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<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
/**
* @package moodlecore
* @subpackage backup-xml
* @copyright 2010 onwards Eloy Lafuente (stronk7) {@link http://stronk7.com}
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
/**
* Class implementing one (more or less complete) UTF-8 XML writer
*
* General purpose class used to output UTF-8 XML contents easily. Can be customized
* using implementations of @xml_output (to define where to send the xml) and
* and @xml_contenttransformer (to perform any transformation in contents before
* outputting the XML).
*
* Has support for attributes, basic w3c xml schemas declaration,
* and performs some content cleaning to avoid potential incorret UTF-8
* mess and has complete exception support.
*
* TODO: Provide UTF-8 safe strtoupper() function if using casefolding and non-ascii tags/attrs names
* TODO: Finish phpdocs
*/
class xml_writer {
protected $output; // @xml_output that defines how to output XML
protected $contenttransformer; // @xml_contenttransformer to modify contents before output
protected $prologue; // Complete string prologue we want to use
protected $xmlschema; // URI to nonamespaceschema to be added to main tag
protected $casefolding; // To define if xml tags must be uppercase (true) or not (false)
protected $level; // current number of open tags, useful for indent text
protected $opentags; // open tags accumulator, to check for errors
protected $lastwastext;// to know when we are writing after text content
protected $nullcontent;// to know if we are going to write one tag with null content
protected $running; // To know if writer is running
public function __construct($output, $contenttransformer = null, $casefolding = false) {
if (!$output instanceof xml_output) {
throw new xml_writer_exception('invalid_xml_output');
}
if (!is_null($contenttransformer) && !$contenttransformer instanceof xml_contenttransformer) {
throw new xml_writer_exception('invalid_xml_contenttransformer');
}
$this->output = $output;
$this->contenttransformer = $contenttransformer;
$this->prologue = null;
$this->xmlschema = null;
$this->casefolding = $casefolding;
$this->level = 0;
$this->opentags = array();
$this->lastwastext = false;
$this->nullcontent = false;
$this->running = null;
}
/**
* Initializes the XML writer, preparing it to accept instructions, also
* invoking the underlying @xml_output init method to be ready for operation
*/
public function start() {
if ($this->running === true) {
throw new xml_writer_exception('xml_writer_already_started');
}
if ($this->running === false) {
throw new xml_writer_exception('xml_writer_already_stopped');
}
$this->output->start(); // Initialize whatever we need in output
if (!is_null($this->prologue)) { // Output prologue
$this->write($this->prologue);
} else {
$this->write($this->get_default_prologue());
}
$this->running = true;
}
/**
* Finishes the XML writer, not accepting instructions any more, also
* invoking the underlying @xml_output finish method to close/flush everything as needed
*/
public function stop() {
if (is_null($this->running)) {
throw new xml_writer_exception('xml_writer_not_started');
}
if ($this->running === false) {
throw new xml_writer_exception('xml_writer_already_stopped');
}
if ($this->level > 0) { // Cannot stop if not at level 0, remaining open tags
throw new xml_writer_exception('xml_writer_open_tags_remaining');
}
$this->output->stop();
$this->running = false;
}
/**
* Set the URI location for the *nonamespace* schema to be used by the (whole) XML document
*/
public function set_nonamespace_schema($uri) {
if ($this->running) {
throw new xml_writer_exception('xml_writer_already_started');
}
$this->xmlschema = $uri;
}
/**
* Define the complete prologue to be used, replacing the simple, default one
*/
public function set_prologue($prologue) {
if ($this->running) {
throw new xml_writer_exception('xml_writer_already_started');
}
$this->prologue = $prologue;
}
/**
* Outputs one XML start tag with optional attributes (name => value array)
*/
public function begin_tag($tag, $attributes = null) {
// TODO: chek the tag name is valid
$pre = $this->level ? "\n" . str_repeat(' ', $this->level * 2) : ''; // Indent
$tag = $this->casefolding ? strtoupper($tag) : $tag; // Follow casefolding
$end = $this->nullcontent ? ' /' : ''; // Tag without content, close it
// Build attributes output
$attrstring = '';
if (!empty($attributes) && is_array($attributes)) {
// TODO: check the attr name is valid
foreach ($attributes as $name => $value) {
$name = $this->casefolding ? strtoupper($name) : $name; // Follow casefolding
$attrstring .= ' ' . $name . '="'.
$this->xml_safe_attr_content($value) . '"';
}
}
// Optional xml schema definition (level 0 only)
$schemastring = '';
if ($this->level == 0 && !empty($this->xmlschema)) {
$schemastring .= "\n " . 'xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"' .
"\n " . 'xsi:noNamespaceSchemaLocation="' . $this->xml_safe_attr_content($this->xmlschema) . '"';
}
// Send to xml_output
$this->write($pre . '<' . $tag . $attrstring . $schemastring . $end . '>');
// Acumulate the tag and inc level
if (!$this->nullcontent) {
array_push($this->opentags, $tag);
$this->level++;
}
$this->lastwastext = false;
}
/**
* Outputs one XML end tag
*/
public function end_tag($tag) {
// TODO: check the tag name is valid
if ($this->level == 0) { // Nothing to end, already at level 0
throw new xml_writer_exception('xml_writer_end_tag_no_match');
}
$pre = $this->lastwastext ? '' : "\n" . str_repeat(' ', ($this->level - 1) * 2); // Indent
$tag = $this->casefolding ? strtoupper($tag) : $tag; // Follow casefolding
$lastopentag = array_pop($this->opentags);
if ($tag != $lastopentag) {
$a = new stdclass();
$a->lastopen = $lastopentag;
$a->tag = $tag;
throw new xml_writer_exception('xml_writer_end_tag_no_match', $a);
}
// Send to xml_output
$this->write($pre . '</' . $tag . '>');
$this->level--;
$this->lastwastext = false;
}
/**
* Outputs one tag completely (open, contents and close)
*/
public function full_tag($tag, $content = null, $attributes = null) {
$content = $this->text_content($content); // First of all, apply transformations
$this->nullcontent = is_null($content) ? true : false; // Is it null content
$this->begin_tag($tag, $attributes);
if (!$this->nullcontent) {
$this->write($content);
$this->lastwastext = true;
$this->end_tag($tag);
}
}
// Protected API starts here
/**
* Send some XML formatted chunk to output.
*/
protected function write($output) {
$this->output->write($output);
}
/**
* Get default prologue contents for this writer if there isn't a custom one
*/
protected function get_default_prologue() {
return "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n";
}
/**
* Clean attribute content and encode needed chars
* (&, <, >, ") - single quotes not needed in this class
* as far as we are enclosing with "
*/
protected function xml_safe_attr_content($content) {
return htmlspecialchars($this->xml_safe_utf8($content), ENT_COMPAT);
}
/**
* Clean text content and encode needed chars
* (&, <, >)
*/
protected function xml_safe_text_content($content) {
return htmlspecialchars($this->xml_safe_utf8($content), ENT_NOQUOTES);
}
/**
* Perform some UTF-8 cleaning, stripping the control chars (\x0-\x1f)
* but tabs (\x9), newlines (\xa) and returns (\xd). The delete control
* char (\x7f) is also included. All them are forbiden in XML 1.0 specs.
* The expression below seems to be UTF-8 safe too because it simply
* ignores the rest of characters. Also normalize linefeeds and return chars.
*/
protected function xml_safe_utf8($content) {
$content = preg_replace('/[\x-\x8\xb-\xc\xe-\x1f\x7f]/is','', $content); // clean CTRL chars
$content = preg_replace("/\r\n|\r/", "\n", $content); // Normalize line&return=>line
return $content;
}
/**
* Returns text contents processed by the corresponding @xml_contenttransformer
*/
protected function text_content($content) {
if (!is_null($this->contenttransformer)) { // Apply content transformation
$content = $this->contenttransformer->process($content);
}
return is_null($content) ? null : $this->xml_safe_text_content($content); // Safe UTF-8 and encode
}
}
/*
* Exception class used by all the @xml_writer stuff
*/
class xml_writer_exception extends moodle_exception {
public function __construct($errorcode, $a=NULL, $debuginfo=null) {
parent::__construct($errorcode, 'error', '', $a, $debuginfo);
}
}