some important stuff we'll need

1 files changed, 326 insertions, 0 deletions

diff --git a/lib/htmlpurifier/library/HTMLPurifier/Lexer.php b/lib/htmlpurifier/library/HTMLPurifier/Lexer.php
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+++ b/lib/htmlpurifier/library/HTMLPurifier/Lexer.php
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+<?php
+
+/**
+ * Forgivingly lexes HTML (SGML-style) markup into tokens.
+ *
+ * A lexer parses a string of SGML-style markup and converts them into
+ * corresponding tokens.  It doesn't check for well-formedness, although its
+ * internal mechanism may make this automatic (such as the case of
+ * HTMLPurifier_Lexer_DOMLex).  There are several implementations to choose
+ * from.
+ *
+ * A lexer is HTML-oriented: it might work with XML, but it's not
+ * recommended, as we adhere to a subset of the specification for optimization
+ * reasons. This might change in the future. Also, most tokenizers are not
+ * expected to handle DTDs or PIs.
+ *
+ * This class should not be directly instantiated, but you may use create() to
+ * retrieve a default copy of the lexer.  Being a supertype, this class
+ * does not actually define any implementation, but offers commonly used
+ * convenience functions for subclasses.
+ *
+ * @note The unit tests will instantiate this class for testing purposes, as
+ *       many of the utility functions require a class to be instantiated.
+ *       This means that, even though this class is not runnable, it will
+ *       not be declared abstract.
+ *
+ * @par
+ *
+ * @note
+ * We use tokens rather than create a DOM representation because DOM would:
+ *
+ * @par
+ *  -# Require more processing and memory to create,
+ *  -# Is not streamable, and
+ *  -# Has the entire document structure (html and body not needed).
+ *
+ * @par
+ * However, DOM is helpful in that it makes it easy to move around nodes
+ * without a lot of lookaheads to see when a tag is closed. This is a
+ * limitation of the token system and some workarounds would be nice.
+ */
+class HTMLPurifier_Lexer
+{
+
+    /**
+     * Whether or not this lexer implements line-number/column-number tracking.
+     * If it does, set to true.
+     */
+    public $tracksLineNumbers = false;
+
+    // -- STATIC ----------------------------------------------------------
+
+    /**
+     * Retrieves or sets the default Lexer as a Prototype Factory.
+     *
+     * By default HTMLPurifier_Lexer_DOMLex will be returned. There are
+     * a few exceptions involving special features that only DirectLex
+     * implements.
+     *
+     * @note The behavior of this class has changed, rather than accepting
+     *       a prototype object, it now accepts a configuration object.
+     *       To specify your own prototype, set %Core.LexerImpl to it.
+     *       This change in behavior de-singletonizes the lexer object.
+     *
+     * @param $config Instance of HTMLPurifier_Config
+     * @return Concrete lexer.
+     */
+    public static function create($config) {
+
+        if (!($config instanceof HTMLPurifier_Config)) {
+            $lexer = $config;
+            trigger_error("Passing a prototype to
+              HTMLPurifier_Lexer::create() is deprecated, please instead
+              use %Core.LexerImpl", E_USER_WARNING);
+        } else {
+            $lexer = $config->get('Core.LexerImpl');
+        }
+
+        $needs_tracking =
+            $config->get('Core.MaintainLineNumbers') ||
+            $config->get('Core.CollectErrors');
+
+        $inst = null;
+        if (is_object($lexer)) {
+            $inst = $lexer;
+        } else {
+
+            if (is_null($lexer)) { do {
+                // auto-detection algorithm
+
+                if ($needs_tracking) {
+                    $lexer = 'DirectLex';
+                    break;
+                }
+
+                if (
+                    class_exists('DOMDocument') &&
+                    method_exists('DOMDocument', 'loadHTML') &&
+                    !extension_loaded('domxml')
+                ) {
+                    // check for DOM support, because while it's part of the
+                    // core, it can be disabled compile time. Also, the PECL
+                    // domxml extension overrides the default DOM, and is evil
+                    // and nasty and we shan't bother to support it
+                    $lexer = 'DOMLex';
+                } else {
+                    $lexer = 'DirectLex';
+                }
+
+            } while(0); } // do..while so we can break
+
+            // instantiate recognized string names
+            switch ($lexer) {
+                case 'DOMLex':
+                    $inst = new HTMLPurifier_Lexer_DOMLex();
+                    break;
+                case 'DirectLex':
+                    $inst = new HTMLPurifier_Lexer_DirectLex();
+                    break;
+                case 'PH5P':
+                    $inst = new HTMLPurifier_Lexer_PH5P();
+                    break;
+                default:
+                    throw new HTMLPurifier_Exception("Cannot instantiate unrecognized Lexer type " . htmlspecialchars($lexer));
+            }
+        }
+
+        if (!$inst) throw new HTMLPurifier_Exception('No lexer was instantiated');
+
+        // once PHP DOM implements native line numbers, or we
+        // hack out something using XSLT, remove this stipulation
+        if ($needs_tracking && !$inst->tracksLineNumbers) {
+            throw new HTMLPurifier_Exception('Cannot use lexer that does not support line numbers with Core.MaintainLineNumbers or Core.CollectErrors (use DirectLex instead)');
+        }
+
+        return $inst;
+
+    }
+
+    // -- CONVENIENCE MEMBERS ---------------------------------------------
+
+    public function __construct() {
+        $this->_entity_parser = new HTMLPurifier_EntityParser();
+    }
+
+    /**
+     * Most common entity to raw value conversion table for special entities.
+     */
+    protected $_special_entity2str =
+            array(
+                    '&quot;' => '"',
+                    '&amp;'  => '&',
+                    '&lt;'   => '<',
+                    '&gt;'   => '>',
+                    '&#39;'  => "'",
+                    '&#039;' => "'",
+                    '&#x27;' => "'"
+            );
+
+    /**
+     * Parses special entities into the proper characters.
+     *
+     * This string will translate escaped versions of the special characters
+     * into the correct ones.
+     *
+     * @warning
+     * You should be able to treat the output of this function as
+     * completely parsed, but that's only because all other entities should
+     * have been handled previously in substituteNonSpecialEntities()
+     *
+     * @param $string String character data to be parsed.
+     * @returns Parsed character data.
+     */
+    public function parseData($string) {
+
+        // following functions require at least one character
+        if ($string === '') return '';
+
+        // subtracts amps that cannot possibly be escaped
+        $num_amp = substr_count($string, '&') - substr_count($string, '& ') -
+            ($string[strlen($string)-1] === '&' ? 1 : 0);
+
+        if (!$num_amp) return $string; // abort if no entities
+        $num_esc_amp = substr_count($string, '&amp;');
+        $string = strtr($string, $this->_special_entity2str);
+
+        // code duplication for sake of optimization, see above
+        $num_amp_2 = substr_count($string, '&') - substr_count($string, '& ') -
+            ($string[strlen($string)-1] === '&' ? 1 : 0);
+
+        if ($num_amp_2 <= $num_esc_amp) return $string;
+
+        // hmm... now we have some uncommon entities. Use the callback.
+        $string = $this->_entity_parser->substituteSpecialEntities($string);
+        return $string;
+    }
+
+    /**
+     * Lexes an HTML string into tokens.
+     *
+     * @param $string String HTML.
+     * @return HTMLPurifier_Token array representation of HTML.
+     */
+    public function tokenizeHTML($string, $config, $context) {
+        trigger_error('Call to abstract class', E_USER_ERROR);
+    }
+
+    /**
+     * Translates CDATA sections into regular sections (through escaping).
+     *
+     * @param $string HTML string to process.
+     * @returns HTML with CDATA sections escaped.
+     */
+    protected static function escapeCDATA($string) {
+        return preg_replace_callback(
+            '/<!\[CDATA\[(.+?)\]\]>/s',
+            array('HTMLPurifier_Lexer', 'CDATACallback'),
+            $string
+        );
+    }
+
+    /**
+     * Special CDATA case that is especially convoluted for <script>
+     */
+    protected static function escapeCommentedCDATA($string) {
+        return preg_replace_callback(
+            '#<!--//--><!\[CDATA\[//><!--(.+?)//--><!\]\]>#s',
+            array('HTMLPurifier_Lexer', 'CDATACallback'),
+            $string
+        );
+    }
+
+    /**
+     * Special Internet Explorer conditional comments should be removed.
+     */
+    protected static function removeIEConditional($string) {
+        return preg_replace(
+            '#<!--\[if [^>]+\]>.*?<!\[endif\]-->#si', // probably should generalize for all strings
+            '',
+            $string
+        );
+    }
+
+    /**
+     * Callback function for escapeCDATA() that does the work.
+     *
+     * @warning Though this is public in order to let the callback happen,
+     *          calling it directly is not recommended.
+     * @params $matches PCRE matches array, with index 0 the entire match
+     *                  and 1 the inside of the CDATA section.
+     * @returns Escaped internals of the CDATA section.
+     */
+    protected static function CDATACallback($matches) {
+        // not exactly sure why the character set is needed, but whatever
+        return htmlspecialchars($matches[1], ENT_COMPAT, 'UTF-8');
+    }
+
+    /**
+     * Takes a piece of HTML and normalizes it by converting entities, fixing
+     * encoding, extracting bits, and other good stuff.
+     * @todo Consider making protected
+     */
+    public function normalize($html, $config, $context) {
+
+        // normalize newlines to \n
+        if ($config->get('Core.NormalizeNewlines')) {
+            $html = str_replace("\r\n", "\n", $html);
+            $html = str_replace("\r", "\n", $html);
+        }
+
+        if ($config->get('HTML.Trusted')) {
+            // escape convoluted CDATA
+            $html = $this->escapeCommentedCDATA($html);
+        }
+
+        // escape CDATA
+        $html = $this->escapeCDATA($html);
+
+        $html = $this->removeIEConditional($html);
+
+        // extract body from document if applicable
+        if ($config->get('Core.ConvertDocumentToFragment')) {
+            $e = false;
+            if ($config->get('Core.CollectErrors')) {
+                $e =& $context->get('ErrorCollector');
+            }
+            $new_html = $this->extractBody($html);
+            if ($e && $new_html != $html) {
+                $e->send(E_WARNING, 'Lexer: Extracted body');
+            }
+            $html = $new_html;
+        }
+
+        // expand entities that aren't the big five
+        $html = $this->_entity_parser->substituteNonSpecialEntities($html);
+
+        // clean into wellformed UTF-8 string for an SGML context: this has
+        // to be done after entity expansion because the entities sometimes
+        // represent non-SGML characters (horror, horror!)
+        $html = HTMLPurifier_Encoder::cleanUTF8($html);
+
+        // if processing instructions are to removed, remove them now
+        if ($config->get('Core.RemoveProcessingInstructions')) {
+            $html = preg_replace('#<\?.+?\?>#s', '', $html);
+        }
+
+        return $html;
+    }
+
+    /**
+     * Takes a string of HTML (fragment or document) and returns the content
+     * @todo Consider making protected
+     */
+    public function extractBody($html) {
+        $matches = array();
+        $result = preg_match('!<body[^>]*>(.*)</body>!is', $html, $matches);
+        if ($result) {
+            return $matches[1];
+        } else {
+            return $html;
+        }
+    }
+
+}
+
+// vim: et sw=4 sts=4