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/*
    nanogui/object.h -- Object base class with support for reference counting

    NanoGUI was developed by Wenzel Jakob <wenzel.jakob@epfl.ch>.
    The widget drawing code is based on the NanoVG demo application
    by Mikko Mononen.

    All rights reserved. Use of this source code is governed by a
    BSD-style license that can be found in the LICENSE.txt file.
*/
#pragma once

#include <nanogui/common.h>
#include <atomic>

NAMESPACE_BEGIN(nanogui)


class NANOGUI_EXPORT Object {
public:
    Object() { }

    Object(const Object &) : m_refCount(0) {}

    int getRefCount() const { return m_refCount; };

    void incRef() const { ++m_refCount; }

    void decRef(bool dealloc = true) const noexcept;
protected:
    virtual ~Object();
private:
    mutable std::atomic<int> m_refCount { 0 };
};

template <typename T> class ref {
public:
    ref() { }

    ref(T *ptr) : m_ptr(ptr) {
        if (m_ptr)
            ((Object *) m_ptr)->incRef();
    }

    ref(const ref &r) : m_ptr(r.m_ptr) {
        if (m_ptr)
            ((Object *) m_ptr)->incRef();
    }

    ref(ref &&r) noexcept : m_ptr(r.m_ptr) {
        r.m_ptr = nullptr;
    }

    ~ref() {
        if (m_ptr)
            ((Object *) m_ptr)->decRef();
    }

    ref& operator=(ref&& r) noexcept {
        if (&r != this) {
            if (m_ptr)
                ((Object *) m_ptr)->decRef();
            m_ptr = r.m_ptr;
            r.m_ptr = nullptr;
        }
        return *this;
    }

    ref& operator=(const ref& r) noexcept {
        if (m_ptr != r.m_ptr) {
            if (r.m_ptr)
                ((Object *) r.m_ptr)->incRef();
            if (m_ptr)
                ((Object *) m_ptr)->decRef();
            m_ptr = r.m_ptr;
        }
        return *this;
    }

    ref& operator=(T *ptr) noexcept {
        if (m_ptr != ptr) {
            if (ptr)
                ((Object *) ptr)->incRef();
            if (m_ptr)
                ((Object *) m_ptr)->decRef();
            m_ptr = ptr;
        }
        return *this;
    }

    bool operator==(const ref &r) const { return m_ptr == r.m_ptr; }

    bool operator!=(const ref &r) const { return m_ptr != r.m_ptr; }

    bool operator==(const T* ptr) const { return m_ptr == ptr; }

    bool operator!=(const T* ptr) const { return m_ptr != ptr; }

    T* operator->() { return m_ptr; }

    const T* operator->() const { return m_ptr; }

    T& operator*() { return *m_ptr; }

    const T& operator*() const { return *m_ptr; }

    operator T* () { return m_ptr; }

    T* get() { return m_ptr; }

    const T* get() const { return m_ptr; }

    operator bool() const { return m_ptr != nullptr; }
private:
    T *m_ptr = nullptr;
};

NAMESPACE_END(nanogui)