Detect if domxml extension is loaded, and use DirectLex accordingly.

Signed-off-by: Edward Z. Yang <edwardzyang@thewritingpot.com>

NEWS

@@ -66,6 +66,7 @@ NEWS ( CHANGELOG and HISTORY )                                     HTMLPurifier
 - Will now throw exception on many error conditions during lexer creation; also
   throw an exception when MaintainLineNumbers is true, but a non-tracksLineNumbers
   is being used.
+- Detect if domxml extension is loaded, and use DirectLEx accordingly.
 . Strategy_MakeWellFormed now operates in-place, saving memory and allowing
   for more interesting filter-backtracking
 . New HTMLPurifier_Injector->rewind() functionality, allows injectors to rewind

library/HTMLPurifier/Lexer.php

@@ -93,9 +93,15 @@ class HTMLPurifier_Lexer
                     break;
                 }
                 
-                if (class_exists('DOMDocument') && method_exists('DOMDocument', 'loadHTML')) {
-                    // check for DOM support, because, surprisingly enough,
-                    // it's *not* part of the core!
+                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';

tests/HTMLPurifier/PHPT/domxml.phpt

@@ -0,0 +1,15 @@
+--TEST--
+DirectLex with domxml test
+--SKIPIF--
+<?php
+if (!extension_loaded('dom')) {
+    echo "skip - dom not available";
+} elseif (!extension_loaded('domxml')) {
+    echo "skip - domxml not loaded";
+}
+--FILE--
+<?php
+require '../library/HTMLPurifier.auto.php';
+echo get_class(HTMLPurifier_Lexer::create(HTMLPurifier_Config::createDefault()));
+--EXPECT--
+HTMLPurifier_Lexer_DirectLex