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jspacker.inc in Advanced CSS/JS Aggregation 8.2

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  1. 8.4 advagg_js_minify/jspacker.inc
  2. 8.3 advagg_js_minify/jspacker.inc

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advagg_js_minify/jspacker.inc
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<?php

// @codingStandardsIgnoreFile
// @ignore comment_docblock_file:file
// @ignore style_curly_braces:file
// @ignore style_string_spacing:file
// @ignore style_else_spacing:file
// @ignore comment_comment_docblock_missing:file
// @ignore comment_comment_eg:file
// @ignore production_code:file
// @ignore druplart_unary:file
// @ignore style_uppercase_constants:file
// @ignore comment_comment_space:file
// @ignore druplart_conditional_assignment:file
// @ignore style_paren_spacing:file
// @ignore style_no_tabs:file
// @ignore :file

/* 9 April 2008. version 1.1
 *
 * This is the php version of the Dean Edwards JavaScript's Packer,
 * Based on :
 *
 * ParseMaster, version 1.0.2 (2005-08-19) Copyright 2005, Dean Edwards
 * a multi-pattern parser.
 * KNOWN BUG: erroneous behavior when using escapeChar with a replacement
 * value that is a function
 *
 * packer, version 2.0.2 (2005-08-19) Copyright 2004-2005, Dean Edwards
 *
 * License: http://creativecommons.org/licenses/LGPL/2.1/
 *
 * Ported to PHP by Nicolas Martin.
 *
 * ----------------------------------------------------------------------
 * changelog:
 * 1.1 : correct a bug, '\0' packed then unpacked becomes '\'.
 * ----------------------------------------------------------------------
 *
 * examples of usage :
 * $myPacker = new JavaScriptPacker($script, 62, true, false);
 * $packed = $myPacker->pack();
 *
 * or
 *
 * $myPacker = new JavaScriptPacker($script, 'Normal', true, false);
 * $packed = $myPacker->pack();
 *
 * or (default values)
 *
 * $myPacker = new JavaScriptPacker($script);
 * $packed = $myPacker->pack();
 *
 *
 * params of the constructor :
 * $script:       the JavaScript to pack, string.
 * $encoding:     level of encoding, int or string :
 *                0,10,62,95 or 'None', 'Numeric', 'Normal', 'High ASCII'.
 *                default: 62.
 * $fastDecode:   include the fast decoder in the packed result, boolean.
 *                default : true.
 * $specialChars: if you are flagged your private and local variables
 *                in the script, boolean.
 *                default: false.
 *
 * The pack() method return the compressed JavasScript, as a string.
 *
 * see http://dean.edwards.name/packer/usage/ for more information.
 *
 * Notes :
 * # need PHP 5 . Tested with PHP 5.1.2, 5.1.3, 5.1.4, 5.2.3
 *
 * # The packed result may be different than with the Dean Edwards
 *   version, but with the same length. The reason is that the PHP
 *   function usort to sort array don't necessarily preserve the
 *   original order of two equal member. The Javascript sort function
 *   in fact preserve this order (but that's not require by the
 *   ECMAScript standard). So the encoded keywords order can be
 *   different in the two results.
 *
 * # Be careful with the 'High ASCII' Level encoding if you use
 *   UTF-8 in your files...
 */
class JavaScriptPacker {

  // constants
  const IGNORE = '$1';

  // validate parameters
  private $_script = '';
  private $_encoding = 62;
  private $_fastDecode = true;
  private $_specialChars = false;
  private $LITERAL_ENCODING = array(
    'None' => 0,
    'Numeric' => 10,
    'Normal' => 62,
    'High ASCII' => 95,
  );
  public function __construct($_script, $_encoding = 62, $_fastDecode = true, $_specialChars = false) {
    $this->_script = $_script . "\n";
    if (array_key_exists($_encoding, $this->LITERAL_ENCODING)) {
      $_encoding = $this->LITERAL_ENCODING[$_encoding];
    }
    $this->_encoding = min((int) $_encoding, 95);
    $this->_fastDecode = $_fastDecode;
    $this->_specialChars = $_specialChars;
  }
  public function pack() {
    $this
      ->_addParser('_basicCompression');
    if ($this->_specialChars) {
      $this
        ->_addParser('_encodeSpecialChars');
    }
    if ($this->_encoding) {
      $this
        ->_addParser('_encodeKeywords');
    }

    // go!
    return $this
      ->_pack($this->_script);
  }

  // apply all parsing routines
  private function _pack($script) {
    for ($i = 0; isset($this->_parsers[$i]); $i++) {
      $script = call_user_func(array(
        &$this,
        $this->_parsers[$i],
      ), $script);
    }
    return $script;
  }

  // keep a list of parsing functions, they'll be executed all at once
  private $_parsers = array();
  private function _addParser($parser) {
    $this->_parsers[] = $parser;
  }

  // zero encoding - just removal of white space and comments
  private function _basicCompression($script) {
    $parser = new ParseMaster();

    // make safe
    $parser->escapeChar = '\\';

    // protect strings
    $parser
      ->add('/\'[^\'\\n\\r]*\'/', self::IGNORE);
    $parser
      ->add('/"[^"\\n\\r]*"/', self::IGNORE);

    // remove comments
    $parser
      ->add('/\\/\\/[^\\n\\r]*[\\n\\r]/', ' ');
    $parser
      ->add('/\\/\\*[^*]*\\*+([^\\/][^*]*\\*+)*\\//', ' ');

    // protect regular expressions
    $parser
      ->add('/\\s+(\\/[^\\/\\n\\r\\*][^\\/\\n\\r]*\\/g?i?)/', '$2');

    // IGNORE
    $parser
      ->add('/[^\\w\\x24\\/\'"*)\\?:]\\/[^\\/\\n\\r\\*][^\\/\\n\\r]*\\/g?i?/', self::IGNORE);

    // remove: ;;; doSomething();
    if ($this->_specialChars) {
      $parser
        ->add('/;;;[^\\n\\r]+[\\n\\r]/');
    }

    // remove redundant semi-colons
    $parser
      ->add('/\\(;;\\)/', self::IGNORE);

    // protect for (;;) loops
    $parser
      ->add('/;+\\s*([};])/', '$2');

    // apply the above
    $script = $parser
      ->exec($script);

    // remove white-space
    $parser
      ->add('/(\\b|\\x24)\\s+(\\b|\\x24)/', '$2 $3');
    $parser
      ->add('/([+\\-])\\s+([+\\-])/', '$2 $3');
    $parser
      ->add('/\\s+/', '');

    // done
    return $parser
      ->exec($script);
  }
  private function _encodeSpecialChars($script) {
    $parser = new ParseMaster();

    // replace: $name -> n, $$name -> na
    $parser
      ->add('/((\\x24+)([a-zA-Z$_]+))(\\d*)/', array(
      'fn' => '_replace_name',
    ));

    // replace: _name -> _0, double-underscore (__name) is ignored
    $regexp = '/\\b_[A-Za-z\\d]\\w*/';

    // build the word list
    $keywords = $this
      ->_analyze($script, $regexp, '_encodePrivate');

    // quick ref
    $encoded = $keywords['encoded'];
    $parser
      ->add($regexp, array(
      'fn' => '_replace_encoded',
      'data' => $encoded,
    ));
    return $parser
      ->exec($script);
  }
  private function _encodeKeywords($script) {

    // escape high-ascii values already in the script (i.e. in strings)
    if ($this->_encoding > 62) {
      $script = $this
        ->_escape95($script);
    }

    // create the parser
    $parser = new ParseMaster();
    $encode = $this
      ->_getEncoder($this->_encoding);

    // for high-ascii, don't encode single character low-ascii
    $regexp = $this->_encoding > 62 ? '/\\w\\w+/' : '/\\w+/';

    // build the word list
    $keywords = $this
      ->_analyze($script, $regexp, $encode);
    $encoded = $keywords['encoded'];

    // encode
    $parser
      ->add($regexp, array(
      'fn' => '_replace_encoded',
      'data' => $encoded,
    ));
    if (empty($script)) {
      return $script;
    }
    else {

      //$res = $parser->exec($script);

      //$res = $this->_bootStrap($res, $keywords);

      //return $res;
      return $this
        ->_bootStrap($parser
        ->exec($script), $keywords);
    }
  }
  private function _analyze($script, $regexp, $encode) {

    // analyse
    // retrieve all words in the script
    $all = array();
    preg_match_all($regexp, $script, $all);
    $_sorted = array();

    // list of words sorted by frequency
    $_encoded = array();

    // dictionary of word->encoding
    $_protected = array();

    // instances of "protected" words
    $all = $all[0];

    // simulate the javascript comportement of global match
    if (!empty($all)) {
      $unsorted = array();

      // same list, not sorted
      $protected = array();

      // "protected" words (dictionary of word->"word")
      $value = array();

      // dictionary of charCode->encoding (eg. 256->ff)
      $this->_count = array();

      // word->count
      $i = count($all);
      $j = 0;

      //$word = null;

      // count the occurrences - used for sorting later
      do {
        --$i;
        $word = '$' . $all[$i];
        if (!isset($this->_count[$word])) {
          $this->_count[$word] = 0;
          $unsorted[$j] = $word;

          // make a dictionary of all of the protected words in this script
          //  these are words that might be mistaken for encoding

          //if (is_string($encode) && method_exists($this, $encode))
          $values[$j] = call_user_func(array(
            &$this,
            $encode,
          ), $j);
          $protected['$' . $values[$j]] = $j++;
        }

        // increment the word counter
        $this->_count[$word]++;
      } while ($i > 0);

      // prepare to sort the word list, first we must protect
      //  words that are also used as codes. we assign them a code
      //  equivalent to the word itself.
      // e.g. if "do" falls within our encoding range
      //      then we store keywords["do"] = "do";
      // this avoids problems when decoding
      $i = count($unsorted);
      do {
        $word = $unsorted[--$i];
        if (isset($protected[$word])) {
          $_sorted[$protected[$word]] = substr($word, 1);
          $_protected[$protected[$word]] = true;
          $this->_count[$word] = 0;
        }
      } while ($i);

      // sort the words by frequency
      // Note: the javascript and php version of sort can be different :
      // in php manual, usort :
      // " If two members compare as equal,
      // their order in the sorted array is undefined."
      // so the final packed script is different of the Dean's javascript version
      // but equivalent.
      // the ECMAscript standard does not guarantee this behaviour,
      // and thus not all browsers (e.g. Mozilla versions dating back to at
      // least 2003) respect this.
      usort($unsorted, array(
        &$this,
        '_sortWords',
      ));
      $j = 0;

      // because there are "protected" words in the list
      //  we must add the sorted words around them
      do {
        if (!isset($_sorted[$i])) {
          $_sorted[$i] = substr($unsorted[$j++], 1);
        }
        $_encoded[$_sorted[$i]] = $values[$i];
      } while (++$i < count($unsorted));
    }
    return array(
      'sorted' => $_sorted,
      'encoded' => $_encoded,
      'protected' => $_protected,
    );
  }
  private $_count = array();
  private function _sortWords($match1, $match2) {
    return $this->_count[$match2] - $this->_count[$match1];
  }

  // build the boot function used for loading and decoding
  private function _bootStrap($packed, $keywords) {
    $ENCODE = $this
      ->_safeRegExp('$encode\\($count\\)');

    // $packed: the packed script
    $packed = "'" . $this
      ->_escape($packed) . "'";

    // $ascii: base for encoding
    $ascii = min(count($keywords['sorted']), $this->_encoding);
    if ($ascii == 0) {
      $ascii = 1;
    }

    // $count: number of words contained in the script
    $count = count($keywords['sorted']);

    // $keywords: list of words contained in the script
    foreach ($keywords['protected'] as $i => $value) {
      $keywords['sorted'][$i] = '';
    }

    // convert from a string to an array
    ksort($keywords['sorted']);
    $keywords = "'" . implode('|', $keywords['sorted']) . "'.split('|')";
    $encode = $this->_encoding > 62 ? '_encode95' : $this
      ->_getEncoder($ascii);
    $encode = $this
      ->_getJSFunction($encode);
    $encode = preg_replace('/_encoding/', '$ascii', $encode);
    $encode = preg_replace('/arguments\\.callee/', '$encode', $encode);
    $inline = '\\$count' . ($ascii > 10 ? '.toString(\\$ascii)' : '');

    // $decode: code snippet to speed up decoding
    if ($this->_fastDecode) {

      // create the decoder
      $decode = $this
        ->_getJSFunction('_decodeBody');
      if ($this->_encoding > 62) {
        $decode = preg_replace('/\\\\w/', '[\\xa1-\\xff]', $decode);
      }
      elseif ($ascii < 36) {
        $decode = preg_replace($ENCODE, $inline, $decode);
      }

      // special case: when $count==0 there are no keywords. I want to keep
      //  the basic shape of the unpacking funcion so i'll frig the code...
      if ($count == 0) {
        $decode = preg_replace($this
          ->_safeRegExp('($count)\\s*=\\s*1'), '$1=0', $decode, 1);
      }
    }

    // boot function
    $unpack = $this
      ->_getJSFunction('_unpack');
    if ($this->_fastDecode) {

      // insert the decoder
      $this->buffer = $decode;
      $unpack = preg_replace_callback('/\\{/', array(
        &$this,
        '_insertFastDecode',
      ), $unpack, 1);
    }
    $unpack = preg_replace('/"/', "'", $unpack);
    if ($this->_encoding > 62) {

      // high-ascii
      // get rid of the word-boundaries for regexp matches
      $unpack = preg_replace('/\'\\\\\\\\b\'\\s*\\+|\\+\\s*\'\\\\\\\\b\'/', '', $unpack);
    }
    if ($ascii > 36 || $this->_encoding > 62 || $this->_fastDecode) {

      // insert the encode function
      $this->buffer = $encode;
      $unpack = preg_replace_callback('/\\{/', array(
        &$this,
        '_insertFastEncode',
      ), $unpack, 1);
    }
    else {

      // perform the encoding inline
      $unpack = preg_replace($ENCODE, $inline, $unpack);
    }

    // pack the boot function too
    $unpackPacker = new JavaScriptPacker($unpack, 0, false, true);
    $unpack = $unpackPacker
      ->pack();

    // arguments
    $params = array(
      $packed,
      $ascii,
      $count,
      $keywords,
    );
    if ($this->_fastDecode) {
      $params[] = 0;
      $params[] = '{}';
    }
    $params = implode(',', $params);

    // the whole thing
    return 'eval(' . $unpack . '(' . $params . "))\n";
  }
  private $buffer;
  private function _insertFastDecode($match) {
    return '{' . $this->buffer . ';';
  }
  private function _insertFastEncode($match) {
    return '{$encode=' . $this->buffer . ';';
  }

  // mmm.. ..which one do i need ??
  private function _getEncoder($ascii) {
    return $ascii > 10 ? $ascii > 36 ? $ascii > 62 ? '_encode95' : '_encode62' : '_encode36' : '_encode10';
  }

  // zero encoding
  // characters: 0123456789
  private function _encode10($charCode) {
    return $charCode;
  }

  // inherent base36 support
  // characters: 0123456789abcdefghijklmnopqrstuvwxyz
  private function _encode36($charCode) {
    return base_convert($charCode, 10, 36);
  }

  // hitch a ride on base36 and add the upper case alpha characters
  // characters: 0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ
  private function _encode62($charCode) {
    $res = '';
    if ($charCode >= $this->_encoding) {
      $res = $this
        ->_encode62((int) ($charCode / $this->_encoding));
    }
    $charCode = $charCode % $this->_encoding;
    if ($charCode > 35) {
      return $res . chr($charCode + 29);
    }
    else {
      return $res . base_convert($charCode, 10, 36);
    }
  }

  // use high-ascii values
  // characters: ¡¢£¤¥¦§¨©ª«¬­®¯°±²³´µ¶·¸¹º»¼½¾¿ÀÁÂÃÄÅÆÇÈÉÊËÌÍÎÏÐÑÒÓÔÕÖ×ØÙÚÛÜÝÞßàáâãäåæçèéêëìíîïðñòóôõö÷øùúûüýþ
  private function _encode95($charCode) {
    $res = '';
    if ($charCode >= $this->_encoding) {
      $res = $this
        ->_encode95($charCode / $this->_encoding);
    }
    return $res . chr($charCode % $this->_encoding + 161);
  }
  private function _safeRegExp($string) {
    return '/' . preg_replace('/\\$/', '\\\\$', $string) . '/';
  }
  private function _encodePrivate($charCode) {
    return "_" . $charCode;
  }

  // protect characters used by the parser
  private function _escape($script) {
    return preg_replace('/([\\\\\'])/', '\\\\$1', $script);
  }

  // protect high-ascii characters already in the script
  private function _escape95($script) {
    return preg_replace_callback('/[\\xa1-\\xff]/', array(
      &$this,
      '_escape95Bis',
    ), $script);
  }
  private function _escape95Bis($match) {
    return '\\x' . (string) dechex(ord($match));
  }
  private function _getJSFunction($aName) {
    if (defined('self::JSFUNCTION' . $aName)) {
      return constant('self::JSFUNCTION' . $aName);
    }
    else {
      return '';
    }
  }

  // JavaScript Functions used.
  // Note : In Dean's version, these functions are converted
  // with 'String(aFunctionName);'.
  // This internal conversion complete the original code, ex :
  // 'while (aBool) anAction();' is converted to
  // 'while (aBool) { anAction(); }'.
  // The JavaScript functions below are corrected.
  // unpacking function - this is the boot strap function
  //  data extracted from this packing routine is passed to
  //  this function when decoded in the target
  // NOTE ! : without the ';' final.
  const JSFUNCTION_unpack = 'function($packed, $ascii, $count, $keywords, $encode, $decode) {
    while ($count--) {
        if ($keywords[$count]) {
            $packed = $packed.replace(new RegExp(\'\\\\b\' + $encode($count) + \'\\\\b\', \'g\'), $keywords[$count]);
        }
    }
    return $packed;
}';

  /*
  'function($packed, $ascii, $count, $keywords, $encode, $decode) {
  while ($count--)
  if ($keywords[$count])
  $packed = $packed.replace(new RegExp(\'\\\\b\' + $encode($count) + \'\\\\b\', \'g\'), $keywords[$count]);
  return $packed;
  }';
  */

  // code-snippet inserted into the unpacker to speed up decoding
  const JSFUNCTION_decodeBody = '    if (!\'\'.replace(/^/, String)) {
        // decode all the values we need
        while ($count--) {
            $decode[$encode($count)] = $keywords[$count] || $encode($count);
        }
        // global replacement function
        $keywords = [function ($encoded) {return $decode[$encoded]}];
        // generic match
        $encode = function () {return \'\\\\w+\'};
        // reset the loop counter -  we are now doing a global replace
        $count = 1;
    }
';

  //};

  /*
  '	if (!\'\'.replace(/^/, String)) {
  // decode all the values we need
  while ($count--) $decode[$encode($count)] = $keywords[$count] || $encode($count);
  // global replacement function
  $keywords = [function ($encoded) {return $decode[$encoded]}];
  // generic match
  $encode = function () {return\'\\\\w+\'};
  // reset the loop counter -  we are now doing a global replace
  $count = 1;
  }';
  */

  // zero encoding
  // characters: 0123456789
  const JSFUNCTION_encode10 = 'function($charCode) {
    return $charCode;
}';

  //;';

  // inherent base36 support
  // characters: 0123456789abcdefghijklmnopqrstuvwxyz
  const JSFUNCTION_encode36 = 'function($charCode) {
    return $charCode.toString(36);
}';

  //;';

  // hitch a ride on base36 and add the upper case alpha characters
  // characters: 0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ
  const JSFUNCTION_encode62 = 'function($charCode) {
    return ($charCode < _encoding ? \'\' : arguments.callee(parseInt($charCode / _encoding))) +
    (($charCode = $charCode % _encoding) > 35 ? String.fromCharCode($charCode + 29) : $charCode.toString(36));
}';

  // use high-ascii values
  // characters: ¡¢£¤¥¦§¨©ª«¬­®¯°±²³´µ¶·¸¹º»¼½¾¿ÀÁÂÃÄÅÆÇÈÉÊËÌÍÎÏÐÑÒÓÔÕÖ×ØÙÚÛÜÝÞßàáâãäåæçèéêëìíîïðñòóôõö÷øùúûüýþ
  const JSFUNCTION_encode95 = 'function($charCode) {
    return ($charCode < _encoding ? \'\' : arguments.callee($charCode / _encoding)) +
        String.fromCharCode($charCode % _encoding + 161);
}';

}
class ParseMaster {
  public $ignoreCase = false;
  public $escapeChar = '';

  // constants
  const EXPRESSION = 0;
  const REPLACEMENT = 1;
  const LENGTH = 2;

  // used to determine nesting levels
  private $GROUPS = '/\\(/';

  //g
  private $SUB_REPLACE = '/\\$\\d/';
  private $INDEXED = '/^\\$\\d+$/';
  private $TRIM = '/([\'"])\\1\\.(.*)\\.\\1\\1$/';
  private $ESCAPE = '/\\\\./';

  //g
  private $QUOTE = '/\'/';
  private $DELETED = '/\\x01[^\\x01]*\\x01/';

  //g
  public function add($expression, $replacement = '') {

    // count the number of sub-expressions
    //  - add one because each pattern is itself a sub-expression
    $length = 1 + preg_match_all($this->GROUPS, $this
      ->_internalEscape((string) $expression), $out);

    // treat only strings $replacement
    if (is_string($replacement)) {

      // does the pattern deal with sub-expressions?
      if (preg_match($this->SUB_REPLACE, $replacement)) {

        // a simple lookup? (e.g. "$2")
        if (preg_match($this->INDEXED, $replacement)) {

          // store the index (used for fast retrieval of matched strings)
          $replacement = (int) substr($replacement, 1) - 1;
        }
        else {

          // a complicated lookup (e.g. "Hello $2 $1")
          // build a function to do the lookup
          $quote = preg_match($this->QUOTE, $this
            ->_internalEscape($replacement)) ? '"' : "'";
          $replacement = array(
            'fn' => '_backReferences',
            'data' => array(
              'replacement' => $replacement,
              'length' => $length,
              'quote' => $quote,
            ),
          );
        }
      }
    }

    // pass the modified arguments
    if (!empty($expression)) {
      $this
        ->_add($expression, $replacement, $length);
    }
    else {
      $this
        ->_add('/^$/', $replacement, $length);
    }
  }
  public function exec($string) {

    // execute the global replacement
    $this->_escaped = array();

    // simulate the _patterns.toSTring of Dean
    $regexp = '/';
    foreach ($this->_patterns as $reg) {
      $regexp .= '(' . substr($reg[self::EXPRESSION], 1, -1) . ')|';
    }
    $regexp = substr($regexp, 0, -1) . '/';
    $regexp .= $this->ignoreCase ? 'i' : '';
    $string = $this
      ->_escape($string, $this->escapeChar);
    $string = preg_replace_callback($regexp, array(
      &$this,
      '_replacement',
    ), $string);
    $string = $this
      ->_unescape($string, $this->escapeChar);
    return preg_replace($this->DELETED, '', $string);
  }
  public function reset() {

    // clear the patterns collection so that this object may be re-used
    $this->_patterns = array();
  }

  // private
  private $_escaped = array();

  // escaped characters
  private $_patterns = array();

  // patterns stored by index
  // create and add a new pattern to the patterns collection
  private function _add() {
    $arguments = func_get_args();
    $this->_patterns[] = $arguments;
  }

  // this is the global replace function (it's quite complicated)
  private function _replacement($arguments) {
    if (empty($arguments)) {
      return '';
    }
    $i = 1;
    $j = 0;

    // loop through the patterns
    while (isset($this->_patterns[$j])) {
      $pattern = $this->_patterns[$j++];

      // do we have a result?
      if (isset($arguments[$i]) && $arguments[$i] != '') {
        $replacement = $pattern[self::REPLACEMENT];
        if (is_array($replacement) && isset($replacement['fn'])) {
          if (isset($replacement['data'])) {
            $this->buffer = $replacement['data'];
          }
          return call_user_func(array(
            &$this,
            $replacement['fn'],
          ), $arguments, $i);
        }
        elseif (is_int($replacement)) {
          return $arguments[$replacement + $i];
        }
        $delete = $this->escapeChar == '' || strpos($arguments[$i], $this->escapeChar) === false ? '' : "\1" . $arguments[$i] . "\1";
        return $delete . $replacement;

        // skip over references to sub-expressions
      }
      else {
        $i += $pattern[self::LENGTH];
      }
    }
  }
  private function _backReferences($match, $offset) {
    $replacement = $this->buffer['replacement'];
    $quote = $this->buffer['quote'];
    $i = $this->buffer['length'];
    while ($i) {
      $replacement = str_replace('$' . $i--, $match[$offset + $i], $replacement);
    }
    return $replacement;
  }
  private function _replace_name($match, $offset) {
    $length = strlen($match[$offset + 2]);
    $start = $length - max($length - strlen($match[$offset + 3]), 0);
    return substr($match[$offset + 1], $start, $length) . $match[$offset + 4];
  }
  private function _replace_encoded($match, $offset) {
    return $this->buffer[$match[$offset]];
  }

  // php : we cannot pass additional data to preg_replace_callback,
  // and we cannot use &$this in create_function, so let's go to lower level
  private $buffer;

  // encode escaped characters
  private function _escape($string, $escapeChar) {
    if ($escapeChar) {
      $this->buffer = $escapeChar;
      return preg_replace_callback('/\\' . $escapeChar . '(.)' . '/', array(
        &$this,
        '_escapeBis',
      ), $string);
    }
    else {
      return $string;
    }
  }
  private function _escapeBis($match) {
    $this->_escaped[] = $match[1];
    return $this->buffer;
  }

  // decode escaped characters
  private function _unescape($string, $escapeChar) {
    if ($escapeChar) {
      $regexp = '/' . '\\' . $escapeChar . '/';
      $this->buffer = array(
        'escapeChar' => $escapeChar,
        'i' => 0,
      );
      return preg_replace_callback($regexp, array(
        &$this,
        '_unescapeBis',
      ), $string);
    }
    else {
      return $string;
    }
  }
  private function _unescapeBis() {
    if (isset($this->_escaped[$this->buffer['i']]) && $this->_escaped[$this->buffer['i']] != '') {
      $temp = $this->_escaped[$this->buffer['i']];
    }
    else {
      $temp = '';
    }
    $this->buffer['i']++;
    return $this->buffer['escapeChar'] . $temp;
  }
  private function _internalEscape($string) {
    return preg_replace($this->ESCAPE, '', $string);
  }

}

Classes