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// Copyright 2021 gRPC authors.
//
// 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.
#ifndef GRPC_SRC_CORE_LIB_PROMISE_SEQ_H
#define GRPC_SRC_CORE_LIB_PROMISE_SEQ_H
#include <grpc/support/port_platform.h>
#include <type_traits>
#include <utility>
#include "src/core/lib/promise/detail/basic_seq.h"
#include "src/core/lib/promise/detail/promise_like.h"
#include "src/core/lib/promise/poll.h"
namespace grpc_core {
namespace promise_detail {
template <typename T>
struct SeqTraits {
using UnwrappedType = T;
using WrappedType = T;
template <typename Next>
static auto CallFactory(Next* next, T&& value) {
return next->Make(std::forward<T>(value));
}
template <typename F, typename Elem>
static auto CallSeqFactory(F& f, Elem&& elem, T&& value) {
return f(std::forward<Elem>(elem), std::forward<T>(value));
}
template <typename Result, typename PriorResult, typename RunNext>
static Poll<Result> CheckResultAndRunNext(PriorResult prior,
RunNext run_next) {
return run_next(std::move(prior));
}
};
template <typename... Fs>
using Seq = BasicSeq<SeqTraits, Fs...>;
template <typename I, typename F, typename Arg>
struct SeqIterTraits {
using Iter = I;
using Factory = F;
using Argument = Arg;
using IterValue = decltype(*std::declval<Iter>());
using StateCreated = decltype(std::declval<F>()(std::declval<IterValue>(),
std::declval<Arg>()));
using State = PromiseLike<StateCreated>;
using Wrapped = typename State::Result;
using Traits = SeqTraits<Wrapped>;
};
template <typename Iter, typename Factory, typename Argument>
struct SeqIterResultTraits {
using IterTraits = SeqIterTraits<Iter, Factory, Argument>;
using Result = BasicSeqIter<IterTraits>;
};
} // namespace promise_detail
// Sequencing combinator.
// Run the first promise.
// Pass its result to the second, and run the returned promise.
// Pass its result to the third, and run the returned promise.
// etc
// Return the final value.
template <typename... Functors>
promise_detail::Seq<Functors...> Seq(Functors... functors) {
return promise_detail::Seq<Functors...>(std::move(functors)...);
}
template <typename F>
F Seq(F functor) {
return functor;
}
// Execute a sequence of operations of unknown length.
// Asynchronously:
// for (element in (begin, end)) {
// argument = wait_for factory(element, argument);
// }
// return argument;
template <typename Iter, typename Factory, typename Argument>
typename promise_detail::SeqIterResultTraits<Iter, Factory, Argument>::Result
SeqIter(Iter begin, Iter end, Argument argument, Factory factory) {
using Result = typename promise_detail::SeqIterResultTraits<Iter, Factory,
Argument>::Result;
return Result(begin, end, std::move(factory), std::move(argument));
}
} // namespace grpc_core
#endif // GRPC_SRC_CORE_LIB_PROMISE_SEQ_H
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