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///////////////////////////////////////////////////////////////////////////////
// Reference implementation of std::generator proposal P2168.
//
// See https://wg21.link/P2168 for details.
//
///////////////////////////////////////////////////////////////////////////////
// Copyright Lewis Baker, Corentin Jabot
//
// Use, modification and distribution is subject to the Boost Software License,
// Version 1.0.
// (See accompanying file LICENSE or http://www.boost.org/LICENSE_1_0.txt)
///////////////////////////////////////////////////////////////////////////////
module;
#include <coroutine>
#include <ranges>
export module nihil.generator:generator_promise;
import :forward;
import :generator_promise_base;
import :promise_base_alloc;
namespace nihil {
export template <typename Generator, typename ByteAllocator, bool ExplicitAllocator = false>
struct generator_promise;
export template <typename Ref, typename Value, typename Alloc, typename ByteAllocator,
bool ExplicitAllocator>
struct generator_promise<generator<Ref, Value, Alloc>, ByteAllocator, ExplicitAllocator> final
: public generator_promise_base<Ref>,
public promise_base_alloc<ByteAllocator>
{
generator_promise() noexcept
: generator_promise_base<Ref>(
std::coroutine_handle<generator_promise>::from_promise(*this))
{
}
auto get_return_object() noexcept -> generator<Ref, Value, Alloc>
{
return generator<Ref, Value, Alloc>{
std::coroutine_handle<generator_promise>::from_promise(*this)};
}
using generator_promise_base<Ref>::yield_value;
template <std::ranges::range Rng>
auto yield_value(nihil::elements_of<Rng> &&x) -> typename generator_promise_base<
Ref>::template yield_sequence_awaiter<generator<Ref, Value, Alloc>>
{
static_assert(!ExplicitAllocator,
"This coroutine has an explicit allocator specified with "
"std::allocator_arg so an allocator needs to be passed "
"explicitely to std::elements_of");
return [](auto &&rng) -> generator<Ref, Value, Alloc> {
for (auto &&e : rng)
co_yield static_cast<decltype(e)>(e);
}(std::forward<Rng>(x.get()));
}
};
} // namespace nihil
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