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