filter_pattern.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_FILTER_PATTERN_H
#define GRPPI_COMMON_FILTER_PATTERN_H
 
#include <type_traits>
 
namespace grppi {
 
template <typename Predicate>
class filter_t {
public:
 
  filter_t(Predicate && p) noexcept :
    predicate_{p}
  {}
 
  template <typename I>
  bool operator()(I && item) const {
    return predicate_(std::forward<I>(item));
  }
 
private:
  Predicate predicate_;
};
 
namespace internal {
 
template<typename T>
struct is_filter : std::false_type {};
 
template<typename T>
struct is_filter<filter_t<T>> : std::true_type {};
 
} // namespace internal
 
template <typename T>
static constexpr bool is_filter = internal::is_filter<std::decay_t<T>>();
 
template <typename T>
using requires_filter = typename std::enable_if_t<is_filter<T>, int>;
 
}
 
#endif