text: /*
   * 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
  