PHP Function to Strip JavaScript White Space and Comments

<?php
/* 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
		// retreive 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]) /*!= null*/) {
					$_sorted[$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]', $decode);
			// perform the encoding inline for lower ascii values
			elseif ($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¿ìÁÃÒÃÃ&à Ã!ÃÆÃ0Ã`Ã9ÃRÍÃ}ÏÐÃÃÃÃÃ"ÃÃÃÜÃ"ÃaÃ:ÃSÝÃ~Ãxàáâãäåæçèéêëìíîïðñòóôõö÷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 =
//_decode = function() {
// does the browser support String.replace where the
//  replacement value is a function?
 
'    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¿ìÁÃÒÃÃ&à Ã!ÃÆÃ0Ã`Ã9ÃRÍÃ}ÏÐÃÃÃÃÃ"ÃÃÃÜÃ"ÃaÃ:ÃSÝÃ~Ãxàáâãäåæçèéêëìíîïðñòóôõö÷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)
				        ? '' : "\x01" . $arguments[$i] . "\x01";
				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);
	}
}
?>