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443 lines
16 KiB
443 lines
16 KiB
<?php
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/**
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* PHP lexer code snarfed from the CVS tree for the lamplib project at
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* http://sourceforge.net/projects/lamplib
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* This project is administered by Markus Baker, Harry Fuecks and Matt
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* Mitchell, and the project code is in the public domain.
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*
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* Thanks, guys!
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*
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* @package moodlecore
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* @copyright Markus Baker, Harry Fuecks and Matt Mitchell
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* @license Public Domain {@link http://sourceforge.net/projects/lamplib}
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*/
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/** LEXER_ENTER = 1 */
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define("LEXER_ENTER", 1);
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/** LEXER_MATCHED = 2 */
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define("LEXER_MATCHED", 2);
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/** LEXER_UNMATCHED = 3 */
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define("LEXER_UNMATCHED", 3);
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/** LEXER_EXIT = 4 */
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define("LEXER_EXIT", 4);
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/** LEXER_SPECIAL = 5 */
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define("LEXER_SPECIAL", 5);
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/**
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* Compounded regular expression. Any of
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* the contained patterns could match and
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* when one does it's label is returned.
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* @package moodlecore
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* @copyright Markus Baker, Harry Fuecks and Matt Mitchell
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* @license Public Domain {@link http://sourceforge.net/projects/lamplib}
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*/
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class ParallelRegex {
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var $_patterns;
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var $_labels;
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var $_regex;
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var $_case;
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/**
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* Constructor. Starts with no patterns.
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* @param bool $case True for case sensitive, false
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* for insensitive.
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* @access public
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*/
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public function __construct($case) {
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$this->_case = $case;
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$this->_patterns = array();
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$this->_labels = array();
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$this->_regex = null;
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}
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/**
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* Old syntax of class constructor. Deprecated in PHP7.
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*
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* @deprecated since Moodle 3.1
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*/
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public function ParallelRegex($case) {
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debugging('Use of class name as constructor is deprecated', DEBUG_DEVELOPER);
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self::__construct($case);
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}
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/**
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* Adds a pattern with an optional label.
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* @param string $pattern Perl style regex, but ( and )
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* lose the usual meaning.
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* @param string $label Label of regex to be returned
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* on a match.
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* @access public
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*/
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function addPattern($pattern, $label = true) {
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$count = count($this->_patterns);
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$this->_patterns[$count] = $pattern;
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$this->_labels[$count] = $label;
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$this->_regex = null;
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}
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/**
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* Attempts to match all patterns at once against
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* a string.
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* @param string $subject String to match against.
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* @param string $match First matched portion of
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* subject.
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* @return bool True on success.
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* @access public
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*/
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function match($subject, &$match) {
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if (count($this->_patterns) == 0) {
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return false;
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}
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if (!preg_match($this->_getCompoundedRegex(), $subject, $matches)) {
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$match = "";
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return false;
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}
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$match = $matches[0];
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for ($i = 1; $i < count($matches); $i++) {
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if ($matches[$i]) {
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return $this->_labels[$i - 1];
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}
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}
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return true;
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}
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/**
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* Compounds the patterns into a single
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* regular expression separated with the
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* "or" operator. Caches the regex.
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* Will automatically escape (, ) and / tokens.
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* @access private
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*/
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function _getCompoundedRegex() {
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if ($this->_regex == null) {
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for ($i = 0; $i < count($this->_patterns); $i++) {
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$this->_patterns[$i] = '(' . str_replace(
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array('/', '(', ')'),
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array('\/', '\(', '\)'),
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$this->_patterns[$i]) . ')';
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}
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$this->_regex = "/" . implode("|", $this->_patterns) . "/" . $this->_getPerlMatchingFlags();
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}
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return $this->_regex;
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}
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/**
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* Accessor for perl regex mode flags to use.
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* @return string Flags as string.
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* @access private
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*/
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function _getPerlMatchingFlags() {
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return ($this->_case ? "msS" : "msSi");
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}
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}
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/**
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* States for a stack machine.
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*
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* @package moodlecore
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* @copyright Markus Baker, Harry Fuecks and Matt Mitchell
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* @license Public Domain {@link http://sourceforge.net/projects/lamplib}
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*/
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class StateStack {
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var $_stack;
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/**
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* Constructor. Starts in named state.
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* @param string $start Starting state name.
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* @access public
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*/
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public function __construct($start) {
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$this->_stack = array($start);
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}
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/**
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* Old syntax of class constructor. Deprecated in PHP7.
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*
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* @deprecated since Moodle 3.1
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*/
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public function StateStack($start) {
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debugging('Use of class name as constructor is deprecated', DEBUG_DEVELOPER);
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self::__construct($start);
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}
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/**
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* Accessor for current state.
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* @return string State as string.
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* @access public
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*/
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function getCurrent() {
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return $this->_stack[count($this->_stack) - 1];
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}
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/**
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* Adds a state to the stack and sets it
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* to be the current state.
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* @param string $state New state.
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* @access public
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*/
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function enter($state) {
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array_push($this->_stack, $state);
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}
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/**
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* Leaves the current state and reverts
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* to the previous one.
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* @return bool False if we drop off
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* the bottom of the list.
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* @access public
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*/
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function leave() {
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if (count($this->_stack) == 1) {
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return false;
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}
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array_pop($this->_stack);
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return true;
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}
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}
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/**
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* Accepts text and breaks it into tokens.
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* Some optimisation to make the sure the
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* content is only scanned by the PHP regex
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* parser once. Lexer modes must not start
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* with leading underscores.
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*
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* @package moodlecore
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* @copyright Markus Baker, Harry Fuecks and Matt Mitchell
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* @license Public Domain {@link http://sourceforge.net/projects/lamplib}
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*/
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class Lexer {
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var $_regexes;
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var $_parser;
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var $_mode;
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var $_mode_handlers;
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var $_case;
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/**
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* Sets up the lexer in case insensitive matching
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* by default.
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* @param object $parser Handling strategy by
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* reference.
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* @param string $start Starting handler.
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* @param bool $case True for case sensitive.
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* @access public
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*/
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public function __construct(&$parser, $start = "accept", $case = false) {
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$this->_case = $case;
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$this->_regexes = array();
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$this->_parser = &$parser;
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$this->_mode = new StateStack($start);
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$this->_mode_handlers = array();
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}
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/**
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* Old syntax of class constructor. Deprecated in PHP7.
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*
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* @deprecated since Moodle 3.1
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*/
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public function Lexer(&$parser, $start = "accept", $case = false) {
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debugging('Use of class name as constructor is deprecated', DEBUG_DEVELOPER);
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self::__construct($parser, $start, $case);
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}
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/**
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* Adds a token search pattern for a particular
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* parsing mode. The pattern does not change the
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* current mode.
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* @param string $pattern Perl style regex, but ( and )
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* lose the usual meaning.
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* @param string $mode Should only apply this
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* pattern when dealing with
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* this type of input.
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* @access public
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*/
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function addPattern($pattern, $mode = "accept") {
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if (!isset($this->_regexes[$mode])) {
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$this->_regexes[$mode] = new ParallelRegex($this->_case);
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}
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$this->_regexes[$mode]->addPattern($pattern);
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}
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/**
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* Adds a pattern that will enter a new parsing
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* mode. Useful for entering parenthesis, strings,
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* tags, etc.
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* @param string $pattern Perl style regex, but ( and )
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* lose the usual meaning.
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* @param string $mode Should only apply this
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* pattern when dealing with
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* this type of input.
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* @param string $new_mode Change parsing to this new
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* nested mode.
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* @access public
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*/
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function addEntryPattern($pattern, $mode, $new_mode) {
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if (!isset($this->_regexes[$mode])) {
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$this->_regexes[$mode] = new ParallelRegex($this->_case);
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}
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$this->_regexes[$mode]->addPattern($pattern, $new_mode);
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}
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/**
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* Adds a pattern that will exit the current mode
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* and re-enter the previous one.
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* @param string $pattern Perl style regex, but ( and )
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* lose the usual meaning.
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* @param string $mode Mode to leave.
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* @access public
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*/
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function addExitPattern($pattern, $mode) {
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if (!isset($this->_regexes[$mode])) {
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$this->_regexes[$mode] = new ParallelRegex($this->_case);
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}
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$this->_regexes[$mode]->addPattern($pattern, "__exit");
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}
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/**
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* Adds a pattern that has a special mode.
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* Acts as an entry and exit pattern in one go.
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* @param string $pattern Perl style regex, but ( and )
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* lose the usual meaning.
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* @param string $mode Should only apply this
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* pattern when dealing with
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* this type of input.
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* @param string $special Use this mode for this one token.
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* @access public
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*/
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function addSpecialPattern($pattern, $mode, $special) {
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if (!isset($this->_regexes[$mode])) {
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$this->_regexes[$mode] = new ParallelRegex($this->_case);
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}
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$this->_regexes[$mode]->addPattern($pattern, "_$special");
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}
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/**
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* Adds a mapping from a mode to another handler.
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* @param string $mode Mode to be remapped.
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* @param string $handler New target handler.
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* @access public
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*/
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function mapHandler($mode, $handler) {
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$this->_mode_handlers[$mode] = $handler;
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}
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/**
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* Splits the page text into tokens. Will fail
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* if the handlers report an error or if no
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* content is consumed. If successful then each
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* unparsed and parsed token invokes a call to the
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* held listener.
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* @param string $raw Raw HTML text.
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* @return bool True on success, else false.
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* @access public
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*/
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function parse($raw) {
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if (!isset($this->_parser)) {
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return false;
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}
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$length = strlen($raw);
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while (is_array($parsed = $this->_reduce($raw))) {
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list($unmatched, $matched, $mode) = $parsed;
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if (!$this->_dispatchTokens($unmatched, $matched, $mode)) {
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return false;
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}
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if (strlen($raw) == $length) {
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return false;
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}
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$length = strlen($raw);
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}
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if (!$parsed) {
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return false;
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}
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return $this->_invokeParser($raw, LEXER_UNMATCHED);
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}
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/**
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* Sends the matched token and any leading unmatched
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* text to the parser changing the lexer to a new
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* mode if one is listed.
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* @param string $unmatched Unmatched leading portion.
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* @param string $matched Actual token match.
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* @param string $mode Mode after match. The "_exit"
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* mode causes a stack pop. An
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* false mode causes no change.
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* @return bool False if there was any error
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* from the parser.
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* @access private
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*/
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function _dispatchTokens($unmatched, $matched, $mode = false) {
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if (!$this->_invokeParser($unmatched, LEXER_UNMATCHED)) {
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return false;
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}
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if ($mode === "__exit") {
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if (!$this->_invokeParser($matched, LEXER_EXIT)) {
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return false;
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}
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return $this->_mode->leave();
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}
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if (strncmp($mode, "_", 1) == 0) {
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$mode = substr($mode, 1);
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$this->_mode->enter($mode);
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if (!$this->_invokeParser($matched, LEXER_SPECIAL)) {
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return false;
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}
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return $this->_mode->leave();
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}
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if (is_string($mode)) {
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$this->_mode->enter($mode);
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return $this->_invokeParser($matched, LEXER_ENTER);
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}
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return $this->_invokeParser($matched, LEXER_MATCHED);
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}
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/**
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* Calls the parser method named after the current
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* mode. Empty content will be ignored.
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* @param string $content Text parsed.
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* @param string $is_match Token is recognised rather
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* than unparsed data.
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* @access private
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*/
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function _invokeParser($content, $is_match) {
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if (($content === "") || ($content === false)) {
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return true;
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}
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$handler = $this->_mode->getCurrent();
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if (isset($this->_mode_handlers[$handler])) {
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$handler = $this->_mode_handlers[$handler];
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}
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return $this->_parser->$handler($content, $is_match);
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}
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/**
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* Tries to match a chunk of text and if successful
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* removes the recognised chunk and any leading
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* unparsed data. Empty strings will not be matched.
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* @param string $raw The subject to parse. This is the
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* content that will be eaten.
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* @return bool|array Three item list of unparsed
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* content followed by the
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* recognised token and finally the
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* action the parser is to take.
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* True if no match, false if there
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* is a parsing error.
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* @access private
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*/
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function _reduce(&$raw) {
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if (!isset($this->_regexes[$this->_mode->getCurrent()])) {
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return false;
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}
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if ($raw === "") {
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return true;
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}
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if ($action = $this->_regexes[$this->_mode->getCurrent()]->match($raw, $match)) {
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$count = strpos($raw, $match);
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$unparsed = substr($raw, 0, $count);
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$raw = substr($raw, $count + strlen($match));
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return array($unparsed, $match, $action);
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}
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return true;
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}
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}
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?>
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