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boost/graph/floyd_warshall_shortest.hpp

// Copyright 2002 Rensselaer Polytechnic Institute

// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)

//  Authors: Lauren Foutz
//           Scott Hill

/*
  This file implements the functions

  template <class VertexListGraph, class DistanceMatrix, 
    class P, class T, class R>
  bool floyd_warshall_initialized_all_pairs_shortest_paths(
    const VertexListGraph& g, DistanceMatrix& d, 
    const bgl_named_params<P, T, R>& params)

  AND

  template <class VertexAndEdgeListGraph, class DistanceMatrix, 
    class P, class T, class R>
  bool floyd_warshall_all_pairs_shortest_paths(
    const VertexAndEdgeListGraph& g, DistanceMatrix& d, 
    const bgl_named_params<P, T, R>& params)
*/


#ifndef BOOST_GRAPH_FLOYD_WARSHALL_HPP
#define BOOST_GRAPH_FLOYD_WARSHALL_HPP

#include <boost/property_map/property_map.hpp>
#include <boost/graph/graph_traits.hpp>
#include <boost/graph/named_function_params.hpp>
#include <boost/graph/graph_concepts.hpp>
#include <boost/graph/relax.hpp>

namespace boost
{
  namespace detail {
    template<typename T, typename BinaryPredicate>
    T min_with_compare(const T& x, const T& y, const BinaryPredicate& compare)
    {
      if (compare(x, y)) return x; 
      else return y;
    }

    template<typename VertexListGraph, typename DistanceMatrix, 
      typename BinaryPredicate, typename BinaryFunction,
      typename Infinity, typename Zero>
    bool floyd_warshall_dispatch(const VertexListGraph& g, 
      DistanceMatrix& d, const BinaryPredicate &compare, 
      const BinaryFunction &combine, const Infinity& inf, 
      const Zero& zero)
    {
      typename graph_traits<VertexListGraph>::vertex_iterator 
        i, lasti, j, lastj, k, lastk;
    
      
      for (boost::tie(k, lastk) = vertices(g); k != lastk; k++)
        for (boost::tie(i, lasti) = vertices(g); i != lasti; i++)
          if(d[*i][*k] != inf)
            for (boost::tie(j, lastj) = vertices(g); j != lastj; j++)
              if(d[*k][*j] != inf)
                d[*i][*j] = 
                  detail::min_with_compare(d[*i][*j], 
                                           combine(d[*i][*k], d[*k][*j]),
                                           compare);
      
      
      for (boost::tie(i, lasti) = vertices(g); i != lasti; i++)
        if (compare(d[*i][*i], zero))
          return false;
      return true;
    }
  }

  template <typename VertexListGraph, typename DistanceMatrix, 
    typename BinaryPredicate, typename BinaryFunction,
    typename Infinity, typename Zero>
  bool floyd_warshall_initialized_all_pairs_shortest_paths(
    const VertexListGraph& g, DistanceMatrix& d, 
    const BinaryPredicate& compare, 
    const BinaryFunction& combine, const Infinity& inf, 
    const Zero& zero)
  {
    function_requires<VertexListGraphConcept<VertexListGraph> >();
  
    return detail::floyd_warshall_dispatch(g, d, compare, combine, 
    inf, zero);
  }
  

  
  template <typename VertexAndEdgeListGraph, typename DistanceMatrix, 
    typename WeightMap, typename BinaryPredicate, 
    typename BinaryFunction, typename Infinity, typename Zero>
  bool floyd_warshall_all_pairs_shortest_paths(
    const VertexAndEdgeListGraph& g, 
    DistanceMatrix& d, const WeightMap& w, 
    const BinaryPredicate& compare, const BinaryFunction& combine, 
    const Infinity& inf, const Zero& zero)
  {
    function_requires<VertexListGraphConcept<VertexAndEdgeListGraph> >();
    function_requires<EdgeListGraphConcept<VertexAndEdgeListGraph> >();
    function_requires<IncidenceGraphConcept<VertexAndEdgeListGraph> >();
  
    typename graph_traits<VertexAndEdgeListGraph>::vertex_iterator 
      firstv, lastv, firstv2, lastv2;
    typename graph_traits<VertexAndEdgeListGraph>::edge_iterator first, last;
  
    
    for(boost::tie(firstv, lastv) = vertices(g); firstv != lastv; firstv++)
      for(boost::tie(firstv2, lastv2) = vertices(g); firstv2 != lastv2; firstv2++)
        d[*firstv][*firstv2] = inf;
    
    
    for(boost::tie(firstv, lastv) = vertices(g); firstv != lastv; firstv++)
      d[*firstv][*firstv] = zero;
    
    
    for(boost::tie(first, last) = edges(g); first != last; first++)
    {
      if (d[source(*first, g)][target(*first, g)] != inf) {
        d[source(*first, g)][target(*first, g)] = 
          detail::min_with_compare(
            get(w, *first), 
            d[source(*first, g)][target(*first, g)],
            compare);
      } else 
        d[source(*first, g)][target(*first, g)] = get(w, *first);
    }
    
    bool is_undirected = is_same<typename 
      graph_traits<VertexAndEdgeListGraph>::directed_category, 
      undirected_tag>::value;
    if (is_undirected)
    {
      for(boost::tie(first, last) = edges(g); first != last; first++)
      {
        if (d[target(*first, g)][source(*first, g)] != inf)
          d[target(*first, g)][source(*first, g)] = 
            detail::min_with_compare(
              get(w, *first), 
              d[target(*first, g)][source(*first, g)],
              compare);
        else 
          d[target(*first, g)][source(*first, g)] = get(w, *first);
      }
    }
    
  
    return detail::floyd_warshall_dispatch(g, d, compare, combine, 
      inf, zero);
  }
  

  namespace detail {        
    template <class VertexListGraph, class DistanceMatrix, 
      class WeightMap, class P, class T, class R>
    bool floyd_warshall_init_dispatch(const VertexListGraph& g, 
      DistanceMatrix& d, WeightMap /*w*/, 
      const bgl_named_params<P, T, R>& params)
    {
      typedef typename property_traits<WeightMap>::value_type WM;
    
      return floyd_warshall_initialized_all_pairs_shortest_paths(g, d,
        choose_param(get_param(params, distance_compare_t()), 
          std::less<WM>()),
        choose_param(get_param(params, distance_combine_t()), 
          closed_plus<WM>()),
        choose_param(get_param(params, distance_inf_t()), 
          std::numeric_limits<WM>::max BOOST_PREVENT_MACRO_SUBSTITUTION()),
        choose_param(get_param(params, distance_zero_t()), 
          WM()));
    }
    

    
    template <class VertexAndEdgeListGraph, class DistanceMatrix, 
      class WeightMap, class P, class T, class R>
    bool floyd_warshall_noninit_dispatch(const VertexAndEdgeListGraph& g, 
      DistanceMatrix& d, WeightMap w, 
      const bgl_named_params<P, T, R>& params)
    {
      typedef typename property_traits<WeightMap>::value_type WM;
    
      return floyd_warshall_all_pairs_shortest_paths(g, d, w,
        choose_param(get_param(params, distance_compare_t()), 
          std::less<WM>()),
        choose_param(get_param(params, distance_combine_t()), 
          closed_plus<WM>()),
        choose_param(get_param(params, distance_inf_t()), 
          std::numeric_limits<WM>::max BOOST_PREVENT_MACRO_SUBSTITUTION()),
        choose_param(get_param(params, distance_zero_t()), 
          WM()));
    }
    

  }   // namespace detail

  
  
  template <class VertexListGraph, class DistanceMatrix, class P, 
    class T, class R>
  bool floyd_warshall_initialized_all_pairs_shortest_paths(
    const VertexListGraph& g, DistanceMatrix& d, 
    const bgl_named_params<P, T, R>& params)
  {
    return detail::floyd_warshall_init_dispatch(g, d, 
      choose_const_pmap(get_param(params, edge_weight), g, edge_weight), 
      params);
  }
  
  template <class VertexListGraph, class DistanceMatrix>
  bool floyd_warshall_initialized_all_pairs_shortest_paths(
    const VertexListGraph& g, DistanceMatrix& d)
  {
    bgl_named_params<int,int> params(0);
    return detail::floyd_warshall_init_dispatch(g, d,
      get(edge_weight, g), params);
  }
  

  
  
  template <class VertexAndEdgeListGraph, class DistanceMatrix, 
    class P, class T, class R>
  bool floyd_warshall_all_pairs_shortest_paths(
    const VertexAndEdgeListGraph& g, DistanceMatrix& d, 
    const bgl_named_params<P, T, R>& params)
  {
    return detail::floyd_warshall_noninit_dispatch(g, d, 
      choose_const_pmap(get_param(params, edge_weight), g, edge_weight), 
      params);
  }
  
  template <class VertexAndEdgeListGraph, class DistanceMatrix>
  bool floyd_warshall_all_pairs_shortest_paths(
    const VertexAndEdgeListGraph& g, DistanceMatrix& d)
  {
    bgl_named_params<int,int> params(0);
    return detail::floyd_warshall_noninit_dispatch(g, d,
      get(edge_weight, g), params);
  }
  

} // namespace boost

#endif