forked from OctaForge/libostd
680 lines
18 KiB
C++
680 lines
18 KiB
C++
/* Coroutines for OctaSTD.
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*
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* This file is part of OctaSTD. See COPYING.md for further information.
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*/
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#ifndef OSTD_COROUTINE_HH
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#define OSTD_COROUTINE_HH
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#include <stdexcept>
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#include <utility>
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#include <tuple>
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#include <type_traits>
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#include <optional>
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#include "ostd/types.hh"
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#include "ostd/range.hh"
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#include "ostd/internal/context.hh"
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namespace ostd {
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struct coroutine_error: std::runtime_error {
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using std::runtime_error::runtime_error;
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};
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template<typename T>
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struct coroutine;
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namespace detail {
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template<typename T>
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using coro_arg = std::add_pointer_t<std::remove_reference_t<T>>;
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/* dealing with args */
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template<typename ...A>
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struct coro_types {
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using yield_type = std::tuple<A...>;
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template<size_t ...I>
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static yield_type get_impl(
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std::tuple<coro_arg<A>...> &args, std::index_sequence<I...>
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) {
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return std::make_tuple(std::forward<A>(*std::get<I>(args))...);
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}
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static yield_type get(std::tuple<coro_arg<A>...> &args) {
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return get_impl(args, std::index_sequence_for<A...>{});
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}
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};
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template<typename A>
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struct coro_types<A> {
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using yield_type = A;
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static yield_type get(std::tuple<coro_arg<A>> &args) {
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return std::forward<A>(*std::get<0>(args));
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}
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};
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template<typename A, typename B>
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struct coro_types<A, B> {
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using yield_type = std::pair<A, B>;
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static yield_type get(std::tuple<coro_arg<A>, coro_arg<B>> &args) {
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return std::make_pair(
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std::forward<A>(*std::get<0>(args)),
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std::forward<B>(*std::get<1>(args))
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);
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}
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};
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template<>
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struct coro_types<> {
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using yield_type = void;
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};
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template<typename ...A>
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using coro_args = typename coro_types<A...>::yield_type;
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/* storing and handling results */
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template<typename R>
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struct coro_rtype {
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using type = std::aligned_storage_t<sizeof(R), alignof(R)>;
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static void store(type &stor, R &&v) {
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new (&stor) R(std::move(v));
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}
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static void store(type &stor, R const &v) {
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new (&stor) R(v);
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}
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static R get(type &stor) {
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R &tstor = *reinterpret_cast<R *>(&stor);
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R ret{std::forward<R>(tstor)};
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/* this way we can make sure result is always uninitialized
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* except when resuming, so no need to keep a bool flag etc.
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*/
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tstor.~R();
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return ret;
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}
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};
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template<typename R>
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struct coro_rtype<R &> {
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using type = R *;
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static void store(type &stor, R &v) {
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stor = &v;
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}
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static R &get(type stor) {
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return *stor;
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}
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};
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template<typename R>
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struct coro_rtype<R &&> {
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using type = std::aligned_storage_t<sizeof(R), alignof(R)>;
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static void store(type &stor, R &&v) {
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new (&stor) R(std::move(v));
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}
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static R &&get(type &stor) {
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R &tstor = *reinterpret_cast<R *>(&stor);
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R ret{std::forward<R>(tstor)};
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tstor.~R();
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return std::move(ret);
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}
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};
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template<typename R>
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using coro_result = typename coro_rtype<R>::type;
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/* default case, yield returns args and takes a value */
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template<typename Y, typename R, typename ...A>
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struct coro_stor {
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template<typename F>
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coro_stor(F &&func): p_func(std::forward<F>(func)) {}
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template<size_t ...I>
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coro_args<A...> get_args(std::index_sequence<I...>) {
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return coro_types<A...>::get(p_args);
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}
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void set_args(coro_arg<A> ...args) {
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p_args = std::make_tuple(args...);
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}
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R get_result() {
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return std::forward<R>(coro_rtype<R>::get(p_result));
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}
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template<size_t ...I>
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void call_helper(Y &&yielder, std::index_sequence<I...>) {
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coro_rtype<R>::store(p_result, std::forward<R>(p_func(
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std::move(yielder),
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std::forward<A>(*std::get<I>(p_args))...
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)));
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}
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void swap(coro_stor &other) {
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using std::swap;
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swap(p_func, other.p_func);
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swap(p_args, other.p_args);
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/* no need to swap result as result is always only alive
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* for the time of a single resume, in which no swap happens
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*/
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}
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std::function<R(Y, A...)> p_func;
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std::tuple<coro_arg<A>...> p_args;
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coro_result<R> p_result;
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};
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/* yield takes a value but doesn't return any args */
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template<typename Y, typename R>
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struct coro_stor<Y, R> {
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template<typename F>
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coro_stor(F &&func): p_func(std::forward<F>(func)) {}
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template<size_t ...I>
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void get_args(std::index_sequence<I...>) {}
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void set_args() {}
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R get_result() {
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return std::forward<R>(coro_rtype<R>::get(p_result));
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}
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template<size_t ...I>
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void call_helper(Y &&yielder, std::index_sequence<I...>) {
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coro_rtype<R>::store(
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p_result, std::forward<R>(p_func(std::move(yielder)))
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);
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}
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void swap(coro_stor &other) {
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std::swap(p_func, other.p_func);
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}
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std::function<R(Y)> p_func;
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coro_result<R> p_result;
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};
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/* yield doesn't take a value and returns args */
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template<typename Y, typename ...A>
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struct coro_stor<Y, void, A...> {
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template<typename F>
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coro_stor(F &&func): p_func(std::forward<F>(func)) {}
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template<size_t ...I>
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coro_args<A...> get_args(std::index_sequence<I...>) {
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return coro_types<A...>::get(p_args);
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}
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void set_args(coro_arg<A> ...args) {
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p_args = std::make_tuple(args...);
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}
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void get_result() {}
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template<size_t ...I>
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void call_helper(Y &&yielder, std::index_sequence<I...>) {
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p_func(std::move(yielder), std::forward<A>(*std::get<I>(p_args))...);
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}
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void swap(coro_stor &other) {
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using std::swap;
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swap(p_func, other.p_func);
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swap(p_args, other.p_args);
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}
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std::function<void(Y, A...)> p_func;
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std::tuple<coro_arg<A>...> p_args;
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};
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/* yield doesn't take a value or return any args */
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template<typename Y>
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struct coro_stor<Y, void> {
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template<typename F>
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coro_stor(F &&func): p_func(std::forward<F>(func)) {}
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template<size_t ...I>
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void get_args(std::index_sequence<I...>) {}
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void set_args() {}
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void get_result() {}
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template<size_t ...I>
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void call_helper(Y &&yielder, std::index_sequence<I...>) {
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p_func(std::move(yielder));
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}
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void swap(coro_stor &other) {
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std::swap(p_func, other.p_func);
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}
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std::function<void(Y)> p_func;
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};
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} /* namespace detail */
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template<typename R, typename ...A>
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struct coroutine<R(A...)>: detail::coroutine_context {
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private:
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using base_t = detail::coroutine_context;
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/* necessary so that context callback can access privates */
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friend struct detail::coroutine_context;
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template<typename RR, typename ...AA>
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struct yielder {
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yielder(coroutine<RR(AA...)> &coro): p_coro(coro) {}
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detail::coro_args<AA...> operator()(RR &&ret) {
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detail::coro_rtype<RR>::store(
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p_coro.p_stor.p_result, std::move(ret)
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);
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p_coro.yield_jump();
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return p_coro.p_stor.get_args(std::index_sequence_for<AA...>{});
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}
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detail::coro_args<AA...> operator()(RR const &ret) {
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detail::coro_rtype<RR>::store(p_coro.p_stor.p_result, ret);
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p_coro.yield_jump();
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return p_coro.p_stor.get_args(std::index_sequence_for<AA...>{});
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}
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private:
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coroutine<RR(AA...)> &p_coro;
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};
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template<typename RR, typename ...AA>
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struct yielder<RR &, AA...> {
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yielder(coroutine<RR &(AA...)> &coro): p_coro(coro) {}
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detail::coro_args<AA...> operator()(RR &ret) {
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detail::coro_rtype<RR &>::store(p_coro.p_stor.p_result, ret);
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p_coro.yield_jump();
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return p_coro.p_stor.get_args(std::index_sequence_for<AA...>{});
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}
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private:
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coroutine<RR &(AA...)> &p_coro;
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};
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template<typename RR, typename ...AA>
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struct yielder<RR &&, AA...> {
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yielder(coroutine<RR &&(AA...)> &coro): p_coro(coro) {}
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detail::coro_args<AA...> operator()(RR &&ret) {
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detail::coro_rtype<RR &&>::store(
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p_coro.p_stor.p_result, std::move(ret)
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);
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p_coro.yield_jump();
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return p_coro.p_stor.get_args(std::index_sequence_for<AA...>{});
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}
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private:
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coroutine<RR &&(AA...)> &p_coro;
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};
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template<typename ...AA>
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struct yielder<void, AA...> {
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yielder(coroutine<void(AA...)> &coro): p_coro(coro) {}
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detail::coro_args<AA...> operator()() {
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p_coro.yield_jump();
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return p_coro.p_stor.get_args(std::index_sequence_for<AA...>{});
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}
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private:
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coroutine<void(AA...)> &p_coro;
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};
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public:
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using yield_type = yielder<R, A...>;
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/* we have no way to assign a function anyway... */
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coroutine() = delete;
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/* 0 means default size decided by the stack allocator */
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template<typename F, typename SA = default_stack>
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coroutine(F func, SA sa = SA{}): base_t(), p_stor(std::move(func)) {
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/* that way there is no context creation/stack allocation */
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if (!p_stor.p_func) {
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this->set_dead();
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return;
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}
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this->template make_context<coroutine<R(A...)>>(sa);
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}
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template<typename SA = default_stack>
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coroutine(std::nullptr_t, SA = SA{0}): base_t(), p_stor() {
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this->set_dead();
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}
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coroutine(coroutine const &) = delete;
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coroutine(coroutine &&c) noexcept:
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base_t(std::move(c)), p_stor(std::move(c.p_stor))
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{
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c.p_stor.p_func = nullptr;
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}
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coroutine &operator=(coroutine const &) = delete;
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coroutine &operator=(coroutine &&c) noexcept {
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base_t::operator=(std::move(c));
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p_stor = std::move(c.p_stor);
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c.p_stor.p_func = nullptr;
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}
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explicit operator bool() const noexcept {
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return !this->is_dead();
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}
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R resume(A ...args) {
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if (this->is_dead()) {
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throw coroutine_error{"dead coroutine"};
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}
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this->set_args(&args...);
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base_t::call();
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return this->get_result();
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}
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R operator()(A ...args) {
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/* duplicate the logic so we don't copy/move the args */
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if (this->is_dead()) {
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throw coroutine_error{"dead coroutine"};
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}
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p_stor.set_args(&args...);
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base_t::call();
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return p_stor.get_result();
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}
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void swap(coroutine &other) noexcept {
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p_stor.swap(other.p_stor);
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base_t::swap(other);
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}
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private:
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void resume_call() {
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p_stor.call_helper(yield_type{*this}, std::index_sequence_for<A...>{});
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}
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detail::coro_stor<yield_type, R, A...> p_stor;
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};
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template<typename R, typename ...A>
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inline void swap(coroutine<R(A...)> &a, coroutine<R(A...)> &b) noexcept {
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a.swap(b);
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}
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template<typename T> struct generator_range;
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namespace detail {
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template<typename T> struct generator_iterator;
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}
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template<typename T>
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struct generator: detail::coroutine_context {
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private:
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using base_t = detail::coroutine_context;
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friend struct detail::coroutine_context;
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template<typename U>
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struct yielder {
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yielder(generator<U> &g): p_gen(g) {}
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void operator()(U &&ret) {
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p_gen.p_result = &ret;
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p_gen.yield_jump();
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}
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void operator()(U const &ret) {
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if constexpr(std::is_const_v<U>) {
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p_gen.p_result = &ret;
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p_gen.yield_jump();
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} else {
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T val{ret};
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p_gen.p_result = &val;
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p_gen.yield_jump();
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}
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}
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private:
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generator<U> &p_gen;
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};
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template<typename U>
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struct yielder<U &> {
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yielder(generator<U> &g): p_gen(g) {}
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void operator()(U &ret) {
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p_gen.p_result = &ret;
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p_gen.yield_jump();
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}
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private:
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generator<U> &p_gen;
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};
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template<typename U>
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struct yielder<U &&> {
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yielder(generator<U> &g): p_gen(g) {}
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void operator()(U &&ret) {
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p_gen.p_result = &ret;
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p_gen.yield_jump();
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}
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private:
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generator<U> &p_gen;
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};
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public:
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using range = generator_range<T>;
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using yield_type = yielder<T>;
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generator() = delete;
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template<typename F, typename SA = default_stack>
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generator(F func, SA sa = SA{}):
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base_t(), p_func(std::move(func))
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{
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/* that way there is no context creation/stack allocation */
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if (!p_func) {
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this->set_dead();
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return;
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}
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this->template make_context<generator<T>>(sa);
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/* generate an initial value */
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resume();
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}
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template<typename SA = default_stack>
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generator(std::nullptr_t, SA = SA{0}):
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base_t(), p_func(nullptr)
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{
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this->set_dead();
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}
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generator(generator const &) = delete;
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generator(generator &&c) noexcept:
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base_t(std::move(c)), p_func(std::move(c.p_func)), p_result(c.p_result)
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{
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c.p_func = nullptr;
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c.p_result = nullptr;
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}
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generator &operator=(generator const &) = delete;
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generator &operator=(generator &&c) noexcept {
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base_t::operator=(std::move(c));
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p_func = std::move(c.p_func);
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p_result = c.p_result;
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c.p_func = nullptr;
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c.p_result = nullptr;
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}
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explicit operator bool() const noexcept {
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return !this->is_dead();
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}
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void resume() {
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if (this->is_dead()) {
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throw coroutine_error{"dead generator"};
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}
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detail::coroutine_context::call();
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}
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T &value() {
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if (!p_result) {
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throw coroutine_error{"no value"};
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}
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return *p_result;
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}
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T const &value() const {
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if (!p_result) {
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throw coroutine_error{"no value"};
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}
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return *p_result;
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}
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bool empty() const noexcept {
|
|
return !p_result;
|
|
}
|
|
|
|
generator_range<T> iter() noexcept;
|
|
|
|
/* for range for loop; they're the same, operator!= bypasses comparing */
|
|
detail::generator_iterator<T> begin() noexcept;
|
|
detail::generator_iterator<T> end() noexcept;
|
|
|
|
void swap(generator &other) noexcept {
|
|
using std::swap;
|
|
swap(p_func, other.p_func);
|
|
swap(p_result, other.p_result);
|
|
detail::coroutine_context::swap(other);
|
|
}
|
|
|
|
private:
|
|
void resume_call() {
|
|
p_func(yield_type{*this});
|
|
/* done, gotta null the item so that empty() returns true */
|
|
p_result = nullptr;
|
|
}
|
|
|
|
std::function<void(yield_type)> p_func;
|
|
/* we can use a pointer because even stack values are alive
|
|
* as long as the coroutine is alive (and it is on every yield)
|
|
*/
|
|
std::remove_reference_t<T> *p_result = nullptr;
|
|
};
|
|
|
|
template<typename T>
|
|
inline void swap(generator<T> &a, generator<T> &b) noexcept {
|
|
a.swap(b);
|
|
}
|
|
|
|
namespace detail {
|
|
template<typename T>
|
|
struct yield_type_base {
|
|
using type = typename generator<T>::yield_type;
|
|
};
|
|
template<typename R, typename ...A>
|
|
struct yield_type_base<R(A...)> {
|
|
using type = typename coroutine<R(A...)>::yield_type;
|
|
};
|
|
}
|
|
|
|
template<typename T>
|
|
using yield_type = typename detail::yield_type_base<T>::type;
|
|
|
|
template<typename T>
|
|
struct generator_range: input_range<generator_range<T>> {
|
|
using range_category = input_range_tag;
|
|
using value_type = T;
|
|
using reference = T &;
|
|
using size_type = size_t;
|
|
using difference_type = ptrdiff_t;
|
|
|
|
generator_range() = delete;
|
|
generator_range(generator<T> &g): p_gen(&g) {}
|
|
|
|
bool empty() const noexcept {
|
|
return p_gen->empty();
|
|
}
|
|
|
|
void pop_front() {
|
|
p_gen->resume();
|
|
}
|
|
|
|
reference front() const {
|
|
return p_gen->value();
|
|
}
|
|
|
|
bool equals_front(generator_range const &g) const noexcept {
|
|
return p_gen == g.p_gen;
|
|
}
|
|
|
|
/* same behavior as on generator itself, for range for loop */
|
|
detail::generator_iterator<T> begin() noexcept;
|
|
detail::generator_iterator<T> end() noexcept;
|
|
|
|
private:
|
|
generator<T> *p_gen;
|
|
};
|
|
|
|
template<typename T>
|
|
generator_range<T> generator<T>::iter() noexcept {
|
|
return generator_range<T>{*this};
|
|
}
|
|
|
|
namespace detail {
|
|
/* deliberately incomplete, only for range for loop */
|
|
template<typename T>
|
|
struct generator_iterator {
|
|
generator_iterator() = delete;
|
|
generator_iterator(generator<T> &g): p_gen(&g) {}
|
|
|
|
bool operator!=(generator_iterator const &) noexcept {
|
|
return !p_gen->empty();
|
|
}
|
|
|
|
T &operator*() const {
|
|
return p_gen->value();
|
|
}
|
|
|
|
generator_iterator &operator++() {
|
|
p_gen->resume();
|
|
return *this;
|
|
}
|
|
|
|
private:
|
|
generator<T> *p_gen;
|
|
};
|
|
} /* namespace detail */
|
|
|
|
template<typename T>
|
|
detail::generator_iterator<T> generator<T>::begin() noexcept {
|
|
return detail::generator_iterator<T>{*this};
|
|
}
|
|
|
|
template<typename T>
|
|
detail::generator_iterator<T> generator<T>::end() noexcept {
|
|
return detail::generator_iterator<T>{*this};
|
|
}
|
|
|
|
template<typename T>
|
|
detail::generator_iterator<T> generator_range<T>::begin() noexcept {
|
|
return detail::generator_iterator<T>{*p_gen};
|
|
}
|
|
|
|
template<typename T>
|
|
detail::generator_iterator<T> generator_range<T>::end() noexcept {
|
|
return detail::generator_iterator<T>{*p_gen};
|
|
}
|
|
|
|
} /* namespace ostd */
|
|
|
|
#endif
|