Generator.h

/*
Copyright [2024] [Yao Yao]

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

*/

#pragma once

#include <coroutine>
#include <exception>
#include <new>

namespace cudapp
{
struct MonoState{};
template <template<typename, size_t> typename G, typename T = MonoState, size_t alignment = 32>
struct PromiseType {
    auto initial_suspend() { return std::suspend_always{}; }
    auto final_suspend() noexcept { return std::suspend_always{}; }
    auto get_return_object() {
        return G<T, alignment>{G<T, alignment>::handle_type::from_promise(*this)};
    }
    void unhandled_exception() {
        std::terminate();
    }
    void return_void() {}
    auto yield_value(T value) {
        mCurrentValue = std::move(value);
        return std::suspend_always{};
    }
    T getCurrentValue() {
        return std::move(mCurrentValue);
    }
    static void* operator new(size_t size) {
        return operator new[](size, static_cast<std::align_val_t>(alignment));
    }
private:
    T mCurrentValue{};
};

template <typename T = MonoState, size_t alignment = 32>
struct Generator {
    using promise_type = PromiseType<Generator, T, alignment>;
    using handle_type =
        std::coroutine_handle<promise_type>;
    T current_value() {
        return coro.promise().getCurrentValue();
    }
    bool move_next() {
        coro.resume();
        return !isDone();
    }
    bool isDone() const {return coro.done();}
    Generator(handle_type h) : coro(h) {}
private:
    handle_type coro;
};
} // namespace cudapp