for_each.h

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/******************************************************************************
 * Copyright 2018 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.
 *****************************************************************************/
 
#ifndef CYBER_BASE_FOR_EACH_H_
#define CYBER_BASE_FOR_EACH_H_
 
#include <type_traits>
 
#include "cyber/base/macros.h"
 
namespace apollo {
namespace cyber {
namespace base {
 
DEFINE_TYPE_TRAIT(HasLess, operator<)  // NOLINT
 
template <class Value, class End>
typename std::enable_if<HasLess<Value>::value && HasLess<End>::value,
                        bool>::type
LessThan(const Value& val, const End& end) {
  return val < end;
}
 
template <class Value, class End>
typename std::enable_if<!HasLess<Value>::value || !HasLess<End>::value,
                        bool>::type
LessThan(const Value& val, const End& end) {
  return val != end;
}
 
#define FOR_EACH(i, begin, end)           \
  for (auto i = (true ? (begin) : (end)); \
       apollo::cyber::base::LessThan(i, (end)); ++i)
 
}  // namespace base
}  // namespace cyber
}  // namespace apollo
 
#endif  // CYBER_BASE_FOR_EACH_H_