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- // (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
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