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//=======================================================================
// Copyright 1997, 1998, 1999, 2000 University of Notre Dame.
// Authors: Andrew Lumsdaine, Lie-Quan Lee, Jeremy G. Siek
//
// 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)
//=======================================================================
#ifndef BOOST_GRAPH_DETAIL_CONNECTED_COMPONENTS_HPP
#define BOOST_GRAPH_DETAIL_CONNECTED_COMPONENTS_HPP
#if defined(__sgi) && !defined(__GNUC__)
#pragma set woff 1234
#endif
#include <boost/operators.hpp>
namespace boost {
namespace detail {
//=========================================================================
// Implementation details of connected_components
// This is used both in the connected_components algorithm and in
// the kosaraju strong components algorithm during the second DFS
// traversal.
template <class ComponentsPA, class DFSVisitor>
class components_recorder : public DFSVisitor
{
typedef typename property_traits<ComponentsPA>::value_type comp_type;
public:
components_recorder(ComponentsPA c,
comp_type& c_count,
DFSVisitor v)
: DFSVisitor(v), m_component(c), m_count(c_count) {}
template <class Vertex, class Graph>
void start_vertex(Vertex u, Graph& g) {
++m_count;
DFSVisitor::start_vertex(u, g);
}
template <class Vertex, class Graph>
void discover_vertex(Vertex u, Graph& g) {
put(m_component, u, m_count);
DFSVisitor::discover_vertex(u, g);
}
protected:
ComponentsPA m_component;
comp_type& m_count;
};
template <class DiscoverTimeMap, class FinishTimeMap, class TimeT,
class DFSVisitor>
class time_recorder : public DFSVisitor
{
public:
time_recorder(DiscoverTimeMap d, FinishTimeMap f, TimeT& t, DFSVisitor v)
: DFSVisitor(v), m_discover_time(d), m_finish_time(f), m_t(t) {}
template <class Vertex, class Graph>
void discover_vertex(Vertex u, Graph& g) {
put(m_discover_time, u, ++m_t);
DFSVisitor::discover_vertex(u, g);
}
template <class Vertex, class Graph>
void finish_vertex(Vertex u, Graph& g) {
put(m_finish_time, u, ++m_t);
DFSVisitor::discover_vertex(u, g);
}
protected:
DiscoverTimeMap m_discover_time;
FinishTimeMap m_finish_time;
TimeT m_t;
};
template <class DiscoverTimeMap, class FinishTimeMap, class TimeT,
class DFSVisitor>
time_recorder<DiscoverTimeMap, FinishTimeMap, TimeT, DFSVisitor>
record_times(DiscoverTimeMap d, FinishTimeMap f, TimeT& t, DFSVisitor vis)
{
return time_recorder<DiscoverTimeMap, FinishTimeMap, TimeT, DFSVisitor>
(d, f, t, vis);
}
//=========================================================================
// Implementation detail of dynamic_components
//-------------------------------------------------------------------------
// Helper functions for the component_index class
// Record the representative vertices in the header array.
// Representative vertices now point to the component number.
template <class Parent, class OutputIterator, class Integer>
inline void
build_components_header(Parent p,
OutputIterator header,
Integer num_nodes)
{
Parent component = p;
Integer component_num = 0;
for (Integer v = 0; v != num_nodes; ++v)
if (p[v] == v) {
*header++ = v;
component[v] = component_num++;
}
}
// Pushes x onto the front of the list. The list is represented in
// an array.
template <class Next, class T, class V>
inline void push_front(Next next, T& head, V x)
{
T tmp = head;
head = x;
next[x] = tmp;
}
// Create a linked list of the vertices in each component
// by reusing the representative array.
template <class Parent1, class Parent2,
class Integer>
void
link_components(Parent1 component, Parent2 header,
Integer num_nodes, Integer num_components)
{
// Make the non-representative vertices point to their component
Parent1 representative = component;
for (Integer v = 0; v != num_nodes; ++v)
if (component[v] >= num_components || header[component[v]] != v)
component[v] = component[representative[v]];
// initialize the "head" of the lists to "NULL"
std::fill_n(header, num_components, num_nodes);
// Add each vertex to the linked list for its component
Parent1 next = component;
for (Integer k = 0; k != num_nodes; ++k)
push_front(next, header[component[k]], k);
}
template <class IndexContainer, class HeaderContainer>
void
construct_component_index(IndexContainer& index, HeaderContainer& header)
{
build_components_header(index.begin(),
std::back_inserter(header),
index.end() - index.begin());
link_components(index.begin(), header.begin(),
index.end() - index.begin(),
header.end() - header.begin());
}
template <class IndexIterator, class Integer, class Distance>
class component_iterator
: boost::forward_iterator_helper<
component_iterator<IndexIterator,Integer,Distance>,
Integer, Distance,Integer*, Integer&>
{
public:
typedef component_iterator self;
IndexIterator next;
Integer node;
typedef std::forward_iterator_tag iterator_category;
typedef Integer value_type;
typedef Integer& reference;
typedef Integer* pointer;
typedef Distance difference_type;
component_iterator() {}
component_iterator(IndexIterator x, Integer i)
: next(x), node(i) {}
Integer operator*() const {
return node;
}
self& operator++() {
node = next[node];
return *this;
}
};
template <class IndexIterator, class Integer, class Distance>
inline bool
operator==(const component_iterator<IndexIterator, Integer, Distance>& x,
const component_iterator<IndexIterator, Integer, Distance>& y)
{
return x.node == y.node;
}
} // namespace detail
} // namespace detail
#if defined(__sgi) && !defined(__GNUC__)
#pragma reset woff 1234
#endif
#endif
|
