141 lines
3.1 KiB
C++
141 lines
3.1 KiB
C++
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#pragma once
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#if !defined(MIJIN_ASYNC_FUTURE_HPP_INCLUDED)
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#define MIJIN_ASYNC_FUTURE_HPP_INCLUDED 1
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#include <optional>
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#include <memory>
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#include <type_traits>
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#include "./signal.hpp"
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#include "../debug/assert.hpp"
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#include "../container/optional.hpp"
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namespace mijin
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{
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//
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// public defines
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//
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//
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// public constants
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//
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//
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// public types
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//
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template<typename TValue>
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class Future;
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// TODO: add support for mutexes and waiting for futures
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namespace impl
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{
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template<typename TValue>
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struct FutureStorage
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{
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Optional<TValue> value;
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void setValue(TValue value_) noexcept { value = std::move(value_); }
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[[nodiscard]] TValue& getValue() noexcept { return value.get(); }
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};
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// template<typename TValue>
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// struct FutureStorage<TValue&>
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// {
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// Optional<TValue*> value;
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//
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// void setValue(TValue& value_) noexcept { value = &value_; }
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// [[nodiscard]] TValue& getValue() const noexcept { return *value.get(); }
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// };
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template<>
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struct FutureStorage<void>
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{
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};
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} // namespace impl
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template<typename TValue>
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class Future
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{
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private:
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impl::FutureStorage<TValue> value_;
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bool isSet_ = false;
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public:
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Future() = default;
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Future(const Future&) = delete;
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Future(Future&&) noexcept = default;
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public:
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Future& operator=(const Future&) = delete;
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Future& operator=(Future&&) noexcept = default;
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[[nodiscard]]
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constexpr explicit operator bool() const noexcept { return ready(); }
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[[nodiscard]]
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constexpr bool operator!() const noexcept { return !ready(); }
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public: // access
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[[nodiscard]]
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constexpr decltype(auto) get() noexcept
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{
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MIJIN_ASSERT(isSet_, "Attempting to get from future that is not ready.");
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if constexpr(std::is_same_v<TValue, void>) {
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return;
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}
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else {
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return value_.getValue();
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}
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}
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[[nodiscard]]
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constexpr decltype(auto) get() const noexcept
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{
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MIJIN_ASSERT(isSet_, "Attempting to get from future that is not ready.");
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if constexpr(std::is_same_v<TValue, void>) {
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return;
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}
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else {
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return value_.getValue();
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}
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}
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[[nodiscard]]
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constexpr bool ready() const noexcept
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{
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return isSet_;
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}
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public: // modification
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template<typename TArg> requires (!std::is_same_v<TValue, void>)
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constexpr void set(TArg&& value) noexcept
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{
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MIJIN_ASSERT(!isSet_, "Trying to set a future twice!");
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value_.setValue(std::move(value));
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isSet_ = true;
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sigSet.emit();
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}
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constexpr void set() noexcept
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{
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MIJIN_ASSERT(!isSet_, "Trying to set a future twice!");
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isSet_ = true;
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if constexpr (std::is_same_v<TValue, void>) {
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sigSet.emit();
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}
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else {
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// would love to make this a compile-time error :/
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MIJIN_ERROR("Attempting to call set(void) on future with value.");
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}
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}
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public: // signals
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Signal<> sigSet;
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};
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template<typename TValue>
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using FuturePtr = std::shared_ptr<Future<TValue>>;
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//
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// public functions
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//
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} // namespace mijin
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#endif // !defined(MIJIN_ASYNC_FUTURE_HPP_INCLUDED)
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