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-rw-r--r--accessible/base/Relation.h105
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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;
+ }
+
+ inline LocalAccessible* LocalNext() {
+ Accessible* next = Next();
+ return next ? next->AsLocal() : nullptr;
+ }
+
+ private:
+ Relation& operator=(const Relation&) = delete;
+ Relation(const Relation&) = delete;
+
+ std::unique_ptr<AccIterable> mFirstIter;
+ AccIterable* mLastIter;
+};
+
+} // namespace a11y
+} // namespace mozilla
+
+#endif