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git.wh0rd.org - tt-rss.git/blob - lib/htmlpurifier/library/HTMLPurifier/Lexer.php
4 * Forgivingly lexes HTML (SGML-style) markup into tokens.
6 * A lexer parses a string of SGML-style markup and converts them into
7 * corresponding tokens. It doesn't check for well-formedness, although its
8 * internal mechanism may make this automatic (such as the case of
9 * HTMLPurifier_Lexer_DOMLex). There are several implementations to choose
12 * A lexer is HTML-oriented: it might work with XML, but it's not
13 * recommended, as we adhere to a subset of the specification for optimization
14 * reasons. This might change in the future. Also, most tokenizers are not
15 * expected to handle DTDs or PIs.
17 * This class should not be directly instantiated, but you may use create() to
18 * retrieve a default copy of the lexer. Being a supertype, this class
19 * does not actually define any implementation, but offers commonly used
20 * convenience functions for subclasses.
22 * @note The unit tests will instantiate this class for testing purposes, as
23 * many of the utility functions require a class to be instantiated.
24 * This means that, even though this class is not runnable, it will
25 * not be declared abstract.
30 * We use tokens rather than create a DOM representation because DOM would:
33 * -# Require more processing and memory to create,
34 * -# Is not streamable, and
35 * -# Has the entire document structure (html and body not needed).
38 * However, DOM is helpful in that it makes it easy to move around nodes
39 * without a lot of lookaheads to see when a tag is closed. This is a
40 * limitation of the token system and some workarounds would be nice.
42 class HTMLPurifier_Lexer
46 * Whether or not this lexer implements line-number/column-number tracking.
47 * If it does, set to true.
49 public $tracksLineNumbers = false ;
51 // -- STATIC ----------------------------------------------------------
54 * Retrieves or sets the default Lexer as a Prototype Factory.
56 * By default HTMLPurifier_Lexer_DOMLex will be returned. There are
57 * a few exceptions involving special features that only DirectLex
60 * @note The behavior of this class has changed, rather than accepting
61 * a prototype object, it now accepts a configuration object.
62 * To specify your own prototype, set %Core.LexerImpl to it.
63 * This change in behavior de-singletonizes the lexer object.
65 * @param $config Instance of HTMLPurifier_Config
66 * @return Concrete lexer.
68 public static function create ( $config ) {
70 if (!( $config instanceof HTMLPurifier_Config
)) {
72 trigger_error ( "Passing a prototype to
73 HTMLPurifier_Lexer::create() is deprecated, please instead
74 use %Core .LexerImpl" , E_USER_WARNING
);
76 $lexer = $config -> get ( 'Core' , 'LexerImpl' );
80 $config -> get ( 'Core' , 'MaintainLineNumbers' ) ||
81 $config -> get ( 'Core' , 'CollectErrors' );
84 if ( is_object ( $lexer )) {
88 if ( is_null ( $lexer )) { do {
89 // auto-detection algorithm
91 if ( $needs_tracking ) {
97 class_exists ( 'DOMDocument' ) &&
98 method_exists ( 'DOMDocument' , 'loadHTML' ) &&
99 ! extension_loaded ( 'domxml' )
101 // check for DOM support, because while it's part of the
102 // core, it can be disabled compile time. Also, the PECL
103 // domxml extension overrides the default DOM, and is evil
104 // and nasty and we shan't bother to support it
107 $lexer = 'DirectLex' ;
110 } while ( 0 ); } // do..while so we can break
112 // instantiate recognized string names
115 $inst = new HTMLPurifier_Lexer_DOMLex ();
118 $inst = new HTMLPurifier_Lexer_DirectLex ();
121 $inst = new HTMLPurifier_Lexer_PH5P ();
124 throw new HTMLPurifier_Exception ( "Cannot instantiate unrecognized Lexer type " . htmlspecialchars ( $lexer ));
128 if (! $inst ) throw new HTMLPurifier_Exception ( 'No lexer was instantiated' );
130 // once PHP DOM implements native line numbers, or we
131 // hack out something using XSLT, remove this stipulation
132 if ( $needs_tracking && ! $inst -> tracksLineNumbers
) {
133 throw new HTMLPurifier_Exception ( 'Cannot use lexer that does not support line numbers with Core.MaintainLineNumbers or Core.CollectErrors (use DirectLex instead)' );
140 // -- CONVENIENCE MEMBERS ---------------------------------------------
142 public function __construct () {
143 $this -> _entity_parser
= new HTMLPurifier_EntityParser ();
147 * Most common entity to raw value conversion table for special entities.
149 protected $_special_entity2str =
161 * Parses special entities into the proper characters.
163 * This string will translate escaped versions of the special characters
164 * into the correct ones.
167 * You should be able to treat the output of this function as
168 * completely parsed, but that's only because all other entities should
169 * have been handled previously in substituteNonSpecialEntities()
171 * @param $string String character data to be parsed.
172 * @returns Parsed character data.
174 public function parseData ( $string ) {
176 // following functions require at least one character
177 if ( $string === '' ) return '' ;
179 // subtracts amps that cannot possibly be escaped
180 $num_amp = substr_count ( $string , '&' ) - substr_count ( $string , '& ' ) -
181 ( $string [ strlen ( $string )- 1 ] === '&' ?
1 : 0 );
183 if (! $num_amp ) return $string ; // abort if no entities
184 $num_esc_amp = substr_count ( $string , '&' );
185 $string = strtr ( $string , $this -> _special_entity2str
);
187 // code duplication for sake of optimization, see above
188 $num_amp_2 = substr_count ( $string , '&' ) - substr_count ( $string , '& ' ) -
189 ( $string [ strlen ( $string )- 1 ] === '&' ?
1 : 0 );
191 if ( $num_amp_2 <= $num_esc_amp ) return $string ;
193 // hmm... now we have some uncommon entities. Use the callback.
194 $string = $this -> _entity_parser
-> substituteSpecialEntities ( $string );
199 * Lexes an HTML string into tokens.
201 * @param $string String HTML.
202 * @return HTMLPurifier_Token array representation of HTML.
204 public function tokenizeHTML ( $string , $config , $context ) {
205 trigger_error ( 'Call to abstract class' , E_USER_ERROR
);
209 * Translates CDATA sections into regular sections (through escaping).
211 * @param $string HTML string to process.
212 * @returns HTML with CDATA sections escaped.
214 protected static function escapeCDATA ( $string ) {
215 return preg_replace_callback (
216 '/<!\[CDATA\[(.+?)\]\]>/s' ,
217 array ( 'HTMLPurifier_Lexer' , 'CDATACallback' ),
223 * Special CDATA case that is especially convoluted for <script>
225 protected static function escapeCommentedCDATA ( $string ) {
226 return preg_replace_callback (
227 '#<!--//--><!\[CDATA\[//><!--(.+?)//--><!\]\]>#s' ,
228 array ( 'HTMLPurifier_Lexer' , 'CDATACallback' ),
234 * Callback function for escapeCDATA() that does the work.
236 * @warning Though this is public in order to let the callback happen,
237 * calling it directly is not recommended.
238 * @params $matches PCRE matches array, with index 0 the entire match
239 * and 1 the inside of the CDATA section.
240 * @returns Escaped internals of the CDATA section.
242 protected static function CDATACallback ( $matches ) {
243 // not exactly sure why the character set is needed, but whatever
244 return htmlspecialchars ( $matches [ 1 ], ENT_COMPAT
, 'UTF-8' );
248 * Takes a piece of HTML and normalizes it by converting entities, fixing
249 * encoding, extracting bits, and other good stuff.
250 * @todo Consider making protected
252 public function normalize ( $html , $config , $context ) {
254 // normalize newlines to \n
255 $html = str_replace ( " \r\n " , " \n " , $html );
256 $html = str_replace ( " \r " , " \n " , $html );
258 if ( $config -> get ( 'HTML' , 'Trusted' )) {
259 // escape convoluted CDATA
260 $html = $this -> escapeCommentedCDATA ( $html );
264 $html = $this -> escapeCDATA ( $html );
266 // extract body from document if applicable
267 if ( $config -> get ( 'Core' , 'ConvertDocumentToFragment' )) {
268 $html = $this -> extractBody ( $html );
271 // expand entities that aren't the big five
272 $html = $this -> _entity_parser
-> substituteNonSpecialEntities ( $html );
274 // clean into wellformed UTF-8 string for an SGML context: this has
275 // to be done after entity expansion because the entities sometimes
276 // represent non-SGML characters (horror, horror!)
277 $html = HTMLPurifier_Encoder
:: cleanUTF8 ( $html );
283 * Takes a string of HTML (fragment or document) and returns the content
284 * @todo Consider making protected
286 public function extractBody ( $html ) {
288 $result = preg_match ( '!<body[^>]*>(.+?)</body>!is' , $html , $matches );
298 // vim: et sw=4 sts=4