gecko-dev/accessible/base/Relation.h

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=2 et sw=2 tw=80: */
/* 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 mozilla_a11y_relation_h_
#define mozilla_a11y_relation_h_
#include "AccIterator.h"
#include <memory>
namespace mozilla {
namespace a11y {
/**
* A collection of relation targets of a certain type. Targets are computed
* lazily while enumerating.
*/
class Relation
{
public:
Relation() : mFirstIter(nullptr), mLastIter(nullptr) { }
explicit Relation(AccIterable* aIter) :
mFirstIter(aIter), mLastIter(aIter) { }
explicit Relation(Accessible* aAcc) :
mFirstIter(nullptr), mLastIter(nullptr)
{ AppendTarget(aAcc); }
Relation(DocAccessible* aDocument, nsIContent* aContent) :
mFirstIter(nullptr), mLastIter(nullptr)
{ AppendTarget(aDocument, aContent); }
Relation(Relation&& aOther) :
mFirstIter(std::move(aOther.mFirstIter)), mLastIter(aOther.mLastIter)
{
aOther.mLastIter = nullptr;
}
Relation& operator = (Relation&& aRH)
{
mFirstIter = std::move(aRH.mFirstIter);
mLastIter = aRH.mLastIter;
aRH.mLastIter = nullptr;
return *this;
}
inline void AppendIter(AccIterable* aIter)
{
if (mLastIter)
mLastIter->mNextIter.reset(aIter);
else
mFirstIter.reset(aIter);
mLastIter = aIter;
}
/**
* Append the given accessible to the set of related accessibles.
*/
inline void AppendTarget(Accessible* aAcc)
{
if (aAcc)
AppendIter(new SingleAccIterator(aAcc));
}
/**
* Append the one accessible for this content node to the set of related
* accessibles.
*/
void AppendTarget(DocAccessible* aDocument, nsIContent* aContent)
{
if (aContent)
AppendTarget(aDocument->GetAccessible(aContent));
}
/**
* compute and return the next related accessible.
*/
inline Accessible* Next()
{
Accessible* target = nullptr;
while (mFirstIter && !(target = mFirstIter->Next()))
mFirstIter = std::move(mFirstIter->mNextIter);
if (!mFirstIter)
mLastIter = nullptr;
return target;
}
private:
Relation& operator = (const Relation&) = delete;
Relation(const Relation&) = delete;
std::unique_ptr<AccIterable> mFirstIter;
AccIterable* mLastIter;
};
} // namespace a11y
} // namespace mozilla
#endif