90 lines
2.4 KiB
C++
90 lines
2.4 KiB
C++
// (C) Copyright 2007-2009 Andrew Sutton
|
|
//
|
|
// Use, modification and distribution are subject to the
|
|
// Boost Software License, Version 1.0 (See accompanying file
|
|
// LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt)
|
|
|
|
#ifndef BOOST_GRAPH_CONSTANT_PROPERTY_HPP
|
|
#define BOOST_GRAPH_CONSTANT_PROPERTY_HPP
|
|
|
|
#include <boost/property_map/property_map.hpp>
|
|
|
|
// TODO: This should really be part of the property maps library rather than
|
|
// the Boost.Graph library.
|
|
|
|
namespace boost
|
|
{
|
|
|
|
/**
|
|
* A constant property is one, that regardless of the edge or vertex given,
|
|
* will always return a constant value.
|
|
*/
|
|
template < typename Key, typename Value >
|
|
struct constant_property_map : public boost::put_get_helper< const Value&,
|
|
constant_property_map< Key, Value > >
|
|
{
|
|
typedef Key key_type;
|
|
typedef Value value_type;
|
|
typedef const Value& reference;
|
|
typedef boost::readable_property_map_tag category;
|
|
|
|
constant_property_map() : m_value() {}
|
|
|
|
constant_property_map(const value_type& value) : m_value(value) {}
|
|
|
|
constant_property_map(const constant_property_map& copy)
|
|
: m_value(copy.m_value)
|
|
{
|
|
}
|
|
|
|
inline reference operator[](const key_type&) const { return m_value; }
|
|
|
|
value_type m_value;
|
|
};
|
|
|
|
template < typename Key, typename Value >
|
|
inline constant_property_map< Key, Value > make_constant_property(
|
|
const Value& value)
|
|
{
|
|
return constant_property_map< Key, Value >(value);
|
|
}
|
|
|
|
/**
|
|
* Same as above, but pretends to be writable as well.
|
|
*/
|
|
template < typename Key, typename Value > struct constant_writable_property_map
|
|
{
|
|
typedef Key key_type;
|
|
typedef Value value_type;
|
|
typedef Value& reference;
|
|
typedef boost::read_write_property_map_tag category;
|
|
|
|
constant_writable_property_map() : m_value() {}
|
|
|
|
constant_writable_property_map(const value_type& value) : m_value(value) {}
|
|
|
|
constant_writable_property_map(const constant_writable_property_map& copy)
|
|
: m_value(copy.m_value)
|
|
{
|
|
}
|
|
|
|
friend Value get(const constant_writable_property_map& me, Key)
|
|
{
|
|
return me.m_value;
|
|
}
|
|
friend void put(const constant_writable_property_map&, Key, Value) {}
|
|
|
|
value_type m_value;
|
|
};
|
|
|
|
template < typename Key, typename Value >
|
|
inline constant_writable_property_map< Key, Value >
|
|
make_constant_writable_property(const Value& value)
|
|
{
|
|
return constant_writable_property_map< Key, Value >(value);
|
|
}
|
|
|
|
} /* namespace boost */
|
|
|
|
#endif
|