source: trunk/yat/utility/StrideIterator.h @ 1615

Last change on this file since 1615 was 1541, checked in by Peter, 13 years ago

fixes #445 so iterator_traits detects when value_type is DataWeight?
and return weighted_iterator_tag. Also weighted_iterator_traits
recognize some normal cases; when reference_type is DataWeight?& or
const DataWeight?& weighted behaviour is performed.

Fixed some incorrect inclusion in WeightedIterator? and removed debug
code in StrideIterator?.

  • Property svn:eol-style set to native
  • Property svn:keywords set to Id
File size: 5.1 KB
Line 
1#ifndef _theplu_yat_utility_stride_iterator_
2#define _theplu_yat_utility_stride_iterator_
3
4// $Id: StrideIterator.h 1541 2008-09-30 17:40:41Z peter $
5
6/*
7  Copyright (C) 2007 Jari Häkkinen, Peter Johansson
8  Copyright (C) 2008 Peter Johansson
9
10  This file is part of the yat library, http://dev.thep.lu.se/yat
11
12  The yat library is free software; you can redistribute it and/or
13  modify it under the terms of the GNU General Public License as
14  published by the Free Software Foundation; either version 3 of the
15  License, or (at your option) any later version.
16
17  The yat library is distributed in the hope that it will be useful,
18  but WITHOUT ANY WARRANTY; without even the implied warranty of
19  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
20  General Public License for more details.
21
22  You should have received a copy of the GNU General Public License
23  along with yat. If not, see <http://www.gnu.org/licenses/>.
24*/
25
26#include "iterator_traits.h"
27
28#include <boost/iterator/iterator_adaptor.hpp>
29
30namespace theplu {
31namespace yat {
32namespace utility {
33
34  // forward declaration
35  template<typename Iter>
36  class StrideIterator;
37
38  /**
39     Specialization for StrideIterator that calls underlying iterator.
40   */
41  template <typename Iter>
42  struct weighted_iterator_traits<StrideIterator<Iter> > {
43    /**
44       StrideIterator is weighted if underlying iterator is weighted.
45    */
46    typedef typename weighted_iterator_traits<Iter>::type type;
47  };
48
49  /**
50     Specialization for StrideIterator using iterator_traits with base()
51   */
52  template <class Iter>
53  struct iterator_traits<StrideIterator<Iter> > {
54    /**
55       data_reference same as for underlying iterator
56     */
57    typedef typename iterator_traits<Iter>::data_reference data_reference;
58
59    /**
60       weight_reference same as for underlying iterator
61     */
62    typedef typename iterator_traits<Iter>::weight_reference weight_reference;
63
64    /**
65       \return data of iterator
66    */
67    data_reference data(StrideIterator<Iter> iter) const 
68    { return iterator_traits<Iter>().data(iter.base()); }
69
70    /**
71       \return weight of iterator
72    */
73    weight_reference weight(StrideIterator<Iter> iter) const 
74    { return iterator_traits<Iter>().weight(iter.base()); }
75
76  };
77
78  /**
79     @brief Adaptor using a stride on underlying iterator
80
81     Works as underlying iterator except that all arithmetic uses the
82     stride, so e.g., ++StrideIterator returns underlying
83     _iterator+stride
84
85  */
86  template<typename Iter>
87  class StrideIterator 
88    : public boost::iterator_adaptor<StrideIterator<Iter>, Iter>
89  {
90    typedef boost::iterator_adaptor<StrideIterator<Iter>,Iter> super_t;
91
92  public:
93    /// type of underlying iterator
94    typedef Iter iterator_type;
95
96    /*
97    /// value type
98    typedef typename std::iterator_traits<Iter>::value_type value_type;
99    /// difference type
100    typedef typename std::iterator_traits<Iter>::difference_type difference_type;
101    /// reference
102    typedef typename std::iterator_traits<Iter>::reference reference;
103    /// pointer
104    typedef typename std::iterator_traits<Iter>::pointer pointer;
105    /// weighted_iterator_tag if iterator is weighted
106    typedef typename yat::utility::weighted_iterator_traits<Iter>::type w_type;
107    */
108
109    /**
110       \brief default constructor
111
112       Using default constructor of BASE iterator.
113     */
114    explicit StrideIterator(size_t stride=1)
115      : StrideIterator::iterator_adaptor_(), stride_(stride) {}
116
117    /**
118       \brief Constructor
119    */
120    explicit StrideIterator(Iter p, size_t stride=1)
121      : StrideIterator::iterator_adaptor_(p), stride_(stride) {}
122
123   
124    /**
125       \brief Copy constructor
126     */
127    StrideIterator(const StrideIterator& other)
128      : StrideIterator::iterator_adaptor_(other.base()), stride_(other.stride()) 
129    {}
130
131    /**
132       \brief Conversion constructor.
133
134       Create a StrideIterator<Iter> from a StrideIterator<I2>. Possible
135       if I2 is convertible to a Iter. Constructor allows implicit
136       conversions such as iterator to const_iterator.
137     */
138    template<typename I2>
139    StrideIterator(StrideIterator<I2> other,
140                   typename boost::enable_if_convertible<I2, Iter>::type* = 0 )
141      : StrideIterator::iterator_adaptor_(other.base()), 
142        stride_(other.stride()) {}
143
144    /**
145        \brief Assignment operator
146     */
147    StrideIterator& operator=(const StrideIterator& rhs)
148    {
149      stride_ = rhs.stride();
150      this->base_reference() = rhs.base();
151      return *this;
152    }
153
154    /**
155       \return stride
156     */
157    inline size_t stride(void) const { return stride_; }
158
159  private:
160    // to give base class access to private parts
161    friend class boost::iterator_core_access;
162   
163    size_t stride_;
164
165    //typedef typename StrideIterator::iterator_adaptor_::difference_type
166    typedef typename StrideIterator::iterator_adaptor_::difference_type
167    difference_t;
168
169    void advance(typename super_t::difference_type n)
170    { this->base_reference() += stride_*n; }
171
172    void decrement(void) { this->base_reference()-=stride_; }
173
174    template <class OtherIterator>
175    typename super_t::difference_type
176    distance_to(const StrideIterator<OtherIterator>& other) const
177    { 
178      // casting to int to avoid loss of sign in numerator
179      return (other.base() - this->base() )/static_cast<int>(stride_); 
180    }
181
182    void increment(void) { this->base_reference()+=stride_; }
183
184  };
185
186
187
188
189
190}}} // of namespace utility, yat, and theplu
191
192#endif
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