mirror of https://github.com/CGAL/cgal
149 lines
3.9 KiB
C
149 lines
3.9 KiB
C
// ============================================================================
|
|
//
|
|
// Copyright (c) 2000 The CGAL Consortium
|
|
//
|
|
// This software and related documentation is part of an INTERNAL release
|
|
// of the Computational Geometry Algorithms Library (CGAL). It is not
|
|
// intended for general use.
|
|
//
|
|
// ----------------------------------------------------------------------------
|
|
//
|
|
// release : $CGAL_Revision $
|
|
// release_date : $CGAL_Date $
|
|
//
|
|
// file : include/CGAL/Rotation_tree_2.C
|
|
// package : $CGAL_Package: Partition_2 $
|
|
// maintainer : Susan Hert <hert@mpi-sb.mpg.de>
|
|
// chapter : Planar Polygon Partitioning
|
|
//
|
|
// revision : $Revision$
|
|
// revision_date : $Date$
|
|
//
|
|
// author(s) : Susan Hert <hert@mpi-sb.mpg.de>
|
|
//
|
|
// coordinator : MPI (Susan Hert <hert@mpi-sb.mpg.de>)
|
|
//
|
|
// implementation: Rotation tree for visibility graph computation
|
|
// ============================================================================
|
|
|
|
#include <iostream>
|
|
|
|
namespace CGAL {
|
|
|
|
|
|
// makes *p the rightmost child of *q
|
|
template<class Traits>
|
|
void Rotation_tree_2<Traits>::set_rightmost_child(Self_iterator p,
|
|
Self_iterator q)
|
|
{
|
|
CGAL_assertion(q != end());
|
|
|
|
if (p != end())
|
|
{
|
|
(*p).clear_right_sibling();
|
|
if (rightmost_child(q) != end())
|
|
{
|
|
(*p).set_left_sibling(rightmost_child(q));
|
|
(*rightmost_child(q)).set_right_sibling(p);
|
|
}
|
|
else
|
|
(*p).clear_left_sibling();
|
|
(*p).set_parent(q);
|
|
(*q).set_rightmost_child(p);
|
|
}
|
|
else
|
|
{
|
|
(*q).clear_rightmost_child();
|
|
}
|
|
}
|
|
|
|
// makes *p the left sibling of *q
|
|
template <class Traits>
|
|
void Rotation_tree_2<Traits>::set_left_sibling(Self_iterator p,
|
|
Self_iterator q)
|
|
{
|
|
if (q == end()) return;
|
|
|
|
if (p != end())
|
|
{
|
|
if (left_sibling(q) != end())
|
|
{
|
|
(*left_sibling(q)).set_right_sibling(p);
|
|
(*p).set_left_sibling(left_sibling(q));
|
|
}
|
|
else
|
|
(*p).clear_left_sibling();
|
|
|
|
(*q).set_left_sibling(p);
|
|
(*p).set_right_sibling(q);
|
|
set_parent(parent(q),p);
|
|
}
|
|
else
|
|
{
|
|
if (left_sibling(q) != end())
|
|
(*(*q).left_sibling()).clear_right_sibling();
|
|
(*q).clear_left_sibling();
|
|
}
|
|
}
|
|
|
|
// makes p the right sibling of q
|
|
template <class Traits>
|
|
void Rotation_tree_2<Traits>::set_right_sibling(Self_iterator p,
|
|
Self_iterator q)
|
|
{
|
|
if (q == end()) return;
|
|
|
|
if (p != end())
|
|
{
|
|
if (right_sibling(q) != end())
|
|
{
|
|
(*right_sibling(q)).set_left_sibling(p);
|
|
(*p).set_right_sibling(right_sibling(q));
|
|
}
|
|
else
|
|
(*p).clear_right_sibling();
|
|
(*q).set_right_sibling(p);
|
|
(*p).set_left_sibling(q);
|
|
set_parent(parent(q),p);
|
|
}
|
|
else
|
|
{
|
|
if (right_sibling(q) != end())
|
|
(*right_sibling(q)).clear_left_sibling();
|
|
(*q).clear_right_sibling();
|
|
}
|
|
}
|
|
|
|
// NOTE: this function does not actually remove the node p from the
|
|
// list; it only reorganizes the pointers so this node is not
|
|
// in the tree structure anymore
|
|
template <class Traits>
|
|
void Rotation_tree_2<Traits>::erase(Self_iterator p)
|
|
{
|
|
CGAL_assertion((*p).is_a_leaf());
|
|
|
|
Self_iterator s;
|
|
s = right_sibling(p);
|
|
if (s != end())
|
|
set_left_sibling(left_sibling(p),s);
|
|
s = left_sibling(p);
|
|
if (s != end())
|
|
set_right_sibling(right_sibling(p),s);
|
|
s = parent(p);
|
|
// if p was the rightmost child of its parent, then set its left
|
|
// sibling as the new rightmost child
|
|
if (rightmost_child(s) == p)
|
|
set_rightmost_child(left_sibling(p),s);
|
|
}
|
|
|
|
template <class Traits>
|
|
std::ostream& operator<<(std::ostream& os, const Rotation_tree_2<Traits>& tree)
|
|
{
|
|
typename Rotation_tree_2<Traits>::const_iterator it;
|
|
for (it = tree.begin(); it != tree.end(); it++)
|
|
os << *it << " " << std::endl;
|
|
return os;
|
|
}
|
|
|
|
}
|