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   1  <?php
   2  /**
   3   * Diff Match and Patch
   4   *
   5   * Copyright 2006 Google Inc.
   6   * http://code.google.com/p/google-diff-match-patch/
   7   *
   8   * php port by Tobias Buschor shwups.ch
   9   *
  10   * Licensed under the Apache License, Version 2.0 (the "License");
  11   * you may not use this file except in compliance with the License.
  12   * You may obtain a copy of the License at
  13   *
  14   *   http://www.apache.org/licenses/LICENSE-2.0
  15   *
  16   * Unless required by applicable law or agreed to in writing, software
  17   * distributed under the License is distributed on an "AS IS" BASIS,
  18   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  19   * See the License for the specific language governing permissions and
  20   * limitations under the License.
  21   */
  22  
  23  /**
  24   * @fileoverview Computes the difference between two texts to create a patch.
  25   * Applies the patch onto another text, allowing for errors.
  26   * @author [email protected] (Neil Fraser)
  27   */
  28  
  29  /**
  30   * Class containing the diff, match and patch methods.
  31   * @constructor
  32   */
  33  class diff_match_patch {
  34  
  35      // Defaults.
  36      // Redefine these in your program to override the defaults.
  37  
  38      // Number of seconds to map a diff before giving up (0 for infinity).
  39      public $Diff_Timeout = 1.0;
  40      // Cost of an empty edit operation in terms of edit characters.
  41      public $Diff_EditCost = 4;
  42      // The size beyond which the double-ended diff activates.
  43      // Double-ending is twice as fast, but less accurate.
  44      public $Diff_DualThreshold = 32;
  45      // At what point is no match declared (0.0 = perfection, 1.0 = very loose).
  46      public $Match_Threshold = 0.5;
  47      // How far to search for a match (0 = exact location, 1000+ = broad match).
  48      // A match this many characters away from the expected location will add
  49      // 1.0 to the score (0.0 is a perfect match).
  50      public $Match_Distance = 1000;
  51      // When deleting a large block of text (over ~64 characters), how close does
  52      // the contents have to match the expected contents. (0.0 = perfection,
  53      // 1.0 = very loose).  Note that Match_Threshold controls how closely the
  54      // end points of a delete need to match.
  55      public $Patch_DeleteThreshold = 0.5;
  56      // Chunk size for context length.
  57      public $Patch_Margin = 4;
  58  
  59      /**
  60       * Compute the number of bits in an int.
  61       * The normal answer for JavaScript is 32.
  62       * @return {number} Max bits
  63  
  64      function getMaxBits() {
  65          var maxbits = 0;
  66          var oldi = 1;
  67          var newi = 2;
  68          while (oldi != newi) {
  69              maxbits++;
  70              oldi = newi;
  71              newi = newi << 1;
  72          }
  73          return maxbits;
  74      }
  75      // How many bits in a number?
  76      this.Match_MaxBits = getMaxBits();
  77      */
  78      //  DIFF FUNCTIONS
  79  
  80      /**
  81       * Find the differences between two texts.  Simplifies the problem by stripping
  82       * any common prefix or suffix off the texts before diffing.
  83       * @param {string} text1 Old string to be diffed.
  84       * @param {string} text2 New string to be diffed.
  85       * @param {boolean} opt_checklines Optional speedup flag.  If present and false,
  86       *     then don't run a line-level diff first to identify the changed areas.
  87       *     Defaults to true, which does a faster, slightly less optimal diff
  88       * @return {Array.<Array.<number|string>>} Array of diff tuples.
  89       */
  90  	function diff_main($text1, $text2, $checklines = true) {
  91          // Check for equality (speedup)
  92          if ($text1 === $text2) {
  93              return array ( array ( DIFF_EQUAL, $text1) );
  94          }
  95  
  96          // Trim off common prefix (speedup)
  97          $commonlength = $this->diff_commonPrefix($text1, $text2);
  98          $commonprefix = mb_substr($text1, 0, $commonlength);
  99          $text1 = mb_substr($text1, $commonlength);
 100          $text2 = mb_substr($text2, $commonlength);
 101  
 102          // Trim off common suffix (speedup)
 103          $commonlength = $this->diff_commonSuffix($text1, $text2);
 104          $commonsuffix = mb_substr($text1, mb_strlen($text1) - $commonlength);
 105          $text1 = mb_substr($text1, 0, mb_strlen($text1) - $commonlength);
 106          $text2 = mb_substr($text2, 0, mb_strlen($text2) - $commonlength);
 107  
 108          // Compute the diff on the middle block
 109          $diffs = $this->diff_compute($text1, $text2, $checklines);
 110  
 111          // Restore the prefix and suffix
 112          if ($commonprefix !== '') {
 113              array_unshift($diffs, array ( DIFF_EQUAL, $commonprefix ));
 114          }
 115          if ($commonsuffix !== '') {
 116              array_push($diffs, array ( DIFF_EQUAL, $commonsuffix ));
 117          }
 118          $this->diff_cleanupMerge($diffs);
 119          return $diffs;
 120      }
 121  
 122      /**
 123       * Find the differences between two texts.  Assumes that the texts do not
 124       * have any common prefix or suffix.
 125       * @param {string} text1 Old string to be diffed.
 126       * @param {string} text2 New string to be diffed.
 127       * @param {boolean} checklines Speedup flag.  If false, then don't run a
 128       *     line-level diff first to identify the changed areas.
 129       *     If true, then run a faster, slightly less optimal diff
 130       * @return {Array.<Array.<number|string>>} Array of diff tuples.
 131       * @private
 132       */
 133  	function diff_compute($text1, $text2, $checklines) {
 134  
 135          if ($text1 === '') {
 136              // Just add some text (speedup)
 137              return array ( array ( DIFF_INSERT, $text2 ) );
 138          }
 139  
 140          if ($text2 === '') {
 141              // Just delete some text (speedup)
 142              return array ( array ( DIFF_DELETE, $text1 ) );
 143          }
 144  
 145          $longtext = mb_strlen($text1) > mb_strlen($text2) ? $text1 : $text2;
 146          $shorttext = mb_strlen($text1) > mb_strlen($text2) ? $text2 : $text1;
 147          $i = mb_strpos($longtext, $shorttext);
 148          if ($i !== false) {
 149              // Shorter text is inside the longer text (speedup)
 150              $diffs = array (
 151                  array ( DIFF_INSERT, mb_substr($longtext, 0, $i) ),
 152                  array ( DIFF_EQUAL, $shorttext ),
 153                  array ( DIFF_INSERT, mb_substr($longtext, $i +mb_strlen($shorttext)) )
 154              );
 155  
 156              // Swap insertions for deletions if diff is reversed.
 157              if (mb_strlen($text1) > mb_strlen($text2)) {
 158                  $diffs[0][0] = $diffs[2][0] = DIFF_DELETE;
 159              }
 160              return $diffs;
 161          }
 162          $longtext = $shorttext = null; // Garbage collect
 163  
 164          // Check to see if the problem can be split in two.
 165          $hm = $this->diff_halfMatch($text1, $text2);
 166          if ($hm) {
 167              // A half-match was found, sort out the return data.
 168              $text1_a = $hm[0];
 169              $text1_b = $hm[1];
 170              $text2_a = $hm[2];
 171              $text2_b = $hm[3];
 172              $mid_common = $hm[4];
 173              // Send both pairs off for separate processing.
 174              $diffs_a = $this->diff_main($text1_a, $text2_a, $checklines);
 175              $diffs_b = $this->diff_main($text1_b, $text2_b, $checklines);
 176              // Merge the results.
 177              return array_merge($diffs_a, array (
 178                  array (
 179                      DIFF_EQUAL,
 180                      $mid_common
 181                  )
 182              ), $diffs_b);
 183          }
 184  
 185          // Perform a real diff.
 186          if ($checklines && (mb_strlen($text1) < 100 || mb_strlen($text2) < 100)) {
 187              // Too trivial for the overhead.
 188              $checklines = false;
 189          }
 190          $linearray = null;
 191          if ($checklines) {
 192              // Scan the text on a line-by-line basis first.
 193              $a = $this->diff_linesToChars($text1, $text2);
 194              $text1 = $a[0];
 195              $text2 = $a[1];
 196              $linearray = $a[2];
 197          }
 198          $diffs = $this->diff_map($text1, $text2);
 199          if (!$diffs) {
 200              // No acceptable result.
 201              $diffs = array (
 202                  array (
 203                      DIFF_DELETE,
 204                      $text1
 205                  ),
 206                  array (
 207                      DIFF_INSERT,
 208                      $text2
 209                  )
 210              );
 211          }
 212          if ($checklines) {
 213              // Convert the diff back to original text.
 214              $this->diff_charsToLines($diffs, $linearray);
 215              // Eliminate freak matches (e.g. blank lines)
 216              $this->diff_cleanupSemantic($diffs);
 217  
 218              // Rediff any replacement blocks, this time character-by-character.
 219              // Add a dummy entry at the end.
 220              array_push($diffs, array (
 221                  DIFF_EQUAL,
 222                  ''
 223              ));
 224              $pointer = 0;
 225              $count_delete = 0;
 226              $count_insert = 0;
 227              $text_delete = '';
 228              $text_insert = '';
 229              while ($pointer < count($diffs)) {
 230                  switch ($diffs[$pointer][0]) {
 231                      case DIFF_INSERT :
 232                          $count_insert++;
 233                          $text_insert .= $diffs[$pointer][1];
 234                          break;
 235                      case DIFF_DELETE :
 236                          $count_delete++;
 237                          $text_delete .= $diffs[$pointer][1];
 238                          break;
 239                      case DIFF_EQUAL :
 240                          // Upon reaching an equality, check for prior redundancies.
 241                          if ($count_delete >= 1 && $count_insert >= 1) {
 242                              // Delete the offending records and add the merged ones.
 243                              $a = $this->diff_main($text_delete, $text_insert, false);
 244                              array_splice($diffs, $pointer - $count_delete - $count_insert, $count_delete + $count_insert);
 245  
 246                              $pointer = $pointer - $count_delete - $count_insert;
 247                              for ($j = count($a) - 1; $j >= 0; $j--) {
 248                                  array_splice($diffs, $pointer, 0, array($a[$j]));
 249                              }
 250                              $pointer = $pointer +count($a);
 251                          }
 252                          $count_insert = 0;
 253                          $count_delete = 0;
 254                          $text_delete = '';
 255                          $text_insert = '';
 256                          break;
 257                  }
 258                  $pointer++;
 259              }
 260              array_pop($diffs); // Remove the dummy entry at the end.
 261          }
 262          return $diffs;
 263      }
 264  
 265      /**
 266       * Split two texts into an array of strings.  Reduce the texts to a string of
 267       * hashes where each Unicode character represents one line.
 268       * @param {string} text1 First string.
 269       * @param {string} text2 Second string.
 270       * @return {Array.<string|Array.<string>>} Three element Array, containing the
 271       *     encoded text1, the encoded text2 and the array of unique strings.  The
 272       *     zeroth element of the array of unique strings is intentionally blank.
 273       * @private
 274       */
 275  	function diff_linesToChars($text1, $text2) {
 276          $lineArray = array(); // e.g. lineArray[4] == 'Hello\n'
 277          $lineHash = array(); // e.g. lineHash['Hello\n'] == 4
 278  
 279          // '\x00' is a valid character, but various debuggers don't like it.
 280          // So we'll insert a junk entry to avoid generating a null character.
 281          $lineArray[0] = '';
 282  
 283          $chars1 = $this->diff_linesToCharsMunge($text1, $lineArray, $lineHash);
 284          $chars2 = $this->diff_linesToCharsMunge($text2, $lineArray, $lineHash);
 285          return array (
 286              $chars1,
 287              $chars2,
 288              $lineArray
 289          );
 290      }
 291  
 292      /**
 293       * Split a text into an array of strings.  Reduce the texts to a string of
 294       * hashes where each Unicode character represents one line.
 295       * Modifies linearray and linehash through being a closure.
 296       * @param {string} text String to encode
 297       * @return {string} Encoded string
 298       * @private
 299       */
 300  	function diff_linesToCharsMunge($text, &$lineArray, &$lineHash) {
 301          $chars = '';
 302          // Walk the text, pulling out a mb_substring for each line.
 303          // text.split('\n') would would temporarily double our memory footprint.
 304          // Modifying text would create many large strings to garbage collect.
 305          $lineStart = 0;
 306          $lineEnd = -1;
 307          // Keeping our own length variable is faster than looking it up.
 308          $lineArrayLength = count($lineArray);
 309          while ($lineEnd < mb_strlen($text) - 1) {
 310              $lineEnd = mb_strpos($text, "\n", $lineStart);
 311              if ($lineEnd === false) {
 312                  $lineEnd = mb_strlen($text) - 1;
 313              }
 314              $line = mb_substr($text, $lineStart, $lineEnd +1 -$lineStart);
 315              $lineStart = $lineEnd +1;
 316  
 317              if ( isset($lineHash[$line]) ) {
 318                  $chars .= mb_chr($lineHash[$line]);
 319              } else {
 320                  $chars .= mb_chr($lineArrayLength);
 321                  $lineHash[$line] = $lineArrayLength;
 322                  $lineArray[$lineArrayLength++] = $line;
 323              }
 324          }
 325          return $chars;
 326      }
 327      /**
 328       * Rehydrate the text in a diff from a string of line hashes to real lines of
 329       * text.
 330       * @param {Array.<Array.<number|string>>} diffs Array of diff tuples.
 331       * @param {Array.<string>} lineArray Array of unique strings.
 332       * @private
 333       */
 334  	function diff_charsToLines(&$diffs, $lineArray) {
 335          for ($x = 0; $x < count($diffs); $x++) {
 336              $chars = $diffs[$x][1];
 337              $text = array ();
 338              for ($y = 0; $y < mb_strlen($chars); $y++) {
 339                  $text[$y] = $lineArray[charCodeAt($chars, $y)];
 340              }
 341              $diffs[$x][1] = implode('',$text);
 342          }
 343      }
 344  
 345      /**
 346       * Explore the intersection points between the two texts.
 347       * @param {string} text1 Old string to be diffed.
 348       * @param {string} text2 New string to be diffed.
 349       * @return {Array.<Array.<number|string>>?} Array of diff tuples or null if no
 350       *     diff available.
 351       * @private
 352       */
 353  	function diff_map($text1, $text2) {
 354          // Don't run for too long.
 355          $ms_end = microtime(true) + $this->Diff_Timeout;
 356          
 357          // Cache the text lengths to prevent multiple calls.
 358          $text1_length = mb_strlen($text1);
 359          $text2_length = mb_strlen($text2);
 360          $max_d = $text1_length + $text2_length -1;
 361          $doubleEnd = $this->Diff_DualThreshold * 2 < $max_d;
 362          $v_map1 = array();
 363          $v_map2 = array();
 364          $v1 = array();
 365          $v2 = array();
 366          $v1[1] = 0;
 367          $v2[1] = 0;
 368          $x = null;
 369          $y = null;
 370          $footstep = null; // Used to track overlapping paths.
 371          $footsteps = array();
 372          $done = false;
 373          // Safari 1.x doesn't have hasOwnProperty
 374          //?    $hasOwnProperty = !!(footsteps.hasOwnProperty);
 375          // If the total number of characters is odd, then the front path will collide
 376          // with the reverse path.
 377          $front = ($text1_length + $text2_length) % 2;
 378          for ($d = 0; $d < $max_d; $d++) {
 379              // Bail out if timeout reached.
 380              if ($this->Diff_Timeout > 0 && microtime(true) > $ms_end) {
 381                  return null; // zzz
 382              }
 383  
 384              // Walk the front path one step.
 385              $v_map1[$d] = array ();
 386              for ($k = -$d; $k <= $d; $k += 2) {
 387                  if ($k == -$d || $k != $d && $v1[$k -1] < $v1[$k +1]) {
 388                      $x = $v1[$k +1];
 389                  } else {
 390                      $x = $v1[$k -1] + 1;
 391                  }
 392                  $y = $x - $k;
 393                  if ($doubleEnd) {
 394                      $footstep = $x . ',' . $y;
 395                      if ($front && isset ($footsteps[$footstep])) {
 396                          $done = true;
 397                      }
 398                      if (!$front) {
 399                          $footsteps[$footstep] = $d;
 400                      }
 401                  }
 402                  while (!$done && ($x < $text1_length) && ($y < $text2_length) && (mb_substr($text1, $x, 1) == mb_substr($text2, $y, 1)) ) {
 403                      $x++;
 404                      $y++;
 405                      if ($doubleEnd) {
 406                          $footstep = $x . ',' . $y;
 407                          if ($front && isset ($footsteps[$footstep])) {
 408                              $done = true;
 409                          }
 410                          if (!$front) {
 411                              $footsteps[$footstep] = $d;
 412                          }
 413                      }
 414                  }
 415                  $v1[$k] = $x;
 416                  $v_map1[$d][$x . ',' . $y] = true;
 417                  if ($x == $text1_length && $y == $text2_length) {
 418                      // Reached the end in single-path mode.
 419                      return $this->diff_path1($v_map1, $text1, $text2);
 420                  }
 421                  elseif ($done) {
 422                      // Front path ran over reverse path.
 423  
 424                      $v_map2 = array_slice($v_map2, 0, $footsteps[$footstep] + 1);
 425                      $a = $this->diff_path1($v_map1, mb_substr($text1, 0, $x), mb_substr($text2, 0, $y));
 426  
 427                      return array_merge($a, $this->diff_path2($v_map2, mb_substr($text1, $x), mb_substr($text2, $y)));
 428                  }
 429              }
 430  
 431              if ($doubleEnd) {
 432                  // Walk the reverse path one step.
 433                  $v_map2[$d] = array();
 434                  for ($k = -$d; $k <= $d; $k += 2) {
 435                      if ($k == -$d || $k != $d && $v2[$k -1] < $v2[$k +1]) {
 436                          $x = $v2[$k +1];
 437                      } else {
 438                          $x = $v2[$k -1] + 1;
 439                      }
 440                      $y = $x - $k;
 441                      $footstep = ($text1_length - $x) . ',' . ($text2_length - $y);
 442                      if (!$front && isset ($footsteps[$footstep])) {
 443                          $done = true;
 444                      }
 445                      if ($front) {
 446                          $footsteps[$footstep] = $d;
 447                      }
 448                      while (!$done && $x < $text1_length && $y < $text2_length && mb_substr($text1, $text1_length - $x -1, 1) == mb_substr($text2, $text2_length - $y -1, 1) ) {
 449                          $x++;
 450                          $y++;
 451                          $footstep = ($text1_length - $x) . ',' . ($text2_length - $y);
 452                          if (!$front && isset ($footsteps[$footstep])) {
 453                              $done = true;
 454                          }
 455                          if ($front) {
 456                              $footsteps[$footstep] = $d;
 457                          }
 458                      }
 459                      $v2[$k] = $x;
 460                      $v_map2[$d][$x . ',' . $y] = true;
 461                      if ($done) {
 462                          // Reverse path ran over front path.
 463                          $v_map1 = array_slice($v_map1, 0, $footsteps[$footstep] + 1);
 464                          $a = $this->diff_path1($v_map1, mb_substr($text1, 0, $text1_length - $x), mb_substr($text2, 0, $text2_length - $y));
 465                          return array_merge($a, $this->diff_path2($v_map2, mb_substr($text1, $text1_length - $x), mb_substr($text2, $text2_length - $y)));
 466                      }
 467                  }
 468              }
 469          }
 470          // Number of diffs equals number of characters, no commonality at all.
 471          return null;
 472      }
 473  
 474      /**
 475       * Work from the middle back to the start to determine the path.
 476       * @param {Array.<Object>} v_map Array of paths.ers
 477       * @param {string} text1 Old string fragment to be diffed.
 478       * @param {string} text2 New string fragment to be diffed.
 479       * @return {Array.<Array.<number|string>>} Array of diff tuples.
 480       * @private
 481       */
 482  	function diff_path1($v_map, $text1, $text2) {
 483          $path = array ();
 484          $x = mb_strlen($text1);
 485          $y = mb_strlen($text2);
 486          /** @type {number?} */
 487          $last_op = null;
 488          for ($d = count($v_map) - 2; $d >= 0; $d--) {
 489              while (1) {
 490                  if (isset ($v_map[$d][($x -1) . ',' . $y])) {
 491                      $x--;
 492                      if ($last_op === DIFF_DELETE) {
 493                          $path[0][1] = mb_substr($text1, $x, 1) . $path[0][1];
 494                      } else {
 495                          array_unshift($path, array (
 496                              DIFF_DELETE,
 497                              mb_substr($text1, $x, 1)
 498                          ));
 499                      }
 500                      $last_op = DIFF_DELETE;
 501                      break;
 502                  } elseif (isset ($v_map[$d][$x . ',' . ($y -1)])) {
 503                      $y--;
 504                      if ($last_op === DIFF_INSERT) {
 505                          $path[0][1] = mb_substr($text2, $y, 1) . $path[0][1];
 506                      } else {
 507                          array_unshift($path, array (
 508                              DIFF_INSERT,
 509                              mb_substr($text2, $y, 1)
 510                          ));
 511                      }
 512                      $last_op = DIFF_INSERT;
 513                      break;
 514                  } else {
 515                      $x--;
 516                      $y--;
 517                      //if (text1.charAt(x) != text2.charAt(y)) {
 518                      //  throw new Error('No diagonal.  Can\'t happen. (diff_path1)');
 519                      //}
 520                      if ($last_op === DIFF_EQUAL) {
 521                          $path[0][1] = mb_substr($text1, $x, 1) . $path[0][1];
 522                      } else {
 523                          array_unshift($path, array (
 524                              DIFF_EQUAL,
 525                              mb_substr($text1, $x, 1)
 526                          ));
 527                      }
 528                      $last_op = DIFF_EQUAL;
 529                  }
 530              }
 531          }
 532          return $path;
 533      }
 534  
 535      /**
 536       * Work from the middle back to the end to determine the path.
 537       * @param {Array.<Object>} v_map Array of paths.
 538       * @param {string} text1 Old string fragment to be diffed.
 539       * @param {string} text2 New string fragment to be diffed.
 540       * @return {Array.<Array.<number|string>>} Array of diff tuples.
 541       * @private
 542       */
 543  	function diff_path2($v_map, $text1, $text2) {
 544          $path = array ();
 545          $pathLength = 0;
 546          $x = mb_strlen($text1);
 547          $y = mb_strlen($text2);
 548          /** @type {number?} */
 549          $last_op = null;
 550          for ($d = count($v_map) - 2; $d >= 0; $d--) {
 551              while (1) {
 552                  if (isset ($v_map[$d][($x -1) . ',' . $y])) {
 553                      $x--;
 554                      if ($last_op === DIFF_DELETE) {
 555                          $path[$pathLength -1][1] .= $text1[mb_strlen($text1) - $x -1];
 556                      } else {
 557                          $path[$pathLength++] = array (
 558                              DIFF_DELETE,
 559                              $text1[mb_strlen($text1) - $x -1]
 560                          );
 561                      }
 562                      $last_op = DIFF_DELETE;
 563                      break;
 564                  }
 565                  elseif (isset ($v_map[$d][$x . ',' . ($y -1)])) {
 566                      $y--;
 567                      if ($last_op === DIFF_INSERT) {
 568                          $path[$pathLength -1][1] .= $text2[mb_strlen($text2) - $y -1];
 569                      } else {
 570                          $path[$pathLength++] = array (
 571                              DIFF_INSERT,
 572                              $text2[mb_strlen($text2) - $y -1]
 573                          );
 574                      }
 575                      $last_op = DIFF_INSERT;
 576                      break;
 577                  } else {
 578                      $x--;
 579                      $y--;
 580                      //if (text1.charAt(text1.length - x - 1) !=
 581                      //    text2.charAt(text2.length - y - 1)) {
 582                      //  throw new Error('No diagonal.  Can\'t happen. (diff_path2)');
 583                      //}
 584                      if ($last_op === DIFF_EQUAL) {
 585                          $path[$pathLength -1][1] .= $text1[mb_strlen($text1) - $x -1];
 586                      } else {
 587                          $path[$pathLength++] = array (
 588                              DIFF_EQUAL,
 589                              $text1[mb_strlen($text1) - $x -1]
 590                          );
 591                      }
 592                      $last_op = DIFF_EQUAL;
 593                  }
 594              }
 595          }
 596          return $path;
 597      }
 598  
 599      /**
 600       * Determine the common prefix of two strings
 601       * @param {string} text1 First string.
 602       * @param {string} text2 Second string.
 603       * @return {number} The number of characters common to the start of each
 604       *     string.
 605       */
 606  	function diff_commonPrefix($text1, $text2) {
 607          for ($i = 0; 1; $i++) {
 608              $t1 = mb_substr($text1, $i, 1);
 609              $t2 = mb_substr($text2, $i, 1);
 610              if($t1==='' || $t2==='' || $t1 !== $t2 ){
 611                  return $i;
 612              }
 613          }
 614      }
 615  
 616      /**
 617       * Determine the common suffix of two strings
 618       * @param {string} text1 First string.
 619       * @param {string} text2 Second string.
 620       * @return {number} The number of characters common to the end of each string.
 621       */
 622  	function diff_commonSuffix($text1, $text2) {
 623          return $this->diff_commonPrefix( strrev($text1), strrev($text2) );
 624      }
 625  
 626      /**
 627       * Do the two texts share a mb_substring which is at least half the length of the
 628       * longer text?
 629       * @param {string} text1 First string.
 630       * @param {string} text2 Second string.
 631       * @return {Array.<string>?} Five element Array, containing the prefix of
 632       *     text1, the suffix of text1, the prefix of text2, the suffix of
 633       *     text2 and the common middle.  Or null if there was no match.
 634       */
 635  	function diff_halfMatch($text1, $text2) {
 636          $longtext = mb_strlen($text1) > mb_strlen($text2) ? $text1 : $text2;
 637          $shorttext = mb_strlen($text1) > mb_strlen($text2) ? $text2 : $text1;
 638          if (mb_strlen($longtext) < 10 || mb_strlen($shorttext) < 1) {
 639              return null; // Pointless.
 640          }
 641  
 642          // First check if the second quarter is the seed for a half-match.
 643          $hm1 = $this->diff_halfMatchI($longtext, $shorttext, ceil(mb_strlen($longtext) / 4));
 644          // Check again based on the third quarter.
 645          $hm2 = $this->diff_halfMatchI($longtext, $shorttext, ceil(mb_strlen($longtext) / 2));
 646  
 647          if (!$hm1 && !$hm2) {
 648              return null;
 649          } elseif (!$hm2) {
 650              $hm = $hm1;
 651          } elseif (!$hm1) {
 652              $hm = $hm2;
 653          } else {
 654              // Both matched.  Select the longest.
 655              $hm = mb_strlen($hm1[4]) > mb_strlen($hm2[4]) ? $hm1 : $hm2;
 656          }
 657  
 658          // A half-match was found, sort out the return data.
 659          if (mb_strlen($text1) > mb_strlen($text2)) {
 660              $text1_a = $hm[0];
 661              $text1_b = $hm[1];
 662              $text2_a = $hm[2];
 663              $text2_b = $hm[3];
 664          } else {
 665              $text2_a = $hm[0];
 666              $text2_b = $hm[1];
 667              $text1_a = $hm[2];
 668              $text1_b = $hm[3];
 669          }
 670          $mid_common = $hm[4];
 671          return array( $text1_a, $text1_b, $text2_a, $text2_b, $mid_common );
 672      }
 673  
 674      /**
 675       * Does a mb_substring of shorttext exist within longtext such that the mb_substring
 676       * is at least half the length of longtext?
 677       * Closure, but does not reference any external variables.
 678       * @param {string} longtext Longer string.
 679       * @param {string} shorttext Shorter string.
 680       * @param {number} i Start index of quarter length mb_substring within longtext
 681       * @return {Array.<string>?} Five element Array, containing the prefix of
 682       *     longtext, the suffix of longtext, the prefix of shorttext, the suffix
 683       *     of shorttext and the common middle.  Or null if there was no match.
 684       * @private
 685       */
 686  	function diff_halfMatchI($longtext, $shorttext, $i) {
 687          // Start with a 1/4 length mb_substring at position i as a seed.
 688          $seed = mb_substr($longtext, $i, floor(mb_strlen($longtext) / 4));
 689  
 690          $j = -1;
 691          $best_common = '';
 692          $best_longtext_a = null;
 693          $best_longtext_b = null;
 694          $best_shorttext_a = null;
 695          $best_shorttext_b = null;
 696          while ( ($j = mb_strpos($shorttext, $seed, $j + 1)) !== false ) {
 697              $prefixLength = $this->diff_commonPrefix(mb_substr($longtext, $i), mb_substr($shorttext, $j));
 698              $suffixLength = $this->diff_commonSuffix(mb_substr($longtext, 0, $i), mb_substr($shorttext, 0, $j));
 699              if (mb_strlen($best_common) < $suffixLength + $prefixLength) {
 700                  $best_common = mb_substr($shorttext, $j - $suffixLength, $suffixLength) . mb_substr($shorttext, $j, $prefixLength);
 701                  $best_longtext_a = mb_substr($longtext, 0, $i - $suffixLength);
 702                  $best_longtext_b = mb_substr($longtext, $i + $prefixLength);
 703                  $best_shorttext_a = mb_substr($shorttext, 0, $j - $suffixLength);
 704                  $best_shorttext_b = mb_substr($shorttext, $j + $prefixLength);
 705              }
 706          }
 707          if (mb_strlen($best_common) >= mb_strlen($longtext) / 2) {
 708              return array (
 709                  $best_longtext_a,
 710                  $best_longtext_b,
 711                  $best_shorttext_a,
 712                  $best_shorttext_b,
 713                  $best_common
 714              );
 715          } else {
 716              return null;
 717          }
 718      }
 719  
 720      /**
 721       * Reduce the number of edits by eliminating semantically trivial equalities.
 722       * @param {Array.<Array.<number|string>>} diffs Array of diff tuples.
 723       */
 724  	function diff_cleanupSemantic(&$diffs) {
 725          $changes = false;
 726          $equalities = array (); // Stack of indices where equalities are found.
 727          $equalitiesLength = 0; // Keeping our own length var is faster in JS.
 728          $lastequality = null; // Always equal to equalities[equalitiesLength-1][1]
 729          $pointer = 0; // Index of current position.
 730          // Number of characters that changed prior to the equality.
 731          $length_changes1 = 0;
 732          // Number of characters that changed after the equality.
 733          $length_changes2 = 0;
 734          while ($pointer < count($diffs)) {
 735              if ($diffs[$pointer][0] == DIFF_EQUAL) { // equality found
 736                  $equalities[$equalitiesLength++] = $pointer;
 737                  $length_changes1 = $length_changes2;
 738                  $length_changes2 = 0;
 739                  $lastequality = $diffs[$pointer][1];
 740              } else { // an insertion or deletion
 741                  $length_changes2 += mb_strlen($diffs[$pointer][1]);
 742                  if ($lastequality !== null && (mb_strlen($lastequality) <= $length_changes1) && (mb_strlen($lastequality) <= $length_changes2)) {
 743                      // Duplicate record
 744                      $zzz_diffs = array_splice($diffs, $equalities[$equalitiesLength -1], 0, array(array (
 745                          DIFF_DELETE,
 746                          $lastequality
 747                      )));
 748                      // Change second copy to insert.
 749                      $diffs[$equalities[$equalitiesLength -1] + 1][0] = DIFF_INSERT;
 750                      // Throw away the equality we just deleted.
 751                      $equalitiesLength--;
 752                      // Throw away the previous equality (it needs to be reevaluated).
 753                      $equalitiesLength--;
 754                      $pointer = $equalitiesLength > 0 ? $equalities[$equalitiesLength -1] : -1;
 755                      $length_changes1 = 0; // Reset the counters.
 756                      $length_changes2 = 0;
 757                      $lastequality = null;
 758                      $changes = true;
 759                  }
 760              }
 761              $pointer++;
 762          }
 763          if ($changes) {
 764              $this->diff_cleanupMerge($diffs);
 765          }
 766          $this->diff_cleanupSemanticLossless($diffs);
 767      }
 768  
 769      /**
 770       * Look for single edits surrounded on both sides by equalities
 771       * which can be shifted sideways to align the edit to a word boundary.
 772       * e.g: The c<ins>at c</ins>ame. -> The <ins>cat </ins>came.
 773       * @param {Array.<Array.<number|string>>} diffs Array of diff tuples.
 774       */
 775  	function diff_cleanupSemanticLossless(&$diffs) {
 776  
 777          $pointer = 1;
 778          // Intentionally ignore the first and last element (don't need checking).
 779          while ($pointer < count($diffs) - 1) {
 780              if ($diffs[$pointer -1][0] == DIFF_EQUAL && $diffs[$pointer +1][0] == DIFF_EQUAL) {
 781                  // This is a single edit surrounded by equalities.
 782                  $equality1 = $diffs[$pointer -1][1];
 783                  $edit = $diffs[$pointer][1];
 784                  $equality2 = $diffs[$pointer +1][1];
 785  
 786                  // First, shift the edit as far left as possible.
 787                  $commonOffset = $this->diff_commonSuffix($equality1, $edit);
 788                  if ($commonOffset !== '') {
 789                      $commonString = mb_substr($edit, mb_strlen($edit) - $commonOffset);
 790                      $equality1 = mb_substr($equality1, 0, mb_strlen($equality1) - $commonOffset);
 791                      $edit = $commonString . mb_substr($edit, 0, mb_strlen($edit) - $commonOffset);
 792                      $equality2 = $commonString . $equality2;
 793                  }
 794  
 795                  // Second, step character by character right, looking for the best fit.
 796                  $bestEquality1 = $equality1;
 797                  $bestEdit = $edit;
 798                  $bestEquality2 = $equality2;
 799                  $bestScore = $this->diff_cleanupSemanticScore($equality1, $edit) + $this->diff_cleanupSemanticScore($edit, $equality2);
 800                  while (isset($equality2[0]) && $edit[0] === $equality2[0]) {
 801                      $equality1 .= $edit[0];
 802                      $edit = mb_substr($edit, 1) . $equality2[0];
 803                      $equality2 = mb_substr($equality2, 1);
 804                      $score = $this->diff_cleanupSemanticScore($equality1, $edit) + $this->diff_cleanupSemanticScore($edit, $equality2);
 805                      // The >= encourages trailing rather than leading whitespace on edits.
 806                      if ($score >= $bestScore) {
 807                          $bestScore = $score;
 808                          $bestEquality1 = $equality1;
 809                          $bestEdit = $edit;
 810                          $bestEquality2 = $equality2;
 811                      }
 812                  }
 813  
 814                  if ($diffs[$pointer -1][1] != $bestEquality1) {
 815                      // We have an improvement, save it back to the diff.
 816                      if ($bestEquality1) {
 817                          $diffs[$pointer -1][1] = $bestEquality1;
 818                      } else {
 819                          $zzz_diffs = array_splice($diffs, $pointer -1, 1);
 820                          $pointer--;
 821                      }
 822                      $diffs[$pointer][1] = $bestEdit;
 823                      if ($bestEquality2) {
 824                          $diffs[$pointer +1][1] = $bestEquality2;
 825                      } else {
 826                          $zzz_diffs = array_splice($diffs, $pointer +1, 1);
 827                          $pointer--;
 828                      }
 829                  }
 830              }
 831              $pointer++;
 832          }
 833      }
 834  
 835      /**
 836       * Given two strings, compute a score representing whether the internal
 837       * boundary falls on logical boundaries.
 838       * Scores range from 5 (best) to 0 (worst).
 839       * Closure, makes reference to regex patterns defined above.
 840       * @param {string} one First string
 841       * @param {string} two Second string
 842       * @return {number} The score.
 843       */
 844  	function diff_cleanupSemanticScore($one, $two) {
 845          // Define some regex patterns for matching boundaries.
 846          $punctuation = '/[^a-zA-Z0-9]/';
 847          $whitespace = '/\s/';
 848          $linebreak = '/[\r\n]/';
 849          $blanklineEnd = '/\n\r?\n$/';
 850          $blanklineStart = '/^\r?\n\r?\n/';
 851  
 852          if (!$one || !$two) {
 853              // Edges are the best.
 854              return 5;
 855          }
 856  
 857          // Each port of this function behaves slightly differently due to
 858          // subtle differences in each language's definition of things like
 859          // 'whitespace'.  Since this function's purpose is largely cosmetic,
 860          // the choice has been made to use each language's native features
 861          // rather than force total conformity.
 862          $score = 0;
 863          // One point for non-alphanumeric.
 864          if (preg_match($punctuation, $one[mb_strlen($one) - 1]) || preg_match($punctuation, $two[0])) {
 865              $score++;
 866              // Two points for whitespace.
 867              if (preg_match($whitespace, $one[mb_strlen($one) - 1] ) || preg_match($whitespace, $two[0])) {
 868                  $score++;
 869                  // Three points for line breaks.
 870                  if (preg_match($linebreak, $one[mb_strlen($one) - 1]) || preg_match($linebreak, $two[0])) {
 871                      $score++;
 872                      // Four points for blank lines.
 873                      if (preg_match($blanklineEnd, $one) || preg_match($blanklineStart, $two)) {
 874                          $score++;
 875                      }
 876                  }
 877              }
 878          }
 879          return $score;
 880      }
 881  
 882      /**
 883       * Reduce the number of edits by eliminating operationally trivial equalities.
 884       * @param {Array.<Array.<number|string>>} diffs Array of diff tuples.
 885       */
 886  	function diff_cleanupEfficiency(&$diffs) {
 887          $changes = false;
 888          $equalities = array (); // Stack of indices where equalities are found.
 889          $equalitiesLength = 0; // Keeping our own length var is faster in JS.
 890          $lastequality = ''; // Always equal to equalities[equalitiesLength-1][1]
 891          $pointer = 0; // Index of current position.
 892          // Is there an insertion operation before the last equality.
 893          $pre_ins = false;
 894          // Is there a deletion operation before the last equality.
 895          $pre_del = false;
 896          // Is there an insertion operation after the last equality.
 897          $post_ins = false;
 898          // Is there a deletion operation after the last equality.
 899          $post_del = false;
 900          while ($pointer < count($diffs)) {
 901              if ($diffs[$pointer][0] == DIFF_EQUAL) { // equality found
 902                  if (mb_strlen($diffs[$pointer][1]) < $this->Diff_EditCost && ($post_ins || $post_del)) {
 903                      // Candidate found.
 904                      $equalities[$equalitiesLength++] = $pointer;
 905                      $pre_ins = $post_ins;
 906                      $pre_del = $post_del;
 907                      $lastequality = $diffs[$pointer][1];
 908                  } else {
 909                      // Not a candidate, and can never become one.
 910                      $equalitiesLength = 0;
 911                      $lastequality = '';
 912                  }
 913                  $post_ins = $post_del = false;
 914              } else { // an insertion or deletion
 915                  if ($diffs[$pointer][0] == DIFF_DELETE) {
 916                      $post_del = true;
 917                  } else {
 918                      $post_ins = true;
 919                  }
 920                  /*
 921                   * Five types to be split:
 922                   * <ins>A</ins><del>B</del>XY<ins>C</ins><del>D</del>
 923                   * <ins>A</ins>X<ins>C</ins><del>D</del>
 924                   * <ins>A</ins><del>B</del>X<ins>C</ins>
 925                   * <ins>A</del>X<ins>C</ins><del>D</del>
 926                   * <ins>A</ins><del>B</del>X<del>C</del>
 927                   */
 928                  if ($lastequality && (($pre_ins && $pre_del && $post_ins && $post_del) || ((mb_strlen($lastequality) < $this->Diff_EditCost / 2) && ($pre_ins + $pre_del + $post_ins + $post_del) == 3))) {
 929                      // Duplicate record
 930                      $zzz_diffs = array_splice($diffs, $equalities[$equalitiesLength -1], 0, array(array (
 931                          DIFF_DELETE,
 932                          $lastequality
 933                      )));
 934                      // Change second copy to insert.
 935                      $diffs[$equalities[$equalitiesLength -1] + 1][0] = DIFF_INSERT;
 936                      $equalitiesLength--; // Throw away the equality we just deleted;
 937                      $lastequality = '';
 938                      if ($pre_ins && $pre_del) {
 939                          // No changes made which could affect previous entry, keep going.
 940                          $post_ins = $post_del = true;
 941                          $equalitiesLength = 0;
 942                      } else {
 943                          $equalitiesLength--; // Throw away the previous equality;
 944                          $pointer = $equalitiesLength > 0 ? $equalities[$equalitiesLength -1] : -1;
 945                          $post_ins = $post_del = false;
 946                      }
 947                      $changes = true;
 948                  }
 949              }
 950              $pointer++;
 951          }
 952  
 953          if ($changes) {
 954              $this->diff_cleanupMerge($diffs);
 955          }
 956      }
 957  
 958      /**
 959       * Reorder and merge like edit sections.  Merge equalities.
 960       * Any edit section can move as long as it doesn't cross an equality.
 961       * @param {Array.<Array.<number|string>>} diffs Array of diff tuples.
 962       */
 963  	function diff_cleanupMerge(&$diffs) {
 964          array_push($diffs, array ( DIFF_EQUAL, '' )); // Add a dummy entry at the end.
 965          $pointer = 0;
 966          $count_delete = 0;
 967          $count_insert = 0;
 968          $text_delete = '';
 969          $text_insert = '';
 970          $commonlength = null;
 971          while ($pointer < count($diffs)) {
 972              switch ($diffs[$pointer][0]) {
 973                  case DIFF_INSERT :
 974                      $count_insert++;
 975                      $text_insert .= $diffs[$pointer][1];
 976                      $pointer++;
 977                      break;
 978                  case DIFF_DELETE :
 979                      $count_delete++;
 980                      $text_delete .= $diffs[$pointer][1];
 981                      $pointer++;
 982                      break;
 983                  case DIFF_EQUAL :
 984                      // Upon reaching an equality, check for prior redundancies.
 985                      if ($count_delete !== 0 || $count_insert !== 0) {
 986                          if ($count_delete !== 0 && $count_insert !== 0) {
 987                              // Factor out any common prefixies.
 988                              $commonlength = $this->diff_commonPrefix($text_insert, $text_delete);
 989                              if ($commonlength !== 0) {
 990                                  if (($pointer - $count_delete - $count_insert) > 0 && $diffs[$pointer - $count_delete - $count_insert -1][0] == DIFF_EQUAL) {
 991                                      $diffs[$pointer - $count_delete - $count_insert -1][1] .= mb_substr($text_insert, 0, $commonlength);
 992                                  } else {
 993                                      array_splice($diffs, 0, 0, array(array (
 994                                          DIFF_EQUAL,
 995                                          mb_substr($text_insert, 0, $commonlength)
 996                                      )));
 997                                      $pointer++;
 998                                  }
 999                                  $text_insert = mb_substr($text_insert, $commonlength);
1000                                  $text_delete = mb_substr($text_delete, $commonlength);
1001                              }
1002                              // Factor out any common suffixies.
1003                              $commonlength = $this->diff_commonSuffix($text_insert, $text_delete);
1004                              if ($commonlength !== 0) {
1005                                  $diffs[$pointer][1] = mb_substr($text_insert, mb_strlen($text_insert) - $commonlength) . $diffs[$pointer][1];
1006                                  $text_insert = mb_substr($text_insert, 0, mb_strlen($text_insert) - $commonlength);
1007                                  $text_delete = mb_substr($text_delete, 0, mb_strlen($text_delete) - $commonlength);
1008                              }
1009                          }
1010                          // Delete the offending records and add the merged ones.
1011                          if ($count_delete === 0) {
1012                              array_splice($diffs, $pointer-$count_delete-$count_insert, $count_delete+$count_insert, array(array(
1013                                  DIFF_INSERT,
1014                                  $text_insert
1015                              )));
1016                          } elseif ($count_insert === 0) {
1017                              array_splice($diffs, $pointer-$count_delete-$count_insert, $count_delete+$count_insert, array(array(
1018                                  DIFF_DELETE,
1019                                  $text_delete
1020                              )));
1021                          } else {
1022                              array_splice($diffs, $pointer-$count_delete-$count_insert, $count_delete+$count_insert, array(array(
1023                                  DIFF_DELETE,
1024                                  $text_delete
1025                              ), array (
1026                                  DIFF_INSERT,
1027                                  $text_insert
1028                              )));
1029                          }
1030                          $pointer = $pointer - $count_delete - $count_insert + ($count_delete ? 1 : 0) + ($count_insert ? 1 : 0) + 1;
1031                      } elseif ($pointer !== 0 && $diffs[$pointer -1][0] == DIFF_EQUAL) {
1032                          // Merge this equality with the previous one.
1033                          $diffs[$pointer -1][1] .= $diffs[$pointer][1];
1034                          array_splice($diffs, $pointer, 1);
1035                      } else {
1036                          $pointer++;
1037                      }
1038                      $count_insert = 0;
1039                      $count_delete = 0;
1040                      $text_delete = '';
1041                      $text_insert = '';
1042                      break;
1043              }
1044          }
1045          if ($diffs[count($diffs) - 1][1] === '') {
1046              array_pop($diffs); // Remove the dummy entry at the end.
1047          }
1048  
1049          // Second pass: look for single edits surrounded on both sides by equalities
1050          // which can be shifted sideways to eliminate an equality.
1051          // e.g: A<ins>BA</ins>C -> <ins>AB</ins>AC
1052          $changes = false;
1053          $pointer = 1;
1054          // Intentionally ignore the first and last element (don't need checking).
1055          while ($pointer < count($diffs) - 1) {
1056              if ($diffs[$pointer-1][0] == DIFF_EQUAL && $diffs[$pointer+1][0] == DIFF_EQUAL) {
1057                  // This is a single edit surrounded by equalities.
1058                  if ( mb_substr($diffs[$pointer][1], mb_strlen($diffs[$pointer][1]) - mb_strlen($diffs[$pointer -1][1])) == $diffs[$pointer -1][1]) {
1059                      // Shift the edit over the previous equality.
1060                      $diffs[$pointer][1] = $diffs[$pointer -1][1] . mb_substr($diffs[$pointer][1], 0, mb_strlen($diffs[$pointer][1]) - mb_strlen($diffs[$pointer -1][1]));
1061                      $diffs[$pointer +1][1] = $diffs[$pointer -1][1] . $diffs[$pointer +1][1];
1062                      array_splice($diffs, $pointer -1, 1);
1063                      $changes = true;
1064                  } elseif (mb_substr($diffs[$pointer][1], 0, mb_strlen($diffs[$pointer +1][1])) == $diffs[$pointer +1][1]) {
1065                      // Shift the edit over the next equality.
1066                      $diffs[$pointer -1][1] .= $diffs[$pointer +1][1];
1067  
1068                      $diffs[$pointer][1] = mb_substr($diffs[$pointer][1], mb_strlen($diffs[$pointer +1][1])) . $diffs[$pointer +1][1];
1069                      array_splice($diffs, $pointer +1, 1);
1070                      $changes = true;
1071                  }
1072              }
1073              $pointer++;
1074          }
1075          // If shifts were made, the diff needs reordering and another shift sweep.
1076          if ($changes) {
1077              $this->diff_cleanupMerge($diffs);
1078          }
1079      }
1080  
1081      /**
1082       * loc is a location in text1, compute and return the equivalent location in
1083       * text2.
1084       * e.g. 'The cat' vs 'The big cat', 1->1, 5->8
1085       * @param {Array.<Array.<number|string>>} diffs Array of diff tuples.
1086       * @param {number} loc Location within text1.
1087       * @return {number} Location within text2.
1088       */
1089  	function diff_xIndex($diffs, $loc) {
1090          $chars1 = 0;
1091          $chars2 = 0;
1092          $last_chars1 = 0;
1093          $last_chars2 = 0;
1094          for ($x = 0; $x < count($diffs); $x++) {
1095              if ($diffs[$x][0] !== DIFF_INSERT) { // Equality or deletion.
1096                  $chars1 += mb_strlen($diffs[$x][1]);
1097              }
1098              if ($diffs[$x][0] !== DIFF_DELETE) { // Equality or insertion.
1099                  $chars2 += mb_strlen($diffs[$x][1]);
1100              }
1101              if ($chars1 > $loc) { // Overshot the location.
1102                  break;
1103              }
1104              $last_chars1 = $chars1;
1105              $last_chars2 = $chars2;
1106          }
1107          // Was the location was deleted?
1108          if (count($diffs) != $x && $diffs[$x][0] === DIFF_DELETE) {
1109              return $last_chars2;
1110          }
1111          // Add the remaining character length.
1112          return $last_chars2 + ($loc - $last_chars1);
1113      }
1114  
1115      /**
1116       * Convert a diff array into a pretty HTML report.
1117       * @param {Array.<Array.<number|string>>} diffs Array of diff tuples.
1118       * @return {string} HTML representation.
1119       */
1120  	function diff_prettyHtml($diffs) {
1121          $html = array ();
1122          $i = 0;
1123          for ($x = 0; $x < count($diffs); $x++) {
1124              $op = $diffs[$x][0]; // Operation (insert, delete, equal)
1125              $data = $diffs[$x][1]; // Text of change.
1126              $text = preg_replace(array (
1127                  '/&/',
1128                  '/</',
1129                  '/>/',
1130                  "/\n/"
1131              ), array (
1132                  '&amp;',
1133                  '&lt;',
1134                  '&gt;',
1135                  '&para;<BR>'
1136              ), $data);
1137  
1138              switch ($op) {
1139                  case DIFF_INSERT :
1140                      $html[$x] = '<INS STYLE="background:#E6FFE6;" TITLE="i=' . $i . '">' . $text . '</INS>';
1141                      break;
1142                  case DIFF_DELETE :
1143                      $html[$x] = '<DEL STYLE="background:#FFE6E6;" TITLE="i=' . $i . '">' . $text . '</DEL>';
1144                      break;
1145                  case DIFF_EQUAL :
1146                      $html[$x] = '<SPAN TITLE="i=' . $i . '">' . $text . '</SPAN>';
1147                      break;
1148              }
1149              if ($op !== DIFF_DELETE) {
1150                  $i += mb_strlen($data);
1151              }
1152          }
1153          return implode('',$html);
1154      }
1155  
1156      /**
1157       * Compute and return the source text (all equalities and deletions).
1158       * @param {Array.<Array.<number|string>>} diffs Array of diff tuples.
1159       * @return {string} Source text.
1160       */
1161  	function diff_text1($diffs) {
1162          $text = array ();
1163          for ($x = 0; $x < count($diffs); $x++) {
1164              if ($diffs[$x][0] !== DIFF_INSERT) {
1165                  $text[$x] = $diffs[$x][1];
1166              }
1167          }
1168          return implode('',$text);
1169      }
1170  
1171      /**
1172       * Compute and return the destination text (all equalities and insertions).
1173       * @param {Array.<Array.<number|string>>} diffs Array of diff tuples.
1174       * @return {string} Destination text.
1175       */
1176  	function diff_text2($diffs) {
1177          $text = array ();
1178          for ($x = 0; $x < count($diffs); $x++) {
1179              if ($diffs[$x][0] !== DIFF_DELETE) {
1180                  $text[$x] = $diffs[$x][1];
1181              }
1182          }
1183          return implode('',$text);
1184      }
1185  
1186      /**
1187       * Compute the Levenshtein distance; the number of inserted, deleted or
1188       * substituted characters.
1189       * @param {Array.<Array.<number|string>>} diffs Array of diff tuples.
1190       * @return {number} Number of changes.
1191       */
1192  	function diff_levenshtein($diffs) {
1193          $levenshtein = 0;
1194          $insertions = 0;
1195          $deletions = 0;
1196          for ($x = 0; $x < count($diffs); $x++) {
1197              $op = $diffs[$x][0];
1198              $data = $diffs[$x][1];
1199              switch ($op) {
1200                  case DIFF_INSERT :
1201                      $insertions += mb_strlen($data);
1202                      break;
1203                  case DIFF_DELETE :
1204                      $deletions += mb_strlen($data);
1205                      break;
1206                  case DIFF_EQUAL :
1207                      // A deletion and an insertion is one substitution.
1208                      $levenshtein += max($insertions, $deletions);
1209                      $insertions = 0;
1210                      $deletions = 0;
1211                      break;
1212              }
1213          }
1214          $levenshtein += max($insertions, $deletions);
1215          return $levenshtein;
1216      }
1217  
1218      /**
1219       * Crush the diff into an encoded string which describes the operations
1220       * required to transform text1 into text2.
1221       * E.g. =3\t-2\t+ing  -> Keep 3 chars, delete 2 chars, insert 'ing'.
1222       * Operations are tab-separated.  Inserted text is escaped using %xx notation.
1223       * @param {Array.<Array.<number|string>>} diffs Array of diff tuples.
1224       * @return {string} Delta text.
1225       */
1226  	function diff_toDelta($diffs) {
1227          $text = array ();
1228          for ($x = 0; $x < count($diffs); $x++) {
1229              switch ($diffs[$x][0]) {
1230                  case DIFF_INSERT :
1231                      $text[$x] = '+' .encodeURI($diffs[$x][1]);
1232                      break;
1233                  case DIFF_DELETE :
1234                      $text[$x] = '-' .mb_strlen($diffs[$x][1]);
1235                      break;
1236                  case DIFF_EQUAL :
1237                      $text[$x] = '=' .mb_strlen($diffs[$x][1]);
1238                      break;
1239              }
1240          }
1241          return str_replace('%20', ' ', implode("\t", $text));
1242      }
1243  
1244      /**
1245       * Given the original text1, and an encoded string which describes the
1246       * operations required to transform text1 into text2, compute the full diff.
1247       * @param {string} text1 Source string for the diff.
1248       * @param {string} delta Delta text.
1249       * @return {Array.<Array.<number|string>>} Array of diff tuples.
1250       * @throws {Error} If invalid input.
1251       */
1252  	function diff_fromDelta($text1, $delta) {
1253          $diffs = array ();
1254          $diffsLength = 0; // Keeping our own length var is faster in JS.
1255          $pointer = 0; // Cursor in text1
1256          $tokens = preg_split("/\t/", $delta);
1257  
1258          for ($x = 0; $x < count($tokens); $x++) {
1259              // Each token begins with a one character parameter which specifies the
1260              // operation of this token (delete, insert, equality).
1261              $param = mb_substr($tokens[$x], 1);
1262              switch ($tokens[$x][0]) {
1263                  case '+' :
1264                      try {
1265                          $diffs[$diffsLength++] = array (
1266                              DIFF_INSERT,
1267                              decodeURI($param)
1268                          );
1269                      } catch (Exception $ex) {
1270                          echo_Exception('Illegal escape in diff_fromDelta: ' . $param);
1271                          // Malformed URI sequence.
1272                      }
1273                      break;
1274                  case '-' :
1275                      // Fall through.
1276                  case '=' :
1277                      $n = (int) $param;
1278                      if ($n < 0) {
1279                          echo_Exception('Invalid number in diff_fromDelta: ' . $param);
1280                      }
1281                      $text = mb_substr($text1, $pointer, $n);
1282                      $pointer += $n;
1283                      if ($tokens[$x][0] == '=') {
1284                          $diffs[$diffsLength++] = array (
1285                              DIFF_EQUAL,
1286                              $text
1287                          );
1288                      } else {
1289                          $diffs[$diffsLength++] = array (
1290                              DIFF_DELETE,
1291                              $text
1292                          );
1293                      }
1294                      break;
1295                  default :
1296                      // Blank tokens are ok (from a trailing \t).
1297                      // Anything else is an error.
1298                      if ($tokens[$x]) {
1299                          echo_Exception('Invalid diff operation in diff_fromDelta: ' . $tokens[$x]);
1300                      }
1301              }
1302          }
1303          if ($pointer != mb_strlen($text1)) {
1304  //            throw new Exception('Delta length (' . $pointer . ') does not equal source text length (' . mb_strlen($text1) . ').');
1305              echo_Exception('Delta length (' . $pointer . ') does not equal source text length (' . mb_strlen($text1) . ').');
1306          }
1307          return $diffs;
1308      }
1309  
1310      //  MATCH FUNCTIONS
1311  
1312      /**
1313       * Locate the best instance of 'pattern' in 'text' near 'loc'.
1314       * @param {string} text The text to search.
1315       * @param {string} pattern The pattern to search for.
1316       * @param {number} loc The location to search around.
1317       * @return {number} Best match index or -1.
1318       */
1319  	function match_main($text, $pattern, $loc) {
1320          $loc = max(0, min($loc, mb_strlen($text)));
1321          if ($text == $pattern) {
1322              // Shortcut (potentially not guaranteed by the algorithm)
1323              return 0;
1324          }
1325          elseif (!mb_strlen($text)) {
1326              // Nothing to match.
1327              return -1;
1328          }
1329          elseif (mb_substr($text, $loc, mb_strlen($pattern)) == $pattern) {
1330              // Perfect match at the perfect spot!  (Includes case of null pattern)
1331              return $loc;
1332          } else {
1333              // Do a fuzzy compare.
1334              return $this->match_bitap($text, $pattern, $loc);
1335          }
1336      }
1337  
1338      /**
1339       * Locate the best instance of 'pattern' in 'text' near 'loc' using the
1340       * Bitap algorithm.
1341       * @param {string} text The text to search.
1342       * @param {string} pattern The pattern to search for.
1343       * @param {number} loc The location to search around.
1344       * @return {number} Best match index or -1.
1345       * @private
1346       */
1347  	function match_bitap($text, $pattern, $loc) {
1348          if (mb_strlen($pattern) > Match_MaxBits) {
1349              echo_Exception('Pattern too long for this browser.');
1350          }
1351  
1352          // Initialise the alphabet.
1353          $s = $this->match_alphabet($pattern);
1354  
1355          // Highest score beyond which we give up.
1356          $score_threshold = $this->Match_Threshold;
1357  
1358          // Is there a nearby exact match? (speedup)
1359          $best_loc = mb_strpos($text, $pattern, $loc);
1360          if ($best_loc !== false) {
1361              $score_threshold = min($this->match_bitapScore(0, $best_loc, $pattern, $loc), $score_threshold);
1362          }
1363  
1364          // What about in the other direction? (speedup)
1365          $best_loc = mb_strrpos( $text, $pattern, min($loc + mb_strlen($pattern), mb_strlen($text)) );
1366          if ($best_loc !== false) {
1367              $score_threshold = min($this->match_bitapScore(0, $best_loc, $pattern, $loc), $score_threshold);
1368          }
1369  
1370          // Initialise the bit arrays.
1371          $matchmask = 1 << (mb_strlen($pattern) - 1);
1372          $best_loc = -1;
1373  
1374          $bin_min = null;
1375          $bin_mid = null;
1376          $bin_max = mb_strlen($pattern) + mb_strlen($text);
1377          $last_rd = null;
1378          for ($d = 0; $d < mb_strlen($pattern); $d++) {
1379              // Scan for the best match; each iteration allows for one more error.
1380              // Run a binary search to determine how far from 'loc' we can stray at this
1381              // error level.
1382              $bin_min = 0;
1383              $bin_mid = $bin_max;
1384              while ($bin_min < $bin_mid) {
1385                  if ($this->match_bitapScore($d, $loc + $bin_mid, $pattern, $loc) <= $score_threshold) {
1386                      $bin_min = $bin_mid;
1387                  } else {
1388                      $bin_max = $bin_mid;
1389                  }
1390                  $bin_mid = floor(($bin_max - $bin_min) / 2 + $bin_min);
1391              }
1392              // Use the result from this iteration as the maximum for the next.
1393              $bin_max = $bin_mid;
1394              $start = max(1, $loc - $bin_mid +1);
1395              $finish = min($loc + $bin_mid, mb_strlen($text)) + mb_strlen($pattern);
1396  
1397              $rd = Array (
1398                  $finish +2
1399              );
1400              $rd[$finish +1] = (1 << $d) - 1;
1401              for ($j = $finish; $j >= $start; $j--) {
1402                  // The alphabet (s) is a sparse hash, so the following line generates
1403                  // warnings.
1404  @                $charMatch = $s[ $text[$j -1] ];
1405                  if ($d === 0) { // First pass: exact match.
1406                      $rd[$j] = (($rd[$j +1] << 1) | 1) & $charMatch;
1407                  } else { // Subsequent passes: fuzzy match.
1408                      $rd[$j] = (($rd[$j +1] << 1) | 1) & $charMatch | ((($last_rd[$j +1] | $last_rd[$j]) << 1) | 1) | $last_rd[$j +1];
1409                  }
1410                  if ($rd[$j] & $matchmask) {
1411                      $score = $this->match_bitapScore($d, $j -1, $pattern, $loc);
1412                      // This match will almost certainly be better than any existing match.
1413                      // But check anyway.
1414                      if ($score <= $score_threshold) {
1415                          // Told you so.
1416                          $score_threshold = $score;
1417                          $best_loc = $j -1;
1418                          if ($best_loc > $loc) {
1419                              // When passing loc, don't exceed our current distance from loc.
1420                              $start = max(1, 2 * $loc - $best_loc);
1421                          } else {
1422                              // Already passed loc, downhill from here on in.
1423                              break;
1424                          }
1425                      }
1426                  }
1427              }
1428              // No hope for a (better) match at greater error levels.
1429              if ($this->match_bitapScore($d +1, $loc, $pattern, $loc) > $score_threshold) {
1430                  break;
1431              }
1432              $last_rd = $rd;
1433          }
1434          return (int)$best_loc;
1435      }
1436  
1437      /**
1438       * Compute and return the score for a match with e errors and x location.
1439       * Accesses loc and pattern through being a closure.
1440       * @param {number} e Number of errors in match.
1441       * @param {number} x Location of match.
1442       * @return {number} Overall score for match (0.0 = good, 1.0 = bad).
1443       * @private
1444       */
1445  	function match_bitapScore($e, $x, $pattern, $loc) {
1446          $accuracy = $e / mb_strlen($pattern);
1447          $proximity = abs($loc - $x);
1448          if (!$this->Match_Distance) {
1449              // Dodge divide by zero error.
1450              return $proximity ? 1.0 : $accuracy;
1451          }
1452          return $accuracy + ($proximity / $this->Match_Distance);
1453      }
1454  
1455      /**
1456       * Initialise the alphabet for the Bitap algorithm.
1457       * @param {string} pattern The text to encode.
1458       * @return {Object} Hash of character locations.
1459       * @private
1460       */
1461  	function match_alphabet($pattern) {
1462          $s = array ();
1463          for ($i = 0; $i < mb_strlen($pattern); $i++) {
1464              $s[ $pattern[$i] ] = 0;
1465          }
1466          for ($i = 0; $i < mb_strlen($pattern); $i++) {
1467              $s[ $pattern[$i] ] |= 1 << (mb_strlen($pattern) - $i - 1);
1468          }
1469          return $s;
1470      }
1471  
1472      //  PATCH FUNCTIONS
1473  
1474      /**
1475       * Increase the context until it is unique,
1476       * but don't let the pattern expand beyond Match_MaxBits.
1477       * @param {patch_obj} patch The patch to grow.
1478       * @param {string} text Source text.
1479       * @private
1480       */
1481  	function patch_addContext($patch, $text) {
1482          $pattern = mb_substr($text, $patch->start2, $patch->length1 );
1483          $previousPattern = null;
1484          $padding = 0;
1485          $i = 0;
1486          while (
1487              (   mb_strlen($pattern) === 0 // Javascript's indexOf/lastIndexOd return 0/strlen respectively if pattern = ''
1488               || mb_strpos($text, $pattern) !== mb_strrpos($text, $pattern)
1489              )
1490              && $pattern !== $previousPattern // avoid infinte loop
1491              && mb_strlen($pattern) < Match_MaxBits - $this->Patch_Margin - $this->Patch_Margin ) {
1492              $padding += $this->Patch_Margin;
1493              $previousPattern = $pattern;
1494              $pattern = mb_substr($text, max($patch->start2 - $padding,0), ($patch->start2 + $patch->length1 + $padding) - max($patch->start2 - $padding,0) );
1495          }
1496          // Add one chunk for good luck.
1497          $padding += $this->Patch_Margin;
1498          // Add the prefix.
1499          $prefix = mb_substr($text, max($patch->start2 - $padding,0), $patch->start2 - max($patch->start2 - $padding,0) );
1500          if ($prefix!=='') {
1501              array_unshift($patch->diffs, array (
1502                  DIFF_EQUAL,
1503                  $prefix
1504              ));
1505          }
1506          // Add the suffix.
1507          $suffix = mb_substr($text, $patch->start2 + $patch->length1, ($patch->start2 + $patch->length1 + $padding) - ($patch->start2 + $patch->length1) );
1508          if ($suffix!=='') {
1509              array_push($patch->diffs, array (
1510                  DIFF_EQUAL,
1511                  $suffix
1512              ));
1513          }
1514  
1515          // Roll back the start points.
1516          $patch->start1 -= mb_strlen($prefix);
1517          $patch->start2 -= mb_strlen($prefix);
1518          // Extend the lengths.
1519          $patch->length1 += mb_strlen($prefix) + mb_strlen($suffix);
1520          $patch->length2 += mb_strlen($prefix) + mb_strlen($suffix);
1521      }
1522  
1523      /**
1524       * Compute a list of patches to turn text1 into text2.
1525       * Use diffs if provided, otherwise compute it ourselves.
1526       * There are four ways to call this function, depending on what data is
1527       * available to the caller:
1528       * Method 1:
1529       * a = text1, b = text2
1530       * Method 2:
1531       * a = diffs
1532       * Method 3 (optimal):
1533       * a = text1, b = diffs
1534       * Method 4 (deprecated, use method 3):
1535       * a = text1, b = text2, c = diffs
1536       *
1537       * @param {string|Array.<Array.<number|string>>} a text1 (methods 1,3,4) or
1538       * Array of diff tuples for text1 to text2 (method 2).
1539       * @param {string|Array.<Array.<number|string>>} opt_b text2 (methods 1,4) or
1540       * Array of diff tuples for text1 to text2 (method 3) or undefined (method 2).
1541       * @param {string|Array.<Array.<number|string>>} opt_c Array of diff tuples for
1542       * text1 to text2 (method 4) or undefined (methods 1,2,3).
1543       * @return {Array.<patch_obj>} Array of patch objects.
1544       */
1545  	function patch_make($a, $opt_b = null, $opt_c = null ) {
1546          if (is_string($a) && is_string($opt_b) && $opt_c === null ) {
1547              // Method 1: text1, text2
1548              // Compute diffs from text1 and text2.
1549              $text1 = $a;
1550              $diffs = $this->diff_main($text1, $opt_b, true);
1551              if ( count($diffs) > 2) {
1552                  $this->diff_cleanupSemantic($diffs);
1553                  $this->diff_cleanupEfficiency($diffs);
1554              }
1555          } elseif ( is_array($a) && $opt_b === null && $opt_c === null) {
1556              // Method 2: diffs
1557              // Compute text1 from diffs.
1558              $diffs = $a;
1559              $text1 = $this->diff_text1($diffs);
1560          } elseif ( is_string($a) && is_array($opt_b) && $opt_c === null) {
1561              // Method 3: text1, diffs
1562              $text1 = $a;
1563              $diffs = $opt_b;
1564          } elseif ( is_string($a) && is_string($opt_b) && is_array($opt_c) ) {
1565              // Method 4: text1, text2, diffs
1566              // text2 is not used.
1567              $text1 = $a;
1568              $diffs = $opt_c;
1569          } else {
1570              echo_Exception('Unknown call format to patch_make.');
1571          }
1572  
1573          if ( count($diffs) === 0) {
1574              return array(); // Get rid of the null case.
1575          }
1576          $patches = array();
1577          $patch = new patch_obj();
1578          $patchDiffLength = 0; // Keeping our own length var is faster in JS.
1579          $char_count1 = 0; // Number of characters into the text1 string.
1580          $char_count2 = 0; // Number of characters into the text2 string.
1581          // Start with text1 (prepatch_text) and apply the diffs until we arrive at
1582          // text2 (postpatch_text).  We recreate the patches one by one to determine
1583          // context info.
1584          $prepatch_text = $text1;
1585          $postpatch_text = $text1;
1586          for ($x = 0; $x < count($diffs); $x++) {
1587              $diff_type = $diffs[$x][0];
1588              $diff_text = $diffs[$x][1];
1589  
1590              if (!$patchDiffLength && $diff_type !== DIFF_EQUAL) {
1591                  // A new patch starts here.
1592                  $patch->start1 = $char_count1;
1593                  $patch->start2 = $char_count2;
1594              }
1595  
1596              switch ($diff_type) {
1597                  case DIFF_INSERT :
1598                      $patch->diffs[$patchDiffLength++] = $diffs[$x];
1599                      $patch->length2 += mb_strlen($diff_text);
1600                      $postpatch_text = mb_substr($postpatch_text, 0, $char_count2) . $diff_text . mb_substr($postpatch_text,$char_count2);
1601                      break;
1602                  case DIFF_DELETE :
1603                      $patch->length1 += mb_strlen($diff_text);
1604                      $patch->diffs[$patchDiffLength++] = $diffs[$x];
1605                      $postpatch_text = mb_substr($postpatch_text, 0, $char_count2) . mb_substr($postpatch_text, $char_count2 + mb_strlen($diff_text) );
1606                      break;
1607                  case DIFF_EQUAL :
1608                      if ( mb_strlen($diff_text) <= 2 * $this->Patch_Margin && $patchDiffLength && count($diffs) != $x + 1) {
1609                          // Small equality inside a patch.
1610                          $patch->diffs[$patchDiffLength++] = $diffs[$x];
1611                          $patch->length1 += mb_strlen($diff_text);
1612                          $patch->length2 += mb_strlen($diff_text);
1613                      } elseif ( mb_strlen($diff_text) >= 2 * $this->Patch_Margin ) {
1614                          // Time for a new patch.
1615                          if ($patchDiffLength) {
1616                              $this->patch_addContext($patch, $prepatch_text);
1617                              array_push($patches,$patch);
1618                              $patch = new patch_obj();
1619                              $patchDiffLength = 0;
1620                              // Unlike Unidiff, our patch lists have a rolling context.
1621                              // http://code.google.com/p/google-diff-match-patch/wiki/Unidiff
1622                              // Update prepatch text & pos to reflect the application of the
1623                              // just completed patch.
1624                              $prepatch_text = $postpatch_text;
1625                              $char_count1 = $char_count2;
1626                          }
1627                      }
1628                      break;
1629              }
1630  
1631              // Update the current character count.
1632              if ($diff_type !== DIFF_INSERT) {
1633                  $char_count1 += mb_strlen($diff_text);
1634              }
1635              if ($diff_type !== DIFF_DELETE) {
1636                  $char_count2 += mb_strlen($diff_text);
1637              }
1638          }
1639          // Pick up the leftover patch if not empty.
1640          if ($patchDiffLength) {
1641              $this->patch_addContext($patch, $prepatch_text);
1642              array_push($patches, $patch);
1643          }
1644  
1645          return $patches;
1646      }
1647  
1648      /**
1649       * Given an array of patches, return another array that is identical.
1650       * @param {Array.<patch_obj>} patches Array of patch objects.
1651       * @return {Array.<patch_obj>} Array of patch objects.
1652       */
1653  	function patch_deepCopy($patches) {
1654          // Making deep copies is hard in JavaScript.
1655          $patchesCopy = array();
1656          for ($x = 0; $x < count($patches); $x++) {
1657              $patch = $patches[$x];
1658              $patchCopy = new patch_obj();
1659              for ($y = 0; $y < count($patch->diffs); $y++) {
1660                  $patchCopy->diffs[$y] = $patch->diffs[$y]; // ?? . slice();
1661              }
1662              $patchCopy->start1 = $patch->start1;
1663              $patchCopy->start2 = $patch->start2;
1664              $patchCopy->length1 = $patch->length1;
1665              $patchCopy->length2 = $patch->length2;
1666              $patchesCopy[$x] = $patchCopy;
1667          }
1668          return $patchesCopy;
1669      }
1670  
1671      /**
1672       * Merge a set of patches onto the text.  Return a patched text, as well
1673       * as a list of true/false values indicating which patches were applied.
1674       * @param {Array.<patch_obj>} patches Array of patch objects.
1675       * @param {string} text Old text.
1676       * @return {Array.<string|Array.<boolean>>} Two element Array, containing the
1677       *      new text and an array of boolean values.
1678       */
1679  	function patch_apply($patches, $text) {
1680          if ( count($patches) == 0) {
1681              return array($text,array());
1682          }
1683  
1684          // Deep copy the patches so that no changes are made to originals.
1685          $patches = $this->patch_deepCopy($patches);
1686  
1687          $nullPadding = $this->patch_addPadding($patches);
1688          $text = $nullPadding . $text . $nullPadding;
1689  
1690          $this->patch_splitMax($patches);
1691          // delta keeps track of the offset between the expected and actual location
1692          // of the previous patch.  If there are patches expected at positions 10 and
1693          // 20, but the first patch was found at 12, delta is 2 and the second patch
1694          // has an effective expected position of 22.
1695          $delta = 0;
1696          $results = array();
1697          for ($x = 0; $x < count($patches) ; $x++) {
1698              $expected_loc = $patches[$x]->start2 + $delta;
1699              $text1 = $this->diff_text1($patches[$x]->diffs);
1700              $start_loc = null;
1701              $end_loc = -1;
1702              if (mb_strlen($text1) > Match_MaxBits) {
1703                  // patch_splitMax will only provide an oversized pattern in the case of
1704                  // a monster delete.
1705                  $start_loc = $this->match_main($text, mb_substr($text1, 0, Match_MaxBits ), $expected_loc);
1706                  if ($start_loc != -1) {
1707                      $end_loc = $this->match_main($text, mb_substr($text1,mb_strlen($text1) - Match_MaxBits), $expected_loc + mb_strlen($text1) - Match_MaxBits);
1708                      if ($end_loc == -1 || $start_loc >= $end_loc) {
1709                          // Can't find valid trailing context.  Drop this patch.
1710                          $start_loc = -1;
1711                      }
1712                  }
1713              } else {
1714                  $start_loc = $this->match_main($text, $text1, $expected_loc);
1715              }
1716              if ($start_loc == -1) {
1717                  // No match found.  :(
1718                  $results[$x] = false;
1719                  // Subtract the delta for this failed patch from subsequent patches.
1720                  $delta -= $patches[$x]->length2 - $patches[$x]->length1;
1721              } else {
1722                  // Found a match.  :)
1723                  $results[$x] = true;
1724                  $delta = $start_loc - $expected_loc;
1725                  $text2 = null;
1726                  if ($end_loc == -1) {
1727                      $text2 = mb_substr($text, $start_loc, mb_strlen($text1) );
1728                  } else {
1729                      $text2 = mb_substr($text, $start_loc, $end_loc + Match_MaxBits - $start_loc);
1730                  }
1731                  if ($text1 == $text2) {
1732                      // Perfect match, just shove the replacement text in.
1733                      $text = mb_substr($text, 0, $start_loc) . $this->diff_text2($patches[$x]->diffs) . mb_substr($text,$start_loc + mb_strlen($text1) );
1734                  } else {
1735                      // Imperfect match.  Run a diff to get a framework of equivalent
1736                      // indices.
1737                      $diffs = $this->diff_main($text1, $text2, false);
1738                      if ( mb_strlen($text1) > Match_MaxBits && $this->diff_levenshtein($diffs) / mb_strlen($text1) > $this->Patch_DeleteThreshold) {
1739                          // The end points match, but the content is unacceptably bad.
1740                          $results[$x] = false;
1741                      } else {
1742                          $this->diff_cleanupSemanticLossless($diffs);
1743                          $index1 = 0;
1744                          $index2 = NULL;
1745                          for ($y = 0; $y < count($patches[$x]->diffs); $y++) {
1746                              $mod = $patches[$x]->diffs[$y];
1747                              if ($mod[0] !== DIFF_EQUAL) {
1748                                  $index2 = $this->diff_xIndex($diffs, $index1);
1749                              }
1750                              if ($mod[0] === DIFF_INSERT) { // Insertion
1751                                  $text = mb_substr($text, 0, $start_loc + $index2) . $mod[1] . mb_substr($text, $start_loc + $index2);
1752                              } elseif ($mod[0] === DIFF_DELETE) { // Deletion
1753                                  $text = mb_substr($text, 0, $start_loc + $index2) . mb_substr($text,$start_loc + $this->diff_xIndex($diffs, $index1 + mb_strlen($mod[1]) ));
1754                              }
1755                              if ($mod[0] !== DIFF_DELETE) {
1756                                  $index1 += mb_strlen($mod[1]);
1757                              }
1758                          }
1759                      }
1760                  }
1761              }
1762          }
1763          // Strip the padding off.
1764          $text = mb_substr($text, mb_strlen($nullPadding), mb_strlen($text) - 2*mb_strlen($nullPadding) );
1765          return array($text, $results);
1766      }
1767  
1768      /**
1769       * Add some padding on text start and end so that edges can match something.
1770       * Intended to be called only from within patch_apply.
1771       * @param {Array.<patch_obj>} patches Array of patch objects.
1772       * @return {string} The padding string added to each side.
1773       */
1774  	function patch_addPadding(&$patches){
1775          $paddingLength = $this->Patch_Margin;
1776          $nullPadding = '';
1777          for ($x = 1; $x <= $paddingLength; $x++) {
1778              $nullPadding .= mb_chr($x);
1779          }
1780  
1781          // Bump all the patches forward.
1782          for ($x = 0; $x < count($patches); $x++) {
1783              $patches[$x]->start1 += $paddingLength;
1784              $patches[$x]->start2 += $paddingLength;
1785          }
1786  
1787          // Add some padding on start of first diff.
1788          $patch = &$patches[0];
1789          $diffs = &$patch->diffs;
1790          if (count($diffs) == 0 || $diffs[0][0] != DIFF_EQUAL) {
1791              // Add nullPadding equality.
1792              array_unshift($diffs, array(DIFF_EQUAL, $nullPadding));
1793              $patch->start1 -= $paddingLength; // Should be 0.
1794              $patch->start2 -= $paddingLength; // Should be 0.
1795              $patch->length1 += $paddingLength;
1796              $patch->length2 += $paddingLength;
1797          } elseif ($paddingLength > mb_strlen($diffs[0][1]) ) {
1798              // Grow first equality.
1799              $extraLength = $paddingLength - mb_strlen($diffs[0][1]);
1800              $diffs[0][1] = mb_substr( $nullPadding , mb_strlen($diffs[0][1]) ) . $diffs[0][1];
1801              $patch->start1 -= $extraLength;
1802              $patch->start2 -= $extraLength;
1803              $patch->length1 += $extraLength;
1804              $patch->length2 += $extraLength;
1805          }
1806  
1807          // Add some padding on end of last diff.
1808          $patch = &$patches[count($patches) - 1];
1809          $diffs = &$patch->diffs;
1810          if ( count($diffs) == 0 || $diffs[ count($diffs) - 1][0] != DIFF_EQUAL) {
1811              // Add nullPadding equality.
1812              array_push($diffs, array(DIFF_EQUAL, $nullPadding) );
1813              $patch->length1 += $paddingLength;
1814              $patch->length2 += $paddingLength;
1815          } elseif ($paddingLength > mb_strlen( $diffs[count($diffs)-1][1] ) ) {
1816              // Grow last equality.
1817              $extraLength = $paddingLength - mb_strlen( $diffs[count($diffs)-1][1] );
1818              $diffs[ count($diffs)-1][1] .= mb_substr($nullPadding,0,$extraLength);
1819              $patch->length1 += $extraLength;
1820              $patch->length2 += $extraLength;
1821          }
1822  
1823          return $nullPadding;
1824      }
1825  
1826      /**
1827       * Look through the patches and break up any which are longer than the maximum
1828       * limit of the match algorithm.
1829       * @param {Array.<patch_obj>} patches Array of patch objects.
1830       */
1831  	function patch_splitMax(&$patches) {
1832          for ($x = 0; $x < count($patches); $x++) {
1833              if ( $patches[$x]->length1 > Match_MaxBits) {
1834                  $bigpatch = $patches[$x];
1835                  // Remove the big old patch.
1836                  array_splice($patches,$x--,1);
1837                  $patch_size = Match_MaxBits;
1838                  $start1 = $bigpatch->start1;
1839                  $start2 = $bigpatch->start2;
1840                  $precontext = '';
1841                  while ( count($bigpatch->diffs) !== 0) {
1842                      // Create one of several smaller patches.
1843                      $patch = new patch_obj();
1844                      $empty = true;
1845                      $patch->start1 = $start1 - mb_strlen($precontext);
1846                      $patch->start2 = $start2 - mb_strlen($precontext);
1847                      if ($precontext !== '') {
1848                          $patch->length1 = $patch->length2 = mb_strlen($precontext);
1849                          array_push($patch->diffs, array(DIFF_EQUAL, $precontext) );
1850                      }
1851                      while ( count($bigpatch->diffs) !== 0 && $patch->length1 < $patch_size - $this->Patch_Margin) {
1852                          $diff_type = $bigpatch->diffs[0][0];
1853                          $diff_text = $bigpatch->diffs[0][1];
1854                          if ($diff_type === DIFF_INSERT) {
1855                              // Insertions are harmless.
1856                              $patch->length2 += mb_strlen($diff_text);
1857                              $start2 += mb_strlen($diff_text);
1858                              array_push($patch->diffs, array_shift($bigpatch->diffs) );
1859                              $empty = false;
1860                          } else
1861                              if ($diff_type === DIFF_DELETE && count($patch->diffs) == 1 && $patch->diffs[0][0] == DIFF_EQUAL && (mb_strlen($diff_text) > 2 * $patch_size) ) {
1862                                  // This is a large deletion.  Let it pass in one chunk.
1863                                  $patch->length1 += mb_strlen($diff_text);
1864                                  $start1 += mb_strlen($diff_text);
1865                                  $empty = false;
1866                                  array_push( $patch->diffs, array($diff_type, $diff_text) );
1867                                  array_shift($bigpatch->diffs);
1868                              } else {
1869                                  // Deletion or equality.  Only take as much as we can stomach.
1870                                  $diff_text = mb_substr($diff_text, 0, $patch_size - $patch->length1 - $this->Patch_Margin);
1871                                  $patch->length1 += mb_strlen($diff_text);
1872                                  $start1 += mb_strlen($diff_text);
1873                                  if ($diff_type === DIFF_EQUAL) {
1874                                      $patch->length2 += mb_strlen($diff_text);
1875                                      $start2 += mb_strlen($diff_text);
1876                                  } else {
1877                                      $empty = false;
1878                                  }
1879                                  array_push($patch->diffs, array($diff_type, $diff_text) );
1880                                  if ($diff_text == $bigpatch->diffs[0][1]) {
1881                                      array_shift($bigpatch->diffs);
1882                                  } else {
1883                                      $bigpatch->diffs[0][1] = mb_substr( $bigpatch->diffs[0][1],mb_strlen($diff_text) );
1884                                  }
1885                              }
1886                      }
1887                      // Compute the head context for the next patch.
1888                      $precontext = $this->diff_text2($patch->diffs);
1889                      $precontext = mb_substr($precontext, mb_strlen($precontext)-$this->Patch_Margin);
1890                      // Append the end context for this patch.
1891                      $postcontext = mb_substr( $this->diff_text1($bigpatch->diffs), 0, $this->Patch_Margin );
1892                      if ($postcontext !== '') {
1893                          $patch->length1 += mb_strlen($postcontext);
1894                          $patch->length2 += mb_strlen($postcontext);
1895                          if ( count($patch->diffs) !== 0 && $patch->diffs[ count($patch->diffs) - 1][0] === DIFF_EQUAL) {
1896                              $patch->diffs[ count($patch->diffs) - 1][1] .= $postcontext;
1897                          } else {
1898                              array_push($patch->diffs, array(DIFF_EQUAL, $postcontext));
1899                          }
1900                      }
1901                      if (!$empty) {
1902                          array_splice($patches, ++$x, 0, array($patch));
1903                      }
1904                  }
1905              }
1906          }
1907      }
1908  
1909      /**
1910       * Take a list of patches and return a textual representation.
1911       * @param {Array.<patch_obj>} patches Array of patch objects.
1912       * @return {string} Text representation of patches.
1913       */
1914  	function patch_toText($patches) {
1915          $text = array();
1916          for ($x = 0; $x < count($patches) ; $x++) {
1917              $text[$x] = $patches[$x];
1918          }
1919          return implode('',$text);
1920      }
1921  
1922      /**
1923       * Parse a textual representation of patches and return a list of patch objects.
1924       * @param {string} textline Text representation of patches.
1925       * @return {Array.<patch_obj>} Array of patch objects.
1926       * @throws {Error} If invalid input.
1927       */
1928  	function patch_fromText($textline) {
1929          $patches = array();
1930          if ($textline === '') {
1931              return $patches;
1932          }
1933          $text = explode("\n",$textline);
1934          foreach($text as $i=>$t){ if($t===''){ unset($text[$i]); } }
1935          $textPointer = 0;
1936          while ($textPointer < count($text) ) {
1937              $m = null;
1938              preg_match('/^@@ -(\d+),?(\d*) \+(\d+),?(\d*) @@$/',$text[$textPointer],$m);
1939              if (!$m) {
1940                  echo_Exception('Invalid patch string: ' . $text[$textPointer]);
1941              }
1942              $patch = new patch_obj();
1943              array_push($patches, $patch);
1944              @$patch->start1 = (int)$m[1];
1945              if (@$m[2] === '') {
1946                  $patch->start1--;
1947                  $patch->length1 = 1;
1948              } elseif ( @$m[2] == '0') {
1949                  $patch->length1 = 0;
1950              } else {
1951                  $patch->start1--;
1952                  @$patch->length1 = (int)$m[2];
1953              }
1954  
1955              @$patch->start2 = (int)$m[3];
1956              if (@$m[4] === '') {
1957                  $patch->start2--;
1958                  $patch->length2 = 1;
1959              } elseif ( @$m[4] == '0') {
1960                  $patch->length2 = 0;
1961              } else {
1962                  $patch->start2--;
1963                  @$patch->length2 = (int)$m[4];
1964              }
1965              $textPointer++;
1966  
1967              while ($textPointer < count($text) ) {
1968                  $sign = $text[$textPointer][0];
1969                  try {
1970                      $line = decodeURI( mb_substr($text[$textPointer],1) );
1971                  } catch (Exception $ex) {
1972                      // Malformed URI sequence.
1973                      throw new Exception('Illegal escape in patch_fromText: ' . $line);
1974                  }
1975                  if ($sign == '-') {
1976                      // Deletion.
1977                      array_push( $patch->diffs, array(DIFF_DELETE, $line) );
1978                  } elseif ($sign == '+') {
1979                      // Insertion.
1980                      array_push($patch->diffs, array(DIFF_INSERT, $line) );
1981                  } elseif ($sign == ' ') {
1982                      // Minor equality.
1983                      array_push($patch->diffs, array(DIFF_EQUAL, $line) );
1984                  } elseif ($sign == '@') {
1985                      // Start of next patch.
1986                      break;
1987                  } elseif ($sign === '') {
1988                      // Blank line?  Whatever.
1989                  } else {
1990                      // WTF?
1991                      echo_Exception('Invalid patch mode "' . $sign . '" in: ' . $line);
1992                  }
1993                  $textPointer++;
1994              }
1995          }
1996          return $patches;
1997      }
1998  }
1999  
2000  /**
2001   * Class representing one patch operation.
2002   * @constructor
2003   */
2004  class patch_obj {
2005      /** @type {Array.<Array.<number|string>>} */
2006      public $diffs = array();
2007      /** @type {number?} */
2008      public $start1 = null;
2009      /** @type {number?} */
2010      public $start2 = null;
2011      /** @type {number} */
2012      public $length1 = 0;
2013      /** @type {number} */
2014      public $length2 = 0;
2015  
2016      /**
2017       * Emmulate GNU diff's format.
2018       * Header: @@ -382,8 +481,9 @@
2019       * Indicies are printed as 1-based, not 0-based.
2020       * @return {string} The GNU diff string.
2021       */
2022  	function toString() {
2023          if ($this->length1 === 0) {
2024              $coords1 = $this->start1 . ',0';
2025          } elseif ($this->length1 == 1) {
2026              $coords1 = $this->start1 + 1;
2027          } else {
2028              $coords1 = ($this->start1 + 1) . ',' . $this->length1;
2029          }
2030          if ($this->length2 === 0) {
2031              $coords2 = $this->start2 . ',0';
2032          } elseif ($this->length2 == 1) {
2033              $coords2 = $this->start2 + 1;
2034          } else {
2035              $coords2 = ($this->start2 + 1) . ',' . $this->length2;
2036          }
2037          $text = array ( '@@ -' . $coords1 . ' +' . $coords2 . " @@\n" );
2038  
2039          // Escape the body of the patch with %xx notation.
2040          for ($x = 0; $x < count($this->diffs); $x++) {
2041              switch ($this->diffs[$x][0]) {
2042                  case DIFF_INSERT :
2043                      $op = '+';
2044                      break;
2045                  case DIFF_DELETE :
2046                      $op = '-';
2047                      break;
2048                  case DIFF_EQUAL :
2049                      $op = ' ';
2050                      break;
2051              }
2052              $text[$x +1] = $op . encodeURI($this->diffs[$x][1]) . "\n";
2053          }
2054          return str_replace('%20', ' ', implode('',$text));
2055      }
2056  	function __toString(){
2057          return $this->toString();
2058      }
2059  }
2060  
2061  define('DIFF_DELETE', -1);
2062  define('DIFF_INSERT', 1);
2063  define('DIFF_EQUAL', 0);
2064  
2065  define('Match_MaxBits', PHP_INT_SIZE * 8);
2066  
2067  
2068  function charCodeAt($str, $pos) {
2069      return mb_ord(mb_substr($str, $pos, 1));
2070  }
2071  function mb_ord($v) {
2072      $k = mb_convert_encoding($v, 'UCS-2LE', 'UTF-8'); 
2073      $k1 = ord(substr($k, 0, 1)); 
2074      $k2 = ord(substr($k, 1, 1)); 
2075      return $k2 * 256 + $k1; 
2076  }
2077  function mb_chr($num){
2078      return mb_convert_encoding('&#'.intval($num).';', 'UTF-8', 'HTML-ENTITIES');
2079  }
2080  
2081  /**
2082   * as in javascript encodeURI() following the MDN description
2083   *
2084   * @link https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/encodeURI
2085   * @param $url
2086   * @return string
2087   */
2088  function encodeURI($url) {
2089      return strtr(rawurlencode($url), array (
2090          '%3B' => ';', '%2C' => ',', '%2F' => '/', '%3F' => '?', '%3A' => ':', '%40' => '@', '%26' => '&', '%3D' => '=',
2091          '%2B' => '+', '%24' => '$', '%21' => '!', '%2A' => '*', '%27' => '\'', '%28' => '(', '%29' => ')', '%23' => '#',
2092      ));
2093  }
2094  
2095  function decodeURI($encoded) {
2096      static $dontDecode;
2097      if (!$dontDecode) {
2098          $table = array (
2099              '%3B' => ';', '%2C' => ',', '%2F' => '/', '%3F' => '?', '%3A' => ':', '%40' => '@', '%26' => '&', '%3D' => '=',
2100              '%2B' => '+', '%24' => '$', '%21' => '!', '%2A' => '*', '%27' => '\'', '%28' => '(', '%29' => ')', '%23' => '#',
2101          );
2102          $dontDecode = array();
2103          foreach ($table as $k => $v) {
2104              $dontDecode[$k] = encodeURI($k);
2105          }
2106      }
2107      return rawurldecode(strtr($encoded, $dontDecode));
2108  }
2109  
2110  function echo_Exception($str){
2111      global $lastException;
2112      $lastException = $str;
2113      echo $str;
2114  }
2115  //mb_internal_encoding("UTF-8");
2116  
2117  ?>