/* -*- 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