factory.h

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/******************************************************************************
 * Copyright 2017 The Apollo Authors. All Rights Reserved.
 *
 * 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 <map>
#include <memory>
#include <utility>
 
#include "cyber/common/macros.h"
 
#include "cyber/common/log.h"
 
namespace apollo {
namespace common {
namespace util {
 
template <typename IdentifierType, class AbstractProduct,
          class ProductCreator = AbstractProduct *(*)(),
          class MapContainer = std::map<IdentifierType, ProductCreator>>
class Factory {
 public:
  bool Register(const IdentifierType &id, ProductCreator creator) {
    return producers_.insert(std::make_pair(id, creator)).second;
  }
 
  bool Contains(const IdentifierType &id) {
    return producers_.find(id) != producers_.end();
  }
 
  bool Unregister(const IdentifierType &id) {
    return producers_.erase(id) == 1;
  }
 
  void Clear() { producers_.clear(); }
 
  bool Empty() const { return producers_.empty(); }
 
  template <typename... Args>
  std::unique_ptr<AbstractProduct> CreateObjectOrNull(const IdentifierType &id,
                                                      Args &&... args) {
    auto id_iter = producers_.find(id);
    if (id_iter != producers_.end()) {
      return std::unique_ptr<AbstractProduct>(
          (id_iter->second)(std::forward<Args>(args)...));
    }
    return nullptr;
  }
 
  template <typename... Args>
  std::unique_ptr<AbstractProduct> CreateObject(const IdentifierType &id,
                                                Args &&... args) {
    auto result = CreateObjectOrNull(id, std::forward<Args>(args)...);
    AERROR_IF(!result) << "Factory could not create Object of type : " << id;
    return result;
  }
 
 private:
  MapContainer producers_;
};
 
}  // namespace util
}  // namespace common
}  // namespace apollo