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309 lines
11 KiB
309 lines
11 KiB
2 years ago
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<?php
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// This file is part of Moodle - http://moodle.org/
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//
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// Moodle is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// Moodle is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
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/**
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* @package moodlecore
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* @subpackage backup-xml
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* @copyright 2010 onwards Eloy Lafuente (stronk7) {@link http://stronk7.com}
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* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
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*/
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/**
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* Class implementing one SAX progressive push parser.
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*
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* SAX parser able to process XML content from files/variables. It supports
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* attributes and case folding and works only with UTF-8 content. It's one
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* progressive push parser because, intead of loading big crunchs of information
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* in memory, it "publishes" (pushes) small information in a "propietary array format" througt
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* the corresponding @progressive_parser_processor, that will be the responsibe for
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* returning information into handy formats to higher levels.
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*
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* Note that, while this progressive parser is able to process any XML file, it is
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* 100% progressive so it publishes the information in the original order it's parsed (that's
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* the expected behaviour) so information belonging to the same path can be returned in
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* different chunks if there are inner levels/paths in the middle. Be warned!
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*
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* The "propietary array format" that the parser publishes to the @progressive_parser_processor
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* is this:
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* array (
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* 'path' => path where the tags belong to,
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* 'level'=> level (1-based) of the tags
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* 'tags => array (
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* 'name' => name of the tag,
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* 'attrs'=> array( name of the attr => value of the attr),
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* 'cdata => cdata of the tag
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* )
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* )
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*
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* TODO: Finish phpdocs
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*/
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class progressive_parser {
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protected $xml_parser; // PHP's low level XML SAX parser
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protected $file; // full path to file being progressively parsed | => mutually exclusive
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protected $contents; // contents being progressively parsed |
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/**
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* @var progressive_parser_processor to be used to publish processed information
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*/
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protected $processor;
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protected $level; // level of the current tag
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protected $path; // path of the current tag
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protected $accum; // accumulated char data of the current tag
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protected $attrs; // attributes of the current tag
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protected $topush; // array containing current level information being parsed to be "pushed"
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protected $prevlevel; // level of the previous tag processed - to detect pushing places
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protected $currtag; // name/value/attributes of the tag being processed
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/**
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* @var \core\progress\base Progress tracker called for each action
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*/
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protected $progress;
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public function __construct($case_folding = false) {
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$this->xml_parser = xml_parser_create('UTF-8');
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xml_parser_set_option($this->xml_parser, XML_OPTION_CASE_FOLDING, $case_folding);
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xml_set_object($this->xml_parser, $this);
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xml_set_element_handler($this->xml_parser, array($this, 'start_tag'), array($this, 'end_tag'));
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xml_set_character_data_handler($this->xml_parser, array($this, 'char_data'));
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$this->file = null;
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$this->contents = null;
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$this->procesor = null;
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$this->level = 0;
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$this->path = '';
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$this->accum = '';
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$this->attrs = array();
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$this->topush = array();
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$this->prevlevel = 0;
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$this->currtag = array();
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}
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/*
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* Sets the XML file to be processed by the parser
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*/
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public function set_file($file) {
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if (!file_exists($file) || (!is_readable($file))) {
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throw new progressive_parser_exception('invalid_file_to_parse');
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}
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$this->file = $file;
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$this->contents = null;
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}
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/*
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* Sets the XML contents to be processed by the parser
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*/
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public function set_contents($contents) {
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if (empty($contents)) {
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throw new progressive_parser_exception('invalid_contents_to_parse');
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}
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$this->contents = $contents;
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$this->file = null;
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}
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/*
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* Define the @progressive_parser_processor in charge of processing the parsed chunks
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*/
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public function set_processor($processor) {
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if (!$processor instanceof progressive_parser_processor) {
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throw new progressive_parser_exception('invalid_parser_processor');
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}
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$this->processor = $processor;
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}
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/**
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* Sets the progress tracker for the parser. If set, the tracker will be
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* called to report indeterminate progress for each chunk of XML.
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*
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* The caller should have already called start_progress on the progress tracker.
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*
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* @param \core\progress\base $progress Progress tracker
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*/
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public function set_progress(\core\progress\base $progress) {
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$this->progress = $progress;
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}
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/*
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* Process the XML, delegating found chunks to the @progressive_parser_processor
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*/
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public function process() {
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if (empty($this->processor)) {
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throw new progressive_parser_exception('undefined_parser_processor');
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}
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if (empty($this->file) && empty($this->contents)) {
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throw new progressive_parser_exception('undefined_xml_to_parse');
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}
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if (is_null($this->xml_parser)) {
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throw new progressive_parser_exception('progressive_parser_already_used');
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}
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if ($this->file) {
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$fh = fopen($this->file, 'r');
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while ($buffer = fread($fh, 8192)) {
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$this->parse($buffer, feof($fh));
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}
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fclose($fh);
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} else {
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$this->parse($this->contents, true);
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}
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xml_parser_free($this->xml_parser);
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$this->xml_parser = null;
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}
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/**
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* Provides one cross-platform dirname function for
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* handling parser paths, see MDL-24381
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*/
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public static function dirname($path) {
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return str_replace('\\', '/', dirname($path));
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}
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// Protected API starts here
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protected function parse($data, $eof) {
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if (!xml_parse($this->xml_parser, $data, $eof)) {
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throw new progressive_parser_exception(
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'xml_parsing_error', null,
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sprintf('XML error: %s at line %d, column %d',
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xml_error_string(xml_get_error_code($this->xml_parser)),
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xml_get_current_line_number($this->xml_parser),
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xml_get_current_column_number($this->xml_parser)));
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}
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}
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protected function publish($data) {
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$this->processor->receive_chunk($data);
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if (!empty($this->progress)) {
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// Report indeterminate progress.
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$this->progress->progress();
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}
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}
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/**
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* Inform to the processor that we have started parsing one path
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*/
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protected function inform_start($path) {
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$this->processor->before_path($path);
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}
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/**
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* Inform to the processor that we have finished parsing one path
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*/
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protected function inform_end($path) {
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$this->processor->after_path($path);
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}
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protected function postprocess_cdata($data) {
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return $this->processor->process_cdata($data);
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}
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protected function start_tag($parser, $tag, $attributes) {
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// Normal update of parser internals
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$this->level++;
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$this->path .= '/' . $tag;
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$this->accum = '';
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$this->attrs = !empty($attributes) ? $attributes : array();
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// Inform processor we are about to start one tag
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$this->inform_start($this->path);
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// Entering a new inner level, publish all the information available
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if ($this->level > $this->prevlevel) {
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if (!empty($this->currtag) && (!empty($this->currtag['attrs']) || !empty($this->currtag['cdata']))) {
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// We always add the last not-empty repetition. Empty ones are ignored.
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if (isset($this->topush['tags'][$this->currtag['name']]) && trim($this->currtag['cdata']) === '') {
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// Do nothing, the tag already exists and the repetition is empty
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} else {
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$this->topush['tags'][$this->currtag['name']] = $this->currtag;
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}
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}
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if (!empty($this->topush['tags'])) {
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$this->publish($this->topush);
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}
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$this->currtag = array();
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$this->topush = array();
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}
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// If not set, build to push common header
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if (empty($this->topush)) {
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$this->topush['path'] = progressive_parser::dirname($this->path);
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$this->topush['level'] = $this->level;
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$this->topush['tags'] = array();
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}
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// Handling a new tag, create it
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$this->currtag['name'] = $tag;
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// And add attributes if present
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if ($this->attrs) {
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$this->currtag['attrs'] = $this->attrs;
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}
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// For the records
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$this->prevlevel = $this->level;
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}
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protected function end_tag($parser, $tag) {
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// Ending rencently started tag, add value to current tag
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if ($this->level == $this->prevlevel) {
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$this->currtag['cdata'] = $this->postprocess_cdata($this->accum);
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// We always add the last not-empty repetition. Empty ones are ignored.
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if (isset($this->topush['tags'][$this->currtag['name']]) && trim($this->currtag['cdata']) === '') {
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// Do nothing, the tag already exists and the repetition is empty
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} else {
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$this->topush['tags'][$this->currtag['name']] = $this->currtag;
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}
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$this->currtag = array();
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}
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// Leaving one level, publish all the information available
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if ($this->level < $this->prevlevel) {
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if (!empty($this->topush['tags'])) {
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$this->publish($this->topush);
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}
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$this->currtag = array();
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$this->topush = array();
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}
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// For the records
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$this->prevlevel = $this->level;
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// Inform processor we have finished one tag
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$this->inform_end($this->path);
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// Normal update of parser internals
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$this->level--;
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$this->path = progressive_parser::dirname($this->path);
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}
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protected function char_data($parser, $data) {
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$this->accum .= $data;
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}
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}
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/*
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* Exception class used by all the @progressive_parser stuff
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*/
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class progressive_parser_exception extends moodle_exception {
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public function __construct($errorcode, $a=NULL, $debuginfo=null) {
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parent::__construct($errorcode, 'error', '', $a, $debuginfo);
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}
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}
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