76 lines
1.9 KiB
C++
76 lines
1.9 KiB
C++
#pragma once
|
|
|
|
#include <coroutine>
|
|
#include <utility>
|
|
|
|
// from https://www.scs.stanford.edu/~dm/blog/c++-coroutines.html
|
|
|
|
namespace EightBit {
|
|
|
|
template<typename T>
|
|
class co_generator_t final {
|
|
public:
|
|
class promise_type;
|
|
|
|
private:
|
|
using handle_t = std::coroutine_handle<promise_type>;
|
|
|
|
public:
|
|
class promise_type final {
|
|
private:
|
|
T value_;
|
|
std::exception_ptr exception_;
|
|
|
|
public:
|
|
template<std::convertible_to<T> From> // C++20 concept
|
|
[[nodiscard]] constexpr std::suspend_always yield_value(From&& from) noexcept {
|
|
value_ = std::forward<From>(from);
|
|
return {};
|
|
}
|
|
|
|
[[nodiscard]] constexpr std::suspend_always initial_suspend() noexcept { return {}; }
|
|
[[nodiscard]] constexpr std::suspend_always final_suspend() noexcept { return {}; }
|
|
|
|
[[nodiscard]] constexpr co_generator_t get_return_object() noexcept {
|
|
return co_generator_t(handle_t::from_promise(*this));
|
|
}
|
|
|
|
constexpr void return_void() {}
|
|
|
|
constexpr void unhandled_exception() noexcept { exception_ = std::current_exception(); }
|
|
|
|
[[nodiscard]] constexpr auto& value() noexcept { return value_; };
|
|
[[nodiscard]] constexpr auto& exception() noexcept { return exception_; };
|
|
};
|
|
|
|
private:
|
|
handle_t h_;
|
|
bool full_ = false;
|
|
|
|
constexpr void fill() {
|
|
if (!full_) {
|
|
h_();
|
|
if (h_.promise().exception())
|
|
std::rethrow_exception(h_.promise().exception());
|
|
full_ = true;
|
|
}
|
|
}
|
|
|
|
public:
|
|
co_generator_t(handle_t h) noexcept : h_(h) {}
|
|
|
|
~co_generator_t() noexcept { h_.destroy(); }
|
|
|
|
constexpr explicit operator bool() {
|
|
fill();
|
|
return !h_.done();
|
|
}
|
|
|
|
[[nodiscard]] constexpr T operator()() {
|
|
fill();
|
|
full_ = false;
|
|
return std::move(h_.promise().value());
|
|
}
|
|
};
|
|
}
|