accessible/base/Relation.h

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=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 mozilla_a11y_relation_h_
   8 #define mozilla_a11y_relation_h_
   9
  10 #include "AccIterator.h"
  11
  12 #include <memory>
  13
  14 namespace mozilla {
  15 namespace a11y {
  16
  17 /**
  18  * A collection of relation targets of a certain type.  Targets are computed
  19  * lazily while enumerating.
  20  */
  21 class Relation {
  22  public:
  23   Relation() : mFirstIter(nullptr), mLastIter(nullptr) {}
  24
  25   explicit Relation(AccIterable* aIter) : mFirstIter(aIter), mLastIter(aIter) {}
  26
  27   explicit Relation(Accessible* aAcc)
  28       : mFirstIter(nullptr), mLastIter(nullptr) {
  29     AppendTarget(aAcc);
  30   }
  31
  32   Relation(DocAccessible* aDocument, nsIContent* aContent)
  33       : mFirstIter(nullptr), mLastIter(nullptr) {
  34     AppendTarget(aDocument, aContent);
  35   }
  36
  37   Relation(Relation&& aOther)
  38       : mFirstIter(std::move(aOther.mFirstIter)), mLastIter(aOther.mLastIter) {
  39     aOther.mLastIter = nullptr;
  40   }
  41
  42   Relation& operator=(Relation&& aRH) {
  43     mFirstIter = std::move(aRH.mFirstIter);
  44     mLastIter = aRH.mLastIter;
  45     aRH.mLastIter = nullptr;
  46     return *this;
  47   }
  48
  49   inline void AppendIter(AccIterable* aIter) {
  50     if (mLastIter)
  51       mLastIter->mNextIter.reset(aIter);
  52     else
  53       mFirstIter.reset(aIter);
  54
  55     mLastIter = aIter;
  56   }
  57
  58   /**
  59    * Append the given accessible to the set of related accessibles.
  60    */
  61   inline void AppendTarget(Accessible* aAcc) {
  62     if (aAcc) AppendIter(new SingleAccIterator(aAcc));
  63   }
  64
  65   /**
  66    * Append the one accessible for this content node to the set of related
  67    * accessibles.
  68    */
  69   void AppendTarget(DocAccessible* aDocument, nsIContent* aContent) {
  70     if (aContent) AppendTarget(aDocument->GetAccessible(aContent));
  71   }
  72
  73   /**
  74    * compute and return the next related accessible.
  75    */
  76   inline Accessible* Next() {
  77     Accessible* target = nullptr;
  78
  79     while (mFirstIter && !(target = mFirstIter->Next()))
  80       mFirstIter = std::move(mFirstIter->mNextIter);
  81
  82     if (!mFirstIter) mLastIter = nullptr;
  83
  84     return target;
  85   }
  86
  87  private:
  88   Relation& operator=(const Relation&) = delete;
  89   Relation(const Relation&) = delete;
  90
  91   std::unique_ptr<AccIterable> mFirstIter;
  92   AccIterable* mLastIter;
  93 };
  94
  95 }  // namespace a11y
  96 }  // namespace mozilla
  97
  98 #endif