piping.h

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/*
 * Copyright 2018-present Facebook, Inc.
 *
 * 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 <folly/experimental/pushmi/traits.h>

namespace folly {
namespace pushmi {

PUSHMI_TEMPLATE(class In, class Op)
(requires lazy::Sender<std::decay_t<In>>&& lazy::Invocable<Op&, In>)
decltype(auto) operator|(In&& in, Op op) {
  return op((In &&) in);
}

PUSHMI_INLINE_VAR constexpr struct pipe_fn {
#if __cpp_fold_expressions >= 201603
  template <class T, class... FN>
  auto operator()(T t, FN... fn) const -> decltype((t | ... | fn)) {
    return (t | ... | fn);
  }
#else
  template <class T, class F>
  auto operator()(T t, F f) const -> decltype(t | f) {
    return t | f;
  }
  template <class T, class F, class... FN, class This = pipe_fn>
  auto operator()(T t, F f, FN... fn) const
      -> decltype(This()((t | f), fn...)) {
    return This()((t | f), fn...);
  }
#endif
} const pipe{};

} // namespace pushmi
} // namespace folly