path: root/lib/dokuwiki/inc/parser/lexer.php

<?php
/**
* Author Markus Baker: http://www.lastcraft.com
* Version adapted from Simple Test: http://sourceforge.net/projects/simpletest/
* For an intro to the Lexer see:
* http://www.phppatterns.com/index.php/article/articleview/106/1/2/
* @author Marcus Baker
* @package Doku
* @subpackage Lexer
* @version $Id: lexer.php,v 1.1 2005/03/23 23:14:09 harryf Exp $
*/

/**
* Init path constant
*/
if(!defined('DOKU_INC')) die('meh.');

/**#@+
 * lexer mode constant
 */
define("DOKU_LEXER_ENTER", 1);
define("DOKU_LEXER_MATCHED", 2);
define("DOKU_LEXER_UNMATCHED", 3);
define("DOKU_LEXER_EXIT", 4);
define("DOKU_LEXER_SPECIAL", 5);
/**#@-*/

/**
 *    Compounded regular expression. Any of
 *    the contained patterns could match and
 *    when one does it's label is returned.
 *    @package Doku
 *    @subpackage Lexer
 */
class Doku_LexerParallelRegex {
    var $_patterns;
    var $_labels;
    var $_regex;
    var $_case;

    /**
     *    Constructor. Starts with no patterns.
     *    @param boolean $case    True for case sensitive, false
     *                            for insensitive.
     *    @access public
     */
    function Doku_LexerParallelRegex($case) {
        $this->_case = $case;
        $this->_patterns = array();
        $this->_labels = array();
        $this->_regex = null;
    }

    /**
     *    Adds a pattern with an optional label.
     *    @param mixed $pattern       Perl style regex. Must be UTF-8
     *                                encoded. If its a string, the (, )
     *                                lose their meaning unless they
     *                                form part of a lookahead or
     *                                lookbehind assertation.
     *    @param string $label        Label of regex to be returned
     *                                on a match. Label must be ASCII
     *    @access public
     */
    function addPattern($pattern, $label = true) {
        $count = count($this->_patterns);
        $this->_patterns[$count] = $pattern;
        $this->_labels[$count] = $label;
        $this->_regex = null;
    }

    /**
     *    Attempts to match all patterns at once against
     *    a string.
     *    @param string $subject      String to match against.
     *    @param string $match        First matched portion of
     *                                subject.
     *    @return boolean             True on success.
     *    @access public
     */
    function match($subject, &$match) {
        if (count($this->_patterns) == 0) {
            return false;
        }
        if (! preg_match($this->_getCompoundedRegex(), $subject, $matches)) {
            $match = "";
            return false;
        }

        $match = $matches[0];
        $size = count($matches);
        for ($i = 1; $i < $size; $i++) {
            if ($matches[$i] && isset($this->_labels[$i - 1])) {
                return $this->_labels[$i - 1];
            }
        }
        return true;
    }

    /**
     *    Attempts to split the string against all patterns at once
     *
     *    @param string $subject      String to match against.
     *    @param array $split         The split result: array containing, pre-match, match & post-match strings
     *    @return boolean             True on success.
     *    @access public
     *
     *    @author Christopher Smith <chris@jalakai.co.uk>
     */
    function split($subject, &$split) {
        if (count($this->_patterns) == 0) {
            return false;
        }

        if (! preg_match($this->_getCompoundedRegex(), $subject, $matches)) {
            if(function_exists('preg_last_error')){
                $err = preg_last_error();
                switch($err){
                    case PREG_BACKTRACK_LIMIT_ERROR:
                        msg('A PCRE backtrack error occured. Try to increase the pcre.backtrack_limit in php.ini',-1);
                        break;
                    case PREG_RECURSION_LIMIT_ERROR:
                        msg('A PCRE recursion error occured. Try to increase the pcre.recursion_limit in php.ini',-1);
                        break;
                    case PREG_BAD_UTF8_ERROR:
                        msg('A PCRE UTF-8 error occured. This might be caused by a faulty plugin',-1);
                        break;
                    case PREG_INTERNAL_ERROR:
                        msg('A PCRE internal error occured. This might be caused by a faulty plugin',-1);
                        break;
                }
            }

            $split = array($subject, "", "");
            return false;
        }

        $idx = count($matches)-2;
        list($pre, $post) = preg_split($this->_patterns[$idx].$this->_getPerlMatchingFlags(), $subject, 2);
        $split = array($pre, $matches[0], $post);

        return isset($this->_labels[$idx]) ? $this->_labels[$idx] : true;
    }

    /**
     *    Compounds the patterns into a single
     *    regular expression separated with the
     *    "or" operator. Caches the regex.
     *    Will automatically escape (, ) and / tokens.
     *    @param array $patterns    List of patterns in order.
     *    @access private
     */
    function _getCompoundedRegex() {
        if ($this->_regex == null) {
            $cnt = count($this->_patterns);
            for ($i = 0; $i < $cnt; $i++) {

                /*
                 * decompose the input pattern into "(", "(?", ")",
                 * "[...]", "[]..]", "[^]..]", "[...[:...:]..]", "\x"...
                 * elements.
                 */
                preg_match_all('/\\\\.|' .
                               '\(\?|' .
                               '[()]|' .
                               '\[\^?\]?(?:\\\\.|\[:[^]]*:\]|[^]\\\\])*\]|' .
                               '[^[()\\\\]+/', $this->_patterns[$i], $elts);

                $pattern = "";
                $level = 0;

                foreach ($elts[0] as $elt) {
                    /*
                     * for "(", ")" remember the nesting level, add "\"
                     * only to the non-"(?" ones.
                     */

                    switch($elt) {
                    case '(':
                        $pattern .= '\(';
                        break;
                    case ')':
                        if ($level > 0)
                            $level--; /* closing (? */
                        else
                            $pattern .= '\\';
                        $pattern .= ')';
                        break;
                    case '(?':
                        $level++;
                        $pattern .= '(?';
                        break;
                    default:
                        if (substr($elt, 0, 1) == '\\')
                            $pattern .= $elt;
                        else
                            $pattern .= str_replace('/', '\/', $elt);
                    }
                }
                $this->_patterns[$i] = "($pattern)";
            }
            $this->_regex = "/" . implode("|", $this->_patterns) . "/" . $this->_getPerlMatchingFlags();
        }
        return $this->_regex;
    }

    /**
     *    Accessor for perl regex mode flags to use.
     *    @return string       Perl regex flags.
     *    @access private
     */
    function _getPerlMatchingFlags() {
        return ($this->_case ? "msS" : "msSi");
    }
}

/**
 *    States for a stack machine.
 *    @package Lexer
 *    @subpackage Lexer
 */
class Doku_LexerStateStack {
    var $_stack;

    /**
     *    Constructor. Starts in named state.
     *    @param string $start        Starting state name.
     *    @access public
     */
    function Doku_LexerStateStack($start) {
        $this->_stack = array($start);
    }

    /**
     *    Accessor for current state.
     *    @return string       State.
     *    @access public
     */
    function getCurrent() {
        return $this->_stack[count($this->_stack) - 1];
    }

    /**
     *    Adds a state to the stack and sets it
     *    to be the current state.
     *    @param string $state        New state.
     *    @access public
     */
    function enter($state) {
        array_push($this->_stack, $state);
    }

    /**
     *    Leaves the current state and reverts
     *    to the previous one.
     *    @return boolean    False if we drop off
     *                       the bottom of the list.
     *    @access public
     */
    function leave() {
        if (count($this->_stack) == 1) {
            return false;
        }
        array_pop($this->_stack);
        return true;
    }
}

/**
 *    Accepts text and breaks it into tokens.
 *    Some optimisation to make the sure the
 *    content is only scanned by the PHP regex
 *    parser once. Lexer modes must not start
 *    with leading underscores.
 *    @package Doku
 *    @subpackage Lexer
 */
class Doku_Lexer {
    var $_regexes;
    var $_parser;
    var $_mode;
    var $_mode_handlers;
    var $_case;

    /**
     *    Sets up the lexer in case insensitive matching
     *    by default.
     *    @param Doku_Parser $parser  Handling strategy by
     *                                    reference.
     *    @param string $start            Starting handler.
     *    @param boolean $case            True for case sensitive.
     *    @access public
     */
    function Doku_Lexer(&$parser, $start = "accept", $case = false) {
        $this->_case = $case;
        $this->_regexes = array();
        $this->_parser = &$parser;
        $this->_mode = &new Doku_LexerStateStack($start);
        $this->_mode_handlers = array();
    }

    /**
     *    Adds a token search pattern for a particular
     *    parsing mode. The pattern does not change the
     *    current mode.
     *    @param string $pattern      Perl style regex, but ( and )
     *                                lose the usual meaning.
     *    @param string $mode         Should only apply this
     *                                pattern when dealing with
     *                                this type of input.
     *    @access public
     */
    function addPattern($pattern, $mode = "accept") {
        if (! isset($this->_regexes[$mode])) {
            $this->_regexes[$mode] = new Doku_LexerParallelRegex($this->_case);
        }
        $this->_regexes[$mode]->addPattern($pattern);
    }

    /**
     *    Adds a pattern that will enter a new parsing
     *    mode. Useful for entering parenthesis, strings,
     *    tags, etc.
     *    @param string $pattern      Perl style regex, but ( and )
     *                                lose the usual meaning.
     *    @param string $mode         Should only apply this
     *                                pattern when dealing with
     *                                this type of input.
     *    @param string $new_mode     Change parsing to this new
     *                                nested mode.
     *    @access public
     */
    function addEntryPattern($pattern, $mode, $new_mode) {
        if (! isset($this->_regexes[$mode])) {
            $this->_regexes[$mode] = new Doku_LexerParallelRegex($this->_case);
        }
        $this->_regexes[$mode]->addPattern($pattern, $new_mode);
    }

    /**
     *    Adds a pattern that will exit the current mode
     *    and re-enter the previous one.
     *    @param string $pattern      Perl style regex, but ( and )
     *                                lose the usual meaning.
     *    @param string $mode         Mode to leave.
     *    @access public
     */
    function addExitPattern($pattern, $mode) {
        if (! isset($this->_regexes[$mode])) {
            $this->_regexes[$mode] = new Doku_LexerParallelRegex($this->_case);
        }
        $this->_regexes[$mode]->addPattern($pattern, "__exit");
    }

    /**
     *    Adds a pattern that has a special mode. Acts as an entry
     *    and exit pattern in one go, effectively calling a special
     *    parser handler for this token only.
     *    @param string $pattern      Perl style regex, but ( and )
     *                                lose the usual meaning.
     *    @param string $mode         Should only apply this
     *                                pattern when dealing with
     *                                this type of input.
     *    @param string $special      Use this mode for this one token.
     *    @access public
     */
    function addSpecialPattern($pattern, $mode, $special) {
        if (! isset($this->_regexes[$mode])) {
            $this->_regexes[$mode] = new Doku_LexerParallelRegex($this->_case);
        }
        $this->_regexes[$mode]->addPattern($pattern, "_$special");
    }

    /**
     *    Adds a mapping from a mode to another handler.
     *    @param string $mode        Mode to be remapped.
     *    @param string $handler     New target handler.
     *    @access public
     */
    function mapHandler($mode, $handler) {
        $this->_mode_handlers[$mode] = $handler;
    }

    /**
     *    Splits the page text into tokens. Will fail
     *    if the handlers report an error or if no
     *    content is consumed. If successful then each
     *    unparsed and parsed token invokes a call to the
     *    held listener.
     *    @param string $raw        Raw HTML text.
     *    @return boolean           True on success, else false.
     *    @access public
     */
    function parse($raw) {
        if (! isset($this->_parser)) {
            return false;
        }
        $initialLength = strlen($raw);
        $length = $initialLength;
        $pos = 0;
        while (is_array($parsed = $this->_reduce($raw))) {
            list($unmatched, $matched, $mode) = $parsed;
            $currentLength = strlen($raw);
            $matchPos = $initialLength - $currentLength - strlen($matched);
            if (! $this->_dispatchTokens($unmatched, $matched, $mode, $pos, $matchPos)) {
                return false;
            }
            if ($currentLength == $length) {
                return false;
            }
            $length = $currentLength;
            $pos = $initialLength - $currentLength;
        }
        if (!$parsed) {
            return false;
        }
        return $this->_invokeParser($raw, DOKU_LEXER_UNMATCHED, $pos);
    }

    /**
     *    Sends the matched token and any leading unmatched
     *    text to the parser changing the lexer to a new
     *    mode if one is listed.
     *    @param string $unmatched    Unmatched leading portion.
     *    @param string $matched      Actual token match.
     *    @param string $mode         Mode after match. A boolean
     *                                false mode causes no change.
     *    @param int $pos         Current byte index location in raw doc
     *                                thats being parsed
     *    @return boolean             False if there was any error
     *                                from the parser.
     *    @access private
     */
    function _dispatchTokens($unmatched, $matched, $mode = false, $initialPos, $matchPos) {
        if (! $this->_invokeParser($unmatched, DOKU_LEXER_UNMATCHED, $initialPos) ){
            return false;
        }
        if ($this->_isModeEnd($mode)) {
            if (! $this->_invokeParser($matched, DOKU_LEXER_EXIT, $matchPos)) {
                return false;
            }
            return $this->_mode->leave();
        }
        if ($this->_isSpecialMode($mode)) {
            $this->_mode->enter($this->_decodeSpecial($mode));
            if (! $this->_invokeParser($matched, DOKU_LEXER_SPECIAL, $matchPos)) {
                return false;
            }
            return $this->_mode->leave();
        }
        if (is_string($mode)) {
            $this->_mode->enter($mode);
            return $this->_invokeParser($matched, DOKU_LEXER_ENTER, $matchPos);
        }
        return $this->_invokeParser($matched, DOKU_LEXER_MATCHED, $matchPos);
    }

    /**
     *    Tests to see if the new mode is actually to leave
     *    the current mode and pop an item from the matching
     *    mode stack.
     *    @param string $mode    Mode to test.
     *    @return boolean        True if this is the exit mode.
     *    @access private
     */
    function _isModeEnd($mode) {
        return ($mode === "__exit");
    }

    /**
     *    Test to see if the mode is one where this mode
     *    is entered for this token only and automatically
     *    leaves immediately afterwoods.
     *    @param string $mode    Mode to test.
     *    @return boolean        True if this is the exit mode.
     *    @access private
     */
    function _isSpecialMode($mode) {
        return (strncmp($mode, "_", 1) == 0);
    }

    /**
     *    Strips the magic underscore marking single token
     *    modes.
     *    @param string $mode    Mode to decode.
     *    @return string         Underlying mode name.
     *    @access private
     */
    function _decodeSpecial($mode) {
        return substr($mode, 1);
    }

    /**
     *    Calls the parser method named after the current
     *    mode. Empty content will be ignored. The lexer
     *    has a parser handler for each mode in the lexer.
     *    @param string $content        Text parsed.
     *    @param boolean $is_match      Token is recognised rather
     *                                  than unparsed data.
     *    @param int $pos         Current byte index location in raw doc
     *                                thats being parsed
     *    @access private
     */
    function _invokeParser($content, $is_match, $pos) {
        if (($content === "") || ($content === false)) {
            return true;
        }
        $handler = $this->_mode->getCurrent();
        if (isset($this->_mode_handlers[$handler])) {
            $handler = $this->_mode_handlers[$handler];
        }

        // modes starting with plugin_ are all handled by the same
        // handler but with an additional parameter
        if(substr($handler,0,7)=='plugin_'){
          list($handler,$plugin) = explode('_',$handler,2);
              return $this->_parser->$handler($content, $is_match, $pos, $plugin);
        }

            return $this->_parser->$handler($content, $is_match, $pos);
        }

    /**
     *    Tries to match a chunk of text and if successful
     *    removes the recognised chunk and any leading
     *    unparsed data. Empty strings will not be matched.
     *    @param string $raw         The subject to parse. This is the
     *                               content that will be eaten.
     *    @return array              Three item list of unparsed
     *                               content followed by the
     *                               recognised token and finally the
     *                               action the parser is to take.
     *                               True if no match, false if there
     *                               is a parsing error.
     *    @access private
     */
    function _reduce(&$raw) {
        if (! isset($this->_regexes[$this->_mode->getCurrent()])) {
            return false;
        }
        if ($raw === "") {
            return true;
        }
        if ($action = $this->_regexes[$this->_mode->getCurrent()]->split($raw, $split)) {
            list($unparsed, $match, $raw) = $split;
            return array($unparsed, $match, $action);
        }
        return true;
    }
}

/**
* Escapes regex characters other than (, ) and /
* @TODO
*/
function Doku_Lexer_Escape($str) {
    //$str = addslashes($str);
    $chars = array(
        '/\\\\/',
        '/\./',
        '/\+/',
        '/\*/',
        '/\?/',
        '/\[/',
        '/\^/',
        '/\]/',
        '/\$/',
        '/\{/',
        '/\}/',
        '/\=/',
        '/\!/',
        '/\</',
        '/\>/',
        '/\|/',
        '/\:/'
        );

    $escaped = array(
        '\\\\\\\\',
        '\.',
        '\+',
        '\*',
        '\?',
        '\[',
        '\^',
        '\]',
        '\$',
        '\{',
        '\}',
        '\=',
        '\!',
        '\<',
        '\>',
        '\|',
        '\:'
        );
    return preg_replace($chars, $escaped, $str);
}

//Setup VIM: ex: et ts=4 sw=4 enc=utf-8 :