differentOwnerPointer.h

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/* Copyright 2016 Yurii Litvinov.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License. */

#pragma once

#include <QtCore/QSharedPointer>

namespace trikKernel {

template<typename T> class DifferentOwnerPointer
{
public:
    DifferentOwnerPointer(const DifferentOwnerPointer<T> &other)
        : mPointer(other.mPointer)
        , mPointerGuard(other.mPointerGuard)
    {
    }

    explicit DifferentOwnerPointer(T &foreignObject)
        : mPointer(&foreignObject)
    {
    }

    explicit DifferentOwnerPointer(const QSharedPointer<T> &sharedObject)
        : mPointer(sharedObject.data())
        , mPointerGuard(sharedObject)
    {
    }

    explicit DifferentOwnerPointer(T * const ownObject)
        : mPointer(ownObject)
        , mPointerGuard(ownObject)
    {
    }

    inline T *operator->()
    {
        return mPointer;
    }

    inline T &operator *()
    {
        return *mPointer;
    }

    inline T *data() const
    {
        return mPointer;
    }

    inline DifferentOwnerPointer<T> &operator =(const DifferentOwnerPointer<T> &other) = default;

private:
    T *mPointer;

    QSharedPointer<T> mPointerGuard;
};

template<typename T>
inline DifferentOwnerPointer<T> createDifferentOwnerPointer(T &foreignObject)
{
    return DifferentOwnerPointer<T>(foreignObject);
}

template<typename T>
inline DifferentOwnerPointer<T> createDifferentOwnerPointer(const QSharedPointer<T> &sharedObject)
{
    return DifferentOwnerPointer<T>(sharedObject);
}

template<typename T>
inline DifferentOwnerPointer<T> createDifferentOwnerPointer(T * const ownObject)
{
    return DifferentOwnerPointer<T>(ownObject);
}

}