tor-browser

The Tor Browser
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nsChildContentList.h (2524B)

      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 "js/TypeDecls.h"  // for Handle, Value, JSObject, JSContext
     11 #include "mozilla/RefPtr.h"
     12 #include "nsINodeList.h"  // base class
     13 #include "nsISupportsImpl.h"
     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__ */