mediawiki-extensions-AbuseFilter/AbuseFilter.parser.php

<?php
if ( ! defined( 'MEDIAWIKI' ) )
	die();
/**
Abuse filter parser.
Copyright (C) Victor Vasiliev, 2008. Based on ideas by Andrew Garrett Distributed under GNU GPL v2 terms.

Types of token:
* T_NONE - special-purpose token
* T_BRACE  - ( or )
* T_COMMA - ,
* T_OP - operator like + or ^
* T_NUMBER - number
* T_STRING - string, in "" or ''
* T_KEYWORD - keyword
* T_ID - identifier

Levels of parsing:
* Conditionls (IF) - if-then-else-end, cond ? a :b
* BoolOps (BO) - &, |, ^
* CompOps (CO) - ==, !=, ===, !==, >, <, >=, <=
* SumRel (SR) - +, -
* MulRel (MR) - *, /, %
* Pow (P) - **
* BoolNeg (BN) - ! operation
* SpecialOperators (SO) - in and like
* Unarys (U) - plus and minus in cases like -5 or -(2 * +2)
* Braces (B) - ( and )
* Functions (F)
* Atom (A) - return value
*/

class AFPToken {
	//Types of tken
	const TNone = 'T_NONE';
	const TID = 'T_ID';
	const TKeyword = 'T_KEYWORD';
	const TString = 'T_STRING';
	const TInt = 'T_INT';
	const TFloat = 'T_FLOAT';
	const TOp = 'T_OP';
	const TBrace = 'T_BRACE';
	const TComma = 'T_COMMA';
	
	var $type;
	var $value;
	var $pos;
	
	public function __construct( $type = self::TNone, $value = null, $pos = 0 ) {
		$this->type = $type;
		$this->value = $value;
		$this->pos = $pos;
	}
}

class AFPData {
	//Datatypes
	const DInt = 'int';
	const DString = 'string';
	const DNull   = 'null';
	const DBool   = 'bool';
	const DFloat  = 'float';
	
	var $type;
	var $data;
	
	public function __construct( $type = self::DNull, $val = null ) {
		$this->type = $type;
		$this->data = $val;
	}
	
	public static function newFromPHPVar( $var ) {
		if( is_string( $var ) )
			return new AFPData( self::DString, $var );
		elseif( is_int( $var ) )
			return new AFPData( self::DInt, $var );
		elseif( is_float( $var ) )
			return new AFPData( self::DFloat, $var );
		elseif( is_bool( $var ) )
			return new AFPData( self::DBool, $var );
		elseif( is_null( $var ) )
			return new AFPData();
		else
			throw new AFPException(
				"Data type " . gettype( $var ) . " is not supported by AbuseFilter" );
	}
	
	public function dup() {
		return new AFPData( $this->type, $this->data );
	}
	
	public static function castTypes( $orig, $target ) {
		if( $orig->type == $target )
			return $orig->dup();
		if( $target == self::DNull ) {
			return new AFPData();
		}
		if( $target == self::DBool ) {
			return new AFPData( self::DBool, (bool)$orig->data );
		}
		if( $target == self::DFloat ) {
			return new AFPData( self::DFloat, doubleval( $orig->data ) );
		}
		if( $target == self::DInt ) {
			return new AFPData( self::DInt, intval( $orig->data ) );
		}
		if( $target == self::DString ) {
			return new AFPData( self::DString, strval( $orig->data ) );
		}
	}
	
	public static function boolInvert( $value ) {
		return new AFPData( self::DBool, !$value->toBool() );
	}
	
	public static function pow( $base, $exponent ) {
		return new AFPData( self::DFloat, pow( $base->toFloat(), $exponent->toFloat() ) );
	}
	
	public static function keywordIn( $a, $b ) {
		$a = $a->toString();
		$b = $b->toString();
		
		if ($a == '' || $b == '') {
			return new AFPData( self::DBool, false );
		}
		
		return new AFPData( self::DBool, in_string( $a, $b ) );
	}
	
	public static function keywordContains( $a, $b ) {
		$a = $a->toString();
		$b = $b->toString();
		
		if ($a == '' || $b == '') {
			return new AFPData( self::DBool, false );
		}
		
		return new AFPData( self::DBool, in_string( $b, $a ) );
	}
	
	public static function keywordLike( $str, $pattern ) {
		$str = $str->toString();
		$pattern = $pattern->toString();
		wfSuppressWarnings();
		$result = fnmatch( $pattern, $str );
		wfRestoreWarnings();
		return new AFPData( self::DBool, (bool)$result );
	}
	
	public static function keywordRegex( $str, $regex ) {
		$str = $str->toString();
		$pattern = $regex->toString();
		
		if (preg_match('/^\/.*\/$/u', $pattern)) {
			$pattern .= 'u';
		} elseif (preg_match( '/^\/.*\/\w+$/u', $pattern ) ) {
			# Nothing
		} else {
			$pattern = "/$pattern/u";
		}
		
		wfSuppressWarnings();
		$result = preg_match( $pattern, $str );
		wfRestoreWarnings();
		return new AFPData( self::DBool, (bool)$result );
	}
	
	public static function unaryMinus( $data ) {
		if ($data->type == self::DInt) {
			return new AFPData( $data->type, -$data->toInt() );
		} else {
			return new AFPData( $data->type, -$data->toFloat() );
		}
	}
	
	public static function boolOp( $a, $b, $op ) {
		$a = $a->toBool();
		$b = $b->toBool();
		if( $op == '|' )
			return new AFPData( self::DBool, $a || $b );
		if( $op == '&' )
			return new AFPData( self::DBool, $a && $b );
		if( $op == '^' )
			return new AFPData( self::DBool, $a xor $b );
		throw new AFPException( "Invalid boolean operation: {$op}" ); // Should never happen.
	}
	
	public static function compareOp( $a, $b, $op ) {
		if( $op == '==' || $op == '=' )
			return new AFPData( self::DBool, $a->toString() === $b->toString() );
		if( $op == '!=' )
			return new AFPData( self::DBool, $a->toString() !== $b->toString() );
		if( $op == '===' )
			return new AFPData( self::DBool, $a->data == $b->data && $a->type == $b->type );
		if( $op == '!==' )
			return new AFPData( self::DBool, $a->data !== $b->data || $a->type != $b->type );
		$a = $a->toString();
		$b = $b->toString();
		if( $op == '>' )
			return new AFPData( self::DBool, $a > $b );
		if( $op == '<' )
			return new AFPData( self::DBool, $a < $b );
		if( $op == '>=' )
			return new AFPData( self::DBool, $a >= $b );
		if( $op == '<=' )
			return new AFPData( self::DBool, $a <= $b );
		throw new AFPException( "Invalid comparison operation: {$op}" ); // Should never happen
	}
	
	public static function mulRel( $a, $b, $op, $pos ) {	
		// Figure out the type.
		if ($a->type == self::DFloat || $b->type == self::DFloat ||
			$a->toFloat() != $a->toString() || $b->toFloat() != $b->toString() ) {
			$type = self::DFloat;
			$a = $a->toFloat();
			$b = $b->toFloat();
		} else {
			$type = self::DInt;
			$a = $a->toInt();
			$b = $b->toInt();
		}

		if ($op != '*' && $b == 0) {
			throw new AFPUserVisibleException( 'dividebyzero', $pos, array($a) );
		}

		$data = null;
		if( $op == '*' )
			$data = $a * $b;
		elseif( $op == '/' )
			$data = $a / $b;
		elseif( $op == '%' )
			$data = $a % $b;
		else
			throw new AFPException( "Invalid multiplication-related operation: {$op}" ); // Should never happen
			
		if ($type == self::DInt)
			$data = intval($data);
		else
			$data = doubleval($data);
		
		return new AFPData( $type, $data );
	}
	
	public static function sum( $a, $b ) {
		if( $a->type == self::DString || $b->type == self::DString )
			return new AFPData( self::DFloat, $a->toString() . $b->toString() );
		else
			return new AFPData( self::DFloat, $a->toFloat() + $b->toFloat() );
	}
	
	public static function sub( $a, $b ) {
		return new AFPData( self::DFloat, $a->toFloat() - $b->toFloat() );
	}
	
	/** Convert shorteners */
	public function toBool() {
		return self::castTypes( $this, self::DBool )->data;
	}
	
	public function toString() {
		return self::castTypes( $this, self::DString )->data;
	}
	
	public function toFloat() {
		return self::castTypes( $this, self::DFloat )->data;
	}
	
	public function toInt() {
		return self::castTypes( $this, self::DInt )->data;
	}
}

class AFPException extends MWException {}

// Exceptions that we might conceivably want to report to ordinary users
// (i.e. exceptions that don't represent bugs in the extension itself)
class AFPUserVisibleException extends AFPException {
	function __construct( $exception_id, $position, $params) {
		$msg = wfMsgExt( 'abusefilter-exception-'.$exception_id, array(), array_merge( array($position), $params ) );
		parent::__construct( $msg );

		$this->mExceptionID = $exception_id;
		$this->mPosition = $position;
		$this->mParams = $params;
	}
}
	
class AbuseFilterParser {
	var $mParams, $mVars, $mCode, $mTokens, $mPos, $mCur;
	
	// length,lcase,ccnorm,rmdoubles,specialratio,rmspecials,norm,count
	static $mFunctions = array(
		'lcase' => 'funcLc',
		'length' => 'funcLen',
		'string' => 'castString',
		'int' => 'castInt',
		'float' => 'castFloat',
		'bool' => 'castBool',
		'norm' => 'funcNorm',
		'ccnorm' => 'funcCCNorm',
		'specialratio' => 'funcSpecialRatio',
		'rmspecials' => 'funcRMSpecials',
		'rmdoubles' => 'funcRMDoubles',
		'rmwhitespace' => 'funcRMWhitespace',
		'count' => 'funcCount',
		'rcount' => 'funcRCount',
		'ip_in_range' => 'funcIPInRange',
	);
	
	// Order is important. The punctuation-matching regex requires that
	//  ** comes before *, etc. They are sorted to make it easy to spot
	//  such errors.
	static $mOps = array(
	'!==', '!=', '!', 	// Inequality
	'**', '*', 			// Multiplication/exponentiation
	'/', '+', '-', '%', // Other arithmetic
	'&', '|', '^', 		// Logic
	'?', ':', 			// Ternery
	'<=','<', 			// Less than
	'>=', '>', 			// Greater than
	'===', '==', '=', 	// Equality
	);
	static $mKeywords = array(
	'in', 'like', 'true', 'false', 'null', 'contains', 'matches',
	'rlike', 'regex', 'if', 'then', 'else', 'end',
	);
	
	static $parserCache = array();
	
	static $funcCache = array();
	
	public function __construct() {
		$this->resetState();
	}
	
	public function resetState() {
		$this->mParams = array();
		$this->mCode = '';
		$this->mTokens = array();
		$this->mVars = new AbuseFilterVariableHolder;
		$this->mPos = 0;
	}
	
	public function checkSyntax( $filter ) {
		try {
			$this->parse($filter);
		} catch (AFPUserVisibleException $excep) {
			return array($excep->getMessage(), $excep->mPosition);
		}
		return true;
	}
	
	public function setVar( $name, $value ) {
		$name = strtolower($name);
		$this->mVars->setVar( $name, $value );
	}
	
	public function setVars( $vars ) {
		if ( is_array( $vars ) ) {
			foreach( $vars as $name => $var ) {
				$this->setVar( $name, $var );
			}
		} elseif ( $vars instanceof AbuseFilterVariableHolder ) {
			$this->mVars->addHolder( $vars );
		}
	}
	
	protected function move( ) {
		wfProfileIn( __METHOD__ );
		list( $val, $type, $code, $offset ) =
			self::nextToken( $this->mCode, $this->mPos );
		
		$token = new AFPToken( $type, $val, $this->mPos );
		$this->mPos = $offset;
		wfProfileOut( __METHOD__ );
		return $this->mCur = $token;
	}
	
	public function parse( $code ) {
		return $this->intEval( $code )->toBool();
	}
	
	public function evaluateExpression( $filter ) {
		return $this->intEval( $filter )->toString();
	}
	
	function intEval( $code ) {
		wfProfileIn( __METHOD__ );
		
		// Setup, resetting
		$this->mCode = $code;
		$this->mPos = 0;
		$this->mLen = strlen( $code );
		
		// Parse the first token
		$this->move();
		
		$result = new AFPData();
		$this->doLevelEntry( $result );
		wfProfileOut( __METHOD__ );
		return $result;
	}
	
	static function lengthCompare( $a, $b ) {
		if ( strlen($a) == strlen($b) ) {
			return 0;
		}
		
		return ( strlen($a) < strlen($b) ) ? -1 : 1;
	}
	
	/* Levels */
	
	/** Handles unexpected characters after the expression */
	protected function doLevelEntry( &$result ) {
		$this->doLevelSet( $result );
		if( $this->mCur->type != AFPToken::TNone ) {
			throw new AFPUserVisibleException( 'unexpectedatend', $this->mCur->pos, array($this->mCur->type) );
		}
	}
	
	/** Handles "=" operator */
	protected function doLevelSet( &$result ) {
		$this->doLevelConditions( $result );
	}

	protected function doLevelConditions( &$result ) {
		if( $this->mCur->type == AFPToken::TKeyword && $this->mCur->value == 'if' ) {
			$this->move();
			$this->doLevelBoolOps( $result );
			if( !($this->mCur->type == AFPToken::TKeyword && $this->mCur->value == 'then') )
				throw new AFPUserVisibleException( 'expectednotfound', $this->mCur->pos, array('then') );
			$this->move();
			$r1 = new AFPData();
			$r2 = new AFPData();
			$this->doLevelConditions( $r1 );
			if( !($this->mCur->type == AFPToken::TKeyword && $this->mCur->value == 'else') )
				throw new AFPUserVisibleException( 'expectednotfound', $this->mCur->pos, array('else') );
			$this->move();
			$this->doLevelConditions( $r2 );
			if( $result->toBool() ) {
				$result = $r1;
			} else {
				$result = $r2;
			}
			if( !($this->mCur->type == AFPToken::TKeyword && $this->mCur->value == 'end') )
				throw new AFPUserVisibleException( 'expectednotfound', $this->mCur->pos, array('end') );
			$this->move();
		} else {
			$this->doLevelBoolOps( $result );
			if( $this->mCur->type == AFPToken::TOp && $this->mCur->value == '?' ) {
				$this->move();
				$r1 = new AFPData();
				$r2 = new AFPData();
				$this->doLevelConditions( $r1 );
				if( !($this->mCur->type == AFPToken::TOp && $this->mCur->value == ':') )
					throw new AFPUserVisibleException( 'expectednotfound', $this->mCur->pos, array(':') );
				$this->move();
				$this->doLevelConditions( $r2 );
				if( $result->toBool() ) {
					$result = $r1;
				} else {
					$result = $r2;
				}
			}
		}
	}

	protected function doLevelBoolOps( &$result ) {
		$this->doLevelCompares( $result );
		$ops = array( '&', '|', '^' );
		while( $this->mCur->type == AFPToken::TOp && in_array( $this->mCur->value, $ops ) ) {
			$op = $this->mCur->value;
			$this->move();
			$r2 = new AFPData();
			$this->doLevelCompares( $r2 );
			wfProfileIn( __METHOD__ );
			$result = AFPData::boolOp( $result, $r2, $op );
			wfProfileOut( __METHOD__ );
		}
	}
	
	protected function doLevelCompares( &$result ) {
		AbuseFilter::triggerLimiter();
		$this->doLevelSumRels( $result );
		$ops = array( '==', '===', '!=', '!==', '<', '>', '<=', '>=', '=' );
		while( $this->mCur->type == AFPToken::TOp && in_array( $this->mCur->value, $ops ) ) {
			$op = $this->mCur->value;
			$this->move();
			$r2 = new AFPData();
			$this->doLevelSumRels( $r2 );
			wfProfileIn( __METHOD__ );
			$result = AFPData::compareOp( $result, $r2, $op );
			wfProfileOut( __METHOD__ );
		}
	}
	
	protected function doLevelSumRels( &$result ) {
		$this->doLevelMulRels( $result );
		wfProfileIn( __METHOD__ );
		$ops = array( '+', '-' );
		while( $this->mCur->type == AFPToken::TOp && in_array( $this->mCur->value, $ops ) ) {
			$op = $this->mCur->value;
			$this->move();
			$r2 = new AFPData();
			$this->doLevelMulRels( $r2 );
			if( $op == '+' )
				$result = AFPData::sum( $result, $r2 );
			if( $op == '-' )
				$result = AFPData::sub( $result, $r2 );
		}
		wfProfileOut( __METHOD__ );
	}

	protected function doLevelMulRels( &$result ) {
		$this->doLevelPow( $result );
		wfProfileIn( __METHOD__ );
		$ops = array( '*', '/', '%' );
		while( $this->mCur->type == AFPToken::TOp && in_array( $this->mCur->value, $ops ) ) {
			$op = $this->mCur->value;
			$this->move();
			$r2 = new AFPData();
			$this->doLevelPow( $r2 );
			$result = AFPData::mulRel( $result, $r2, $op, $this->mCur->pos );
		}
		wfProfileOut( __METHOD__ );
	}

	protected function doLevelPow( &$result ) {
		$this->doLevelBoolInvert( $result );
		wfProfileIn( __METHOD__ );
		while( $this->mCur->type == AFPToken::TOp && $this->mCur->value == '**' ) {
			$this->move();
			$expanent = new AFPData();
			$this->doLevelBoolInvert( $expanent );
			$result = AFPData::pow( $result, $expanent );
		}
		wfProfileOut( __METHOD__ );
	}
	
	protected function doLevelBoolInvert( &$result ) {
		if( $this->mCur->type == AFPToken::TOp && $this->mCur->value == '!' ) {
			$this->move();
			$this->doLevelSpecialWords( $result );
			wfProfileIn( __METHOD__ );
			$result = AFPData::boolInvert( $result );
			wfProfileOut( __METHOD__ );
		} else {
			$this->doLevelSpecialWords( $result );
		}
	}
	
	protected function doLevelSpecialWords( &$result ) {
		$this->doLevelUnarys( $result );
		$keyword = strtolower($this->mCur->value);
		$specwords = array( 'in' => 'keywordIn', 'like' => 'keywordLike', 'matches' => 'keywordLike', 'contains' => 'keywordContains', 'rlike' => 'keywordRegex', 'regex' => 'keywordRegex' );
		if( $this->mCur->type == AFPToken::TKeyword && in_array( $keyword, array_keys($specwords) ) ) {
			$func = $specwords[$keyword];
			$this->move();
			$r2 = new AFPData();
			$this->doLevelUnarys( $r2 );
			wfProfileIn( __METHOD__ );
			wfProfileIn( __METHOD__."-$func" );
			$result = AFPData::$func( $result, $r2 );
			wfProfileOut( __METHOD__."-$func" );
			wfProfileOut( __METHOD__ );
		}
	}
	
	protected function doLevelUnarys( &$result ) {
		$op = $this->mCur->value;
		if( $this->mCur->type == AFPToken::TOp && ( $op == "+" || $op == "-" ) ) {
			$this->move();
			$this->doLevelBraces( $result );
			wfProfileIn( __METHOD__ );
			if( $op == '-' ) {
				$result = AFPData::unaryMinus( $result );
			}
			wfProfileOut( __METHOD__ );
		} else {
			$this->doLevelBraces( $result );
		}
	}
	
	protected function doLevelBraces( &$result ) {
		if( $this->mCur->type == AFPToken::TBrace && $this->mCur->value == '(' ) {
			$this->move();
			$this->doLevelSet( $result );
			if( !($this->mCur->type == AFPToken::TBrace && $this->mCur->value == ')') )
				throw new AFPUserVisibleException( 'expectednotfound', $this->mCur->pos, array(')') );
			$this->move();
		} else {
			$this->doLevelFunction( $result );
		}
	}
	
	protected function doLevelFunction( &$result ) {
		if( $this->mCur->type == AFPToken::TID && isset( self::$mFunctions[$this->mCur->value] ) ) {
			wfProfileIn( __METHOD__ );
			$func = self::$mFunctions[$this->mCur->value];
			$this->move();
			if( $this->mCur->type != AFPToken::TBrace || $this->mCur->value != '(' )
				throw new AFPUserVisibleException( 'expectednotfound', $this->mCur->pos, array('(') );
			wfProfileIn( __METHOD__."-loadargs" );
			$args = array();
			do {
				$this->move();
				$r = new AFPData();
				$this->doLevelSet( $r );
				$args[] = $r;
			} while( $this->mCur->type == AFPToken::TComma );
			
			if( $this->mCur->type != AFPToken::TBrace || $this->mCur->value != ')' ) {
				throw new AFPUserVisibleException( 'expectednotfound', $this->mCur->pos, array(')') );
			}
			wfProfileOut( __METHOD__."-loadargs" );
			
			wfProfileIn( __METHOD__."-$func" );
			
			$funcHash = md5($func.serialize($args));
			
			if (isset(self::$funcCache[$funcHash])) {
				$result = self::$funcCache[$funcHash];
			} else {
				AbuseFilter::triggerLimiter();
				$result = self::$funcCache[$funcHash] = $this->$func( $args );
			}
			
			if (count(self::$funcCache) > 1000) {
				self::$funcCache = array();
			}
			
			wfProfileOut( __METHOD__."-$func" );
			
			$this->move();
			wfProfileOut( __METHOD__ );
		} else {
			$this->doLevelAtom( $result );
		}
	}
	
	protected function doLevelAtom( &$result ) {
		wfProfileIn( __METHOD__ );
		$tok = $this->mCur->value;
		switch( $this->mCur->type ) {
			case AFPToken::TID:
				$var = strtolower($tok);
				$result = $this->getVarValue( $var );
				break;
			case AFPToken::TString:
				$result = new AFPData( AFPData::DString, $tok );
				break;
			case AFPToken::TFloat:
				$result = new AFPData( AFPData::DFloat, $tok );
				break;
			case AFPToken::TInt:
				$result = new AFPData( AFPData::DInt, $tok );
				break;
			case AFPToken::TKeyword:
				if( $tok == "true" )
					$result = new AFPData( AFPData::DBool, true );
				elseif( $tok == "false" )
					$result = new AFPData( AFPData::DBool, false );
				elseif( $tok == "null" )
					$result = new AFPData();
				else
					throw new AFPUserVisibleException( 'unrecognisedkeyword',
														$this->mCur->pos,
														array($tok) );
				break;
			case AFPToken::TBrace:
			if( $this->mCur->value == ')' )
				return;        // Handled at the entry level
			default:
				throw new AFPUserVisibleException( 'unexpectedtoken',
													$this->mCur->pos,
													array(
														$this->mCur->type,
														$this->mCur->value
													) );
		}
		$this->move();
		wfProfileOut( __METHOD__ );
	}
	
	protected function getVarValue( $var ) {
		$var = strtolower($var);
		$builderValues = AbuseFilter::getBuilderValues();
		if ( ! array_key_exists( $var, $builderValues['vars'] ) ) {
			// If the variable is invalid, throw an exception
			throw new AFPUserVisibleException( 'unrecognisedvar',
												$this->mCur->pos,
												array( $var ) );
		} else {
			return $this->mVars->getVar( $var );
		}
	}
	
	/* End of levels */
	
	static function nextToken( $code, $offset ) {
		$tok = '';
		
		static $lastInput = array();
		
		// Check for infinite loops
		if ( $lastInput == array( $code, $offset ) ) {
			// Should never happen
			throw new AFPException( "Entered infinite loop. Offset $offset of $code" );
		}
		
		$lastInput = array( $code, $offset );
			
		// Spaces
		$matches = array();
		if ( preg_match( '/\s+/u', $code, $matches, PREG_OFFSET_CAPTURE, $offset ) &&
				$matches[0][1] == $offset ) {
			$offset += strlen($matches[0][0]);		
		}
		
		if( $offset >= strlen($code) ) return array( '', AFPToken::TNone, $code, $offset );

		// Comments
		if ( substr($code, $offset, 2) == '/*' ) {
			$end = strpos( $code, '*/', $offset );
			
			return self::nextToken( $code, $end + 2 );
		}
		
		// Commas
		if( $code[$offset] == ',' ) {
			$offset++;
			return array( ',', AFPToken::TComma, $code, $offset );
		}
		
		// Braces
		
		if( $code[$offset] == '(' or $code[$offset] == ')' ) {
			return array( $code[$offset], AFPToken::TBrace, $code, $offset + 1 );
		}
		
		// Strings
		
		if( $code[$offset] == '"' || $code[$offset] == "'" ) {
			$type = $code[$offset];
			$offset++;
			while( $offset < strlen($code) ) {
			
				if( $code[$offset] == $type ) {
					$offset++;
					return array( $tok, AFPToken::TString, $code, $offset );
				}
				
				// Performance: Use a PHP function (implemented in C)
				//  to scan ahead.
				$addLength = strcspn( $code, $type."\\", $offset );
				if ($addLength) {
					$tok .= substr( $code, $offset, $addLength );
					$offset += $addLength;
				} elseif( $code[$offset] == '\\' ) {
					if( $code[$offset + 1] == '\\' )
						$tok .= '\\';
					elseif( $code[$offset + 1] == $type )
						$tok .= $type;
					elseif( $code[$offset + 1] == 'n' )
						$tok .= "\n";
					elseif( $code[$offset + 1] == 'r' )
						$tok .= "\r";
					elseif( $code[$offset + 1] == 't' )
						$tok .= "\t";
					elseif( $code[$offset + 1] == 'x' ) {
						$chr = substr( $code, $offset + 2, 2 );
						
						if ( preg_match( '/^[0-9A-Fa-f]{2}$/', $chr ) ) {
							$chr = base_convert( $chr, 16, 10 );
							$tok .= chr($chr);
							$offset += 2; # \xXX -- 2 done later
						} else {
							$tok .= 'x';
						}
					} else {
						$tok .= "\\" . $code[$offset + 1];
					}
					
					$offset+=2;
					
				} else {
					$tok .= $code[$offset];
					$offset++;
				}
			}
			throw new AFPUserVisibleException( 'unclosedstring', $offset, array() );;
		}
		
		// Find operators
		
		static $operator_regex = null;
		// Match using a regex. Regexes are faster than PHP
		if (!$operator_regex) {
			$quoted_operators = array();
			
			foreach( self::$mOps as $op )
				$quoted_operators[] = preg_quote( $op, '/' );
			$operator_regex = '/('.implode('|', $quoted_operators).')/';
		}
		
		$matches = array();
		
		preg_match( $operator_regex, $code, $matches, PREG_OFFSET_CAPTURE, $offset );
		
		if( count( $matches ) && $matches[0][1] == $offset ) {
			$tok = $matches[0][0];
			$offset += strlen( $tok );
			return array( $tok, AFPToken::TOp, $code, $offset );
		}
		
		// Find bare numbers
		
		$bases = array( 'b' => 2,
						'x' => 16,
						'o' => 8 );
		$baseChars = array(
						2 => '[01]',
						16 => '[0-9A-Fa-f]',
						8 => '[0-8]',
						10 => '[0-9.]',
						);
		$baseClass = '['.implode('', array_keys($bases)).']';
		$radixRegex = "/([0-9A-Fa-f]*(?:\.\d*)?)($baseClass)?/u";
		$matches = array();
		
		preg_match( $radixRegex, $code, $matches, PREG_OFFSET_CAPTURE, $offset );
		
		if ( count( $matches ) && $matches[0][1] == $offset ) {
			$input = $matches[1][0];
			$baseChar = @$matches[2][0];
			$num = null;
			
			// Sometimes the base char gets mixed in with the rest of it because
			//  the regex targets hex, too.
			//  This mostly happens with binary
			if (!$baseChar && !empty( $bases[ substr( $input, -1 ) ] ) ) {
				$baseChar = substr( $input, -1, 1 );
				$input = substr( $input, 0, -1 );
			}
			
			if ($baseChar) {
				$base = $bases[$baseChar];
			} else {
				$base = 10;
			}
			
			// Check against the appropriate character class for input validation
			$baseRegex = "/^".$baseChars[$base]."+$/";

			if ( preg_match( $baseRegex, $input ) ) {
				if ($base != 10) {
					$num = base_convert( $input, $base, 10 );
				} else {
					$num = $input;
				}
						
				$offset += strlen( $matches[0][0] );
				
				$float = in_string( '.', $input );
				
				return array(
					$float
						? doubleval( $num )
						: intval( $num ),
					$float
						? AFPToken::TFloat
						: AFPToken::TInt,
					$code,
					$offset
				);
			}
		}
		
		// The rest are considered IDs
		
		// Regex match > PHP
		$idSymbolRegex = '/[0-9A-Za-z_]+/';
		$matches = array();
		preg_match( $idSymbolRegex, $code, $matches, PREG_OFFSET_CAPTURE, $offset );
		
		if ( $matches[0][1] == $offset ) {
			$tok = $matches[0][0];
			
			$type = in_array( $tok, self::$mKeywords )
				? AFPToken::TKeyword
				: AFPToken::TID;
				
			return array( $tok, $type, $code, $offset + strlen($tok) );
		}
		
		throw new AFPUserVisibleException(
			'unrecognisedtoken', $offset, array( substr( $code, $offset ) ) );
	}
	
	//Built-in functions
	protected function funcLc( $args ) {
		global $wgContLang;
		if( count( $args ) < 1 )
			throw new AFPExpection( "No params passed to lc()" );
		$s = $args[0]->toString();
		return new AFPData( AFPData::DString, $wgContLang->lc( $s ) );
	}
	
	protected function funcLen( $args ) {
		if( count( $args ) < 1 )
			throw new AFPExpection( "No params passed to len()" );
		$s = $args[0]->toString();
		return new AFPData( AFPData::DInt, mb_strlen( $s, 'utf-8' ) );
	}
	
	protected function funcSimpleNorm( $args ) {
		if( count( $args ) < 1 )
			throw new AFPExpection( "No params passed to simplenorm()" );
		$s = $args[0]->toString();
		
		$s = preg_replace( '/[\d\W]+/', '', $s );
		$s = strtolower( $value );
		return new AFPData( AFPData::DString, $s );
	}
	
	protected function funcSpecialRatio( $args ) {
		if( count( $args ) < 1 )
			throw new AFPExpection( "No params passed to specialratio()" );
		$s = $args[0]->toString();
		
		if (!strlen($s)) {
			return new AFPData( AFPData::DFloat, 0 );
		}
		
		$nospecials = $this->rmspecials( $s );
		
		$val = 1. - ((mb_strlen($nospecials) / mb_strlen($s)));
		
		return new AFPData( AFPData::DFloat, $val );
	}
	
	protected function funcCount( $args ) {
		if( count( $args ) < 1 )
			throw new AFPExpection( "No params passed to ".__METHOD__ );
			
		$offset = -1;
		
		if (count($args) == 1) {
			$count = count( explode( ",", $args[0]->toString() ) );
		} else {
			$needle = $args[0]->toString();
			$haystack = $args[1]->toString();
			
			$count = 0;
			while ( ($offset = strpos( $haystack, $needle, $offset + 1 )) !== false ) {
				$count++;
			}
		}
		
		return new AFPData( AFPData::DInt, $count );
	}
	
	protected function funcRCount( $args ) {
		if( count( $args ) < 1 )
			throw new AFPExpection( "No params passed to ".__METHOD__ );
			
		$offset = -1;
		
		if (count($args) == 1) {
			$count = count( explode( ",", $args[0]->toString() ) );
		} else {
			$needle = $args[0]->toString();
			$haystack = $args[1]->toString();

			## Munge the regex			
			if (preg_match('/^\/.*\/$/u', $needle)) {
				$needle .= 'u';
			} elseif (preg_match( '/^\/.*\/\w+$/u', $needle ) ) {
				# Nothing
			} else {
				$needle = "/$needle/u";
			}
			
			$count = 0;
			$matches = array();
			$count = preg_match_all( $needle, $haystack, $matches );
		}
		
		return new AFPData( AFPData::DInt, $count );
	}
	
	protected function funcIPInRange( $args ) {
		if( count( $args ) < 2 )
			throw new AFPExpection( "No params passed to ".__METHOD__ );
			
		$ip = $args[0]->toString();
		$range = $args[1]->toString();
		
		$result = IP::isInRange( $ip, $range );
		
		return new AFPData( AFPData::DBool, $result );
	}
	
	protected function funcCCNorm( $args ) {
		if( count( $args ) < 1 )
			throw new AFPExpection( "No params passed to ".__METHOD__ );
		$s = $args[0]->toString();
		
		$s = $this->ccnorm( $s );
		
		return new AFPData( AFPData::DString, $s );
	}
	
	protected function ccnorm( $s ) {
		if (!class_exists( 'AntiSpoof' ) ) {
			return $s;
		}
		
		// Normalise confusable characters.
		$chars = AntiSpoof::stringToList( $s );
		$chars = AntiSpoof::equivString( $chars );
		$s = AntiSpoof::listToString( $chars );
		
		return $s;
	}
	
	protected function rmspecials( $s ) {
		$orig = $s;
		$s = preg_replace( '/[^\p{L}\p{N}]/u', '', $s );
		
		return $s;
	}
	
	protected function rmdoubles( $s ) {
		$last = -1;
		$ret = array();
		
		$chars = AntiSpoof::stringToList( $s );
		
		foreach( $chars as $char) {
			if ($char != $last)
				$ret[] = $char;
			$last = $char;
		}
		
		return AntiSpoof::listToString($ret);
	}
	
	protected function rmwhitespace( $s ) {
		return preg_replace( '/\s+/u', '', $s );
	}
	
	protected function funcRMSpecials( $args ) {
		if( count( $args ) < 1 )
			throw new AFPExpection( "No params passed to ".__METHOD__ );
		$s = $args[0]->toString();
		
		$s = $this->rmspecials( $s );
		
		return new AFPData( AFPData::DString, $s );
	}
	
	protected function funcRMWhitespace( $args ) {
		if( count( $args ) < 1 )
			throw new AFPExpection( "No params passed to ".__METHOD__ );
		$s = $args[0]->toString();
		
		$s = $this->rmwhitespace( $s );
		
		return new AFPData( AFPData::DString, $s );
	}
	
	protected function funcRMDoubles( $args ) {
		if( count( $args ) < 1 )
			throw new AFPExpection( "No params passed to ".__METHOD__ );
		$s = $args[0]->toString();
		
		$s = $this->rmdoubles( $s );
		
		return new AFPData( AFPData::DString, $s );
	}
	
	protected function funcNorm( $args ) {
		if( count( $args ) < 1 )
			throw new AFPExpection( "No params passed to ".__METHOD__ );
		$s = $args[0]->toString();
		
		$s = $this->ccnorm($s);
		$s = $this->rmdoubles( $s );
		$s = $this->rmspecials( $s );
		$s = $this->rmwhitespace( $s );
		
		return new AFPData( AFPData::DString, $s );
	}
	
	protected function castString( $args ) {
		if ( count( $args ) < 1)
			throw new AFPUserVisibleException( 'noparams', $this->mCur->pos, array(__METHOD__) );
		$val = $args[0];
		
		return new AFPData( AFPData::DString, $val->data );
	}
	
	protected function castInt( $args ) {
		if ( count( $args ) < 1)
			throw new AFPUserVisibleException( 'noparams', $this->mCur->pos, array(__METHOD__) );
		$val = $args[0];
		
		return new AFPData( AFPData::DInt, intval($val->data) );
	}

	protected function castFloat( $args ) {
		if ( count( $args ) < 1)
			throw new AFPUserVisibleException( 'noparams', $this->mCur->pos, array(__METHOD__) );
		$val = $args[0];
		
		return new AFPData( AFPData::DFloat, doubleval($val->data) );
	}
	
	protected function castBool( $args ) {
		if ( count( $args ) < 1)
			throw new AFPUserVisibleException( 'noparams', $this->mCur->pos, array(__METHOD__) );
		$val = $args[0];
		
		return new AFPData( AFPData::DBool, (bool)($val->data) );
	}
}

 ## Taken from http://au2.php.net/manual/en/function.fnmatch.php#71725
 ### Attribution: jk at ricochetsolutions dot com

if(!function_exists('fnmatch')) {

    function fnmatch($pattern, $string) {
        return preg_match("#^".strtr(preg_quote($pattern, '#'), array('\*' => '.*', '\?' => '.'))."$#i", $string);
    } // end

} // end if