1 files changed, 139 insertions, 0 deletions
diff --git a/library/HTMLPurifier/Lexer/PEARSax3.php b/library/HTMLPurifier/Lexer/PEARSax3.php
new file mode 100644
index 000000000..1d358c7b6
--- /dev/null
+++ b/library/HTMLPurifier/Lexer/PEARSax3.php
@@ -0,0 +1,139 @@
+<?php
+
+/**
+ * Proof-of-concept lexer that uses the PEAR package XML_HTMLSax3 to parse HTML.
+ *
+ * PEAR, not suprisingly, also has a SAX parser for HTML.  I don't know
+ * very much about implementation, but it's fairly well written.  However, that
+ * abstraction comes at a price: performance. You need to have it installed,
+ * and if the API changes, it might break our adapter. Not sure whether or not
+ * it's UTF-8 aware, but it has some entity parsing trouble (in all areas,
+ * text and attributes).
+ *
+ * Quite personally, I don't recommend using the PEAR class, and the defaults
+ * don't use it. The unit tests do perform the tests on the SAX parser too, but
+ * whatever it does for poorly formed HTML is up to it.
+ *
+ * @todo Generalize so that XML_HTMLSax is also supported.
+ *
+ * @warning Entity-resolution inside attributes is broken.
+ */
+
+class HTMLPurifier_Lexer_PEARSax3 extends HTMLPurifier_Lexer
+{
+
+    /**
+     * Internal accumulator array for SAX parsers.
+     */
+    protected $tokens = array();
+    protected $last_token_was_empty;
+
+    private $parent_handler;
+    private $stack = array();
+
+    public function tokenizeHTML($string, $config, $context) {
+
+        $this->tokens = array();
+        $this->last_token_was_empty = false;
+
+        $string = $this->normalize($string, $config, $context);
+
+        $this->parent_handler = set_error_handler(array($this, 'muteStrictErrorHandler'));
+
+        $parser = new XML_HTMLSax3();
+        $parser->set_object($this);
+        $parser->set_element_handler('openHandler','closeHandler');
+        $parser->set_data_handler('dataHandler');
+        $parser->set_escape_handler('escapeHandler');
+
+        // doesn't seem to work correctly for attributes
+        $parser->set_option('XML_OPTION_ENTITIES_PARSED', 1);
+
+        $parser->parse($string);
+
+        restore_error_handler();
+
+        return $this->tokens;
+
+    }
+
+    /**
+     * Open tag event handler, interface is defined by PEAR package.
+     */
+    public function openHandler(&$parser, $name, $attrs, $closed) {
+        // entities are not resolved in attrs
+        foreach ($attrs as $key => $attr) {
+            $attrs[$key] = $this->parseData($attr);
+        }
+        if ($closed) {
+            $this->tokens[] = new HTMLPurifier_Token_Empty($name, $attrs);
+            $this->last_token_was_empty = true;
+        } else {
+            $this->tokens[] = new HTMLPurifier_Token_Start($name, $attrs);
+        }
+        $this->stack[] = $name;
+        return true;
+    }
+
+    /**
+     * Close tag event handler, interface is defined by PEAR package.
+     */
+    public function closeHandler(&$parser, $name) {
+        // HTMLSax3 seems to always send empty tags an extra close tag
+        // check and ignore if you see it:
+        // [TESTME] to make sure it doesn't overreach
+        if ($this->last_token_was_empty) {
+            $this->last_token_was_empty = false;
+            return true;
+        }
+        $this->tokens[] = new HTMLPurifier_Token_End($name);
+        if (!empty($this->stack)) array_pop($this->stack);
+        return true;
+    }
+
+    /**
+     * Data event handler, interface is defined by PEAR package.
+     */
+    public function dataHandler(&$parser, $data) {
+        $this->last_token_was_empty = false;
+        $this->tokens[] = new HTMLPurifier_Token_Text($data);
+        return true;
+    }
+
+    /**
+     * Escaped text handler, interface is defined by PEAR package.
+     */
+    public function escapeHandler(&$parser, $data) {
+        if (strpos($data, '--') === 0) {
+            // remove trailing and leading double-dashes
+            $data = substr($data, 2);
+            if (strlen($data) >= 2 && substr($data, -2) == "--") {
+                $data = substr($data, 0, -2);
+            }
+            if (isset($this->stack[sizeof($this->stack) - 1]) &&
+                $this->stack[sizeof($this->stack) - 1] == "style") {
+                $this->tokens[] = new HTMLPurifier_Token_Text($data);
+            } else {
+                $this->tokens[] = new HTMLPurifier_Token_Comment($data);
+            }
+            $this->last_token_was_empty = false;
+        }
+        // CDATA is handled elsewhere, but if it was handled here:
+        //if (strpos($data, '[CDATA[') === 0) {
+        //    $this->tokens[] = new HTMLPurifier_Token_Text(
+        //        substr($data, 7, strlen($data) - 9) );
+        //}
+        return true;
+    }
+
+    /**
+     * An error handler that mutes strict errors
+     */
+    public function muteStrictErrorHandler($errno, $errstr, $errfile=null, $errline=null, $errcontext=null) {
+        if ($errno == E_STRICT) return;
+        return call_user_func($this->parent_handler, $errno, $errstr, $errfile, $errline, $errcontext);
+    }
+
+}
+
+// vim: et sw=4 sts=4