forked from OctaForge/libostd
543 lines
14 KiB
C++
543 lines
14 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 <signal.h>
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#include <memory>
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#include <exception>
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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/platform.hh"
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#include "ostd/range.hh"
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/* from boost.context */
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#ifdef OSTD_PLATFORM_WIN32
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# if (defined(i386) || defined(__i386__) || defined(__i386) || \
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defined(__i486__) || defined(__i586__) || defined(__i686__) || \
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defined(__X86__) || defined(_X86_) || defined(__THW_INTEL__) || \
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defined(__I86__) || defined(__INTEL__) || defined(__IA32__) || \
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defined(_M_IX86) || defined(_I86_))
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# define OSTD_CONTEXT_CDECL __cdecl
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# endif
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#endif
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#ifndef OSTD_CONTEXT_CDECL
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#define OSTD_CONTEXT_CDECL
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#endif
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namespace ostd {
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constexpr size_t COROUTINE_DEFAULT_STACK_SIZE = SIGSTKSZ;
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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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template<typename T>
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struct coroutine_range;
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namespace detail {
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/* from boost.fcontext */
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using fcontext_t = void *;
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struct transfer_t {
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fcontext_t ctx;
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void *data;
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};
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extern "C" OSTD_EXPORT
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transfer_t OSTD_CONTEXT_CDECL ostd_jump_fcontext(
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fcontext_t const to, void *vp
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);
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extern "C" OSTD_EXPORT
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fcontext_t OSTD_CONTEXT_CDECL ostd_make_fcontext(
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void *sp, size_t size, void (*fn)(transfer_t)
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);
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extern "C" OSTD_EXPORT
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transfer_t OSTD_CONTEXT_CDECL ostd_ontop_fcontext(
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fcontext_t const to, void *vp, transfer_t (*fn)(transfer_t)
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);
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struct forced_unwind {
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fcontext_t ctx;
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forced_unwind(fcontext_t c): ctx(c) {}
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};
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struct coroutine_context {
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protected:
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coroutine_context() {}
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coroutine_context(coroutine_context const &) = delete;
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coroutine_context(coroutine_context &&c):
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p_stack(std::move(c.p_stack)), p_coro(c.p_coro), p_orig(c.p_orig),
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p_except(std::move(c.p_except))
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{
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c.p_coro = c.p_orig = nullptr;
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}
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coroutine_context &operator=(coroutine_context const &) = delete;
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coroutine_context &operator=(coroutine_context &&c) {
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swap(c);
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return *this;
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}
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void call() {
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coro_jump();
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if (p_except) {
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std::rethrow_exception(std::move(p_except));
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}
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}
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void unwind() {
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ostd_ontop_fcontext(
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std::exchange(p_coro, nullptr), nullptr,
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[](transfer_t t) -> transfer_t {
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throw forced_unwind{t.ctx};
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}
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);
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}
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void coro_jump() {
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p_coro = ostd_jump_fcontext(p_coro, this).ctx;
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}
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void yield_jump() {
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p_orig = ostd_jump_fcontext(p_orig, nullptr).ctx;
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}
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void swap(coroutine_context &other) noexcept {
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std::swap(p_stack, other.p_stack);
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std::swap(p_coro, other.p_coro);
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std::swap(p_orig, other.p_orig);
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std::swap(p_except, other.p_except);
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}
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void make_context(size_t ss, void (*callp)(transfer_t)) {
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p_stack = std::unique_ptr<byte[]>{new byte[ss]};
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p_coro = ostd_make_fcontext(p_stack.get() + ss, ss, callp);
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}
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/* TODO: new'ing the stack is sub-optimal */
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std::unique_ptr<byte[]> p_stack;
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fcontext_t p_coro;
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fcontext_t p_orig;
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std::exception_ptr p_except;
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};
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/* like reference_wrapper but for any value */
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template<typename T>
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struct arg_wrapper {
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arg_wrapper() = default;
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arg_wrapper(T arg): p_arg(std::move(arg)) {}
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void operator=(T arg) {
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p_arg = std::move(arg);
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}
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operator T &&() {
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return std::move(p_arg);
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}
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void swap(arg_wrapper &other) {
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std::swap(p_arg, other.p_arg);
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}
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private:
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T p_arg = T{};
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};
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template<typename T>
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struct arg_wrapper<T &&> {
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arg_wrapper() = default;
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arg_wrapper(T &&arg): p_arg(&arg) {}
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void operator=(T &&arg) {
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p_arg = &arg;
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}
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operator T &&() {
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return *p_arg;
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}
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void swap(arg_wrapper &other) {
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std::swap(p_arg, other.p_arg);
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}
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private:
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T *p_arg = nullptr;
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};
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template<typename T>
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struct arg_wrapper<T &> {
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arg_wrapper() = default;
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arg_wrapper(T &arg): p_arg(&arg) {}
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void operator=(T &arg) {
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p_arg = &arg;
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}
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operator T &() {
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return *p_arg;
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}
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void swap(arg_wrapper &other) {
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std::swap(p_arg, other.p_arg);
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}
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private:
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T *p_arg = nullptr;
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};
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template<typename T>
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inline void swap(arg_wrapper<T> &a, arg_wrapper<T> &b) {
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a.swap(b);
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}
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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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};
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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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};
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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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};
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template<typename ...A>
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using coro_args = typename coro_types<A...>::yield_type;
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template<typename ...A, size_t ...I>
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inline coro_args<A...> yield_ret(
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std::tuple<arg_wrapper<A>...> &args, std::index_sequence<I...>
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) {
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if constexpr(sizeof...(A) == 1) {
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return std::forward<A...>(std::get<0>(args));
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} else if constexpr(sizeof...(A) == 2) {
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return std::make_pair(std::forward<A>(std::get<I>(args))...);
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} else {
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return std::move(args);
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}
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}
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/* default case, yield returns args and takes a value */
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template<typename R, typename ...A>
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struct coro_base: coroutine_context {
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protected:
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coro_base() {}
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coro_base(coro_base const &) = delete;
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coro_base(coro_base &&c) = default;
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coro_base &operator=(coro_base const &) = delete;
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coro_base &operator=(coro_base &&c) = default;
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struct yielder {
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yielder(coro_base<R, A...> &coro): p_coro(coro) {}
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coro_args<A...> operator()(R &&ret) {
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p_coro.p_result = std::forward<R>(ret);
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p_coro.yield_jump();
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return yield_ret(
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p_coro.p_args, std::make_index_sequence<sizeof...(A)>{}
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);
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}
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private:
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coro_base<R, A...> &p_coro;
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};
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template<typename F, size_t ...I>
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void call_helper(F &func, std::index_sequence<I...>) {
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p_result = std::forward<R>(
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func(yielder{*this}, std::forward<A>(std::get<I>(p_args))...)
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);
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}
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R call(A ...args) {
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p_args = std::make_tuple(arg_wrapper<A>(std::forward<A>(args))...);
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coroutine_context::call();
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return std::forward<R>(p_result);
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}
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void swap(coro_base &other) {
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std::swap(p_args, other.p_args);
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std::swap(p_result, other.p_result);
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coroutine_context::swap(other);
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}
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std::tuple<arg_wrapper<A>...> p_args;
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arg_wrapper<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 R>
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struct coro_base<R>: coroutine_context {
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coroutine_range<R> iter();
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protected:
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coro_base() {}
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coro_base(coro_base const &) = delete;
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coro_base(coro_base &&c) = default;
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coro_base &operator=(coro_base const &) = delete;
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coro_base &operator=(coro_base &&c) = default;
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struct yielder {
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yielder(coro_base<R> &coro): p_coro(coro) {}
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void operator()(R &&ret) {
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p_coro.p_result = std::forward<R>(ret);
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p_coro.yield_jump();
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}
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private:
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coro_base<R> &p_coro;
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};
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template<typename F, size_t ...I>
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void call_helper(F &func, std::index_sequence<I...>) {
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p_result = std::forward<R>(func(yielder{*this}));
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}
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R call() {
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coroutine_context::call();
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return std::forward<R>(this->p_result);
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}
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void swap(coro_base &other) {
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std::swap(p_result, other.p_result);
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coroutine_context::swap(other);
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}
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arg_wrapper<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 ...A>
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struct coro_base<void, A...>: coroutine_context {
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protected:
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coro_base() {}
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coro_base(coro_base const &) = delete;
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coro_base(coro_base &&c) = default;
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coro_base &operator=(coro_base const &) = delete;
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coro_base &operator=(coro_base &&c) = default;
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struct yielder {
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yielder(coro_base<void, A...> &coro): p_coro(coro) {}
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coro_args<A...> operator()() {
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p_coro.yield_jump();
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return yield_ret(
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p_coro.p_args, std::make_index_sequence<sizeof...(A)>{}
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);
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}
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private:
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coro_base<void, A...> &p_coro;
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};
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template<typename F, size_t ...I>
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void call_helper(F &func, std::index_sequence<I...>) {
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func(yielder{*this}, std::forward<A>(std::get<I>(p_args))...);
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}
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void call(A ...args) {
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p_args = std::make_tuple(arg_wrapper<A>(std::forward<A>(args))...);
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coroutine_context::call();
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}
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void swap(coro_base &other) {
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std::swap(p_args, other.p_args);
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coroutine_context::swap(other);
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}
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std::tuple<arg_wrapper<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<>
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struct coro_base<void>: coroutine_context {
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protected:
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coro_base() {}
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coro_base(coro_base const &) = delete;
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coro_base(coro_base &&c) = default;
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coro_base &operator=(coro_base const &) = delete;
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coro_base &operator=(coro_base &&c) = default;
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struct yielder {
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yielder(coro_base<void> &coro): p_coro(coro) {}
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void operator()() {
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p_coro.yield_jump();
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}
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private:
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coro_base<void> &p_coro;
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};
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template<typename F, size_t ...I>
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void call_helper(F &func, std::index_sequence<I...>) {
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func(yielder{*this});
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}
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void call() {
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coroutine_context::call();
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}
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void swap(coro_base &other) {
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coroutine_context::swap(other);
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}
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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::coro_base<R, A...> {
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private:
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using base_t = detail::coro_base<R, A...>;
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public:
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using yield_type = typename detail::coro_base<R, A...>::yielder;
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template<typename F>
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coroutine(F func, size_t ss = COROUTINE_DEFAULT_STACK_SIZE):
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p_func(std::move(func))
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{
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if (!p_func) {
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return;
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}
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this->make_context(ss, &context_call);
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}
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coroutine(coroutine const &) = delete;
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coroutine(coroutine &&c):
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detail::coro_base<R, A...>(std::move(c)), p_func(std::move(c.p_func))
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{
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c.p_func = nullptr;
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}
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coroutine &operator=(coroutine const &) = delete;
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coroutine &operator=(coroutine &&c) {
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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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c.p_func = nullptr;
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}
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~coroutine() {
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/* we have to check both because of potential moves */
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if (!p_func) {
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return;
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}
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this->unwind();
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}
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operator bool() const {
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return bool(p_func);
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}
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R resume(A ...args) {
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if (!p_func) {
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throw coroutine_error{"dead coroutine"};
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}
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return this->call(std::forward<A>(args)...);
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}
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R operator()(A ...args) {
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return resume(std::forward<A>(args)...);
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}
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void swap(coroutine &other) {
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std::swap(p_func, other.p_func);
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base_t::swap(other);
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}
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private:
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static void context_call(detail::transfer_t t) {
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auto &self = *(static_cast<coroutine *>(t.data));
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self.p_orig = t.ctx;
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try {
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self.call_helper(self.p_func, std::index_sequence_for<A...>{});
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} catch (detail::forced_unwind v) {
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self.p_orig = v.ctx;
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} catch (...) {
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self.p_except = std::current_exception();
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}
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self.p_func = nullptr;
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self.yield_jump();
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}
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std::function<R(yield_type, A...)> p_func;
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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) {
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a.swap(b);
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}
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template<typename T>
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struct coroutine_range: input_range<coroutine_range<T>> {
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using range_category = input_range_tag;
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using value_type = T;
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using reference = T &;
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using size_type = size_t;
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using difference_type = stream_off_t;
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coroutine_range() = delete;
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coroutine_range(coroutine<T()> &c): p_coro(&c) {
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pop_front();
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}
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coroutine_range(coroutine_range const &r):
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p_coro(r.p_coro), p_item(r.p_item) {}
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bool empty() const {
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return !p_item;
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}
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void pop_front() {
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if (*p_coro) {
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p_item = (*p_coro)();
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} else {
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p_item = std::nullopt;
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}
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}
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reference front() const {
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return p_item.value();
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}
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bool equals_front(coroutine_range const &g) {
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return p_coro == g.p_coro;
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}
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private:
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coroutine<T()> *p_coro;
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mutable std::optional<T> p_item;
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};
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namespace detail {
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template<typename R>
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coroutine_range<R> coro_base<R>::iter() {
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return coroutine_range<R>{static_cast<coroutine<R()> &>(*this)};
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}
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}
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} /* namespace ostd */
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#endif
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