task_promise.hxx

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#pragma once
#include <ice/assert.hxx>
#include <ice/task_promise_base.hxx>
 
namespace ice
{
 
    template<typename Value>
    class TaskPromise : public ice::TaskPromiseBase
    {
    public:
        inline auto get_return_object() noexcept -> ice::Task<Value>;
 
        template<typename Other = Value>
            requires std::is_nothrow_move_assignable_v<Value> && std::is_nothrow_convertible_v<Other&&, Value>
        inline void return_value(Other&& value) noexcept
        {
            static_assert(std::is_nothrow_move_assignable_v<Value>, "We enforce noexcept everywhere.");
            _value = std::forward<Other>(value);
        }
 
        inline auto result() & noexcept -> Value&
        {
            return _value;
        }
 
        inline auto result() && noexcept -> Value&&
        {
            return std::move(_value);
        }
 
    private:
        Value _value;
    };
 
    template<typename T>
    class TaskPromise<T&> : public ice::TaskPromiseBase
    {
    public:
        inline auto get_return_object() noexcept -> ice::Task<T&>;
 
        inline void return_value(T& value) noexcept
        {
            _value = ice::addressof(value);
        }
 
        inline auto result() const noexcept -> T&
        {
            ICE_ASSERT(_value != nullptr, "Trying to access result from unfinished task!");
            return *_value;
        }
 
    private:
        T* _value = nullptr;
    };
 
    template<>
    class TaskPromise<void> : public ice::TaskPromiseBase
    {
    public:
        inline auto get_return_object() noexcept -> ice::Task<void>;
 
        constexpr void return_void() const noexcept { }
 
        constexpr void result() const noexcept { }
    };
 
} // namespace ice