accessible/base/TreeWalker.h

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #ifndef mozilla_a11y_TreeWalker_h_
   7 #define mozilla_a11y_TreeWalker_h_
   8
   9 #include "mozilla/Attributes.h"
  10 #include <stdint.h>
  11
  12 class nsIContent;
  13
  14 namespace mozilla {
  15 namespace a11y {
  16
  17 class Accessible;
  18 class DocAccessible;
  19
  20 struct WalkState;
  21
  22 /**
  23  * This class is used to walk the DOM tree to create accessible tree.
  24  */
  25 class TreeWalker MOZ_FINAL
  26 {
  27 public:
  28   enum {
  29     // used to walk the existing tree of the given node
  30     eWalkCache = 1,
  31     // used to walk the context tree starting from given node
  32     eWalkContextTree = 2 | eWalkCache
  33   };
  34
  35   /**
  36    * Constructor
  37    *
  38    * @param aContext [in] container accessible for the given node, used to
  39    *                   define accessible context
  40    * @param aNode    [in] the node the search will be prepared relative to
  41    * @param aFlags   [in] flags (see enum above)
  42    */
  43   TreeWalker(Accessible* aContext, nsIContent* aNode, uint32_t aFlags = 0);
  44   ~TreeWalker();
  45
  46   /**
  47    * Return the next child accessible.
  48    *
  49    * @note Returned accessible is bound to the document, if the accessible is
  50    *       rejected during tree creation then the caller should be unbind it
  51    *       from the document.
  52    */
  53   Accessible* NextChild()
  54   {
  55     return NextChildInternal(false);
  56   }
  57
  58 private:
  59   TreeWalker();
  60   TreeWalker(const TreeWalker&);
  61   TreeWalker& operator =(const TreeWalker&);
  62
  63   /**
  64    * Return the next child accessible.
  65    *
  66    * @param  aNoWalkUp  [in] specifies the walk direction, true means we
  67    *                     shouldn't go up through the tree if we failed find
  68    *                     accessible children.
  69    */
  70   Accessible* NextChildInternal(bool aNoWalkUp);
  71
  72   /**
  73    * Create new state for the given node and push it on top of stack.
  74    *
  75    * @note State stack is used to navigate up/down the DOM subtree during
  76    *        accessible children search.
  77    */
  78   void PushState(nsIContent* aNode);
  79
  80   /**
  81    * Pop state from stack.
  82    */
  83   void PopState();
  84
  85   DocAccessible* mDoc;
  86   Accessible* mContext;
  87   int32_t mChildFilter;
  88   uint32_t mFlags;
  89   WalkState* mState;
  90 };
  91
  92 } // namespace a11y
  93 } // namespace mozilla
  94
  95 #endif // mozilla_a11y_TreeWalker_h_