axmol/core/2d/ActionCoroutine.h

/****************************************************************************
Copyright (c) 2008-2010 Ricardo Quesada
Copyright (c) 2010-2012 cocos2d-x.org
Copyright (c) 2011      Zynga Inc.
Copyright (c) 2013-2016 Chukong Technologies Inc.
Copyright (c) 2017-2018 Xiamen Yaji Software Co., Ltd.
Copyright (c) 2019-present Axmol Engine contributors (see AUTHORS.md).

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#ifndef __ACTION_CCCOROUTINE_ACTION_H__
#define __ACTION_CCCOROUTINE_ACTION_H__

#include "2d/Action.h"

#if __has_include(<coroutine>)
#    include <coroutine>
namespace axstd
{
using suspend_always = std::suspend_always;
template <typename _Ty>
using coroutine_handle = std::coroutine_handle<_Ty>;
}  // namespace axstd
#elif __has_include(<experimental/coroutine>)
// fallback to experimental, currently only for android, in the future may don't required,
// for example: we upgrade ndk in the future releases of axmol
#    include <experimental/coroutine>
namespace axstd
{
using suspend_always = std::experimental::suspend_always;
template <typename _Ty>
using coroutine_handle = std::experimental::coroutine_handle<_Ty>;
}  // namespace axstd
#else
#    error This compiler missing c++20 coroutine
#endif

namespace ax
{

/**
 * @addtogroup actions
 * @{
 */

class AX_DLL Coroutine
{
public:
    class promise_type;

    using handle = axstd::coroutine_handle<promise_type>;
    class promise_type
    {
    public:
        virtual ~promise_type() { AX_SAFE_RELEASE(_currentAction); }

        Action* currentAction() const noexcept { return _currentAction; }

        auto final_suspend() const noexcept { return axstd::suspend_always{}; }

        auto get_return_object() noexcept { return Coroutine(handle::from_promise(*this)); }

        auto initial_suspend() const noexcept { return axstd::suspend_always{}; }

        auto yield_value(Action* action)
        {
            AX_SAFE_RELEASE(_currentAction);
            _currentAction = action;
            AX_SAFE_RETAIN(_currentAction);
            return axstd::suspend_always{};
        }

        void return_void() {}
        void unhandled_exception() {}

        void resume() { handle::from_promise(*this).resume(); }

    private:
        Action* _currentAction{nullptr};
    };

    Coroutine()                 = default;
    Coroutine(const Coroutine&) = delete;
    Coroutine(Coroutine&& rhs) noexcept;
    virtual ~Coroutine();

    Coroutine& operator=(const Coroutine&) = delete;
    Coroutine& operator=(Coroutine&& rhs) noexcept;

    Action* currentAction() const noexcept;
    bool isDone() const;
    bool moveNext() const;

private:
    Coroutine(handle h) noexcept : _handle{h} {}

    handle _handle;
};

/**
 *@brief Base class for Coroutine actions.
 *@ingroup Actions
 */
class AX_DLL ActionCoroutine : public Action
{
public:
    /**
     * @brief Create the action with coroutine.
     * @param coroutine A callback function need to be executed.
     * @return A pointer of ActionCoroutine. If creation failed, return nil.
     * @lua NA
     */
    static ActionCoroutine* create(const std::function<Coroutine()>& function);

    //
    // Overrides
    //
    virtual bool isDone() const override;
    virtual void step(float dt) override;

public:
    ActionCoroutine() = default;
    virtual ~ActionCoroutine() {}

    /** initializes the action with the Coroutine
     * @lua NA
     */
    bool initWithCoroutine(const std::function<Coroutine()>& function) noexcept;

protected:
    /** Coroutine */
    Coroutine _coroutine;

private:
    AX_DISALLOW_COPY_AND_ASSIGN(ActionCoroutine);
};

}

#endif  // __ACTION_CCCOROUTINE_ACTION_H__