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 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

 /* This Source Code Form is subject to the terms of the Mozilla Public

  * License, v. 2.0. If a copy of the MPL was not distributed with this

  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

 #ifndef nsContentIndexCache_h__

 #define nsContentIndexCache_h__

 #include "js/HashTable.h"

 class nsIContent;

 namespace mozilla {

 namespace dom {

 class Element;

 } // namespace dom

 } // namespace mozilla

 /*

  * A class that computes and caches the indices used for :nth-* pseudo-class

  * matching.

  */

 class nsNthIndexCache {

 private:

   typedef mozilla::dom::Element Element;

 public:

   /**

    * Constructor and destructor out of line so that we don't try to

    * instantiate the hashtable template all over the place.

    */

   nsNthIndexCache();

   ~nsNthIndexCache();

   // Returns a 1-based index of the child in its parent.  If the child

   // is not in its parent's child list (i.e., it is anonymous content),

   // returns 0.

   // If aCheckEdgeOnly is true, the function will return 1 if the result

   // is 1, and something other than 1 (maybe or maybe not a valid

   // result) otherwise.

   // This must only be called on nodes which have a non-null parent.

   int32_t GetNthIndex(Element* aChild, bool aIsOfType, bool aIsFromEnd,

                       bool aCheckEdgeOnly);

   void Reset();

 private:

   /**

    * Returns true if aSibling and aElement should be considered in the same

    * list for nth-index purposes, taking aIsOfType into account.

    */

   inline bool SiblingMatchesElement(nsIContent* aSibling, Element* aElement,

                                     bool aIsOfType);

   // This node's index for this cache.

   // If -2, needs to be computed.

   // If -1, needs to be computed but known not to be 1.

   // If 0, the node is not at any index in its parent.

   typedef int32_t CacheEntry;

   class SystemAllocPolicy {

   public:

     void *malloc_(size_t bytes) { return ::malloc(bytes); }

     void *calloc_(size_t bytes) { return ::calloc(bytes, 1); }

     void *realloc_(void *p, size_t bytes) { return ::realloc(p, bytes); }

     void free_(void *p) { ::free(p); }

     void reportAllocOverflow() const {}

   };

   typedef js::HashMap<nsIContent*, CacheEntry, js::DefaultHasher<nsIContent*>,

                       SystemAllocPolicy> Cache;

   /**

    * Returns true if aResult has been set to the correct value for aChild and

    * no more work needs to be done.  Returns false otherwise.

    *

    * aResult is an inout parameter.  The in value is the number of elements

    * that are in the half-open range (aSibling, aChild] (so including aChild

    * but not including aSibling) that match aChild.  The out value is the

    * correct index for aChild if this function returns true and the number of

    * elements in the closed range [aSibling, aChild] that match aChild

    * otherwise.

    */

   inline bool IndexDeterminedFromPreviousSibling(nsIContent* aSibling,

                                                  Element* aChild,

                                                  bool aIsOfType,

                                                  bool aIsFromEnd,

                                                  const Cache& aCache,

                                                  int32_t& aResult);

   // Caches of indices for :nth-child(), :nth-last-child(),

   // :nth-of-type(), :nth-last-of-type(), keyed by Element*.

   //

   // The first subscript is 0 for -child and 1 for -of-type, the second

   // subscript is 0 for nth- and 1 for nth-last-.

   Cache mCaches[2][2];

 };

 #endif /* nsContentIndexCache_h__ */