root/sandbox/sigis/christian.gonzalez/trunk/core/src/dijkstra_boost_wrapper.cpp

/*
 * Shortest path algorithm for PostgreSQL
 * *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 */

#include <boost/config.hpp>
#include <boost/graph/graph_traits.hpp>
#include <boost/graph/adjacency_list.hpp>
#include <boost/graph/dijkstra_shortest_paths.hpp>
#include <boost/ptr_container/ptr_vector.hpp>

#include <iostream>
#include "dijkstra.h"

using namespace std; //Everything in 'std' is accessed directly.
using namespace boost; //Everything in 'boost' library is accessed directly.

// Maximal number of nodes in the path (to avoid infinite loops)
#define MAX_NODES 1000000000

struct Vertex
{
    int id;
    float8 cost;
};

int
boost_dijkstra(edge_t *edges, unsigned int ntuplas, int start_vertex, int end_vertex,
               bool directed, path_element_t **path, int *path_count, char **err_msg)
{

  typedef adjacency_list < listS, vecS, directedS, no_property, Vertex> graph_t;
  typedef graph_traits < graph_t >::vertex_descriptor vertex_descriptor;
  typedef graph_traits < graph_t >::edge_descriptor edge_descriptor;

  //const unsigned int num_nodes = ntuplas*2;
  const unsigned int num_nodes = 1;

  //Creating the Graph
  graph_t graph(num_nodes);

  for (unsigned int j = 0; j < ntuplas; ++j)
  {
    edge_descriptor e;
    bool inserted;

    tie(e, inserted) = add_edge(edges[j].source, edges[j].target, graph);
    graph[e].id = edges[j].id;
    graph[e].cost = edges[j].cost;

    if(directed)
    {

      if(edges[j].bidirectional != 0 && edges[j].bidirectional)
      {
        tie(e, inserted) = add_edge(edges[j].target, edges[j].source, graph);
        graph[e].id = edges[j].id;
        graph[e].cost = edges[j].cost;
      }

      if (edges[j].reverse_cost != 0)
      {
        tie(e, inserted) = add_edge(edges[j].target, edges[j].source, graph);
        graph[e].id = edges[j].id;
        graph[e].cost = edges[j].reverse_cost;
      }
    }
    else
    {
      //adding edges in reverse position, because the graph is undirected
      tie(e, inserted) = add_edge(edges[j].target, edges[j].source, graph);
      graph[e].id = edges[j].id;
      graph[e].cost = edges[j].cost;
    }
  }

  vector<vertex_descriptor> predecessors(num_vertices(graph));

  vertex_descriptor _source = vertex(start_vertex, graph);

  if (_source < 0 /*|| _source >= num_nodes*/)
  {
     *err_msg = (char *) "Starting vertex not found";
     return -1;
  }

  vertex_descriptor _target = vertex(end_vertex, graph);

  if (_target < 0 /*|| _target >= num_nodes*/)
  {
    *err_msg = (char *) "Ending vertex not found";
    return -1;
  }

  vector<float8> distances(num_vertices(graph));

  // Calling Boost function
  dijkstra_shortest_paths(graph, _source,
      predecessor_map(&predecessors[0]).weight_map(get(&Vertex::cost, graph)).distance_map(&distances[0]));

  vector<int> path_vect;

  int max = MAX_NODES;

  path_vect.push_back(_target);

  while (_target != _source)
  {
    if (_target == predecessors[_target])
    {
        *err_msg = (char *) "No path found";
        return 0;
    }
    _target = predecessors[_target];

    path_vect.push_back(_target);
    if (!max--)
    {
        *err_msg = (char *) "Overflow";
        return -1;
    }
   }

  *path = (path_element_t *) malloc(sizeof(path_element_t) * (path_vect.size() + 1));
  *path_count = path_vect.size();

  for(int i = path_vect.size() - 1, j = 0; i >= 0; i--, j++)
  {
    graph_traits < graph_t >::vertex_descriptor v_src;
    graph_traits < graph_t >::vertex_descriptor v_targ;
    graph_traits < graph_t >::edge_descriptor e;
    graph_traits < graph_t >::out_edge_iterator out_i, out_end;

    (*path)[j].vertex_id = path_vect.at(i);

    (*path)[j].edge_id = -1;
    (*path)[j].cost = distances[_target];

    if (i == 0)
    {
      continue;
    }

    v_src = path_vect.at(i);
    v_targ = path_vect.at(i - 1);

    for (tie(out_i, out_end) = out_edges(v_src, graph); out_i != out_end; ++out_i)
    {
      graph_traits < graph_t >::vertex_descriptor v, targ;
      e = *out_i;
      v = source(e, graph);
      targ = target(e, graph);

      if (targ == v_targ)
      {
        (*path)[j].edge_id = graph[*out_i].id;
        (*path)[j].cost = graph[*out_i].cost;
        break;
      }
    }
  }

  return EXIT_SUCCESS;
}