From bf6ce67fc176cf8376b0db9f0f0886f089a67610 Mon Sep 17 00:00:00 2001
From: "Edward Z. Yang" <edwardzyang@thewritingpot.com>
Date: Sun, 17 Jun 2007 21:27:39 +0000
Subject: [PATCH] [1.7.0] Prototype-declarations for Lexer removed in favor of
 configuration determination of Lexer implementations.

git-svn-id: http://htmlpurifier.org/svnroot/htmlpurifier/trunk@1153 48356398-32a2-884e-a903-53898d9a118a
---
 NEWS                           |   2 +
 library/HTMLPurifier.php       |   9 ++-
 library/HTMLPurifier/Lexer.php | 136 +++++++++++++++++++++++----------
 3 files changed, 105 insertions(+), 42 deletions(-)

diff --git a/NEWS b/NEWS
index cdec03e4..3464dcb8 100644
--- a/NEWS
+++ b/NEWS
@@ -26,6 +26,8 @@ NEWS ( CHANGELOG and HISTORY )                                     HTMLPurifier
   DefinitionID directive (%HTML.DefinitionID for HTMLDefinition).
 # Contents between <script> tags are now completely removed if <script>
   is not allowed
+# Prototype-declarations for Lexer removed in favor of configuration
+  determination of Lexer implementations.
 ! HTML Purifier now works in PHP 4.3.2.
 ! Configuration form-editing API makes tweaking HTMLPurifier_Config a
   breeze!
diff --git a/library/HTMLPurifier.php b/library/HTMLPurifier.php
index a25414d0..f21f199c 100644
--- a/library/HTMLPurifier.php
+++ b/library/HTMLPurifier.php
@@ -69,7 +69,7 @@ class HTMLPurifier
     var $config;
     var $filters;
     
-    var $lexer, $strategy, $generator;
+    var $strategy, $generator;
     
     /**
      * Final HTMLPurifier_Context of last run purification. Might be an array.
@@ -89,7 +89,6 @@ class HTMLPurifier
         
         $this->config = HTMLPurifier_Config::create($config);
         
-        $this->lexer        = HTMLPurifier_Lexer::create();
         $this->strategy     = new HTMLPurifier_Strategy_Core();
         $this->generator    = new HTMLPurifier_Generator();
         
@@ -117,6 +116,10 @@ class HTMLPurifier
         
         $config = $config ? HTMLPurifier_Config::create($config) : $this->config;
         
+        // implementation is partially environment dependant, partially
+        // configuration dependant
+        $lexer = HTMLPurifier_Lexer::create($config);
+        
         $context = new HTMLPurifier_Context();
         $html = HTMLPurifier_Encoder::convertToUTF8($html, $config, $context);
         
@@ -130,7 +133,7 @@ class HTMLPurifier
                 // list of tokens
                 $this->strategy->execute(
                     // list of un-purified tokens
-                    $this->lexer->tokenizeHTML(
+                    $lexer->tokenizeHTML(
                         // un-purified HTML
                         $html, $config, $context
                     ),
diff --git a/library/HTMLPurifier/Lexer.php b/library/HTMLPurifier/Lexer.php
index ec113265..f3af0487 100644
--- a/library/HTMLPurifier/Lexer.php
+++ b/library/HTMLPurifier/Lexer.php
@@ -19,6 +19,37 @@ HTMLPurifier_ConfigSchema::define(
     'drop all sections except the content between body.'
 );
 
+HTMLPurifier_ConfigSchema::define(
+    'Core', 'LexerImpl', null, 'mixed/null', '
+<p>
+  This parameter determines what lexer implementation can be used. The
+  valid values are:
+</p>
+<dl>
+  <dt><em>null</em></dt>
+  <dd>
+    Recommended, the lexer implementation will be auto-detected based on
+    your PHP-version and configuration.
+  </dd>
+  <dt><em>string</em> lexer identifier</dt>
+  <dd>
+    This is a slim way of manually overridding the implementation.
+    Currently recognized values are: DOMLex (the default PHP5 implementation)
+    and DirectLex (the default PHP4 implementation). Only use this if
+    you know what you are doing: usually, the auto-detection will
+    manage things for cases you aren\'t even aware of.
+  </dd>
+  <dt><em>object</em> lexer instance</dt>
+  <dd>
+    Super-advanced: you can specify your own, custom, implementation that
+    implements the interface defined by <code>HTMLPurifier_Lexer</code>.
+    I may remove this option simply because I don\'t expect anyone
+    to use it.
+  </dd>
+</dl>
+'
+);
+
 /**
  * Forgivingly lexes HTML (SGML-style) markup into tokens.
  * 
@@ -63,11 +94,76 @@ HTMLPurifier_ConfigSchema::define(
 class HTMLPurifier_Lexer
 {
     
+    // -- STATIC ----------------------------------------------------------
+    
+    /**
+     * Retrieves or sets the default Lexer as a Prototype Factory.
+     * 
+     * Depending on what PHP version you are running, the abstract base
+     * Lexer class will determine which concrete Lexer is best for you:
+     * HTMLPurifier_Lexer_DirectLex for PHP 4, and HTMLPurifier_Lexer_DOMLex
+     * for PHP 5 and beyond.  This general rule has a few exceptions to it
+     * involving special features that only DirectLex implements.
+     * 
+     * @static
+     * 
+     * @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.
+     * 
+     * @note In PHP4, it is possible to call this factory method from 
+     *       subclasses, such usage is not recommended and not
+     *       forwards-compatible.
+     * 
+     * @param $prototype Optional prototype lexer or configuration object
+     * @return Concrete lexer.
+     */
+    function create($config) {
+        
+        if (!is_a($config, '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 = $config->get('Core', 'LexerImpl');
+        }
+        
+        if (is_object($lexer)) {
+            return $lexer;
+        }
+        
+        if (is_null($lexer)) { do {
+            // auto-detectection algorithm
+            
+            if (version_compare(PHP_VERSION, "5", ">=") && // check for PHP5
+                class_exists('DOMDocument')) { // check for DOM support
+                $lexer = 'DOMLex';
+            } else {
+                $lexer = 'DirectLex';
+            }
+            
+        } while(0); } // do..while so we can break
+        
+        // instantiate recognized string names
+        switch ($lexer) {
+            case 'DOMLex':
+                return new HTMLPurifier_Lexer_DOMLex();
+            case 'DirectLex':
+                return new HTMLPurifier_Lexer_DirectLex();
+            default:
+                trigger_error("Cannot instantiate unrecognized Lexer type " . htmlspecialchars($lexer), E_USER_ERROR);
+        }
+        
+    }
+    
+    // -- CONVENIENCE MEMBERS ---------------------------------------------
+    
     function HTMLPurifier_Lexer() {
         $this->_entity_parser = new HTMLPurifier_EntityParser();
     }
     
-    
     /**
      * Most common entity to raw value conversion table for special entities.
      * @protected
@@ -131,44 +227,6 @@ class HTMLPurifier_Lexer
         trigger_error('Call to abstract class', E_USER_ERROR);
     }
     
-    /**
-     * Retrieves or sets the default Lexer as a Prototype Factory.
-     * 
-     * Depending on what PHP version you are running, the abstract base
-     * Lexer class will determine which concrete Lexer is best for you:
-     * HTMLPurifier_Lexer_DirectLex for PHP 4, and HTMLPurifier_Lexer_DOMLex
-     * for PHP 5 and beyond.
-     * 
-     * Passing the optional prototype lexer parameter will override the
-     * default with your own implementation.  A copy/reference of the prototype
-     * lexer will now be returned when you request a new lexer.
-     * 
-     * @static
-     * 
-     * @note
-     * Though it is possible to call this factory method from subclasses,
-     * such usage is not recommended.
-     * 
-     * @param $prototype Optional prototype lexer.
-     * @return Concrete lexer.
-     */
-    function create($prototype = null) {
-        // we don't really care if it's a reference or a copy
-        static $lexer = null;
-        if ($prototype) {
-            $lexer = $prototype;
-        }
-        if (empty($lexer)) {
-            if (version_compare(PHP_VERSION, "5", ">=") && // check for PHP5
-                class_exists('DOMDocument')) { // check for DOM support
-                $lexer = new HTMLPurifier_Lexer_DOMLex();
-            } else {
-                $lexer = new HTMLPurifier_Lexer_DirectLex();
-            }
-        }
-        return $lexer;
-    }
-    
     /**
      * Translates CDATA sections into regular sections (through escaping).
      *