Edge.hh

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/*
 * Copyright (C) 2017 Open Source Robotics Foundation
 *
 * 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 GZ_MATH_GRAPH_EDGE_HH_
#define GZ_MATH_GRAPH_EDGE_HH_
 
// uint64_t
#include <cstdint>
#include <functional>
#include <map>
#include <ostream>
#include <set>
 
#include <gz/math/config.hh>
#include <gz/math/graph/Vertex.hh>
#include <gz/utils/NeverDestroyed.hh>
 
namespace gz::math
{
// Inline bracket to help doxygen filtering.
inline namespace GZ_MATH_VERSION_NAMESPACE {
namespace graph
{
  using EdgeId = uint64_t;
 
  template<typename E>
  struct EdgeInitializer
  {
    // cppcheck-suppress noExplicitConstructor
    EdgeInitializer(const VertexId_P &_vertices,
                    const E &_data = E(),
                    const double _weight = 1)
      : vertices(_vertices),
        data(_data),
        weight(_weight)
    {
    };
 
    public: VertexId_P vertices;
 
    public: E data;
 
    public: double weight = 1;
  };
 
  template<typename E>
  class Edge
  {
    public: explicit Edge(const VertexId_P &_vertices,
                          const E &_data,
                          const double _weight,
                          const EdgeId &_id = kNullId)
      : id(_id),
        vertices(_vertices),
        data(_data),
        weight(_weight)
    {
    }
 
    public: EdgeId Id() const
    {
      return this->id;
    }
 
    public: VertexId_P Vertices() const
    {
      if (!this->Valid())
        return {kNullId, kNullId};
 
      return this->vertices;
    }
 
    public: const E &Data() const
    {
      return this->data;
    }
 
    public: E &Data()
    {
      return this->data;
    }
 
    public: double Weight() const
    {
      return this->weight;
    }
 
    public: void SetWeight(double _newWeight)
    {
      this->weight = _newWeight;
    }
 
    public: virtual VertexId From(const VertexId &_from) const = 0;
 
    public: virtual VertexId To(const VertexId &_to) const = 0;
 
    public: bool Valid() const
    {
      return this->id != kNullId;
    }
 
    private: EdgeId id = kNullId;
 
    private: VertexId_P vertices;
 
    private: E data;
 
    private: double weight = 1.0;
  };
 
  using EdgeId_S = std::set<EdgeId>;
 
  template<typename EdgeType>
  using EdgeRef_M = std::map<EdgeId, std::reference_wrapper<const EdgeType>>;
 
  template<typename E>
  class UndirectedEdge : public Edge<E>
  {
    // Deprecated in favor of NullEdge().
    public: static UndirectedEdge<E> GZ_DEPRECATED(8) NullEdge;
 
    public: explicit UndirectedEdge(const VertexId_P &_vertices,
                                    const E &_data,
                                    double _weight,
                                    const EdgeId &_id = kNullId)
      : Edge<E>(_vertices, _data, _weight, _id)
    {
    }
 
    // Documentation inherited.
    public: VertexId From(const VertexId &_from) const override
    {
      if (!this->Valid())
        return kNullId;
 
      if (this->Vertices().first != _from && this->Vertices().second != _from)
        return kNullId;
 
      if (this->Vertices().first == _from)
        return this->Vertices().second;
 
      return this->Vertices().first;
    }
 
    // Documentation inherited.
    public: VertexId To(const VertexId &_to) const override
    {
      return this->From(_to);
    }
 
    public: friend std::ostream &operator<<(std::ostream &_out,
                                            const UndirectedEdge<E> &_e)
    {
      auto vertices = _e.Vertices();
      _out << "  " << vertices.first << " -- " << vertices.second
           << " [label=" << _e.Weight() << "];" << std::endl;
      return _out;
    }
  };
 
  // Deprecated in favor of NullEdge().
  template<typename E>
  UndirectedEdge<E> UndirectedEdge<E>::NullEdge(
    VertexId_P(kNullId, kNullId), E(), 1.0, kNullId);
 
  template<typename E>
  class DirectedEdge : public Edge<E>
  {
    // Deprecated in favor of NullEdge().
    public: static DirectedEdge<E> GZ_DEPRECATED(8) NullEdge;
 
    public: explicit DirectedEdge(const VertexId_P &_vertices,
                                  const E &_data,
                                  double _weight,
                                  const EdgeId &_id = kNullId)
      : Edge<E>(_vertices, _data, _weight, _id)
    {
    }
 
    public: VertexId Tail() const
    {
      return this->Vertices().first;
    }
 
    public: VertexId Head() const
    {
      return this->Vertices().second;
    }
 
    // Documentation inherited.
    public: VertexId From(const VertexId &_from) const override
    {
      if (_from != this->Tail())
        return kNullId;
 
      return this->Head();
    }
 
    // Documentation inherited.
    public: VertexId To(const VertexId &_to) const override
    {
      if (_to != this->Head())
        return kNullId;
 
      return this->Tail();
    }
 
    public: friend std::ostream &operator<<(std::ostream &_out,
                                            const DirectedEdge<E> &_e)
    {
      _out << "  " << _e.Tail() << " -> " << _e.Head()
           << " [label=" << _e.Weight() << "];" << std::endl;
      return _out;
    }
  };
 
  // Deprecated in favor of NullEdge().
  template<typename E>
  DirectedEdge<E> DirectedEdge<E>::NullEdge(
    VertexId_P(kNullId, kNullId), E(), 1.0, kNullId);
 
  template<typename E, typename EdgeType>
  EdgeType &NullEdge()
  {
    static gz::utils::NeverDestroyed<EdgeType> e(
      VertexId_P(kNullId, kNullId), E(), 1.0, kNullId);
    return e.Access();
  }
}  // namespace graph
}  // namespace GZ_MATH_VERSION_NAMESPACE
}  // namespace gz::math
#endif  // GZ_MATH_GRAPH_EDGE_HH_