common/context.h

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/*
 * Copyright 2018 Universidad Carlos III de Madrid
 * 
 * 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 GRPPI_COMMON_CONTEXT_H
#define GRPPI_COMMON_CONTEXT_H
 
#include <type_traits>
 
namespace grppi {
 
template <typename ExecutionPolicy, typename Transformer>
class context_t {
public:
 
  using transformer_type = Transformer;
  using execution_policy_type = ExecutionPolicy;
 
  context_t(ExecutionPolicy & e, Transformer && t) noexcept :
    execution_policy_{e}, transformer_{t}
  {}
 
  ExecutionPolicy & execution_policy(){
    return execution_policy_;
  }
  
 
  Transformer & transformer(){
    return transformer_;
  }
 
  template <typename I>
  auto operator()(I && item) const {
    return transformer_(std::forward<I>(item));
  }
 
private:
  ExecutionPolicy& execution_policy_;
  Transformer transformer_;
};
 
namespace internal {
 
template<typename T>
struct is_context : std::false_type {};
 
template<typename E, typename T>
struct is_context<context_t<E,T>> : std::true_type {};
 
} // namespace internal
 
template <typename T>
static constexpr bool is_context = internal::is_context<std::decay_t<T>>();
 
template <typename T>
using requires_context = typename std::enable_if_t<is_context<T>, int>;
 
}
 
#endif