164 lines
5.0 KiB
C++
Executable File
164 lines
5.0 KiB
C++
Executable File
// Copyright (c) 20009 INRIA Sophia-Antipolis (France).
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// All rights reserved.
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//
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// This file is part of CGAL (www.cgal.org); you can redistribute it and/or
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// modify it under the terms of the GNU Lesser General Public License as
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// published by the Free Software Foundation; either version 3 of the License,
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// or (at your option) any later version.
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//
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// Licensees holding a valid commercial license may use this file in
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// accordance with the commercial license agreement provided with the software.
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//
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// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
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// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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//
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// $URL$
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// $Id$
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// SPDX-License-Identifier: LGPL-3.0+
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//
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// Author(s) : Laurent Saboret
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#ifndef CGAL_INDEX_PROPERTY_MAP_H
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#define CGAL_INDEX_PROPERTY_MAP_H
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#include <CGAL/property_map.h>
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#include <boost/shared_ptr.hpp>
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#include <iterator>
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#include <map>
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namespace CGAL {
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/// \cond SKIP_IN_MANUAL
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// ----------------------------------------------------------------------------
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// Private section
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// ----------------------------------------------------------------------------
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namespace internal {
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/// Functor for operator< that compares iterators address.
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template <typename Iterator>
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struct Compare_iterator_address
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{
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bool operator()(const Iterator& lhs, const Iterator& rhs) const
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{
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return (&*lhs < &*rhs);
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}
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};
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} /* namespace internal */
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// ----------------------------------------------------------------------------
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// Public section
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// ----------------------------------------------------------------------------
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/// Template class "index" property map, which associates a 0-based index (unsigned int)
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/// to the `[first, beyond)` range of elements.
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///
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/// 2 specializations exist:
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/// - if Iter is a random access iterator (typically vector and deque),
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/// get() just calls std::distance() and is very efficient;
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/// - else, the property map allocates a std::map to store indices
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/// and get() requires a lookup in the map.
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///
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/// @heading Is Model for the Concepts:
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/// Model of the `ReadablePropertyMap` concept.
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///
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/// @heading Parameters:
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/// @param Iter iterator over input elements.
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/// @param iterator_tag Iter's iterator category.
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// This is the default variant that creates a temporary std::map<Iter,unsigned int>.
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template <class Iter,
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typename iterator_tag=typename std::iterator_traits<Iter>::iterator_category>
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class Index_property_map
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: public boost::associative_property_map< std::map<Iter,
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unsigned int,
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internal::Compare_iterator_address<Iter> > >
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{
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// std::map to store indices
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typedef typename std::map<Iter,
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unsigned int,
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internal::Compare_iterator_address<Iter> >
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Index_map;
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// base class = property map
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typedef typename boost::associative_property_map<Index_map>
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Base;
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public:
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Index_property_map(
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Iter first, ///< iterator over the first element (index 0)
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Iter beyond) ///< past-the-end iterator over the elements
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: m_index_map(new Index_map) // Allocate std::map
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{
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// Index elements in std::map
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Iter it;
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unsigned int index;
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for (it = first, index = 0; it != beyond; it++, index++)
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(*m_index_map)[it] = index;
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// Wrap std::map in property map
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(Base&)(*this) = *m_index_map;
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}
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private:
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// Property maps must be lightweight classes => share std::map
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boost::shared_ptr<Index_map> m_index_map;
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};
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/// @cond SKIP_IN_MANUAL
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// This variant is optimized for a random access container.
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template <class Iter>
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class Index_property_map<Iter,
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std::random_access_iterator_tag>
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{
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public:
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// Property maps' required types
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typedef boost::readable_property_map_tag category;
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typedef std::size_t value_type;
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typedef value_type reference;
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typedef Iter key_type;
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Index_property_map(
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Iter first, ///< iterator over the first element (index 0)
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Iter /*beyond*/) ///< past-the-end iterator over the elements
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: m_first(first)
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{}
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/// Free function to access the map elements.
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friend inline
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reference get(const Index_property_map& map, key_type p)
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{
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return std::distance(map.m_first, p);
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}
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private:
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Iter m_first; // iterator over the first element (index 0)
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};
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/// @endcond
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/// Free function to create an Index_property_map property map.
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///
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/// @tparam Iter iterator over input elements.
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///
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/// @return an "index" property map, which associates a 0-based index (unsigned int)
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/// to the `[first, beyond)` range of elements.
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template <class Iter>
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Index_property_map<Iter>
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make_index_property_map(
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Iter first, ///< iterator over the first element (index 0)
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Iter beyond) ///< past-the-end iterator over the elements
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{
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return Index_property_map<Iter>(first, beyond);
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}
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/// \endcond
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} // namespace CGAL
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#endif // CGAL_INDEX_PROPERTY_MAP_H
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