Файл: framework/thirdparty/php-peg/Parser.php
Строк: 255
<?php
/**
* We cache the last regex result. This is a low-cost optimization, because we have to do an un-anchored match + check match position anyway
* (alternative is to do an anchored match on a string cut with substr, but that is very slow for long strings). We then don't need to recheck
* for any position between current position and eventual match position - result will be the same
*
* Of course, the next regex might be outside that bracket - after the bracket if other matches have progressed beyond the match position, or before
* the bracket if a failed match + restore has moved the current position backwards - so we have to check that too.
*/
class ParserRegexp {
function __construct( $parser, $rx ) {
$this->parser = $parser ;
$this->rx = $rx . 'Sx' ;
$this->matches = NULL ;
$this->match_pos = NULL ; // NULL is no-match-to-end-of-string, unless check_pos also == NULL, in which case means undefined
$this->check_pos = NULL ;
}
function match() {
$current_pos = $this->parser->pos ;
$dirty = $this->check_pos === NULL || $this->check_pos > $current_pos || ( $this->match_pos !== NULL && $this->match_pos < $current_pos ) ;
if ( $dirty ) {
$this->check_pos = $current_pos ;
$matched = preg_match( $this->rx, $this->parser->string, $this->matches, PREG_OFFSET_CAPTURE, $this->check_pos) ;
if ( $matched ) $this->match_pos = $this->matches[0][1] ; else $this->match_pos = NULL ;
}
if ( $this->match_pos === $current_pos ) {
$this->parser->pos += strlen( $this->matches[0][0] );
return $this->matches[0][0] ;
}
return FALSE ;
}
}
/**
* Parser base class
* - handles current position in string
* - handles matching that position against literal or rx
* - some abstraction of code that would otherwise be repeated many times in a compiled grammer, mostly related to calling user functions
* for result construction and building
*/
class Parser {
function __construct( $string ) {
$this->string = $string ;
$this->pos = 0 ;
$this->depth = 0 ;
$this->regexps = array() ;
}
function whitespace() {
$matched = preg_match( '/[ t]+/', $this->string, $matches, PREG_OFFSET_CAPTURE, $this->pos ) ;
if ( $matched && $matches[0][1] == $this->pos ) {
$this->pos += strlen( $matches[0][0] );
return ' ' ;
}
return FALSE ;
}
function literal( $token ) {
/* Debugging: * / print( "Looking for token '$token' @ '" . substr( $this->string, $this->pos ) . "'n" ) ; /* */
$toklen = strlen( $token ) ;
$substr = substr( $this->string, $this->pos, $toklen ) ;
if ( $substr == $token ) {
$this->pos += $toklen ;
return $token ;
}
return FALSE ;
}
function rx( $rx ) {
if ( !isset( $this->regexps[$rx] ) ) $this->regexps[$rx] = new ParserRegexp( $this, $rx ) ;
return $this->regexps[$rx]->match() ;
}
function expression( $result, $stack, $value ) {
$stack[] = $result; $rv = false;
/* Search backwards through the sub-expression stacks */
for ( $i = count($stack) - 1 ; $i >= 0 ; $i-- ) {
$node = $stack[$i];
if ( isset($node[$value]) ) { $rv = $node[$value]; break; }
foreach ($this->typestack($node['_matchrule']) as $type) {
$callback = array($this, "{$type}_DLR{$value}");
if ( is_callable( $callback ) ) { $rv = call_user_func( $callback ) ; if ($rv !== FALSE) break; }
}
}
if ($rv === false) $rv = @$this->$value;
if ($rv === false) $rv = @$this->$value();
return is_array($rv) ? $rv['text'] : ($rv ? $rv : '');
}
function packhas( $key, $pos ) {
return false ;
}
function packread( $key, $pos ) {
throw 'PackRead after PackHas=>false in Parser.php' ;
}
function packwrite( $key, $pos, $res ) {
return $res ;
}
function typestack( $name ) {
$prop = "match_{$name}_typestack";
return $this->$prop;
}
function construct( $matchrule, $name, $arguments = null ) {
$result = array( '_matchrule' => $matchrule, 'name' => $name, 'text' => '' );
if ($arguments) $result = array_merge($result, $arguments) ;
foreach ($this->typestack($matchrule) as $type) {
$callback = array( $this, "{$type}__construct" ) ;
if ( is_callable( $callback ) ) {
call_user_func_array( $callback, array( &$result ) ) ;
break;
}
}
return $result ;
}
function finalise( &$result ) {
foreach ($this->typestack($result['_matchrule']) as $type) {
$callback = array( $this, "{$type}__finalise" ) ;
if ( is_callable( $callback ) ) {
call_user_func_array( $callback, array( &$result ) ) ;
break;
}
}
return $result ;
}
function store ( &$result, $subres, $storetag = NULL ) {
$result['text'] .= $subres['text'] ;
$storecalled = false;
foreach ($this->typestack($result['_matchrule']) as $type) {
$callback = array( $this, $storetag ? "{$type}_{$storetag}" : "{$type}_{$subres['name']}" ) ;
if ( is_callable( $callback ) ) {
call_user_func_array( $callback, array( &$result, $subres ) ) ;
$storecalled = true; break;
}
$globalcb = array( $this, "{$type}_STR" ) ;
if ( is_callable( $globalcb ) ) {
call_user_func_array( $globalcb, array( &$result, $subres ) ) ;
$storecalled = true; break;
}
}
if ( $storetag && !$storecalled ) {
if ( !isset( $result[$storetag] ) ) $result[$storetag] = $subres ;
else {
if ( isset( $result[$storetag]['text'] ) ) $result[$storetag] = array( $result[$storetag] ) ;
$result[$storetag][] = $subres ;
}
}
}
}
/**
* By inheriting from Packrat instead of Parser, the parser will run in linear time (instead of exponential like
* Parser), but will require a lot more memory, since every match-attempt at every position is memorised.
*
* We now use a string as a byte-array to store position information rather than a straight array for memory reasons. This
* means there is a (roughly) 8MB limit on the size of the string we can parse
*
* @author Hamish Friedlander
*/
class Packrat extends Parser {
function __construct( $string ) {
parent::__construct( $string ) ;
$max = unpack( 'N', "x00xFDxFFxFF" ) ;
if ( strlen( $string ) > $max[1] ) user_error( 'Attempting to parse string longer than Packrat Parser can handle', E_USER_ERROR ) ;
$this->packstatebase = str_repeat( "xFF", strlen( $string )*3 ) ;
$this->packstate = array() ;
$this->packres = array() ;
}
function packhas( $key, $pos ) {
$pos *= 3 ;
return isset( $this->packstate[$key] ) && $this->packstate[$key][$pos] != "xFF" ;
}
function packread( $key, $pos ) {
$pos *= 3 ;
if ( $this->packstate[$key][$pos] == "xFE" ) return FALSE ;
$this->pos = ord($this->packstate[$key][$pos]) << 16 | ord($this->packstate[$key][$pos+1]) << 8 | ord($this->packstate[$key][$pos+2]) ;
return $this->packres["$key:$pos"] ;
}
function packwrite( $key, $pos, $res ) {
if ( !isset( $this->packstate[$key] ) ) $this->packstate[$key] = $this->packstatebase ;
$pos *= 3 ;
if ( $res !== FALSE ) {
$i = pack( 'N', $this->pos ) ;
$this->packstate[$key][$pos] = $i[1] ;
$this->packstate[$key][$pos+1] = $i[2] ;
$this->packstate[$key][$pos+2] = $i[3] ;
$this->packres["$key:$pos"] = $res ;
}
else {
$this->packstate[$key][$pos] = "xFE" ;
}
return $res ;
}
}
/**
* FalseOnlyPackrat only remembers which results where false. Experimental.
*
* @author Hamish Friedlander
*/
class FalseOnlyPackrat extends Parser {
function __construct( $string ) {
parent::__construct( $string ) ;
$this->packstatebase = str_repeat( '.', strlen( $string ) ) ;
$this->packstate = array() ;
}
function packhas( $key, $pos ) {
return isset( $this->packstate[$key] ) && $this->packstate[$key][$pos] == 'F' ;
}
function packread( $key, $pos ) {
return FALSE ;
}
function packwrite( $key, $pos, $res ) {
if ( !isset( $this->packstate[$key] ) ) $this->packstate[$key] = $this->packstatebase ;
if ( $res === FALSE ) {
$this->packstate[$key][$pos] = 'F' ;
}
return $res ;
}
}
/**
* Conservative Packrat will only memo-ize a result on the second hit, making it more memory-lean than Packrat,
* but less likely to go exponential that Parser. Because the store logic is much more complicated this is a net
* loss over Parser for many simple grammars.
*
* @author Hamish Friedlander
*/
class ConservativePackrat extends Parser {
function packhas( $key, $pos ) {
return isset( $this->packres[$key] ) && $this->packres[$key] !== NULL ;
}
function packread( $key, $pos ) {
$this->pos = $this->packpos[$key];
return $this->packres[$key] ;
}
function packwrite( $key, $pos, $res ) {
if ( isset( $this->packres[$key] ) ) {
$this->packres[$key] = $res ;
$this->packpos[$key] = $this->pos ;
}
else {
$this->packres[$key] = NULL ;
}
return $res ;
}
}