circular_check.hpp

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// Copyright 2015 TIER IV, Inc. 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 OPENSCENARIO_INTERPRETER__UTILITY__CIRCULAR_CHECK_HPP_
#define OPENSCENARIO_INTERPRETER__UTILITY__CIRCULAR_CHECK_HPP_
 
#include <unordered_map>
#include <utility>
 
namespace openscenario_interpreter
{
inline namespace utility
{
namespace detail
{
template <class Node, class NodeToChildren, class NodeToBool>
bool circular_check(const Node & node, NodeToChildren && node_to_children, NodeToBool & visit_flag)
{
  if (visit_flag[node]) {
    return true;
  }
 
  visit_flag[node] = true;
 
  for (auto && child : node_to_children(node)) {
    if (child == node) continue;
 
    if (circular_check(child, node_to_children, visit_flag)) {
      return true;
    }
    visit_flag[child] = false;
  }
 
  return false;
}
}  // namespace detail
 
template <class Node, class NodeToChildren, class Hash = std::hash<Node>>
bool circular_check(const Node & init, NodeToChildren && node_to_children)
{
  std::unordered_map<Node, bool, Hash> visit_flag;
  return detail::circular_check(init, node_to_children, visit_flag);
}
}  // namespace utility
}  // namespace openscenario_interpreter
#endif  // OPENSCENARIO_INTERPRETER__UTILITY__CIRCULAR_CHECK_HPP_