dom/base/nsChildContentList.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef nsChildContentList_h__
   8 #define nsChildContentList_h__
   9
  10 #include "mozilla/RefPtr.h"
  11 #include "nsISupportsImpl.h"
  12 #include "nsINodeList.h"   // base class
  13 #include "js/TypeDecls.h"  // for Handle, Value, JSObject, JSContext
  14
  15 class nsIContent;
  16 class nsINode;
  17
  18 /**
  19  * Class that implements the nsINodeList interface (a list of children of
  20  * the content), by holding a reference to the content and delegating Length
  21  * and Item to its existing child list.
  22  * @see nsINodeList
  23  */
  24 class nsAttrChildContentList : public nsINodeList {
  25  public:
  26   explicit nsAttrChildContentList(nsINode* aNode) : mNode(aNode) {}
  27
  28   NS_DECL_CYCLE_COLLECTING_ISUPPORTS
  29   NS_DECL_CYCLE_COLLECTION_SKIPPABLE_WRAPPERCACHE_CLASS(nsAttrChildContentList)
  30
  31   // nsWrapperCache
  32   JSObject* WrapObject(JSContext*, JS::Handle<JSObject*> aGivenProto) override;
  33
  34   // nsINodeList interface
  35   int32_t IndexOf(nsIContent* aContent) override;
  36   nsIContent* Item(uint32_t aIndex) override;
  37   uint32_t Length() override;
  38   nsINode* GetParentObject() final { return mNode; }
  39
  40   virtual void InvalidateCacheIfAvailable() {}
  41
  42  protected:
  43   virtual ~nsAttrChildContentList() = default;
  44
  45   // The node whose children make up the list.
  46   RefPtr<nsINode> mNode;
  47 };
  48
  49 class nsParentNodeChildContentList final : public nsAttrChildContentList {
  50  public:
  51   explicit nsParentNodeChildContentList(nsINode* aNode)
  52       : nsAttrChildContentList(aNode) {
  53     ValidateCache();
  54   }
  55
  56   // nsINodeList interface
  57   int32_t IndexOf(nsIContent* aContent) override;
  58   nsIContent* Item(uint32_t aIndex) override;
  59   uint32_t Length() override;
  60
  61   void InvalidateCacheIfAvailable() final { InvalidateCache(); }
  62
  63   void InvalidateCache() {
  64     mIsCacheValid = false;
  65     mCachedChildArray.Clear();
  66   }
  67
  68  private:
  69   ~nsParentNodeChildContentList() = default;
  70
  71   // Return true if validation succeeds, false otherwise
  72   void ValidateCache();
  73   void EnsureCacheValid() {
  74     if (!mIsCacheValid) {
  75       ValidateCache();
  76     }
  77     MOZ_ASSERT(mIsCacheValid);
  78   }
  79
  80   // Whether cached array of child nodes is valid
  81   bool mIsCacheValid = false;
  82
  83   // Cached array of child nodes
  84   AutoTArray<nsIContent*, 8> mCachedChildArray;
  85 };
  86
  87 #endif /* nsChildContentList_h__ */