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/**
* @file circulator.h
* @brief Circular iterator adapter
*//*
* Copyright 2006 MenTaLguY <mental@rydia.net>
*
* This library is free software; you can redistribute it and/or
* modify it either under the terms of the GNU Lesser General Public
* License version 2.1 as published by the Free Software Foundation
* (the "LGPL") or, at your option, under the terms of the Mozilla
* Public License Version 1.1 (the "MPL"). If you do not alter this
* notice, a recipient may use your version of this file under either
* the MPL or the LGPL.
*
* You should have received a copy of the LGPL along with this library
* in the file COPYING-LGPL-2.1; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
* You should have received a copy of the MPL along with this library
* in the file COPYING-MPL-1.1
*
* The contents of this file are subject to the Mozilla Public License
* Version 1.1 (the "License"); you may not use this file except in
* compliance with the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
* OF ANY KIND, either express or implied. See the LGPL or the MPL for
* the specific language governing rights and limitations.
*
*/
#ifndef SEEN_Circulator_H
#define SEEN_Circulator_H
#include <iterator>
namespace Geom {
/** @brief Circular iterator adapter
* This iterator adapter will loop indefinitely over a set of values
* from a random access container. */
template <typename Iterator>
class Circulator {
public:
typedef std::random_access_iterator_tag iterator_category;
typedef typename std::iterator_traits<Iterator>::value_type value_type;
typedef typename std::iterator_traits<Iterator>::difference_type difference_type;
typedef typename std::iterator_traits<Iterator>::pointer pointer;
typedef typename std::iterator_traits<Iterator>::reference reference;
Circulator(Iterator const &first,
Iterator const &last,
Iterator const &pos)
: _first(first), _last(last), _pos(pos)
{
match_random_access(iterator_category(first));
}
reference operator*() const {
return *_pos;
}
pointer operator->() const {
return &*_pos;
}
Circulator &operator++() {
if ( _first == _last ) return *this;
++_pos;
if ( _pos == _last ) _pos = _first;
return *this;
}
Circulator operator++(int) {
Circulator saved=*this;
++(*this);
return saved;
}
Circulator &operator--() {
if ( _pos == _first ) _pos = _last;
--_pos;
return *this;
}
Circulator operator--(int) {
Circulator saved=*this;
--(*this);
return saved;
}
Circulator &operator+=(int n) {
_pos = _offset(n);
return *this;
}
Circulator operator+(int n) const {
return Circulator(_first, _last, _offset(n));
}
Circulator &operator-=(int n) {
_pos = _offset(-n);
return *this;
}
Circulator operator-(int n) const {
return Circulator(_first, _last, _offset(-n));
}
difference_type operator-(Circulator const &other) {
return _pos - other._pos;
}
reference operator[](int n) const {
return *_offset(n);
}
private:
void match_random_access(iterator_category) {}
Iterator _offset(int n) {
difference_type range=( _last - _first );
difference_type offset=( _pos - _first + n );
if ( offset < 0 ) {
// modulus not well-defined for negative numbers in C++
offset += ( ( -offset / range ) + 1 ) * range;
} else if ( offset >= range ) {
offset %= range;
}
return _first + offset;
}
Iterator _first;
Iterator _last;
Iterator _pos;
};
}
template <typename T>
Geom::Circulator<T> operator+(int n, Geom::Circulator<T> const &c) {
return c + n;
}
#endif // SEEN_Circulator_H
/*
Local Variables:
mode:c++
c-file-style:"stroustrup"
c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
indent-tabs-mode:nil
fill-column:99
End:
*/
// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:fileencoding=utf-8:textwidth=99 :
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