42 using System.Runtime.InteropServices;
  43
  44 namespace System.Text {
  45
  46         [Serializable]
  47         [ComVisible (true)]
  48         [MonoLimitation ("Serialization format not compatible with .NET")]
  49         [StructLayout (LayoutKind.Sequential)]
  50         public sealed class StringBuilder : ISerializable
  51         {
  52                 private int _length;
  53                 private string _str;
  54                 private string _cached_str;
  55
  56                 private int _maxCapacity;
  57                 internal const int DefaultCapacity = 16;
  58
  59                 public StringBuilder(string value, int startIndex, int length, int capacity)
  60                         : this (value, startIndex, length, capacity, Int32.MaxValue)
  61                 {
  62                 }
  63
  64                 private StringBuilder(string value, int startIndex, int length, int capacity, int maxCapacity)
  65                 {
  66                         // first, check the parameters and throw appropriate exceptions if needed
  67                         if (null == value)
  68                                 value = "";
  69
  70                         // make sure startIndex is zero or positive
  71                         if (startIndex < 0)
  72                                 throw new System.ArgumentOutOfRangeException ("startIndex", startIndex, "StartIndex cannot be less than zero.");
  73
  74                         // make sure length is zero or positive
  75                         if(length < 0)
  76                                 throw new System.ArgumentOutOfRangeException ("length", length, "Length cannot be less than zero.");
  77
  78                         if (capacity < 0)
  79                                 throw new System.ArgumentOutOfRangeException ("capacity", capacity, "capacity must be greater than zero.");
  80
  81                         if (maxCapacity < 1)
  82                                 throw new System.ArgumentOutOfRangeException ("maxCapacity", "maxCapacity is less than one.");
  83                         if (capacity > maxCapacity)
  84                                 throw new System.ArgumentOutOfRangeException ("capacity", "Capacity exceeds maximum capacity.");
  85
  86                         // make sure startIndex and length give a valid substring of value
  87                         // re-ordered to avoid possible integer overflow
  88                         if (startIndex > value.Length - length)
  89                                 throw new System.ArgumentOutOfRangeException ("startIndex", startIndex, "StartIndex and length must refer to a location within the string.");
  90
  91                         if (capacity == 0) {
  92                                 if (maxCapacity > DefaultCapacity)
  93                                         capacity = DefaultCapacity;
  94                                 else
  95                                         _str = _cached_str = String.Empty;
  96                         }
  97                         _maxCapacity = maxCapacity;
  98
  99                         if (_str == null)
 100                                 _str = String.InternalAllocateStr ((length > capacity) ? length : capacity);
 101                         if (length > 0)
 102                                 String.CharCopy (_str, 0, value, startIndex, length);
 103
 104                         _length = length;
 105                 }
 106
 107                 public StringBuilder () : this (null) {}
 108
 109                 public StringBuilder(int capacity) : this (String.Empty, 0, 0, capacity) {}
 110
 111                 public StringBuilder(int capacity, int maxCapacity) : this (String.Empty, 0, 0, capacity, maxCapacity) { }
 112
 113                 public StringBuilder (string value)
 114                 {
 115                         /*
 116                          * This is an optimization to avoid allocating the internal string
 117                          * until the first Append () call.
 118                          * The runtime pinvoke marshalling code needs to be aware of this.
 119                          */
 120                         if (null == value)
 121                                 value = "";
 122
 123                         _length = value.Length;
 124                         _str = _cached_str = value;
 125                         _maxCapacity = Int32.MaxValue;
 126                 }
 127
 128                 public StringBuilder( string value, int capacity) : this(value == null ? "" : value, 0, value == null ? 0 : value.Length, capacity) {}
 129
 130                 public int MaxCapacity {
 131                         get {
 132                                 return _maxCapacity;
 133                         }
 134                 }
 135
 136                 public int Capacity {
 137                         get {
 138                                 if (_str.Length == 0)
 139                                         return Math.Min (_maxCapacity, DefaultCapacity);
 140
 141                                 return _str.Length;
 142                         }
 143
 144                         set {
 145                                 if (value < _length)
 146                                         throw new ArgumentException( "Capacity must be larger than length" );
 147
 148                                 if (value > _maxCapacity)
 149                                         throw new ArgumentOutOfRangeException ("value", "Should be less than or equal to MaxCapacity");
 150
 151                                 InternalEnsureCapacity(value);
 152                         }
 153                 }
 154
 155                 public int Length {
 156                         get {
 157                                 return _length;
 158                         }
 159
 160                         set {
 161                                 if( value < 0 || value > _maxCapacity)
 162                                         throw new ArgumentOutOfRangeException();
 163
 164                                 if (value == _length)
 165                                         return;
 166
 167                                 if (value < _length) {
 168                                         // LAMESPEC:  The spec is unclear as to what to do
 169                                         // with the capacity when truncating the string.
 170
 171                                         // Do as MS, keep the capacity
 172
 173                                         // Make sure that we invalidate any cached string.
 174                                         InternalEnsureCapacity (value);
 175                                         _length = value;
 176                                 } else {
 177                                         // Expand the capacity to the new length and
 178                                         // pad the string with NULL characters.
 179                                         Append('\0', value - _length);
 180                                 }
 181                         }
 182                 }
 183
 184                 [IndexerName("Chars")]
 185                 public char this [int index] {
 186                         get {
 187                                 if (index >= _length || index < 0)
 188                                         throw new IndexOutOfRangeException();
 189
 190                                 return _str [index];
 191                         }
 192
 193                         set {
 194                                 if (index >= _length || index < 0)
 195                                         throw new IndexOutOfRangeException();
 196
 197                                 if (null != _cached_str)
 198                                         InternalEnsureCapacity (_length);
 199
 200                                 _str.InternalSetChar (index, value);
 201                         }
 202                 }
 203
 204                 public override string ToString ()
 205                 {
 206                         if (_length == 0)
 207                                 return String.Empty;
 208
 209                         if (null != _cached_str)
 210                                 return _cached_str;
 211
 212                         // If we only have a half-full buffer we return a new string.
 213                         if (_length < (_str.Length >> 1) || (_str.Length > string.LOS_limit && _length <= string.LOS_limit))
 214                         {
 215                                 // use String.SubstringUnchecked instead of String.Substring
 216                                 // as the former is guaranteed to create a new string object
 217                                 _cached_str = _str.SubstringUnchecked (0, _length);
 218                                 return _cached_str;
 219                         }
 220
 221                         _cached_str = _str;
 222                         _str.InternalSetLength(_length);
 223
 224                         return _str;
 225                 }
 226
 227                 public string ToString (int startIndex, int length)
 228                 {
 229                         // re-ordered to avoid possible integer overflow
 230                         if (startIndex < 0 || length < 0 || startIndex > _length - length)
 231                                 throw new ArgumentOutOfRangeException();
 232
 233                         // use String.SubstringUnchecked instead of String.Substring
 234                         // as the former is guaranteed to create a new string object
 235                         if (startIndex == 0 && length == _length)
 236                                 return ToString ();
 237                         else
 238                                 return _str.SubstringUnchecked (startIndex, length);
 239                 }
 240
 241                 public int EnsureCapacity (int capacity)
 242                 {
 243                         if (capacity < 0)
 244                                 throw new ArgumentOutOfRangeException ("Capacity must be greater than 0." );
 245
 246                         if( capacity <= _str.Length )
 247                                 return _str.Length;
 248
 249                         InternalEnsureCapacity (capacity);
 250
 251                         return _str.Length;
 252                 }
 253
 254                 public bool Equals (StringBuilder sb)
 255                 {
 256                         if (((object)sb) == null)
 257                                 return false;
 258
 259                         if (_length == sb.Length && _str == sb._str )
 260                                 return true;
 261
 262                         return false;
 263                 }
 264
 265                 public StringBuilder Remove (int startIndex, int length)
 266                 {
 267                         // re-ordered to avoid possible integer overflow
 268                         if (startIndex < 0 || length < 0 || startIndex > _length - length)
 269                                 throw new ArgumentOutOfRangeException();
 270
 271                         if (null != _cached_str)
 272                                 InternalEnsureCapacity (_length);
 273
 274                         // Copy everything after the 'removed' part to the start
 275                         // of the removed part and truncate the sLength
 276                         if (_length - (startIndex + length) > 0)
 277                                 String.CharCopy (_str, startIndex, _str, startIndex + length, _length - (startIndex + length));
 278
 279                         _length -= length;
 280
 281                         return this;
 282                 }
 283
 284                 public StringBuilder Replace (char oldChar, char newChar)
 285                 {
 286                         return Replace( oldChar, newChar, 0, _length);
 287                 }
 288
 289                 public StringBuilder Replace (char oldChar, char newChar, int startIndex, int count)
 290                 {
 291                         // re-ordered to avoid possible integer overflow
 292                         if (startIndex > _length - count || startIndex < 0 || count < 0)
 293                                 throw new ArgumentOutOfRangeException();
 294
 295                         if (null != _cached_str)
 296                                 InternalEnsureCapacity (_str.Length);
 297
 298                         for (int replaceIterate = startIndex; replaceIterate < startIndex + count; replaceIterate++ ) {
 299                                 if( _str [replaceIterate] == oldChar )
 300                                         _str.InternalSetChar (replaceIterate, newChar);
 301                         }
 302
 303                         return this;
 304                 }
 305
 306                 public StringBuilder Replace( string oldValue, string newValue ) {
 307                         return Replace (oldValue, newValue, 0, _length);
 308                 }
 309
 310                 public StringBuilder Replace( string oldValue, string newValue, int startIndex, int count )
 311                 {
 312                         if (oldValue == null)
 313                                 throw new ArgumentNullException ("The old value cannot be null.");
 314
 315                         if (startIndex < 0 || count < 0 || startIndex > _length - count)
 316                                 throw new ArgumentOutOfRangeException ();
 317
 318                         if (oldValue.Length == 0)
 319                                 throw new ArgumentException ("The old value cannot be zero length.");
 320
 321                         string substr = _str.Substring(startIndex, count);
 322                         string replace = substr.Replace(oldValue, newValue);
 323                         // return early if no oldValue was found
 324                         if ((object) replace == (object) substr)
 325                                 return this;
 326
 327                         InternalEnsureCapacity (replace.Length + (_length - count));
 328
 329                         // shift end part
 330                         if (replace.Length < count)
 331                                 String.CharCopy (_str, startIndex + replace.Length, _str, startIndex + count, _length - startIndex  - count);
 332                         else if (replace.Length > count)
 333                                 String.CharCopyReverse (_str, startIndex + replace.Length, _str, startIndex + count, _length - startIndex  - count);
 334
 335                         // copy middle part back into _str
 336                         String.CharCopy (_str, startIndex, replace, 0, replace.Length);
 337
 338                         _length = replace.Length + (_length - count);
 339
 340                         return this;
 341                 }
 342
 343
 344                 /* The Append Methods */
 345                 public StringBuilder Append (char[] value)
 346                 {
 347                         if (value == null)
 348                                 return this;
 349
 350                         int needed_cap = _length + value.Length;
 351                         if (null != _cached_str || _str.Length < needed_cap)
 352                                 InternalEnsureCapacity (needed_cap);
 353
 354                         String.CharCopy (_str, _length, value, 0, value.Length);
 355                         _length = needed_cap;
 356
 357                         return this;
 358                 }
 359
 360                 public StringBuilder Append (string value)
 361                 {
 362                         if (value == null)
 363                                 return this;
 364
 365                         if (_length == 0 && value.Length < _maxCapacity && value.Length > _str.Length) {
 366                                 _length = value.Length;
 367                                 _str = _cached_str = value;
 368                                 return this;
 369                         }
 370
 371                         int needed_cap = _length + value.Length;
 372                         if (null != _cached_str || _str.Length < needed_cap)
 373                                 InternalEnsureCapacity (needed_cap);
 374
 375                         String.CharCopy (_str, _length, value, 0, value.Length);
 376                         _length = needed_cap;
 377                         return this;
 378                 }
 379
 380                 public StringBuilder Append (bool value) {
 381                         return Append (value.ToString());
 382                 }
 383
 384                 public StringBuilder Append (byte value) {
 385                         return Append (value.ToString());
 386                 }
 387
 388                 public StringBuilder Append (decimal value) {
 389                         return Append (value.ToString());
 390                 }
 391
 392                 public StringBuilder Append (double value) {
 393                         return Append (value.ToString());
 394                 }
 395
 396                 public StringBuilder Append (short value) {
 397                         return Append (value.ToString());
 398                 }
 399
 400                 public StringBuilder Append (int value) {
 401                         return Append (value.ToString());
 402                 }
 403
 404                 public StringBuilder Append (long value) {
 405                         return Append (value.ToString());
 406                 }
 407
 408                 public StringBuilder Append (object value) {
 409                         if (value == null)
 410                                 return this;
 411
 412                         return Append (value.ToString());
 413                 }
 414
 415                 [CLSCompliant(false)]
 416                 public StringBuilder Append (sbyte value) {
 417                         return Append (value.ToString());
 418                 }
 419
 420                 public StringBuilder Append (float value) {
 421                         return Append (value.ToString());
 422                 }
 423
 424                 [CLSCompliant(false)]
 425                 public StringBuilder Append (ushort value) {
 426                         return Append (value.ToString());
 427                 }
 428
 429                 [CLSCompliant(false)]
 430                 public StringBuilder Append (uint value) {
 431                         return Append (value.ToString());
 432                 }
 433
 434                 [CLSCompliant(false)]
 435                 public StringBuilder Append (ulong value) {
 436                         return Append (value.ToString());
 437                 }
 438
 439                 public StringBuilder Append (char value)
 440                 {
 441                         int needed_cap = _length + 1;
 442                         if (null != _cached_str || _str.Length < needed_cap)
 443                                 InternalEnsureCapacity (needed_cap);
 444
 445                         _str.InternalSetChar(_length, value);
 446                         _length = needed_cap;
 447
 448                         return this;
 449                 }
 450
 451                 public StringBuilder Append (char value, int repeatCount)
 452                 {
 453                         if( repeatCount < 0 )
 454                                 throw new ArgumentOutOfRangeException();
 455
 456                         InternalEnsureCapacity (_length + repeatCount);
 457
 458                         for (int i = 0; i < repeatCount; i++)
 459                                 _str.InternalSetChar (_length++, value);
 460
 461                         return this;
 462                 }
 463
 464                 public StringBuilder Append( char[] value, int startIndex, int charCount )
 465                 {
 466                         if (value == null) {
 467                                 if (!(startIndex == 0 && charCount == 0))
 468                                         throw new ArgumentNullException ("value");
 469
 470                                 return this;
 471                         }
 472
 473                         if ((charCount < 0 || startIndex < 0) || (startIndex > value.Length - charCount))
 474                                 throw new ArgumentOutOfRangeException();
 475
 476                         int needed_cap = _length + charCount;
 477                         InternalEnsureCapacity (needed_cap);
 478
 479                         String.CharCopy (_str, _length, value, startIndex, charCount);
 480                         _length = needed_cap;
 481
 482                         return this;
 483                 }
 484
 485                 public StringBuilder Append (string value, int startIndex, int count)
 486                 {
 487                         if (value == null) {
 488                                 if (startIndex != 0 && count != 0)
 489                                         throw new ArgumentNullException ("value");
 490
 491                                 return this;
 492                         }
 493
 494                         if ((count < 0 || startIndex < 0) || (startIndex > value.Length - count))
 495                                 throw new ArgumentOutOfRangeException();
 496
 497                         int needed_cap = _length + count;
 498                         if (null != _cached_str || _str.Length < needed_cap)
 499                                 InternalEnsureCapacity (needed_cap);
 500
 501                         String.CharCopy (_str, _length, value, startIndex, count);
 502
 503                         _length = needed_cap;
 504
 505                         return this;
 506                 }
 507
 508                 internal unsafe StringBuilder Append (char* value, int valueCount)
 509                 {
 510                         int needed_cap = _length + valueCount;
 511                         InternalEnsureCapacity (needed_cap);
 512
 513                         fixed (char* src = _str) {
 514                                 String.CharCopy (src + _length, value, valueCount);
 515                         }
 516                         _length = needed_cap;
 517
 518                         return this;
 519                 }
 520
 521                 public StringBuilder Clear ()
 522                 {
 523                         Length = 0;
 524                         return this;
 525                 }
 526
 527                 [ComVisible (false)]
 528                 public StringBuilder AppendLine ()
 529                 {
 530                         return Append (System.Environment.NewLine);
 531                 }
 532
 533                 [ComVisible (false)]
 534                 public StringBuilder AppendLine (string value)
 535                 {
 536                         return Append (value).Append (System.Environment.NewLine);
 537                 }
 538
 539                 public StringBuilder AppendFormat (string format, params object[] args)
 540                 {
 541                         return AppendFormat (null, format, args);
 542                 }
 543
 544                 public StringBuilder AppendFormat (IFormatProvider provider,
 545                                                    string format,
 546                                                    params object[] args)
 547                 {
 548                         String.FormatHelper (this, provider, format, args);
 549                         return this;
 550                 }
 551
 552                 public
 553                 StringBuilder AppendFormat (string format, object arg0)
 554                 {
 555                         return AppendFormat (null, format, new object [] { arg0 });
 556                 }
 557
 558                 public
 559                 StringBuilder AppendFormat (string format, object arg0, object arg1)
 560                 {
 561                         return AppendFormat (null, format, new object [] { arg0, arg1 });
 562                 }
 563
 564                 public
 565                 StringBuilder AppendFormat (string format, object arg0, object arg1, object arg2)
 566                 {
 567                         return AppendFormat (null, format, new object [] { arg0, arg1, arg2 });
 568                 }
 569
 570                 /*  The Insert Functions */
 571
 572                 public StringBuilder Insert (int index, char[] value)
 573                 {
 574                         return Insert (index, new string (value));
 575                 }
 576
 577                 public StringBuilder Insert (int index, string value)
 578                 {
 579                         if( index > _length || index < 0)
 580                                 throw new ArgumentOutOfRangeException();
 581
 582                         if (value == null || value.Length == 0)
 583                                 return this;
 584
 585                         InternalEnsureCapacity (_length + value.Length);
 586
 587                         // Move everything to the right of the insert point across
 588                         String.CharCopyReverse (_str, index + value.Length, _str, index, _length - index);
 589
 590                         // Copy in stuff from the insert buffer
 591                         String.CharCopy (_str, index, value, 0, value.Length);
 592
 593                         _length += value.Length;
 594
 595                         return this;
 596                 }
 597
 598                 public StringBuilder Insert( int index, bool value ) {
 599                         return Insert (index, value.ToString());
 600                 }
 601
 602                 public StringBuilder Insert( int index, byte value ) {
 603                         return Insert (index, value.ToString());
 604                 }
 605
 606                 public StringBuilder Insert( int index, char value)
 607                 {
 608                         if (index > _length || index < 0)
 609                                 throw new ArgumentOutOfRangeException ("index");
 610
 611                         InternalEnsureCapacity (_length + 1);
 612
 613                         // Move everything to the right of the insert point across
 614                         String.CharCopyReverse (_str, index + 1, _str, index, _length - index);
 615
 616                         _str.InternalSetChar (index, value);
 617                         _length++;
 618
 619                         return this;
 620                 }
 621
 622                 public StringBuilder Insert( int index, decimal value ) {
 623                         return Insert (index, value.ToString());
 624                 }
 625
 626                 public StringBuilder Insert( int index, double value ) {
 627                         return Insert (index, value.ToString());
 628                 }
 629
 630                 public StringBuilder Insert( int index, short value ) {
 631                         return Insert (index, value.ToString());
 632                 }
 633
 634                 public StringBuilder Insert( int index, int value ) {
 635                         return Insert (index, value.ToString());
 636                 }
 637
 638                 public StringBuilder Insert( int index, long value ) {
 639                         return Insert (index, value.ToString());
 640                 }
 641
 642                 public StringBuilder Insert( int index, object value ) {
 643                         return Insert (index, value.ToString());
 644                 }
 645
 646                 [CLSCompliant(false)]
 647                 public StringBuilder Insert( int index, sbyte value ) {
 648                         return Insert (index, value.ToString() );
 649                 }
 650
 651                 public StringBuilder Insert (int index, float value) {
 652                         return Insert (index, value.ToString() );
 653                 }
 654
 655                 [CLSCompliant(false)]
 656                 public StringBuilder Insert (int index, ushort value) {
 657                         return Insert (index, value.ToString() );
 658                 }
 659
 660                 [CLSCompliant(false)]
 661                 public StringBuilder Insert (int index, uint value) {
 662                         return Insert ( index, value.ToString() );
 663                 }
 664
 665                 [CLSCompliant(false)]
 666                 public StringBuilder Insert (int index, ulong value) {
 667                         return Insert ( index, value.ToString() );
 668                 }
 669
 670                 public StringBuilder Insert (int index, string value, int count)
 671                 {
 672                         // LAMESPEC: The spec says to throw an exception if
 673                         // count < 0, while MS throws even for count < 1!
 674                         if ( count < 0 )
 675                                 throw new ArgumentOutOfRangeException();
 676
 677                         if (value != null && value != String.Empty)
 678                                 for (int insertCount = 0; insertCount < count; insertCount++)
 679                                         Insert( index, value );
 680
 681                         return this;
 682                 }
 683
 684                 public StringBuilder Insert (int index, char [] value, int startIndex, int charCount)
 685                 {
 686                         if (value == null) {
 687                                 if (startIndex == 0 && charCount == 0)
 688                                         return this;
 689
 690                                 throw new ArgumentNullException ("value");
 691                         }
 692
 693                         if (charCount < 0 || startIndex < 0 || startIndex > value.Length - charCount)
 694                                 throw new ArgumentOutOfRangeException ();
 695
 696                         return Insert (index, new String (value, startIndex, charCount));
 697                 }
 698
 699                 private void InternalEnsureCapacity (int size)
 700                 {
 701                         if (size > _str.Length || (object) _cached_str == (object) _str) {
 702                                 int capacity = _str.Length;
 703
 704                                 // Try double buffer, if that doesn't work, set the length as capacity
 705                                 if (size > capacity) {
 706
 707                                         // The first time a string is appended, we just set _cached_str
 708                                         // and _str to it. This allows us to do some optimizations.
 709                                         // Below, we take this into account.
 710                                         if ((object) _cached_str == (object) _str && capacity < DefaultCapacity)
 711                                                 capacity = DefaultCapacity;
 712
 713                                         capacity = capacity << 1;
 714                                         if (size > capacity)
 715                                                 capacity = size;
 716
 717                                         if (capacity >= Int32.MaxValue || capacity < 0)
 718                                                 capacity = Int32.MaxValue;
 719
 720                                         if (capacity > _maxCapacity && size <= _maxCapacity)
 721                                                 capacity = _maxCapacity;
 722
 723                                         if (capacity > _maxCapacity)
 724                                                 throw new ArgumentOutOfRangeException ("size", "capacity was less than the current size.");
 725                                 }
 726
 727                                 string tmp = String.InternalAllocateStr (capacity);
 728                                 if (_length > 0)
 729                                         String.CharCopy (tmp, 0, _str, 0, _length);
 730
 731                                 _str = tmp;
 732                         }
 733
 734                         _cached_str = null;
 735                 }
 736
 737                 [ComVisible (false)]
 738                 public void CopyTo (int sourceIndex, char [] destination, int destinationIndex, int count)
 739                 {
 740                         if (destination == null)
 741                                 throw new ArgumentNullException ("destination");
 742                         if ((Length - count < sourceIndex) ||
 743                             (destination.Length -count < destinationIndex) ||
 744                             (sourceIndex < 0 || destinationIndex < 0 || count < 0))
 745                                 throw new ArgumentOutOfRangeException ();
 746
 747                         for (int i = 0; i < count; i++)
 748                                 destination [destinationIndex+i] = _str [sourceIndex+i];
 749                 }
 750
 751                 void ISerializable.GetObjectData (SerializationInfo info, StreamingContext context)
 752                 {
 753                         info.AddValue ("m_MaxCapacity", _maxCapacity);
 754                         info.AddValue ("Capacity", Capacity);
 755                         info.AddValue ("m_StringValue", ToString ());
 756                         info.AddValue ("m_currentThread", 0);
 757                 }
 758
 759                 StringBuilder (SerializationInfo info, StreamingContext context)
 760                 {
 761                         string s = info.GetString ("m_StringValue");
 762                         if (s == null)
 763                                 s = "";
 764                         _length = s.Length;
 765                         _str = _cached_str = s;
 766
 767                         _maxCapacity = info.GetInt32 ("m_MaxCapacity");
 768                         if (_maxCapacity < 0)
 769                                 _maxCapacity = Int32.MaxValue;
 770                         Capacity = info.GetInt32 ("Capacity");
 771                 }
 772         }
 773 }