276 lines
6.8 KiB
C++
276 lines
6.8 KiB
C++
// Copyright (c) 2010,2011 Tel-Aviv University (Israel).
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// All rights reserved.
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//
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// This file is part of CGAL (www.cgal.org).
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//
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// $URL: https://github.com/CGAL/cgal/blob/v5.1/Arrangement_on_surface_2/include/CGAL/Arr_face_index_map.h $
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// $Id: Arr_face_index_map.h 0779373 2020-03-26T13:31:46+01:00 Sébastien Loriot
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// SPDX-License-Identifier: GPL-3.0-or-later OR LicenseRef-Commercial
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//
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//
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// Author(s) : Ron Wein <wein@post.tau.ac.il>
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#ifndef CGAL_ARR_FACE_INDEX_MAP_H
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#define CGAL_ARR_FACE_INDEX_MAP_H
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#include <CGAL/license/Arrangement_on_surface_2.h>
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#include <CGAL/disable_warnings.h>
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/*! \file
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* Definition of the Arr_face_index_map<Arrangement> class.
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*/
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#include <CGAL/Arr_observer.h>
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#include <CGAL/Unique_hash_map.h>
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#include <CGAL/property_map.h>
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#include <boost/graph/properties.hpp>
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namespace CGAL {
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/*! \class
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* An auxiliary class that automatically maintains a mapping of the
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* arrangement faces to the indices 0, ..., (n -1), where n is the number
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* of faces in the arrangement.
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*/
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template <class Arrangement_>
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class Arr_face_index_map : public Arr_observer<Arrangement_>
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{
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public:
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typedef Arrangement_ Arrangement_2;
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typedef typename Arrangement_2::Face_handle Face_handle;
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// Boost property type definitions:
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typedef boost::readable_property_map_tag category;
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typedef unsigned int value_type;
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typedef value_type reference;
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typedef Face_handle key_type;
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private:
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typedef Arr_face_index_map<Arrangement_2> Self;
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typedef Arr_observer<Arrangement_2> Base;
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typedef Unique_hash_map<Face_handle, unsigned int> Index_map;
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// Data members:
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unsigned int n_faces; // The current number of faces.
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Index_map index_map; // Mapping faces to indices.
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std::vector<Face_handle> rev_map; // Mapping indices to faces.
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enum {MIN_REV_MAP_SIZE = 32};
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public:
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/*! Default constructor. */
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Arr_face_index_map () :
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Base (),
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n_faces (0),
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rev_map (MIN_REV_MAP_SIZE)
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{}
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/*! Constructor with an associated arrangement. */
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Arr_face_index_map (const Arrangement_2& arr) :
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Base (const_cast<Arrangement_2&> (arr))
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{
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_init();
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}
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/*! Copy constructor. */
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Arr_face_index_map (const Self& other) :
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Base (const_cast<Arrangement_2&> (*(other.arrangement())))
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{
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_init();
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}
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/*! Assignment operator. */
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Self& operator= (const Self& other)
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{
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if (this == &other)
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return (*this);
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this->detach();
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this->attach (const_cast<Arrangement_2&> (*(other.arrangement())));
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return (*this);
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}
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/*!
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* Get the index of a given face.
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* \param f A handle to the face.
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* \pre f is a valid face in the arrangement.
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*/
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unsigned int operator[] (Face_handle f) const
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{
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return (index_map[f]);
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}
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/*!
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* Get the face given its index.
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* \param i The index of the face.
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* \pre i is less than the number of faces in the arrangement.
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*/
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Face_handle face (const int i) const
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{
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CGAL_precondition((unsigned int) i < n_faces);
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return (rev_map[i]);
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}
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/// \name Notification functions, to keep the mapping up-to-date.
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//@{
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/*!
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* Update the mapping after the arrangement has been assigned with another
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* arrangement.
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*/
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virtual void after_assign ()
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{
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_init();
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}
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/*!
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* Update the mapping after the arrangement is cleared.
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*/
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virtual void after_clear ()
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{
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_init();
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}
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/*!
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* Update the mapping after attaching to a new arrangement.
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*/
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virtual void after_attach ()
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{
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_init();
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}
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/*!
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* Update the mapping after detaching the arrangement.
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*/
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virtual void after_detach ()
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{
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n_faces = 0;
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index_map.clear();
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}
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/*!
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* Update the mapping after the creation of a new face is split from another
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* face.
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* \param f A handle to the existing face.
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* \param new_f A handle to the newly created face.
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*/
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virtual void after_split_face (Face_handle /* f */,
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Face_handle new_f,
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bool /* is_hole */)
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{
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// Update the number of vertices.
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n_faces++;
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// If necessary, allocate memory for the reverse mapping.
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if (rev_map.size() < n_faces)
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rev_map.resize(2 * n_faces);
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// Update the mapping of the newly created face.
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index_map[new_f] = n_faces - 1;
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rev_map[n_faces - 1] = new_f;
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return;
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}
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/*!
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* Update the mapping before the merge of two faces.
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* \param f1 A handle to the face that is going to remain.
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* \param f2 A handle to the face that is about to be removed.
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*/
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virtual void before_merge_face (Face_handle /* f1 */,
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Face_handle f2,
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typename
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Arrangement_2::Halfedge_handle /* e */)
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{
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// Update the number of faces.
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n_faces--;
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// Reduce memory consumption in case the number of faces has
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// drastically decreased.
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if (2*n_faces+1 < rev_map.size() &&
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rev_map.size() / 2 >= MIN_REV_MAP_SIZE)
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{
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rev_map.resize (rev_map.size() / 2);
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}
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// Get the current face index, and assign this index to the face
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// currently indexed (n - 1).
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unsigned int index = index_map[f2];
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if (index == n_faces)
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return;
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Face_handle last_f = rev_map[n_faces];
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index_map[last_f] = index;
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rev_map[index] = last_f;
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// Clear the reverse mapping for the last face.
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rev_map[n_faces] = Face_handle();
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return;
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}
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//@}
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private:
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/*! Initialize the map for the given arrangement. */
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void _init ()
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{
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// Get the number of faces and allocate the reverse map accordingly.
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n_faces = static_cast<unsigned int>(this->arrangement()->number_of_faces());
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if (n_faces < MIN_REV_MAP_SIZE)
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rev_map.resize (MIN_REV_MAP_SIZE);
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else
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rev_map.resize (n_faces);
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// Clear the current mapping.
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index_map.clear();
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// Create the initial mapping.
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typename Arrangement_2::Face_iterator fit;
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Face_handle fh;
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unsigned int index = 0;
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for (fit = this->arrangement()->faces_begin();
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fit != this->arrangement()->faces_end(); ++fit, ++index)
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{
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// Map the current face to the current index.
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fh = fit;
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index_map[fh] = index;
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rev_map[index] = fh;
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}
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return;
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}
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};
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/*!
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* Get the index property-map function. Provided so that boost is able to
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* access the Arr_face_index_map above.
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* \param index_map The index map.
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* \param f A face handle.
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* \return The face index.
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*/
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template<class Arrangement>
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unsigned int get (const CGAL::Arr_face_index_map<Arrangement>& index_map,
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typename Arrangement::Face_handle f)
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{
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return (index_map[f]);
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}
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} //namespace CGAL
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#include <CGAL/enable_warnings.h>
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#endif
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