deba@348: /* -*- mode: C++; indent-tabs-mode: nil; -*-
deba@348:  *
deba@348:  * This file is a part of LEMON, a generic C++ optimization library.
deba@348:  *
deba@348:  * Copyright (C) 2003-2008
deba@348:  * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
deba@348:  * (Egervary Research Group on Combinatorial Optimization, EGRES).
deba@348:  *
deba@348:  * Permission to use, modify and distribute this software is granted
deba@348:  * provided that this copyright notice appears in all copies. For
deba@348:  * precise terms see the accompanying LICENSE file.
deba@348:  *
deba@348:  * This software is provided "AS IS" with no warranty of any kind,
deba@348:  * express or implied, and with no claim as to its suitability for any
deba@348:  * purpose.
deba@348:  *
deba@348:  */
deba@348: 
deba@348: #ifndef LEMON_NAUTY_READER_H
deba@348: #define LEMON_NAUTY_READER_H
deba@348: 
deba@348: #include <vector>
deba@348: #include <iostream>
deba@348: #include <string>
deba@348: 
deba@348: /// \ingroup nauty_group
deba@348: /// \file
deba@348: /// \brief Nauty file reader.
kpeter@351: 
deba@348: namespace lemon {
deba@348: 
deba@348:   /// \ingroup nauty_group
deba@348:   ///
deba@348:   /// \brief Nauty file reader
deba@348:   ///
deba@348:   /// The \e geng program is in the \e gtools suite of the nauty
deba@348:   /// package. This tool can generate all non-isomorphic undirected
kpeter@352:   /// graphs of several classes with given node number (e.g.
deba@348:   /// general, connected, biconnected, triangle-free, 4-cycle-free,
deba@348:   /// bipartite and graphs with given edge number and degree
kpeter@358:   /// constraints). This function reads a \e nauty \e graph6 \e format
deba@348:   /// line from the given stream and builds it in the given graph.
deba@348:   ///
deba@348:   /// The site of nauty package: http://cs.anu.edu.au/~bdm/nauty/
deba@348:   ///
kpeter@352:   /// For example, the number of all non-isomorphic planar graphs
kpeter@352:   /// can be computed with the following code.
deba@348:   ///\code
deba@348:   /// int num = 0;
deba@348:   /// SmartGraph graph;
kpeter@359:   /// while (readNautyGraph(graph, std::cin)) {
deba@350:   ///   PlanarityChecking<SmartGraph> pc(graph);
deba@348:   ///   if (pc.run()) ++num;
deba@348:   /// }
deba@348:   /// std::cout << "Number of planar graphs: " << num << std::endl;
deba@348:   ///\endcode
deba@348:   ///
deba@348:   /// The nauty files are quite huge, therefore instead of the direct
kpeter@352:   /// file generation pipelining is recommended. For example,
deba@348:   ///\code
kpeter@352:   /// ./geng -c 10 | ./num_of_planar_graphs
deba@348:   ///\endcode
deba@348:   template <typename Graph>
kpeter@359:   std::istream& readNautyGraph(Graph& graph, std::istream& is = std::cin) {
deba@348:     graph.clear();
deba@348: 
deba@348:     std::string line;
deba@348:     if (getline(is, line)) {
deba@348:       int index = 0;
deba@348: 
deba@348:       int n;
deba@348: 
deba@348:       if (line[index] == '>') {
deba@348:         index += 10;
deba@348:       }
deba@348: 
deba@348:       char c = line[index++]; c -= 63;
deba@348:       if (c != 63) {
deba@348:         n = int(c);
deba@348:       } else {
deba@348:         c = line[index++]; c -= 63;
deba@348:         n = (int(c) << 12);
deba@348:         c = line[index++]; c -= 63;
deba@348:         n |= (int(c) << 6);
deba@348:         c = line[index++]; c -= 63;
deba@348:         n |= int(c);
deba@348:       }
deba@348: 
deba@348:       std::vector<typename Graph::Node> nodes;
deba@348:       for (int i = 0; i < n; ++i) {
deba@348:         nodes.push_back(graph.addNode());
deba@348:       }
deba@348: 
deba@348:       int bit = -1;
deba@348:       for (int j = 0; j < n; ++j) {
deba@348:         for (int i = 0; i < j; ++i) {
deba@348:           if (bit == -1) {
deba@348:             c = line[index++]; c -= 63;
deba@348:             bit = 5;
deba@348:           }
deba@348:           bool b = (c & (1 << (bit--))) != 0;
deba@348: 
deba@348:           if (b) {
deba@348:             graph.addEdge(nodes[i], nodes[j]);
deba@348:           }
deba@348:         }
deba@348:       }
deba@348:     }
deba@348:     return is;
deba@348:   }
deba@348: }
deba@348: 
deba@348: #endif