Merge pull request #1 from friendica/master

test pull request

6 files changed, 443 insertions, 419 deletions

diff --git a/library/HTMLPurifier/Strategy/Composite.php b/library/HTMLPurifier/Strategy/Composite.php
index 816490b79..d7d35ce7d 100644
--- a/library/HTMLPurifier/Strategy/Composite.php
+++ b/library/HTMLPurifier/Strategy/Composite.php
@@ -8,18 +8,23 @@ abstract class HTMLPurifier_Strategy_Composite extends HTMLPurifier_Strategy
 
     /**
      * List of strategies to run tokens through.
+     * @type HTMLPurifier_Strategy[]
      */
     protected $strategies = array();
 
-    abstract public function __construct();
-
-    public function execute($tokens, $config, $context) {
+    /**
+     * @param HTMLPurifier_Token[] $tokens
+     * @param HTMLPurifier_Config $config
+     * @param HTMLPurifier_Context $context
+     * @return HTMLPurifier_Token[]
+     */
+    public function execute($tokens, $config, $context)
+    {
         foreach ($this->strategies as $strategy) {
             $tokens = $strategy->execute($tokens, $config, $context);
         }
         return $tokens;
     }
-
 }
 
 // vim: et sw=4 sts=4
diff --git a/library/HTMLPurifier/Strategy/Core.php b/library/HTMLPurifier/Strategy/Core.php
index d90e15860..4414c17d6 100644
--- a/library/HTMLPurifier/Strategy/Core.php
+++ b/library/HTMLPurifier/Strategy/Core.php
@@ -5,14 +5,13 @@
  */
 class HTMLPurifier_Strategy_Core extends HTMLPurifier_Strategy_Composite
 {
-
-    public function __construct() {
+    public function __construct()
+    {
         $this->strategies[] = new HTMLPurifier_Strategy_RemoveForeignElements();
         $this->strategies[] = new HTMLPurifier_Strategy_MakeWellFormed();
         $this->strategies[] = new HTMLPurifier_Strategy_FixNesting();
         $this->strategies[] = new HTMLPurifier_Strategy_ValidateAttributes();
     }
-
 }
 
 // vim: et sw=4 sts=4
diff --git a/library/HTMLPurifier/Strategy/FixNesting.php b/library/HTMLPurifier/Strategy/FixNesting.php
index f81802391..6fa673db9 100644
--- a/library/HTMLPurifier/Strategy/FixNesting.php
+++ b/library/HTMLPurifier/Strategy/FixNesting.php
@@ -10,12 +10,12 @@
  * document type definitions, such as the chameleon nature of ins/del
  * tags and global child exclusions.
  *
- * The first major objective of this strategy is to iterate through all the
- * nodes (not tokens) of the list of tokens and determine whether or not
- * their children conform to the element's definition.  If they do not, the
- * child definition may optionally supply an amended list of elements that
- * is valid or require that the entire node be deleted (and the previous
- * node rescanned).
+ * The first major objective of this strategy is to iterate through all
+ * the nodes and determine whether or not their children conform to the
+ * element's definition.  If they do not, the child definition may
+ * optionally supply an amended list of elements that is valid or
+ * require that the entire node be deleted (and the previous node
+ * rescanned).
  *
  * The second objective is to ensure that explicitly excluded elements of
  * an element do not appear in its children.  Code that accomplishes this
@@ -25,24 +25,33 @@
  * @note Whether or not unrecognized children are silently dropped or
  *       translated into text depends on the child definitions.
  *
- * @todo Enable nodes to be bubbled out of the structure.
+ * @todo Enable nodes to be bubbled out of the structure.  This is
+ *       easier with our new algorithm.
  */
 
 class HTMLPurifier_Strategy_FixNesting extends HTMLPurifier_Strategy
 {
 
-    public function execute($tokens, $config, $context) {
+    /**
+     * @param HTMLPurifier_Token[] $tokens
+     * @param HTMLPurifier_Config $config
+     * @param HTMLPurifier_Context $context
+     * @return array|HTMLPurifier_Token[]
+     */
+    public function execute($tokens, $config, $context)
+    {
+
         //####################################################################//
         // Pre-processing
 
+        // O(n) pass to convert to a tree, so that we can efficiently
+        // refer to substrings
+        $top_node = HTMLPurifier_Arborize::arborize($tokens, $config, $context);
+
         // get a copy of the HTML definition
         $definition = $config->getHTMLDefinition();
 
-        // insert implicit "parent" node, will be removed at end.
-        // DEFINITION CALL
-        $parent_name = $definition->info_parent;
-        array_unshift($tokens, new HTMLPurifier_Token_Start($parent_name));
-        $tokens[] = new HTMLPurifier_Token_End($parent_name);
+        $excludes_enabled = !$config->get('Core.DisableExcludes');
 
         // setup the context variable 'IsInline', for chameleon processing
         // is 'false' when we are not inline, 'true' when it must always
@@ -57,272 +66,116 @@ class HTMLPurifier_Strategy_FixNesting extends HTMLPurifier_Strategy
         //####################################################################//
         // Loop initialization
 
-        // stack that contains the indexes of all parents,
-        // $stack[count($stack)-1] being the current parent
-        $stack = array();
-
         // stack that contains all elements that are excluded
         // it is organized by parent elements, similar to $stack,
         // but it is only populated when an element with exclusions is
         // processed, i.e. there won't be empty exclusions.
-        $exclude_stack = array();
+        $exclude_stack = array($definition->info_parent_def->excludes);
 
         // variable that contains the start token while we are processing
         // nodes. This enables error reporting to do its job
-        $start_token = false;
-        $context->register('CurrentToken', $start_token);
+        $node = $top_node;
+        // dummy token
+        list($token, $d) = $node->toTokenPair();
+        $context->register('CurrentNode', $node);
+        $context->register('CurrentToken', $token);
 
         //####################################################################//
         // Loop
 
-        // iterate through all start nodes. Determining the start node
-        // is complicated so it has been omitted from the loop construct
-        for ($i = 0, $size = count($tokens) ; $i < $size; ) {
-
-            //################################################################//
-            // Gather information on children
-
-            // child token accumulator
-            $child_tokens = array();
-
-            // scroll to the end of this node, report number, and collect
-            // all children
-            for ($j = $i, $depth = 0; ; $j++) {
-                if ($tokens[$j] instanceof HTMLPurifier_Token_Start) {
-                    $depth++;
-                    // skip token assignment on first iteration, this is the
-                    // token we currently are on
-                    if ($depth == 1) continue;
-                } elseif ($tokens[$j] instanceof HTMLPurifier_Token_End) {
-                    $depth--;
-                    // skip token assignment on last iteration, this is the
-                    // end token of the token we're currently on
-                    if ($depth == 0) break;
-                }
-                $child_tokens[] = $tokens[$j];
-            }
-
-            // $i is index of start token
-            // $j is index of end token
-
-            $start_token = $tokens[$i]; // to make token available via CurrentToken
-
-            //################################################################//
-            // Gather information on parent
-
-            // calculate parent information
-            if ($count = count($stack)) {
-                $parent_index = $stack[$count-1];
-                $parent_name  = $tokens[$parent_index]->name;
-                if ($parent_index == 0) {
-                    $parent_def   = $definition->info_parent_def;
-                } else {
-                    $parent_def   = $definition->info[$parent_name];
-                }
-            } else {
-                // processing as if the parent were the "root" node
-                // unknown info, it won't be used anyway, in the future,
-                // we may want to enforce one element only (this is
-                // necessary for HTML Purifier to clean entire documents
-                $parent_index = $parent_name = $parent_def = null;
-            }
-
-            // calculate context
-            if ($is_inline === false) {
-                // check if conditions make it inline
-                if (!empty($parent_def) && $parent_def->descendants_are_inline) {
-                    $is_inline = $count - 1;
-                }
-            } else {
-                // check if we're out of inline
-                if ($count === $is_inline) {
-                    $is_inline = false;
-                }
-            }
-
-            //################################################################//
-            // Determine whether element is explicitly excluded SGML-style
-
-            // determine whether or not element is excluded by checking all
-            // parent exclusions. The array should not be very large, two
-            // elements at most.
-            $excluded = false;
-            if (!empty($exclude_stack)) {
-                foreach ($exclude_stack as $lookup) {
-                    if (isset($lookup[$tokens[$i]->name])) {
-                        $excluded = true;
-                        // no need to continue processing
-                        break;
-                    }
+        // We need to implement a post-order traversal iteratively, to
+        // avoid running into stack space limits.  This is pretty tricky
+        // to reason about, so we just manually stack-ify the recursive
+        // variant:
+        //
+        //  function f($node) {
+        //      foreach ($node->children as $child) {
+        //          f($child);
+        //      }
+        //      validate($node);
+        //  }
+        //
+        // Thus, we will represent a stack frame as array($node,
+        // $is_inline, stack of children)
+        // e.g. array_reverse($node->children) - already processed
+        // children.
+
+        $parent_def = $definition->info_parent_def;
+        $stack = array(
+            array($top_node,
+                  $parent_def->descendants_are_inline,
+                  $parent_def->excludes, // exclusions
+                  0)
+            );
+
+        while (!empty($stack)) {
+            list($node, $is_inline, $excludes, $ix) = array_pop($stack);
+            // recursive call
+            $go = false;
+            $def = empty($stack) ? $definition->info_parent_def : $definition->info[$node->name];
+            while (isset($node->children[$ix])) {
+                $child = $node->children[$ix++];
+                if ($child instanceof HTMLPurifier_Node_Element) {
+                    $go = true;
+                    $stack[] = array($node, $is_inline, $excludes, $ix);
+                    $stack[] = array($child,
+                        // ToDo: I don't think it matters if it's def or
+                        // child_def, but double check this...
+                        $is_inline || $def->descendants_are_inline,
+                        empty($def->excludes) ? $excludes
+                                              : array_merge($excludes, $def->excludes),
+                        0);
+                    break;
                 }
-            }
-
-            //################################################################//
-            // Perform child validation
-
-            if ($excluded) {
-                // there is an exclusion, remove the entire node
-                $result = false;
-                $excludes = array(); // not used, but good to initialize anyway
+            };
+            if ($go) continue;
+            list($token, $d) = $node->toTokenPair();
+            // base case
+            if ($excludes_enabled && isset($excludes[$node->name])) {
+                $node->dead = true;
+                if ($e) $e->send(E_ERROR, 'Strategy_FixNesting: Node excluded');
             } else {
-                // DEFINITION CALL
-                if ($i === 0) {
-                    // special processing for the first node
-                    $def = $definition->info_parent_def;
-                } else {
-                    $def = $definition->info[$tokens[$i]->name];
-
+                // XXX I suppose it would be slightly more efficient to
+                // avoid the allocation here and have children
+                // strategies handle it
+                $children = array();
+                foreach ($node->children as $child) {
+                    if (!$child->dead) $children[] = $child;
                 }
-
-                if (!empty($def->child)) {
-                    // have DTD child def validate children
-                    $result = $def->child->validateChildren(
-                        $child_tokens, $config, $context);
+                $result = $def->child->validateChildren($children, $config, $context);
+                if ($result === true) {
+                    // nop
+                    $node->children = $children;
+                } elseif ($result === false) {
+                    $node->dead = true;
+                    if ($e) $e->send(E_ERROR, 'Strategy_FixNesting: Node removed');
                 } else {
-                    // weird, no child definition, get rid of everything
-                    $result = false;
-                }
-
-                // determine whether or not this element has any exclusions
-                $excludes = $def->excludes;
-            }
-
-            // $result is now a bool or array
-
-            //################################################################//
-            // Process result by interpreting $result
-
-            if ($result === true || $child_tokens === $result) {
-                // leave the node as is
-
-                // register start token as a parental node start
-                $stack[] = $i;
-
-                // register exclusions if there are any
-                if (!empty($excludes)) $exclude_stack[] = $excludes;
-
-                // move cursor to next possible start node
-                $i++;
-
-            } elseif($result === false) {
-                // remove entire node
-
-                if ($e) {
-                    if ($excluded) {
-                        $e->send(E_ERROR, 'Strategy_FixNesting: Node excluded');
-                    } else {
-                        $e->send(E_ERROR, 'Strategy_FixNesting: Node removed');
-                    }
-                }
-
-                // calculate length of inner tokens and current tokens
-                $length = $j - $i + 1;
-
-                // perform removal
-                array_splice($tokens, $i, $length);
-
-                // update size
-                $size -= $length;
-
-                // there is no start token to register,
-                // current node is now the next possible start node
-                // unless it turns out that we need to do a double-check
-
-                // this is a rought heuristic that covers 100% of HTML's
-                // cases and 99% of all other cases. A child definition
-                // that would be tricked by this would be something like:
-                // ( | a b c) where it's all or nothing. Fortunately,
-                // our current implementation claims that that case would
-                // not allow empty, even if it did
-                if (!$parent_def->child->allow_empty) {
-                    // we need to do a double-check
-                    $i = $parent_index;
-                    array_pop($stack);
-                }
-
-                // PROJECTED OPTIMIZATION: Process all children elements before
-                // reprocessing parent node.
-
-            } else {
-                // replace node with $result
-
-                // calculate length of inner tokens
-                $length = $j - $i - 1;
-
-                if ($e) {
-                    if (empty($result) && $length) {
-                        $e->send(E_ERROR, 'Strategy_FixNesting: Node contents removed');
-                    } else {
-                        $e->send(E_WARNING, 'Strategy_FixNesting: Node reorganized');
+                    $node->children = $result;
+                    if ($e) {
+                        // XXX This will miss mutations of internal nodes. Perhaps defer to the child validators
+                        if (empty($result) && !empty($children)) {
+                            $e->send(E_ERROR, 'Strategy_FixNesting: Node contents removed');
+                        } else if ($result != $children) {
+                            $e->send(E_WARNING, 'Strategy_FixNesting: Node reorganized');
+                        }
                     }
                 }
-
-                // perform replacement
-                array_splice($tokens, $i + 1, $length, $result);
-
-                // update size
-                $size -= $length;
-                $size += count($result);
-
-                // register start token as a parental node start
-                $stack[] = $i;
-
-                // register exclusions if there are any
-                if (!empty($excludes)) $exclude_stack[] = $excludes;
-
-                // move cursor to next possible start node
-                $i++;
-
             }
-
-            //################################################################//
-            // Scroll to next start node
-
-            // We assume, at this point, that $i is the index of the token
-            // that is the first possible new start point for a node.
-
-            // Test if the token indeed is a start tag, if not, move forward
-            // and test again.
-            $size = count($tokens);
-            while ($i < $size and !$tokens[$i] instanceof HTMLPurifier_Token_Start) {
-                if ($tokens[$i] instanceof HTMLPurifier_Token_End) {
-                    // pop a token index off the stack if we ended a node
-                    array_pop($stack);
-                    // pop an exclusion lookup off exclusion stack if
-                    // we ended node and that node had exclusions
-                    if ($i == 0 || $i == $size - 1) {
-                        // use specialized var if it's the super-parent
-                        $s_excludes = $definition->info_parent_def->excludes;
-                    } else {
-                        $s_excludes = $definition->info[$tokens[$i]->name]->excludes;
-                    }
-                    if ($s_excludes) {
-                        array_pop($exclude_stack);
-                    }
-                }
-                $i++;
-            }
-
         }
 
         //####################################################################//
         // Post-processing
 
-        // remove implicit parent tokens at the beginning and end
-        array_shift($tokens);
-        array_pop($tokens);
-
         // remove context variables
         $context->destroy('IsInline');
+        $context->destroy('CurrentNode');
         $context->destroy('CurrentToken');
 
         //####################################################################//
         // Return
 
-        return $tokens;
-
+        return HTMLPurifier_Arborize::flatten($node, $config, $context);
     }
-
 }
 
 // vim: et sw=4 sts=4
diff --git a/library/HTMLPurifier/Strategy/MakeWellFormed.php b/library/HTMLPurifier/Strategy/MakeWellFormed.php
index c73658400..e389e0011 100644
--- a/library/HTMLPurifier/Strategy/MakeWellFormed.php
+++ b/library/HTMLPurifier/Strategy/MakeWellFormed.php
@@ -2,66 +2,97 @@
 
 /**
  * Takes tokens makes them well-formed (balance end tags, etc.)
+ *
+ * Specification of the armor attributes this strategy uses:
+ *
+ *      - MakeWellFormed_TagClosedError: This armor field is used to
+ *        suppress tag closed errors for certain tokens [TagClosedSuppress],
+ *        in particular, if a tag was generated automatically by HTML
+ *        Purifier, we may rely on our infrastructure to close it for us
+ *        and shouldn't report an error to the user [TagClosedAuto].
  */
 class HTMLPurifier_Strategy_MakeWellFormed extends HTMLPurifier_Strategy
 {
 
     /**
      * Array stream of tokens being processed.
+     * @type HTMLPurifier_Token[]
      */
     protected $tokens;
 
     /**
-     * Current index in $tokens.
+     * Current token.
+     * @type HTMLPurifier_Token
      */
-    protected $t;
+    protected $token;
+
+    /**
+     * Zipper managing the true state.
+     * @type HTMLPurifier_Zipper
+     */
+    protected $zipper;
 
     /**
      * Current nesting of elements.
+     * @type array
      */
     protected $stack;
 
     /**
      * Injectors active in this stream processing.
+     * @type HTMLPurifier_Injector[]
      */
     protected $injectors;
 
     /**
      * Current instance of HTMLPurifier_Config.
+     * @type HTMLPurifier_Config
      */
     protected $config;
 
     /**
      * Current instance of HTMLPurifier_Context.
+     * @type HTMLPurifier_Context
      */
     protected $context;
 
-    public function execute($tokens, $config, $context) {
-
+    /**
+     * @param HTMLPurifier_Token[] $tokens
+     * @param HTMLPurifier_Config $config
+     * @param HTMLPurifier_Context $context
+     * @return HTMLPurifier_Token[]
+     * @throws HTMLPurifier_Exception
+     */
+    public function execute($tokens, $config, $context)
+    {
         $definition = $config->getHTMLDefinition();
 
         // local variables
         $generator = new HTMLPurifier_Generator($config, $context);
         $escape_invalid_tags = $config->get('Core.EscapeInvalidTags');
+        // used for autoclose early abortion
+        $global_parent_allowed_elements = $definition->info_parent_def->child->getAllowedElements($config);
         $e = $context->get('ErrorCollector', true);
-        $t = false; // token index
         $i = false; // injector index
-        $token      = false; // the current token
-        $reprocess  = false; // whether or not to reprocess the same token
+        list($zipper, $token) = HTMLPurifier_Zipper::fromArray($tokens);
+        if ($token === NULL) {
+            return array();
+        }
+        $reprocess = false; // whether or not to reprocess the same token
         $stack = array();
 
         // member variables
-        $this->stack   =& $stack;
-        $this->t       =& $t;
-        $this->tokens  =& $tokens;
-        $this->config  = $config;
+        $this->stack =& $stack;
+        $this->tokens =& $tokens;
+        $this->token =& $token;
+        $this->zipper =& $zipper;
+        $this->config = $config;
         $this->context = $context;
 
         // context variables
         $context->register('CurrentNesting', $stack);
-        $context->register('InputIndex',     $t);
-        $context->register('InputTokens',    $tokens);
-        $context->register('CurrentToken',   $token);
+        $context->register('InputZipper', $zipper);
+        $context->register('CurrentToken', $token);
 
         // -- begin INJECTOR --
 
@@ -73,9 +104,13 @@ class HTMLPurifier_Strategy_MakeWellFormed extends HTMLPurifier_Strategy
         unset($injectors['Custom']); // special case
         foreach ($injectors as $injector => $b) {
             // XXX: Fix with a legitimate lookup table of enabled filters
-            if (strpos($injector, '.') !== false) continue;
+            if (strpos($injector, '.') !== false) {
+                continue;
+            }
             $injector = "HTMLPurifier_Injector_$injector";
-            if (!$b) continue;
+            if (!$b) {
+                continue;
+            }
             $this->injectors[] = new $injector;
         }
         foreach ($def_injectors as $injector) {
@@ -83,7 +118,9 @@ class HTMLPurifier_Strategy_MakeWellFormed extends HTMLPurifier_Strategy
             $this->injectors[] = $injector;
         }
         foreach ($custom_injectors as $injector) {
-            if (!$injector) continue;
+            if (!$injector) {
+                continue;
+            }
             if (is_string($injector)) {
                 $injector = "HTMLPurifier_Injector_$injector";
                 $injector = new $injector;
@@ -95,14 +132,16 @@ class HTMLPurifier_Strategy_MakeWellFormed extends HTMLPurifier_Strategy
         // variables for performance reasons
         foreach ($this->injectors as $ix => $injector) {
             $error = $injector->prepare($config, $context);
-            if (!$error) continue;
+            if (!$error) {
+                continue;
+            }
             array_splice($this->injectors, $ix, 1); // rm the injector
             trigger_error("Cannot enable {$injector->name} injector because $error is not allowed", E_USER_WARNING);
         }
 
         // -- end INJECTOR --
 
-        // a note on punting:
+        // a note on reprocessing:
         //      In order to reduce code duplication, whenever some code needs
         //      to make HTML changes in order to make things "correct", the
         //      new HTML gets sent through the purifier, regardless of its
@@ -111,70 +150,75 @@ class HTMLPurifier_Strategy_MakeWellFormed extends HTMLPurifier_Strategy
         //      punt ($reprocess = true; continue;) and it does that for us.
 
         // isset is in loop because $tokens size changes during loop exec
-        for (
-            $t = 0;
-            $t == 0 || isset($tokens[$t - 1]);
-            // only increment if we don't need to reprocess
-            $reprocess ? $reprocess = false : $t++
-        ) {
+        for (;;
+             // only increment if we don't need to reprocess
+             $reprocess ? $reprocess = false : $token = $zipper->next($token)) {
 
             // check for a rewind
-            if (is_int($i) && $i >= 0) {
+            if (is_int($i)) {
                 // possibility: disable rewinding if the current token has a
                 // rewind set on it already. This would offer protection from
                 // infinite loop, but might hinder some advanced rewinding.
-                $rewind_to = $this->injectors[$i]->getRewind();
-                if (is_int($rewind_to) && $rewind_to < $t) {
-                    if ($rewind_to < 0) $rewind_to = 0;
-                    while ($t > $rewind_to) {
-                        $t--;
-                        $prev = $tokens[$t];
+                $rewind_offset = $this->injectors[$i]->getRewindOffset();
+                if (is_int($rewind_offset)) {
+                    for ($j = 0; $j < $rewind_offset; $j++) {
+                        if (empty($zipper->front)) break;
+                        $token = $zipper->prev($token);
                         // indicate that other injectors should not process this token,
                         // but we need to reprocess it
-                        unset($prev->skip[$i]);
-                        $prev->rewind = $i;
-                        if ($prev instanceof HTMLPurifier_Token_Start) array_pop($this->stack);
-                        elseif ($prev instanceof HTMLPurifier_Token_End) $this->stack[] = $prev->start;
+                        unset($token->skip[$i]);
+                        $token->rewind = $i;
+                        if ($token instanceof HTMLPurifier_Token_Start) {
+                            array_pop($this->stack);
+                        } elseif ($token instanceof HTMLPurifier_Token_End) {
+                            $this->stack[] = $token->start;
+                        }
                     }
                 }
                 $i = false;
             }
 
             // handle case of document end
-            if (!isset($tokens[$t])) {
+            if ($token === NULL) {
                 // kill processing if stack is empty
-                if (empty($this->stack)) break;
+                if (empty($this->stack)) {
+                    break;
+                }
 
                 // peek
                 $top_nesting = array_pop($this->stack);
                 $this->stack[] = $top_nesting;
 
-                // send error
+                // send error [TagClosedSuppress]
                 if ($e && !isset($top_nesting->armor['MakeWellFormed_TagClosedError'])) {
                     $e->send(E_NOTICE, 'Strategy_MakeWellFormed: Tag closed by document end', $top_nesting);
                 }
 
                 // append, don't splice, since this is the end
-                $tokens[] = new HTMLPurifier_Token_End($top_nesting->name);
+                $token = new HTMLPurifier_Token_End($top_nesting->name);
 
                 // punt!
                 $reprocess = true;
                 continue;
             }
 
-            $token = $tokens[$t];
-
-            //echo '<br>'; printTokens($tokens, $t); printTokens($this->stack);
+            //echo '<br>'; printZipper($zipper, $token);//printTokens($this->stack);
             //flush();
 
             // quick-check: if it's not a tag, no need to process
             if (empty($token->is_tag)) {
                 if ($token instanceof HTMLPurifier_Token_Text) {
                     foreach ($this->injectors as $i => $injector) {
-                        if (isset($token->skip[$i])) continue;
-                        if ($token->rewind !== null && $token->rewind !== $i) continue;
-                        $injector->handleText($token);
-                        $this->processToken($token, $i);
+                        if (isset($token->skip[$i])) {
+                            continue;
+                        }
+                        if ($token->rewind !== null && $token->rewind !== $i) {
+                            continue;
+                        }
+                        // XXX fuckup
+                        $r = $token;
+                        $injector->handleText($r);
+                        $token = $this->processToken($r, $i);
                         $reprocess = true;
                         break;
                     }
@@ -193,12 +237,22 @@ class HTMLPurifier_Strategy_MakeWellFormed extends HTMLPurifier_Strategy
             $ok = false;
             if ($type === 'empty' && $token instanceof HTMLPurifier_Token_Start) {
                 // claims to be a start tag but is empty
-                $token = new HTMLPurifier_Token_Empty($token->name, $token->attr);
+                $token = new HTMLPurifier_Token_Empty(
+                    $token->name,
+                    $token->attr,
+                    $token->line,
+                    $token->col,
+                    $token->armor
+                );
                 $ok = true;
             } elseif ($type && $type !== 'empty' && $token instanceof HTMLPurifier_Token_Empty) {
                 // claims to be empty but really is a start tag
-                $this->swap(new HTMLPurifier_Token_End($token->name));
-                $this->insertBefore(new HTMLPurifier_Token_Start($token->name, $token->attr));
+                // NB: this assignment is required
+                $old_token = $token;
+                $token = new HTMLPurifier_Token_End($token->name);
+                $token = $this->insertBefore(
+                    new HTMLPurifier_Token_Start($old_token->name, $old_token->attr, $old_token->line, $old_token->col, $old_token->armor)
+                );
                 // punt (since we had to modify the input stream in a non-trivial way)
                 $reprocess = true;
                 continue;
@@ -211,55 +265,96 @@ class HTMLPurifier_Strategy_MakeWellFormed extends HTMLPurifier_Strategy
                 // ...unless they also have to close their parent
                 if (!empty($this->stack)) {
 
+                    // Performance note: you might think that it's rather
+                    // inefficient, recalculating the autoclose information
+                    // for every tag that a token closes (since when we
+                    // do an autoclose, we push a new token into the
+                    // stream and then /process/ that, before
+                    // re-processing this token.)  But this is
+                    // necessary, because an injector can make an
+                    // arbitrary transformations to the autoclosing
+                    // tokens we introduce, so things may have changed
+                    // in the meantime.  Also, doing the inefficient thing is
+                    // "easy" to reason about (for certain perverse definitions
+                    // of "easy")
+
                     $parent = array_pop($this->stack);
                     $this->stack[] = $parent;
 
+                    $parent_def = null;
+                    $parent_elements = null;
+                    $autoclose = false;
                     if (isset($definition->info[$parent->name])) {
-                        $elements = $definition->info[$parent->name]->child->getAllowedElements($config);
-                        $autoclose = !isset($elements[$token->name]);
-                    } else {
-                        $autoclose = false;
+                        $parent_def = $definition->info[$parent->name];
+                        $parent_elements = $parent_def->child->getAllowedElements($config);
+                        $autoclose = !isset($parent_elements[$token->name]);
                     }
 
                     if ($autoclose && $definition->info[$token->name]->wrap) {
-                        // Check if an element can be wrapped by another 
-                        // element to make it valid in a context (for 
+                        // Check if an element can be wrapped by another
+                        // element to make it valid in a context (for
                         // example, <ul><ul> needs a <li> in between)
                         $wrapname = $definition->info[$token->name]->wrap;
                         $wrapdef = $definition->info[$wrapname];
                         $elements = $wrapdef->child->getAllowedElements($config);
-                        $parent_elements = $definition->info[$parent->name]->child->getAllowedElements($config);
                         if (isset($elements[$token->name]) && isset($parent_elements[$wrapname])) {
                             $newtoken = new HTMLPurifier_Token_Start($wrapname);
-                            $this->insertBefore($newtoken);
+                            $token = $this->insertBefore($newtoken);
                             $reprocess = true;
                             continue;
                         }
                     }
 
                     $carryover = false;
-                    if ($autoclose && $definition->info[$parent->name]->formatting) {
+                    if ($autoclose && $parent_def->formatting) {
                         $carryover = true;
                     }
 
                     if ($autoclose) {
-                        // errors need to be updated
-                        $new_token = new HTMLPurifier_Token_End($parent->name);
-                        $new_token->start = $parent;
-                        if ($carryover) {
-                            $element = clone $parent;
-                            $element->armor['MakeWellFormed_TagClosedError'] = true;
-                            $element->carryover = true;
-                            $this->processToken(array($new_token, $token, $element));
-                        } else {
-                            $this->insertBefore($new_token);
+                        // check if this autoclose is doomed to fail
+                        // (this rechecks $parent, which his harmless)
+                        $autoclose_ok = isset($global_parent_allowed_elements[$token->name]);
+                        if (!$autoclose_ok) {
+                            foreach ($this->stack as $ancestor) {
+                                $elements = $definition->info[$ancestor->name]->child->getAllowedElements($config);
+                                if (isset($elements[$token->name])) {
+                                    $autoclose_ok = true;
+                                    break;
+                                }
+                                if ($definition->info[$token->name]->wrap) {
+                                    $wrapname = $definition->info[$token->name]->wrap;
+                                    $wrapdef = $definition->info[$wrapname];
+                                    $wrap_elements = $wrapdef->child->getAllowedElements($config);
+                                    if (isset($wrap_elements[$token->name]) && isset($elements[$wrapname])) {
+                                        $autoclose_ok = true;
+                                        break;
+                                    }
+                                }
+                            }
                         }
-                        if ($e && !isset($parent->armor['MakeWellFormed_TagClosedError'])) {
-                            if (!$carryover) {
-                                $e->send(E_NOTICE, 'Strategy_MakeWellFormed: Tag auto closed', $parent);
+                        if ($autoclose_ok) {
+                            // errors need to be updated
+                            $new_token = new HTMLPurifier_Token_End($parent->name);
+                            $new_token->start = $parent;
+                            // [TagClosedSuppress]
+                            if ($e && !isset($parent->armor['MakeWellFormed_TagClosedError'])) {
+                                if (!$carryover) {
+                                    $e->send(E_NOTICE, 'Strategy_MakeWellFormed: Tag auto closed', $parent);
+                                } else {
+                                    $e->send(E_NOTICE, 'Strategy_MakeWellFormed: Tag carryover', $parent);
+                                }
+                            }
+                            if ($carryover) {
+                                $element = clone $parent;
+                                // [TagClosedAuto]
+                                $element->armor['MakeWellFormed_TagClosedError'] = true;
+                                $element->carryover = true;
+                                $token = $this->processToken(array($new_token, $token, $element));
                             } else {
-                                $e->send(E_NOTICE, 'Strategy_MakeWellFormed: Tag carryover', $parent);
+                                $token = $this->insertBefore($new_token);
                             }
+                        } else {
+                            $token = $this->remove();
                         }
                         $reprocess = true;
                         continue;
@@ -271,20 +366,26 @@ class HTMLPurifier_Strategy_MakeWellFormed extends HTMLPurifier_Strategy
 
             if ($ok) {
                 foreach ($this->injectors as $i => $injector) {
-                    if (isset($token->skip[$i])) continue;
-                    if ($token->rewind !== null && $token->rewind !== $i) continue;
-                    $injector->handleElement($token);
-                    $this->processToken($token, $i);
+                    if (isset($token->skip[$i])) {
+                        continue;
+                    }
+                    if ($token->rewind !== null && $token->rewind !== $i) {
+                        continue;
+                    }
+                    $r = $token;
+                    $injector->handleElement($r);
+                    $token = $this->processToken($r, $i);
                     $reprocess = true;
                     break;
                 }
                 if (!$reprocess) {
                     // ah, nothing interesting happened; do normal processing
-                    $this->swap($token);
                     if ($token instanceof HTMLPurifier_Token_Start) {
                         $this->stack[] = $token;
                     } elseif ($token instanceof HTMLPurifier_Token_End) {
-                        throw new HTMLPurifier_Exception('Improper handling of end tag in start code; possible error in MakeWellFormed');
+                        throw new HTMLPurifier_Exception(
+                            'Improper handling of end tag in start code; possible error in MakeWellFormed'
+                        );
                     }
                 }
                 continue;
@@ -298,13 +399,15 @@ class HTMLPurifier_Strategy_MakeWellFormed extends HTMLPurifier_Strategy
             // make sure that we have something open
             if (empty($this->stack)) {
                 if ($escape_invalid_tags) {
-                    if ($e) $e->send(E_WARNING, 'Strategy_MakeWellFormed: Unnecessary end tag to text');
-                    $this->swap(new HTMLPurifier_Token_Text(
-                        $generator->generateFromToken($token)
-                    ));
+                    if ($e) {
+                        $e->send(E_WARNING, 'Strategy_MakeWellFormed: Unnecessary end tag to text');
+                    }
+                    $token = new HTMLPurifier_Token_Text($generator->generateFromToken($token));
                 } else {
-                    $this->remove();
-                    if ($e) $e->send(E_WARNING, 'Strategy_MakeWellFormed: Unnecessary end tag removed');
+                    if ($e) {
+                        $e->send(E_WARNING, 'Strategy_MakeWellFormed: Unnecessary end tag removed');
+                    }
+                    $token = $this->remove();
                 }
                 $reprocess = true;
                 continue;
@@ -318,10 +421,15 @@ class HTMLPurifier_Strategy_MakeWellFormed extends HTMLPurifier_Strategy
             if ($current_parent->name == $token->name) {
                 $token->start = $current_parent;
                 foreach ($this->injectors as $i => $injector) {
-                    if (isset($token->skip[$i])) continue;
-                    if ($token->rewind !== null && $token->rewind !== $i) continue;
-                    $injector->handleEnd($token);
-                    $this->processToken($token, $i);
+                    if (isset($token->skip[$i])) {
+                        continue;
+                    }
+                    if ($token->rewind !== null && $token->rewind !== $i) {
+                        continue;
+                    }
+                    $r = $token;
+                    $injector->handleEnd($r);
+                    $token = $this->processToken($r, $i);
                     $this->stack[] = $current_parent;
                     $reprocess = true;
                     break;
@@ -349,13 +457,15 @@ class HTMLPurifier_Strategy_MakeWellFormed extends HTMLPurifier_Strategy
             // we didn't find the tag, so remove
             if ($skipped_tags === false) {
                 if ($escape_invalid_tags) {
-                    $this->swap(new HTMLPurifier_Token_Text(
-                        $generator->generateFromToken($token)
-                    ));
-                    if ($e) $e->send(E_WARNING, 'Strategy_MakeWellFormed: Stray end tag to text');
+                    if ($e) {
+                        $e->send(E_WARNING, 'Strategy_MakeWellFormed: Stray end tag to text');
+                    }
+                    $token = new HTMLPurifier_Token_Text($generator->generateFromToken($token));
                 } else {
-                    $this->remove();
-                    if ($e) $e->send(E_WARNING, 'Strategy_MakeWellFormed: Stray end tag removed');
+                    if ($e) {
+                        $e->send(E_WARNING, 'Strategy_MakeWellFormed: Stray end tag removed');
+                    }
+                    $token = $this->remove();
                 }
                 $reprocess = true;
                 continue;
@@ -366,7 +476,7 @@ class HTMLPurifier_Strategy_MakeWellFormed extends HTMLPurifier_Strategy
             if ($e) {
                 for ($j = $c - 1; $j > 0; $j--) {
                     // notice we exclude $j == 0, i.e. the current ending tag, from
-                    // the errors...
+                    // the errors... [TagClosedSuppress]
                     if (!isset($skipped_tags[$j]->armor['MakeWellFormed_TagClosedError'])) {
                         $e->send(E_NOTICE, 'Strategy_MakeWellFormed: Tag closed by element end', $skipped_tags[$j]);
                     }
@@ -381,24 +491,24 @@ class HTMLPurifier_Strategy_MakeWellFormed extends HTMLPurifier_Strategy
                 $new_token->start = $skipped_tags[$j];
                 array_unshift($replace, $new_token);
                 if (isset($definition->info[$new_token->name]) && $definition->info[$new_token->name]->formatting) {
+                    // [TagClosedAuto]
                     $element = clone $skipped_tags[$j];
                     $element->carryover = true;
                     $element->armor['MakeWellFormed_TagClosedError'] = true;
                     $replace[] = $element;
                 }
             }
-            $this->processToken($replace);
+            $token = $this->processToken($replace);
             $reprocess = true;
             continue;
         }
 
-        $context->destroy('CurrentNesting');
-        $context->destroy('InputTokens');
-        $context->destroy('InputIndex');
         $context->destroy('CurrentToken');
+        $context->destroy('CurrentNesting');
+        $context->destroy('InputZipper');
 
-        unset($this->injectors, $this->stack, $this->tokens, $this->t);
-        return $tokens;
+        unset($this->injectors, $this->stack, $this->tokens);
+        return $zipper->toArray($token);
     }
 
     /**
@@ -417,25 +527,38 @@ class HTMLPurifier_Strategy_MakeWellFormed extends HTMLPurifier_Strategy
      * If $token is an integer, that number of tokens (with the first token
      * being the current one) will be deleted.
      *
-     * @param $token Token substitution value
-     * @param $injector Injector that performed the substitution; default is if
+     * @param HTMLPurifier_Token|array|int|bool $token Token substitution value
+     * @param HTMLPurifier_Injector|int $injector Injector that performed the substitution; default is if
      *        this is not an injector related operation.
+     * @throws HTMLPurifier_Exception
      */
-    protected function processToken($token, $injector = -1) {
-
+    protected function processToken($token, $injector = -1)
+    {
         // normalize forms of token
-        if (is_object($token)) $token = array(1, $token);
-        if (is_int($token))    $token = array($token);
-        if ($token === false)  $token = array(1);
-        if (!is_array($token)) throw new HTMLPurifier_Exception('Invalid token type from injector');
-        if (!is_int($token[0])) array_unshift($token, 1);
-        if ($token[0] === 0) throw new HTMLPurifier_Exception('Deleting zero tokens is not valid');
+        if (is_object($token)) {
+            $token = array(1, $token);
+        }
+        if (is_int($token)) {
+            $token = array($token);
+        }
+        if ($token === false) {
+            $token = array(1);
+        }
+        if (!is_array($token)) {
+            throw new HTMLPurifier_Exception('Invalid token type from injector');
+        }
+        if (!is_int($token[0])) {
+            array_unshift($token, 1);
+        }
+        if ($token[0] === 0) {
+            throw new HTMLPurifier_Exception('Deleting zero tokens is not valid');
+        }
 
         // $token is now an array with the following form:
         // array(number nodes to delete, new node 1, new node 2, ...)
 
         $delete = array_shift($token);
-        $old = array_splice($this->tokens, $this->t, $delete, $token);
+        list($old, $r) = $this->zipper->splice($this->token, $delete, $token);
 
         if ($injector > -1) {
             // determine appropriate skips
@@ -446,30 +569,32 @@ class HTMLPurifier_Strategy_MakeWellFormed extends HTMLPurifier_Strategy
             }
         }
 
-    }
+        return $r;
 
-    /**
-     * Inserts a token before the current token. Cursor now points to this token
-     */
-    private function insertBefore($token) {
-        array_splice($this->tokens, $this->t, 0, array($token));
     }
 
     /**
-     * Removes current token. Cursor now points to new token occupying previously
-     * occupied space.
+     * Inserts a token before the current token. Cursor now points to
+     * this token.  You must reprocess after this.
+     * @param HTMLPurifier_Token $token
      */
-    private function remove() {
-        array_splice($this->tokens, $this->t, 1);
+    private function insertBefore($token)
+    {
+        // NB not $this->zipper->insertBefore(), due to positioning
+        // differences
+        $splice = $this->zipper->splice($this->token, 0, array($token));
+
+        return $splice[1];
     }
 
     /**
-     * Swap current token with new token. Cursor points to new token (no change).
+     * Removes current token. Cursor now points to new token occupying previously
+     * occupied space.  You must reprocess after this.
      */
-    private function swap($token) {
-        $this->tokens[$this->t] = $token;
+    private function remove()
+    {
+        return $this->zipper->delete();
     }
-
 }
 
 // vim: et sw=4 sts=4
diff --git a/library/HTMLPurifier/Strategy/RemoveForeignElements.php b/library/HTMLPurifier/Strategy/RemoveForeignElements.php
index cf3a33e40..1a8149ecc 100644
--- a/library/HTMLPurifier/Strategy/RemoveForeignElements.php
+++ b/library/HTMLPurifier/Strategy/RemoveForeignElements.php
@@ -11,19 +11,29 @@
 class HTMLPurifier_Strategy_RemoveForeignElements extends HTMLPurifier_Strategy
 {
 
-    public function execute($tokens, $config, $context) {
+    /**
+     * @param HTMLPurifier_Token[] $tokens
+     * @param HTMLPurifier_Config $config
+     * @param HTMLPurifier_Context $context
+     * @return array|HTMLPurifier_Token[]
+     */
+    public function execute($tokens, $config, $context)
+    {
         $definition = $config->getHTMLDefinition();
         $generator = new HTMLPurifier_Generator($config, $context);
         $result = array();
 
         $escape_invalid_tags = $config->get('Core.EscapeInvalidTags');
-        $remove_invalid_img  = $config->get('Core.RemoveInvalidImg');
+        $remove_invalid_img = $config->get('Core.RemoveInvalidImg');
 
         // currently only used to determine if comments should be kept
         $trusted = $config->get('HTML.Trusted');
+        $comment_lookup = $config->get('HTML.AllowedComments');
+        $comment_regexp = $config->get('HTML.AllowedCommentsRegexp');
+        $check_comments = $comment_lookup !== array() || $comment_regexp !== null;
 
         $remove_script_contents = $config->get('Core.RemoveScriptContents');
-        $hidden_elements     = $config->get('Core.HiddenElements');
+        $hidden_elements = $config->get('Core.HiddenElements');
 
         // remove script contents compatibility
         if ($remove_script_contents === true) {
@@ -48,34 +58,31 @@ class HTMLPurifier_Strategy_RemoveForeignElements extends HTMLPurifier_Strategy
             $e =& $context->get('ErrorCollector');
         }
 
-        foreach($tokens as $token) {
+        foreach ($tokens as $token) {
             if ($remove_until) {
                 if (empty($token->is_tag) || $token->name !== $remove_until) {
                     continue;
                 }
             }
-            if (!empty( $token->is_tag )) {
+            if (!empty($token->is_tag)) {
                 // DEFINITION CALL
 
                 // before any processing, try to transform the element
-                if (
-                    isset($definition->info_tag_transform[$token->name])
-                ) {
+                if (isset($definition->info_tag_transform[$token->name])) {
                     $original_name = $token->name;
                     // there is a transformation for this tag
                     // DEFINITION CALL
                     $token = $definition->
-                                info_tag_transform[$token->name]->
-                                    transform($token, $config, $context);
-                    if ($e) $e->send(E_NOTICE, 'Strategy_RemoveForeignElements: Tag transform', $original_name);
+                        info_tag_transform[$token->name]->transform($token, $config, $context);
+                    if ($e) {
+                        $e->send(E_NOTICE, 'Strategy_RemoveForeignElements: Tag transform', $original_name);
+                    }
                 }
 
                 if (isset($definition->info[$token->name])) {
-
                     // mostly everything's good, but
                     // we need to make sure required attributes are in order
-                    if (
-                        ($token instanceof HTMLPurifier_Token_Start || $token instanceof HTMLPurifier_Token_Empty) &&
+                    if (($token instanceof HTMLPurifier_Token_Start || $token instanceof HTMLPurifier_Token_Empty) &&
                         $definition->info[$token->name]->required_attr &&
                         ($token->name != 'img' || $remove_invalid_img) // ensure config option still works
                     ) {
@@ -88,7 +95,13 @@ class HTMLPurifier_Strategy_RemoveForeignElements extends HTMLPurifier_Strategy
                             }
                         }
                         if (!$ok) {
-                            if ($e) $e->send(E_ERROR, 'Strategy_RemoveForeignElements: Missing required attribute', $name);
+                            if ($e) {
+                                $e->send(
+                                    E_ERROR,
+                                    'Strategy_RemoveForeignElements: Missing required attribute',
+                                    $name
+                                );
+                            }
                             continue;
                         }
                         $token->armor['ValidateAttributes'] = true;
@@ -102,7 +115,9 @@ class HTMLPurifier_Strategy_RemoveForeignElements extends HTMLPurifier_Strategy
 
                 } elseif ($escape_invalid_tags) {
                     // invalid tag, generate HTML representation and insert in
-                    if ($e) $e->send(E_WARNING, 'Strategy_RemoveForeignElements: Foreign element to text');
+                    if ($e) {
+                        $e->send(E_WARNING, 'Strategy_RemoveForeignElements: Foreign element to text');
+                    }
                     $token = new HTMLPurifier_Token_Text(
                         $generator->generateFromToken($token)
                     );
@@ -117,9 +132,13 @@ class HTMLPurifier_Strategy_RemoveForeignElements extends HTMLPurifier_Strategy
                         } else {
                             $remove_until = false;
                         }
-                        if ($e) $e->send(E_ERROR, 'Strategy_RemoveForeignElements: Foreign meta element removed');
+                        if ($e) {
+                            $e->send(E_ERROR, 'Strategy_RemoveForeignElements: Foreign meta element removed');
+                        }
                     } else {
-                        if ($e) $e->send(E_ERROR, 'Strategy_RemoveForeignElements: Foreign element removed');
+                        if ($e) {
+                            $e->send(E_ERROR, 'Strategy_RemoveForeignElements: Foreign element removed');
+                        }
                     }
                     continue;
                 }
@@ -128,26 +147,46 @@ class HTMLPurifier_Strategy_RemoveForeignElements extends HTMLPurifier_Strategy
                 if ($textify_comments !== false) {
                     $data = $token->data;
                     $token = new HTMLPurifier_Token_Text($data);
-                } elseif ($trusted) {
-                    // keep, but perform comment cleaning
+                } elseif ($trusted || $check_comments) {
+                    // always cleanup comments
+                    $trailing_hyphen = false;
                     if ($e) {
                         // perform check whether or not there's a trailing hyphen
                         if (substr($token->data, -1) == '-') {
-                            $e->send(E_NOTICE, 'Strategy_RemoveForeignElements: Trailing hyphen in comment removed');
+                            $trailing_hyphen = true;
                         }
                     }
                     $token->data = rtrim($token->data, '-');
                     $found_double_hyphen = false;
                     while (strpos($token->data, '--') !== false) {
-                        if ($e && !$found_double_hyphen) {
-                            $e->send(E_NOTICE, 'Strategy_RemoveForeignElements: Hyphens in comment collapsed');
-                        }
-                        $found_double_hyphen = true; // prevent double-erroring
+                        $found_double_hyphen = true;
                         $token->data = str_replace('--', '-', $token->data);
                     }
+                    if ($trusted || !empty($comment_lookup[trim($token->data)]) ||
+                        ($comment_regexp !== null && preg_match($comment_regexp, trim($token->data)))) {
+                        // OK good
+                        if ($e) {
+                            if ($trailing_hyphen) {
+                                $e->send(
+                                    E_NOTICE,
+                                    'Strategy_RemoveForeignElements: Trailing hyphen in comment removed'
+                                );
+                            }
+                            if ($found_double_hyphen) {
+                                $e->send(E_NOTICE, 'Strategy_RemoveForeignElements: Hyphens in comment collapsed');
+                            }
+                        }
+                    } else {
+                        if ($e) {
+                            $e->send(E_NOTICE, 'Strategy_RemoveForeignElements: Comment removed');
+                        }
+                        continue;
+                    }
                 } else {
                     // strip comments
-                    if ($e) $e->send(E_NOTICE, 'Strategy_RemoveForeignElements: Comment removed');
+                    if ($e) {
+                        $e->send(E_NOTICE, 'Strategy_RemoveForeignElements: Comment removed');
+                    }
                     continue;
                 }
             } elseif ($token instanceof HTMLPurifier_Token_Text) {
@@ -160,12 +199,9 @@ class HTMLPurifier_Strategy_RemoveForeignElements extends HTMLPurifier_Strategy
             // we removed tokens until the end, throw error
             $e->send(E_ERROR, 'Strategy_RemoveForeignElements: Token removed to end', $remove_until);
         }
-
         $context->destroy('CurrentToken');
-
         return $result;
     }
-
 }
 
 // vim: et sw=4 sts=4
diff --git a/library/HTMLPurifier/Strategy/ValidateAttributes.php b/library/HTMLPurifier/Strategy/ValidateAttributes.php
index c3328a9d4..fbb3d27c8 100644
--- a/library/HTMLPurifier/Strategy/ValidateAttributes.php
+++ b/library/HTMLPurifier/Strategy/ValidateAttributes.php
@@ -7,8 +7,14 @@
 class HTMLPurifier_Strategy_ValidateAttributes extends HTMLPurifier_Strategy
 {
 
-    public function execute($tokens, $config, $context) {
-
+    /**
+     * @param HTMLPurifier_Token[] $tokens
+     * @param HTMLPurifier_Config $config
+     * @param HTMLPurifier_Context $context
+     * @return HTMLPurifier_Token[]
+     */
+    public function execute($tokens, $config, $context)
+    {
         // setup validator
         $validator = new HTMLPurifier_AttrValidator();
 
@@ -19,21 +25,21 @@ class HTMLPurifier_Strategy_ValidateAttributes extends HTMLPurifier_Strategy
 
             // only process tokens that have attributes,
             //   namely start and empty tags
-            if (!$token instanceof HTMLPurifier_Token_Start && !$token instanceof HTMLPurifier_Token_Empty) continue;
+            if (!$token instanceof HTMLPurifier_Token_Start && !$token instanceof HTMLPurifier_Token_Empty) {
+                continue;
+            }
 
             // skip tokens that are armored
-            if (!empty($token->armor['ValidateAttributes'])) continue;
+            if (!empty($token->armor['ValidateAttributes'])) {
+                continue;
+            }
 
             // note that we have no facilities here for removing tokens
             $validator->validateToken($token, $config, $context);
-
-            $tokens[$key] = $token; // for PHP 4
         }
         $context->destroy('CurrentToken');
-
         return $tokens;
     }
-
 }
 
 // vim: et sw=4 sts=4