source: trunk/yat/utility/iterator_traits.h @ 937

Last change on this file since 937 was 937, checked in by Peter, 14 years ago

changing name of IteratorTraits? to iterator_traits

  • Property svn:eol-style set to native
  • Property svn:keywords set to Id
File size: 3.9 KB
Line 
1#ifndef _theplu_yat_utility_iterator_traits_
2#define _theplu_yat_utility_iterator_traits_
3
4// $Id: iterator_traits.h 937 2007-10-05 23:11:18Z peter $
5
6/*
7  Copyright (C) 2007 Peter Johansson
8
9  This file is part of the yat library, http://trac.thep.lu.se/trac/yat
10
11  The yat library is free software; you can redistribute it and/or
12  modify it under the terms of the GNU General Public License as
13  published by the Free Software Foundation; either version 2 of the
14  License, or (at your option) any later version.
15
16  The yat library is distributed in the hope that it will be useful,
17  but WITHOUT ANY WARRANTY; without even the implied warranty of
18  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
19  General Public License for more details.
20
21  You should have received a copy of the GNU General Public License
22  along with this program; if not, write to the Free Software
23  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
24  02111-1307, USA.
25*/
26
27#include "yat/utility/IteratorWeighted.h"
28
29namespace theplu {
30namespace yat {
31namespace utility {
32
33  /*
34    Struct to be used to make compile-time decision that Iterator is
35    unweighted, which is the default.
36   */ 
37  struct unweighted_type {
38    typedef unweighted_type type;
39  };
40   
41  /*
42    Struct to be used to make compile-time decision that Iterator is
43    weighted. Some algorithms come in also in a weighted version in
44    this tag could be used to decide on using them (rather than
45    unweighted cousin).
46   */ 
47  struct weighted_type {
48    typedef weighted_type type;
49  };
50
51  // All iterators should default to unweighted type ...
52  template <class T>
53  struct weighted_iterator_traits {
54    typedef unweighted_type type;
55  };
56
57  // but specialized to return weighted type for some things
58  template <class U, class V>
59  struct weighted_iterator_traits<yat::utility::IteratorWeighted<U,V> > {
60    typedef weighted_type type;
61  };
62
63
64
65  /*
66    struct used to determine if a pair of iterators should be treated
67    as weighted
68
69  template <class T1, class T2>
70  struct weighted_iterator_traits2 {
71    typedef weighted_type type;
72  };
73
74  // but specialized to return weighted type for some things
75  template <class T1, class T2>
76  struct weighted_iterator_traits2<yat::utility::IteratorWeighted<U,V> > {
77    typedef weighted_type type;
78  };
79  */
80
81  // check (at compile time) that iterator is unweighted.
82  inline void check_iterator_is_unweighted(unweighted_type x){} 
83  template <class Iter>
84  void check_iterator_is_unweighted(Iter iter) 
85  { check_iterator_is_unweighted(typename 
86                                 weighted_iterator_traits<Iter>::type());
87  }
88
89
90  /*
91    Function to be used to make compile-time decision how to return
92    data from an iterator separating two cases: weighted and
93    unweighted.
94
95    In this way unweighted iterators can be used in a weighted context.
96   */ 
97  // Peter, perhaps these should be templatized, but for now return
98  // type double is hard coded.
99  template <class Iter>
100  double iterator_traits_data(Iter iter)
101  { return iterator_traits_data(iter, typename 
102                                weighted_iterator_traits<Iter>::type()); } 
103
104  template <class Iter>
105  double iterator_traits_data(Iter i, weighted_type)
106  { return i.data(); } 
107
108  template <class Iter>
109  double iterator_traits_data(Iter i, unweighted_type)
110  { return *i; } 
111
112  /*
113    Function to be used to make compile-time decision how to return
114    data from an iterator separating two cases: weighted and
115    unweighted.
116
117    In this way unweighted iterators can be used in a weighted context
118    and weight will be set to unity.
119   */ 
120  // Peter, perhaps these should be templatized, but for now return
121  // type double is hard coded.
122  template <class Iter>
123  double iterator_traits_weight(Iter iter)
124  { return iterator_traits_weight(iter, typename 
125                                  weighted_iterator_traits<Iter>::type()); } 
126
127  template <class Iter>
128  double iterator_traits_weight(Iter i, weighted_type)
129  { return i.weight(); } 
130
131  template <class Iter>
132  double iterator_traits_weight(Iter i, unweighted_type)
133  { return 1.0; } 
134
135
136}}} // of namespace utility, yat, and theplu
137
138#endif
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