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/* Copyright (c) 1997-2015
Ewgenij Gawrilow, Michael Joswig (Technische Universitaet Berlin, Germany)
http://www.polymake.org
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, or (at your option) any
later version: http://www.gnu.org/licenses/gpl.txt.
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.
--------------------------------------------------------------------------------
*/
#ifndef POLYMAKE_GRAPH_BFS_ITERATOR_H
#define POLYMAKE_GRAPH_BFS_ITERATOR_H
#include "polymake/GenericGraph.h"
#include "polymake/Bitset.h"
#include "polymake/list"
#include "polymake/vector"
#include <cassert>
namespace polymake { namespace graph {
template <typename Dist=int>
class NodeVisitor {
protected:
std::vector<Dist> dist;
public:
NodeVisitor() {}
template <typename Graph>
NodeVisitor(const GenericGraph<Graph>& G, int start_node)
: dist(G.top().dim(), Dist(-1))
{
if (!dist.empty()) dist[start_node]=0;
}
template <typename Graph>
void reset(const GenericGraph<Graph>&, int start_node)
{
fill(pm::entire(dist), Dist(-1));
if (!dist.empty()) dist[start_node]=0;
}
bool seen(int n) const { return dist[n]>=0; }
void add(int n, int n_from) { dist[n]=dist[n_from]+1; }
static const bool check_edges=false;
void check(int,int) {}
const Dist& operator[] (int n) const { return dist[n]; }
};
template <bool _inversed=false>
class BoolNodeVisitor {
protected:
Bitset visited;
int n_nodes;
public:
BoolNodeVisitor() {}
template <typename Graph>
BoolNodeVisitor(const GenericGraph<Graph>& G, int start_node)
: visited(G.top().dim(), _inversed && !G.top().has_gaps()), n_nodes(G.nodes())
{
if (_inversed && G.top().has_gaps()) visited=nodes(G);
if (G.top().dim()) add(start_node);
}
template <typename Graph>
void reset(const GenericGraph<Graph>& G, int start_node)
{
if (_inversed) {
if (G.top().has_gaps())
visited=nodes(G);
else
visited=sequence(0,n_nodes);
visited-=start_node;
} else {
visited.clear();
visited+=start_node;
}
}
bool seen(int n) const { return _inversed^visited.contains(n); }
void add(int n, int=0) { if (_inversed) visited-=n; else visited+=n; }
static const bool check_edges=false;
void check(int,int) {}
const Bitset& get_visited_nodes() const { return visited; }
};
template <typename> class Visitor;
template <typename> class Reversed;
template <typename Graph, typename Params=void>
class BFSiterator {
public:
typedef typename pm::extract_type_param<Params, Visitor, BoolNodeVisitor<> >::type visitor_type;
static const bool reverse_edges=pm::extract_bool_param<Params,Reversed>::value;
protected:
const Graph *graph;
std::list<int> queue;
visitor_type visitor;
int unvisited;
template <typename EdgeList>
void next_step(int n, const EdgeList& edge_list)
{
for (typename Entire<EdgeList>::const_iterator e=entire(edge_list); !e.at_end(); ++e) {
const int nn= reverse_edges ? e.from_node() : e.to_node();
if (visitor.seen(nn)) {
if (visitor.check_edges) visitor.check(nn,n);
} else {
visitor.add(nn,n);
queue.push_back(nn);
--unvisited;
}
}
}
public:
typedef std::forward_iterator_tag iterator_category;
typedef int value_type;
typedef const int& reference;
typedef const int* pointer;
typedef ptrdiff_t difference_type;
typedef BFSiterator iterator;
typedef BFSiterator const_iterator;
BFSiterator() : graph(0) {}
BFSiterator(const Graph& graph_arg, int start_node)
: graph(&graph_arg), visitor(graph_arg, start_node), unvisited(graph_arg.nodes()-1)
{
if (unvisited>=0) {
if (POLYMAKE_DEBUG) {
if (start_node<0 || start_node>=graph->dim())
throw std::runtime_error("BFSiterator - start node out of range");
}
queue.push_back(start_node);
}
}
reference operator* () const { return queue.front(); }
pointer operator-> () const { return &queue.front(); }
iterator& operator++ ()
{
const int n=queue.front(); queue.pop_front();
if (visitor.check_edges || unvisited>0) {
if (reverse_edges)
next_step(n, graph->in_edges(n));
else
next_step(n, graph->out_edges(n));
}
return *this;
}
const iterator operator++ (int) { iterator copy(*this); operator++(); return copy; }
void skip_node() { queue.pop_front(); }
int unvisited_nodes() const { return unvisited; }
const visitor_type& node_visitor() const { return visitor; }
reference last_unvisited() const { return queue.back(); }
bool at_end() const { return queue.empty(); }
bool operator== (const iterator& it) const
{
return at_end() ? it.at_end() : !it.at_end() && queue.front()==it.queue.front();
}
bool operator!= (const iterator& it) const { return !operator==(it); }
void reset(int start_node)
{
const int dim=graph->dim();
if (dim>0) {
if (POLYMAKE_DEBUG) {
if (start_node<0 || start_node>=dim)
throw std::runtime_error("BFSiterator::reset - start node out of range");
}
queue.clear();
visitor.reset(*graph,start_node);
queue.push_back(start_node);
unvisited=graph->nodes()-1;
}
}
};
} }
namespace pm {
template <typename Graph, typename Params>
struct check_iterator_feature< polymake::graph::BFSiterator<Graph,Params>, end_sensitive > : True {};
}
#endif // POLYMAKE_GRAPH_BFS_ITERATOR_H
// Local Variables:
// mode:C++
// c-basic-offset:3
// indent-tabs-mode:nil
// End:
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