mcs/class/corlib/System/String.cs

   1 //
   2 // System.String.cs
   3 //
   4 // Authors:
   5 //        Patrik Torstensson (patrik.torstensson@labs2.com)
   6 //   Jeffrey Stedfast (fejj@ximian.com)
   7 //   Dan Lewis (dihlewis@yahoo.co.uk)
   8 //
   9 // (C) 2001 Ximian, Inc.  http://www.ximian.com
  10 //
  11
  12 using System;
  13 using System.Text;
  14 using System.Collections;
  15 using System.Globalization;
  16 using System.Runtime.CompilerServices;
  17
  18 namespace System {
  19         public sealed class String : IConvertible, IComparable, ICloneable, IEnumerable {
  20                 private int length;
  21
  22                 public static readonly String Empty = "";
  23
  24                 [CLSCompliant(false), MethodImplAttribute(MethodImplOptions.InternalCall)]
  25                 unsafe public extern String(char *value);
  26
  27                 [CLSCompliant(false), MethodImplAttribute(MethodImplOptions.InternalCall)]
  28                 unsafe public extern String(char *value, int sindex, int length);
  29
  30                 [CLSCompliant(false), MethodImplAttribute(MethodImplOptions.InternalCall)]
  31                 unsafe public extern String(sbyte *value);
  32
  33                 [CLSCompliant(false), MethodImplAttribute(MethodImplOptions.InternalCall)]
  34                 unsafe public extern String(sbyte *value, int sindex, int length);
  35
  36                 [CLSCompliant(false), MethodImplAttribute(MethodImplOptions.InternalCall)]
  37                 unsafe public extern String(sbyte *value, int sindex, int length, Encoding enc);
  38
  39                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
  40                 public extern String(char [] val, int sindex, int length);
  41
  42                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
  43                 public extern String(char [] val);
  44
  45                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
  46                 public extern String(char c, int count);
  47
  48                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
  49                 public extern override int GetHashCode();
  50
  51                 public static bool Equals(String str1, String str2) {
  52                         if ((Object) str1 == (Object) str2)
  53                                 return true;
  54
  55                         if (null == (Object) str1 || null == (Object) str2)
  56                                 return false;
  57                         if (str1.length != str2.length)
  58                                 return false;
  59
  60                         return Compare(str1, 0, str2, 0, str1.length, false) == 0;
  61                 }
  62
  63                 public static bool operator == (String str1, String str2) {
  64                         return Equals(str1, str2);
  65                 }
  66
  67                 public static bool operator != (String str1, String str2) {
  68                         return !Equals(str1, str2);
  69                 }
  70
  71                 public override bool Equals(Object obj) {
  72                         if (null == obj)
  73                                 return false;
  74
  75                         if (!(obj is String))
  76                                 return false;
  77
  78                         return Compare (this, (String)obj, false) == 0;
  79                 }
  80
  81                 public bool Equals(String value) {
  82                         if (null == value)
  83                                 return false;
  84
  85                         if (length != value.length)
  86                                 return false;
  87                         return Compare (this, 0, value, 0, length, false) == 0;
  88                 }
  89
  90                 [IndexerName("Chars")]
  91                 public extern char this[int index] {
  92                         [MethodImplAttribute(MethodImplOptions.InternalCall)]
  93                         get;
  94                 }
  95
  96                 public Object Clone() {
  97                         return this;
  98                 }
  99
 100                 public TypeCode GetTypeCode () {
 101                         return TypeCode.String;
 102                 }
 103
 104                 public void CopyTo(int sindex, char[] dest, int dindex, int count) {
 105                         // LAMESPEC: should I null-terminate?
 106
 107                         if (dest == null)
 108                                 throw new ArgumentNullException();
 109
 110                         if (sindex < 0 || dindex < 0 || count < 0)
 111                                 throw new ArgumentOutOfRangeException ();
 112
 113                         if (sindex + count > Length)
 114                                 throw new ArgumentOutOfRangeException ();
 115
 116                         if (dindex + count > dest.Length)
 117                                 throw new ArgumentOutOfRangeException ();
 118
 119                         InternalCopyTo(sindex, dest, dindex, count);
 120                 }
 121
 122                 public char[] ToCharArray() {
 123                         return ToCharArray(0, length);
 124                 }
 125
 126                 public char[] ToCharArray(int sindex, int length) {
 127                         if (sindex < 0 || length < 0 || sindex + length > this.length)
 128                                 throw new ArgumentOutOfRangeException ();
 129
 130                         char [] tmp = new char[length];
 131
 132                         InternalCopyTo(sindex, tmp, 0, length);
 133
 134                         return tmp;
 135                 }
 136
 137                 public String [] Split(params char [] separator) {
 138                         return Split(separator, Int32.MaxValue);
 139                 }
 140
 141                 public String[] Split(char[] separator, int count) {
 142                         if (null == separator) {
 143                                 separator = WhiteChars;
 144                         }
 145
 146                         if (count < 0)
 147                                 throw new ArgumentOutOfRangeException ();
 148
 149                         if (count == 0)
 150                                 return new String[1] { ToString() };
 151
 152                         return InternalSplit(separator, count);
 153                 }
 154
 155                 public String Substring (int sindex) {
 156                         if (sindex < 0 || sindex > this.length) {
 157                                 throw new ArgumentOutOfRangeException();
 158                         }
 159
 160                         string tmp = InternalAllocateStr(this.length - sindex);
 161                         InternalStrcpy(tmp, 0, this, sindex, length - sindex);
 162
 163                         return tmp;
 164                 }
 165
 166                 public String Substring (int sindex, int length) {
 167                         if (length < 0 || sindex < 0 || sindex + length > this.length) {
 168                                 throw new ArgumentOutOfRangeException();
 169                         }
 170
 171                         if (length == 0)
 172                                 return String.Empty;
 173
 174                         string tmp = InternalAllocateStr(length);
 175                         InternalStrcpy(tmp, 0, this, sindex, length);
 176
 177                         return tmp;
 178                 }
 179
 180                 private static readonly char[] WhiteChars = {  (char) 0x9, (char) 0xA, (char) 0xB, (char) 0xC, (char) 0xD, (char) 0x20, (char) 0xA0, (char) 0x2000, (char) 0x2001, (char) 0x2002, (char) 0x2003, (char) 0x2004, (char) 0x2005,
 181                                                                                                                                                           (char) 0x2006, (char) 0x2007, (char) 0x2008, (char) 0x2009, (char) 0x200A, (char) 0x200B, (char) 0x3000, (char) 0xFEFF };
 182
 183                 public String Trim(params char[] chars) {
 184                         if (null == chars || chars.Length == 0)
 185                                 chars = WhiteChars;
 186
 187                         return InternalTrim(chars, 0);
 188                 }
 189
 190                 public String TrimStart(params char[] chars) {
 191                         if (null == chars || chars.Length == 0)
 192                                 chars = WhiteChars;
 193
 194                         return InternalTrim(chars, 1);
 195                 }
 196
 197                 public String TrimEnd(params char[] chars) {
 198                         if (null == chars || chars.Length == 0)
 199                                 chars = WhiteChars;
 200
 201                         return InternalTrim(chars, 2);
 202                 }
 203
 204                 public static int Compare(String s1, String s2) {
 205                         return Compare(s1, s2, false);
 206                 }
 207
 208                 public static int Compare(String s1, String s2, bool inCase) {
 209                         if (null == s1) {
 210                                 if (null == s2)
 211                                         return 0;
 212                                 else
 213                                         return -1;
 214                         } else if (null == s2)
 215                                 return 1;
 216
 217                         return InternalCompare(s1, 0, s2, 0, Math.Max(s1.length, s2.length), inCase);
 218                 }
 219
 220                 [MonoTODO()]
 221                 public static int Compare(String s1, String s2, bool inCase, CultureInfo culture) {
 222                         return Compare(s1, s2, inCase);
 223                 }
 224
 225                 public static int Compare(String s1, int i1, String s2, int i2, int length) {
 226                         return Compare(s1, i1, s2, i2, length, false);
 227                 }
 228
 229                 public static int Compare(String s1, int i1, String s2, int i2, int length, bool inCase) {
 230                         if (null == s1) {
 231                                 if (null == s2)
 232                                         return 0;
 233                                 else
 234                                         return -1;
 235                         } else if (null == s2)
 236                                 return 1;
 237
 238                         if (length < 0 || i1 < 0 || i2 < 0)
 239                                 throw new ArgumentOutOfRangeException ();
 240
 241                         if (i1 > s1.length || i2 > s2.length)
 242                                 throw new ArgumentOutOfRangeException ();
 243
 244                         if (length == 0)
 245                                 return 0;
 246
 247                         return InternalCompare(s1, i1, s2, i2, length, inCase);
 248                 }
 249
 250                 [MonoTODO()]
 251                 public static int Compare(String s1, int i1, String s2, int i2, int length, bool inCase, CultureInfo culture) {
 252                         return Compare(s1, i1, s2, i2, length, inCase);
 253                 }
 254
 255                 public int CompareTo(Object value) {
 256                         if (null == value)
 257                                 return 1;
 258
 259                         if (!(value is String))
 260                                 throw new ArgumentException();
 261
 262                         return String.Compare(this, (String) value, false);
 263                 }
 264
 265                 public int CompareTo(String str) {
 266                         if (null == str)
 267                                 return 1;
 268
 269                         return Compare(this, str, false);
 270                 }
 271
 272                 public static int CompareOrdinal(String s1, String s2) {
 273                         if (null == s1 || null == s2) {
 274                                 if ((Object)s1 == (Object) s2) {
 275                                         return 0;
 276                                 }
 277
 278                                 return (s1 == null) ? -1 : 1;
 279                         }
 280
 281                         return InternalCompare(s1, 0, s2, 0, Math.Max(s1.length, s2.length), false);
 282                 }
 283
 284                 public static int CompareOrdinal(String s1, int i1, String s2, int i2, int length) {
 285                         if (null == s1 || null == s2) {
 286                                 if ((Object)s1 == (Object) s2) {
 287                                         return 0;
 288                                 }
 289
 290                                 return (s1 == null) ? -1 : 1;
 291                         }
 292
 293                         if (i1 < 0 || i2 < 0 || length < 0)
 294                                 throw new ArgumentOutOfRangeException ();
 295
 296                         if (i1 > s1.length || i2 > s2.length)
 297                                 throw new ArgumentOutOfRangeException ();
 298
 299                         return InternalCompare(s1, i1, s2, i2, length, false);
 300                 }
 301
 302                 public bool EndsWith(String value) {
 303                         if (null == value)
 304                                 throw new ArgumentNullException();
 305
 306                         if (value.length > this.length) {
 307                                 return false;
 308                         }
 309
 310                         return (0 == Compare(this, length - value.length, value, 0, value.length));
 311                 }
 312
 313                 public int IndexOfAny(char [] arr) {
 314                         if (null == arr)
 315                                 throw new ArgumentNullException();
 316
 317                         return InternalIndexOfAny(arr, 0, this.length);
 318                 }
 319
 320                 public int IndexOfAny(char [] arr, int sindex) {
 321                         if (null == arr)
 322                                 throw new ArgumentNullException();
 323                         if (sindex < 0 || sindex >= this.length)
 324                                 throw new ArgumentOutOfRangeException();
 325
 326                         return InternalIndexOfAny(arr, sindex, this.length - sindex);
 327                 }
 328
 329                 public int IndexOfAny(char [] arr, int sindex, int count) {
 330                         if (null == arr)
 331                                 throw new ArgumentNullException();
 332                         if (sindex < 0 || count < 0 || sindex + count > this.length)
 333                                 throw new ArgumentOutOfRangeException ();
 334
 335                         return InternalIndexOfAny(arr, sindex, count);
 336                 }
 337
 338                 public int IndexOf(char value) {
 339                         return InternalIndexOf(value, 0, this.length);
 340                 }
 341
 342                 public int IndexOf(String value) {
 343                         return IndexOf(value, 0, this.length);
 344                 }
 345
 346                 public int IndexOf(char value, int sindex) {
 347                         if (sindex < 0 || sindex >= this.length) {
 348                                 throw new ArgumentOutOfRangeException();
 349                         }
 350
 351                         return InternalIndexOf(value, sindex, this.length - sindex);
 352                 }
 353
 354                 public int IndexOf(String value, int sindex) {
 355                         return IndexOf(value, sindex, this.length - sindex);
 356                 }
 357
 358                 public int IndexOf(char value, int sindex, int count) {
 359                         if (sindex < 0 || count < 0 || sindex + count > this.length)
 360                                 throw new ArgumentOutOfRangeException ();
 361
 362                         if (sindex == 0 && this.length == 0)
 363                                 return -1;
 364
 365                         return InternalIndexOf(value, sindex, count);
 366                 }
 367
 368                 public int IndexOf(String value, int sindex, int count) {
 369                         if (null == value)
 370                                 throw new ArgumentNullException();
 371
 372                         if (sindex < 0 || count < 0 || sindex + count > this.length)
 373                                 throw new ArgumentOutOfRangeException ();
 374
 375                         if (sindex == 0 && this.length == 0)
 376                                 return -1;
 377
 378                         return InternalIndexOf(value, sindex, count);
 379                 }
 380
 381                 public int LastIndexOfAny(char [] arr) {
 382                         if (null == arr)
 383                                 throw new ArgumentNullException();
 384
 385                         return InternalLastIndexOfAny(arr, this.length - 1, this.length);
 386                 }
 387
 388                 public int LastIndexOfAny(char [] arr, int sindex) {
 389                         if (null == arr)
 390                                 throw new ArgumentNullException();
 391
 392                         if (sindex < 0 || sindex > this.length)
 393                                 throw new ArgumentOutOfRangeException();
 394
 395                         if (this.length == 0)
 396                                 return -1;
 397
 398                         return InternalLastIndexOfAny(arr, sindex, sindex + 1);
 399                 }
 400
 401                 public int LastIndexOfAny(char [] arr, int sindex, int count) {
 402                         if (null == arr)
 403                                 throw new ArgumentNullException();
 404
 405                         if (sindex < 0 || count < 0 || sindex > this.length || sindex - count < -1)
 406                                 throw new ArgumentOutOfRangeException();
 407
 408                         if (this.length == 0)
 409                                 return -1;
 410
 411                         return InternalLastIndexOfAny(arr, sindex, count);
 412                 }
 413
 414                 public int LastIndexOf(char value) {
 415                         return InternalLastIndexOf(value, this.length - 1, this.length);
 416                 }
 417
 418                 public int LastIndexOf(String value) {
 419                         if (null == value)
 420                                 throw new ArgumentNullException();
 421
 422                         return InternalLastIndexOf(value, this.length - 1, this.length);
 423                 }
 424
 425                 public int LastIndexOf(char value, int sindex){
 426                         return LastIndexOf(value, sindex, sindex + 1);
 427                 }
 428
 429                 public int LastIndexOf(String value, int sindex) {
 430                         return LastIndexOf(value, sindex, sindex + 1);
 431                 }
 432
 433                 public int LastIndexOf(char value, int sindex, int count) {
 434                         if (count < 0 || sindex < 0)
 435                                 throw new ArgumentOutOfRangeException ();
 436
 437                         if (count > this.length || sindex > this.length)
 438                                 throw new ArgumentOutOfRangeException ();
 439
 440                         if (sindex == 0 && this.length == 0)
 441                                 return -1;
 442
 443                         return InternalLastIndexOf(value, sindex, count);
 444                 }
 445
 446                 public int LastIndexOf(String value, int sindex, int count) {
 447                         if (null == value)
 448                                 throw new ArgumentNullException();
 449
 450                         if (sindex < 0 || sindex > this.length)
 451                                 throw new ArgumentOutOfRangeException ();
 452
 453                         if (count < 0 || count - sindex <= 0)
 454                                 throw new ArgumentOutOfRangeException ();
 455
 456                         if (sindex == 0 && this.length == 0)
 457                                 return -1;
 458
 459                         return InternalLastIndexOf(value, sindex, count);
 460                 }
 461
 462                 public String PadLeft(int width) {
 463                         return PadLeft(width, ' ');
 464                 }
 465
 466                 public String PadLeft(int width, char chr) {
 467                         if (width < 0)
 468                                 throw new ArgumentException();
 469
 470                         if (width < this.length)
 471                                 return String.Copy(this);
 472
 473                         return InternalPad(width, chr, false);
 474                 }
 475
 476                 public String PadRight(int width) {
 477                         return PadRight(width, ' ');
 478                 }
 479
 480                 public String PadRight(int width, char chr) {
 481                         if (width < 0)
 482                                 throw new ArgumentException();
 483
 484                         if (width < this.length)
 485                                 return String.Copy(this);
 486
 487                         return InternalPad(width, chr, true);
 488                 }
 489
 490                 public bool StartsWith(String value) {
 491                         if (null == value)
 492                                 throw new ArgumentNullException();
 493
 494                         if (this.length < value.length)
 495                                 return false;
 496
 497                         return (0 == Compare(this, 0, value, 0 , value.length));
 498                 }
 499
 500
 501                 public String Replace (char oldChar, char newChar) {
 502                         return InternalReplace(oldChar, newChar);
 503                 }
 504
 505                 public String Replace(String oldValue, String newValue) {
 506                         if (null == oldValue)
 507                                 throw new ArgumentNullException();
 508
 509                         return InternalReplace(oldValue, newValue);
 510                 }
 511
 512                 public String Remove(int sindex, int count) {
 513                         if (sindex < 0 || count < 0 || sindex + count > this.length)
 514                                 throw new ArgumentOutOfRangeException ();
 515
 516                         return InternalRemove(sindex, count);
 517                 }
 518
 519                 public String ToLower() {
 520                         return InternalToLower();
 521                 }
 522
 523                 public String ToLower(CultureInfo culture) {
 524                         throw new NotImplementedException();
 525                 }
 526
 527                 public String ToUpper() {
 528                         return InternalToUpper();
 529                 }
 530
 531                 public String ToUpper(CultureInfo culture) {
 532                         throw new NotImplementedException();
 533                 }
 534
 535                 public override String ToString() {
 536                         return this;
 537                 }
 538
 539                 public String ToString(IFormatProvider provider) {
 540                         return this;
 541                 }
 542
 543                 public String Trim() {
 544                         return Trim(null);
 545                 }
 546
 547                 public static String Format(String format, Object arg0) {
 548                         return Format(null, format, new Object[] {arg0});
 549                 }
 550
 551                 public static String Format(String format, Object arg0, Object arg1) {
 552                         return Format(null, format, new Object[] {arg0, arg1});
 553                 }
 554
 555                 public static String Format(String format, Object arg0, Object arg1, Object arg2) {
 556                         return Format(null, format, new Object[] {arg0, arg1, arg2});
 557                 }
 558
 559                 public static string Format (string format, params object[] args) {
 560                         return Format (null, format, args);
 561                 }
 562
 563                 public static string Format (IFormatProvider provider, string format, params object[] args) {
 564                         if (format == null || args == null)
 565                                 throw new ArgumentNullException ();
 566
 567                         StringBuilder result = new StringBuilder ();
 568
 569                         int ptr = 0;
 570                         int start = ptr;
 571                         while (ptr < format.length) {
 572                                 char c = format[ptr ++];
 573
 574                                 if (c == '{') {
 575                                         result.Append (format, start, ptr - start - 1);
 576
 577                                         // check for escaped open bracket
 578
 579                                         if (format[ptr] == '{') {
 580                                                 start = ptr ++;
 581                                                 continue;
 582                                         }
 583
 584                                         // parse specifier
 585
 586                                         int n, width;
 587                                         bool left_align;
 588                                         string arg_format;
 589
 590                                         ParseFormatSpecifier (format, ref ptr, out n, out width, out left_align, out arg_format);
 591                                         if (n >= args.Length)
 592                                                 throw new FormatException ("Index (zero based) must be greater than or equal to zero and less than the size of the argument list.");
 593
 594                                         // format argument
 595
 596                                         object arg = args[n];
 597
 598                                         string str;
 599                                         if (arg == null)
 600                                                 str = "";
 601                                         else if (arg is IFormattable)
 602                                                 str = ((IFormattable)arg).ToString (arg_format, provider);
 603                                         else
 604                                                 str = arg.ToString ();
 605
 606                                         // pad formatted string and append to result
 607
 608                                         if (width > str.length) {
 609                                                 string pad = new String (' ', width - str.length);
 610
 611                                                 if (left_align) {
 612                                                         result.Append (str);
 613                                                         result.Append (pad);
 614                                                 }
 615                                                 else {
 616                                                         result.Append (pad);
 617                                                         result.Append (str);
 618                                                 }
 619                                         }
 620                                         else
 621                                                 result.Append (str);
 622
 623                                         start = ptr;
 624                                 }
 625                                 else if (c == '}' && format[ptr] == '}') {
 626                                         result.Append (format, start, ptr - start - 1);
 627                                         start = ptr ++;
 628                                 }
 629                         }
 630
 631                         if (start < format.length)
 632                                 result.Append (format.Substring (start));
 633
 634                         return result.ToString ();
 635                 }
 636
 637                 public static String Copy (String str) {
 638                         if (str == null)
 639                                 throw new ArgumentNullException ();
 640
 641                         int length = str.length;
 642
 643                         String tmp = InternalAllocateStr(length);
 644                         InternalStrcpy(tmp, 0, str);
 645                         return tmp;
 646                 }
 647
 648                 public static String Concat(Object obj) {
 649                         if (null == obj)
 650                                 return String.Empty;
 651
 652                         return obj.ToString();
 653                 }
 654
 655                 public static String Concat(Object obj1, Object obj2) {
 656                         if (null == obj1)
 657                                 obj1 = String.Empty;
 658
 659                         if (null == obj2)
 660                                 obj2 = String.Empty;
 661
 662                         return Concat(obj1.ToString(), obj2.ToString());
 663                 }
 664
 665                 public static String Concat(Object obj1, Object obj2, Object obj3) {
 666                         if (null == obj1)
 667                                 obj1 = String.Empty;
 668
 669                         if (null == obj2)
 670                                 obj2 = String.Empty;
 671
 672                         if (null == obj3)
 673                                 obj3 = String.Empty;
 674
 675                         return Concat(obj1.ToString(), obj2.ToString(), obj3.ToString());
 676                 }
 677
 678                 //
 679                 // I can not find the "__arglist" argument on the spec
 680                 //
 681 #if !__MonoCS__
 682                 [CLSCompliant(false)]
 683                 public static String Concat (Object arg0, Object arg1, Object arg2, Object arg3, __arglist)
 684                 {
 685                         throw new NotImplementedException();
 686                 }
 687 #endif
 688                 public static String Concat(String s1, String s2) {
 689                         if (null == s1) {
 690                                 if (null == s2) { return String.Empty; }
 691                                 return s2;
 692                         }
 693
 694                         if (null == s2) { return s1; }
 695
 696                         String tmp = InternalAllocateStr(s1.length + s2.length);
 697
 698                         InternalStrcpy(tmp, 0, s1);
 699                         InternalStrcpy(tmp, s1.length, s2);
 700
 701                         return tmp;
 702                 }
 703
 704                 public static String Concat(String s1, String s2, String s3) {
 705                         if (null == s1 && null == s2 && null == s3) {
 706                                 return String.Empty;
 707                         }
 708
 709                         if (null == s1) { s1 = String.Empty; }
 710                         if (null == s2) { s2 = String.Empty; }
 711                         if (null == s3) { s3 = String.Empty; }
 712
 713                         String tmp = InternalAllocateStr(s1.length + s2.length + s3.length);
 714
 715                         InternalStrcpy(tmp, 0, s1);
 716                         InternalStrcpy(tmp, s1.length, s2);
 717                         InternalStrcpy(tmp, s1.length + s2.length, s3);
 718
 719                         return tmp;
 720                 }
 721
 722                 public static String Concat(String s1, String s2, String s3, String s4) {
 723                         if (null == s1 && null == s2 && null == s3 && null == s4) {
 724                                 return String.Empty;
 725                         }
 726
 727                         if (null == s1) { s1 = String.Empty; }
 728                         if (null == s2) { s2 = String.Empty; }
 729                         if (null == s3) { s3 = String.Empty; }
 730                         if (null == s4) { s4 = String.Empty; }
 731
 732                         String tmp = InternalAllocateStr(s1.length + s2.length + s3.length + s4.length);
 733
 734                         InternalStrcpy(tmp, 0, s1);
 735                         InternalStrcpy(tmp, s1.length, s2);
 736                         InternalStrcpy(tmp, s1.length + s2.length, s3);
 737                         InternalStrcpy(tmp, s1.length + s2.length + s3.length, s4);
 738
 739                         return tmp;
 740                 }
 741
 742                 public static String Concat(params Object[] args) {
 743                         string [] strings;
 744                         int len, i, currentpos;
 745
 746                         if (null == args)
 747                                 throw new ArgumentNullException ();
 748
 749                         strings = new string [args.Length];
 750                         len = 0;
 751                         i = 0;
 752                         foreach (object arg in args) {
 753                                 /* use Empty for each null argument */
 754                                 if (arg == null)
 755                                         strings[i] = String.Empty;
 756                                 else
 757                                         strings[i] = arg.ToString ();
 758                                 len += strings[i].length;
 759                                 i++;
 760                         }
 761
 762                         if (len == 0)
 763                                 return String.Empty;
 764
 765                         currentpos = 0;
 766
 767                         String tmp = InternalAllocateStr(len);
 768                         for (i = 0; i < strings.Length; i++) {
 769                                 InternalStrcpy(tmp, currentpos, strings[i]);
 770                                 currentpos += strings[i].length;
 771                         }
 772
 773                         return tmp;
 774                 }
 775
 776                 public static String Concat(params String[] values) {
 777                         int len, i, currentpos;
 778
 779                         if (values == null)
 780                                 throw new ArgumentNullException ();
 781
 782                         len = 0;
 783                         foreach (string value in values)
 784                                 len += value != null ? value.length : 0;
 785
 786                         if (len == 0)
 787                                 return String.Empty;
 788
 789                         currentpos = 0;
 790
 791                         String tmp = InternalAllocateStr(len);
 792                         for (i = 0; i < values.Length; i++) {
 793                                 if (values[i] == null)
 794                                         continue;
 795
 796                                 InternalStrcpy(tmp, currentpos, values[i]);
 797                                 currentpos += values[i].length;
 798                         }
 799
 800                         return tmp;
 801                 }
 802
 803                 public String Insert(int sindex, String value) {
 804                         if (null == value)
 805                                 throw new ArgumentNullException();
 806
 807                         if (sindex < 0 || sindex > this.length)
 808                                 throw new ArgumentOutOfRangeException();
 809
 810                         return InternalInsert(sindex, value);
 811                 }
 812
 813
 814                 public static string Intern (string str) {
 815                         if (null == str)
 816                                 throw new ArgumentNullException ();
 817
 818                         return InternalIntern(str);
 819                 }
 820
 821                 public static string IsInterned (string str) {
 822                         if (null == str)
 823                                 throw new ArgumentNullException();
 824
 825                         return InternalIsInterned(str);
 826                 }
 827
 828                 public static string Join (string separator, string [] value) {
 829                         if (value == null)
 830                                 throw new ArgumentNullException ();
 831
 832                         return Join(separator, value, 0, value.Length);
 833                 }
 834
 835                 public static string Join(string separator, string[] value, int sindex, int count) {
 836                         if (value == null)
 837                                 throw new ArgumentNullException ();
 838
 839                         if (sindex + count > value.Length)
 840                                 throw new ArgumentOutOfRangeException ();
 841
 842                         if (sindex == value.Length)
 843                                 return String.Empty;
 844
 845                         return InternalJoin(separator, value, sindex, count);
 846                 }
 847
 848                 bool IConvertible.ToBoolean (IFormatProvider provider) {
 849                         return Convert.ToBoolean (this);
 850                 }
 851
 852                 byte IConvertible.ToByte (IFormatProvider provider) {
 853                         return Convert.ToByte (this);
 854                 }
 855
 856                 char IConvertible.ToChar (IFormatProvider provider) {
 857                         return Convert.ToChar (this);
 858                 }
 859
 860                 DateTime IConvertible.ToDateTime (IFormatProvider provider) {
 861                         return Convert.ToDateTime (this);
 862                 }
 863
 864                 decimal IConvertible.ToDecimal (IFormatProvider provider) {
 865                         return Convert.ToDecimal (this);
 866                 }
 867
 868                 double IConvertible.ToDouble (IFormatProvider provider) {
 869                         return Convert.ToDouble (this);
 870                 }
 871
 872                 short IConvertible.ToInt16 (IFormatProvider provider) {
 873                         return Convert.ToInt16 (this);
 874                 }
 875
 876                 int IConvertible.ToInt32 (IFormatProvider provider) {
 877                         return Convert.ToInt32 (this);
 878                 }
 879
 880                 long IConvertible.ToInt64 (IFormatProvider provider) {
 881                         return Convert.ToInt64 (this);
 882                 }
 883
 884                 [CLSCompliant(false)]
 885                 sbyte IConvertible.ToSByte (IFormatProvider provider) {
 886                         return Convert.ToSByte (this);
 887                 }
 888
 889                 float IConvertible.ToSingle (IFormatProvider provider) {
 890                         return Convert.ToSingle (this);
 891                 }
 892                 string IConvertible.ToString (IFormatProvider format) {
 893                         return this;
 894                 }
 895
 896                 object IConvertible.ToType (Type conversionType, IFormatProvider provider) {
 897                         return Convert.ToType (this, conversionType,  provider);
 898                 }
 899
 900                 [CLSCompliant(false)]
 901                 ushort IConvertible.ToUInt16 (IFormatProvider provider) {
 902                         return Convert.ToUInt16 (this);
 903                 }
 904
 905                 [CLSCompliant(false)]
 906                 uint IConvertible.ToUInt32 (IFormatProvider provider) {
 907                         return Convert.ToUInt32 (this);
 908                 }
 909
 910                 [CLSCompliant(false)]
 911                 ulong IConvertible.ToUInt64 (IFormatProvider provider) {
 912                         return Convert.ToUInt64 (this);
 913                 }
 914
 915                 TypeCode IConvertible.GetTypeCode () {
 916                         return TypeCode.String;
 917                 }
 918
 919                 public int Length {
 920                         get {
 921                                 return length;
 922                         }
 923                 }
 924
 925                 public CharEnumerator GetEnumerator () {
 926                         return new CharEnumerator (this);
 927                 }
 928
 929                 IEnumerator IEnumerable.GetEnumerator () {
 930                         return new CharEnumerator (this);
 931                 }
 932
 933                 private static void ParseFormatSpecifier (string str, ref int ptr, out int n, out int width, out bool left_align, out string format) {
 934                         // parses format specifier of form:
 935                         //   N,[[-]M][:F]}
 936                         //
 937                         // where:
 938
 939                         try {
 940                                 // N = argument number (non-negative integer)
 941
 942                                 n = ParseDecimal (str, ref ptr);
 943                                 if (n < 0)
 944                                         throw new FormatException ("Input string was not in correct format.");
 945
 946                                 // M = width (non-negative integer)
 947
 948                                 if (str[ptr] == ',') {
 949                                         left_align = (str[++ ptr] == '-');
 950                                         if (left_align)
 951                                                 ++ ptr;
 952
 953                                         width = ParseDecimal (str, ref ptr);
 954                                         if (width < 0)
 955                                                 throw new FormatException ("Input string was not in correct format.");
 956                                 }
 957                                 else {
 958                                         width = 0;
 959                                         left_align = false;
 960                                 }
 961
 962                                 // F = argument format (string)
 963
 964                                 if (str[ptr] == ':') {
 965                                         int start = ++ ptr;
 966                                         while (str[ptr] != '}')
 967                                                 ++ ptr;
 968
 969                                         format = str.Substring (start, ptr - start);
 970                                 }
 971                                 else
 972                                         format = null;
 973
 974                                 if (str[ptr ++] != '}')
 975                                         throw new FormatException ("Input string was not in correct format.");
 976                         }
 977                         catch (IndexOutOfRangeException) {
 978                                 throw new FormatException ("Input string was not in correct format.");
 979                         }
 980                 }
 981
 982                 private static int ParseDecimal (string str, ref int ptr) {
 983                         int p = ptr;
 984                         int n = 0;
 985                         while (true) {
 986                                 char c = str[p];
 987                                 if (c < '0' || '9' < c)
 988                                         break;
 989
 990                                 n = n * 10 + c - '0';
 991                                 ++ p;
 992                         }
 993
 994                         if (p == ptr)
 995                                 return -1;
 996
 997                         ptr = p;
 998                         return n;
 999                 }
1000
1001                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
1002                 private extern static string InternalJoin(string separator, string[] value, int sindex, int count);
1003
1004                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
1005                 private extern String InternalInsert(int sindex, String value);
1006
1007                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
1008                 private extern String InternalReplace(char oldChar, char newChar);
1009
1010                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
1011                 private extern String InternalReplace(String oldValue, String newValue);
1012
1013                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
1014                 private extern String InternalRemove(int sindex, int count);
1015
1016                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
1017                 private extern void InternalCopyTo(int sindex, char[] dest, int dindex, int count);
1018
1019                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
1020                 private extern String[] InternalSplit(char[] separator, int count);
1021
1022                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
1023                 private extern String InternalTrim(char[] chars, int typ);
1024
1025                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
1026                 private extern int InternalIndexOf(char value, int sindex, int count);
1027
1028                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
1029                 private extern int InternalIndexOf(string value, int sindex, int count);
1030
1031                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
1032                 private extern int InternalIndexOfAny(char [] arr, int sindex, int count);
1033
1034                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
1035                 private extern int InternalLastIndexOf(char value, int sindex, int count);
1036
1037                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
1038                 private extern int InternalLastIndexOf(String value, int sindex, int count);
1039
1040                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
1041                 private extern int InternalLastIndexOfAny(char [] anyOf, int sindex, int count);
1042
1043                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
1044                 private extern String InternalPad(int width, char chr, bool right);
1045
1046                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
1047                 private extern String InternalToLower();
1048
1049                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
1050                 private extern String InternalToUpper();
1051
1052                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
1053                 private extern static String InternalAllocateStr(int length);
1054
1055                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
1056                 private extern static void InternalStrcpy(String dest, int destPos, String src);
1057
1058                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
1059                 private extern static void InternalStrcpy(String dest, int destPos, String src, int startPos, int count);
1060
1061                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
1062                 private extern static string InternalIntern(string str);
1063
1064                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
1065                 private extern static string InternalIsInterned(string str);
1066
1067                 [MethodImplAttribute(MethodImplOptions.InternalCall)]
1068                 private extern static int InternalCompare(String s1, int i1, String s2, int i2, int length, bool inCase);
1069         }
1070 }