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1 | /* |
2 | Copyright (c) Marshall Clow 2008-2012. | |
3 | ||
4 | Distributed under the Boost Software License, Version 1.0. (See accompanying | |
5 | file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) | |
6 | ||
7 | Revision history: | |
8 | 27 June 2009 mtc First version | |
9 | 23 Oct 2010 mtc Added predicate version | |
10 | ||
11 | */ | |
12 | ||
13 | /// \file clamp.hpp | |
14 | /// \brief Clamp algorithm | |
15 | /// \author Marshall Clow | |
16 | /// | |
17 | /// Suggested by olafvdspek in https://svn.boost.org/trac/boost/ticket/3215 | |
18 | ||
19 | #ifndef BOOST_ALGORITHM_CLAMP_HPP | |
20 | #define BOOST_ALGORITHM_CLAMP_HPP | |
21 | ||
22 | #include <functional> // For std::less | |
23 | #include <iterator> // For std::iterator_traits | |
24 | #include <cassert> | |
25 | ||
26 | #include <boost/range/begin.hpp> | |
27 | #include <boost/range/end.hpp> | |
28 | #include <boost/mpl/identity.hpp> // for identity | |
29 | #include <boost/utility/enable_if.hpp> // for boost::disable_if | |
30 | ||
31 | namespace boost { namespace algorithm { | |
32 | ||
33 | /// \fn clamp ( T const& val, | |
34 | /// typename boost::mpl::identity<T>::type const & lo, | |
35 | /// typename boost::mpl::identity<T>::type const & hi, Pred p ) | |
36 | /// \return the value "val" brought into the range [ lo, hi ] | |
37 | /// using the comparison predicate p. | |
38 | /// If p ( val, lo ) return lo. | |
39 | /// If p ( hi, val ) return hi. | |
40 | /// Otherwise, return the original value. | |
41 | /// | |
42 | /// \param val The value to be clamped | |
43 | /// \param lo The lower bound of the range to be clamped to | |
44 | /// \param hi The upper bound of the range to be clamped to | |
45 | /// \param p A predicate to use to compare the values. | |
46 | /// p ( a, b ) returns a boolean. | |
47 | /// | |
48 | template<typename T, typename Pred> | |
49 | T const & clamp ( T const& val, | |
50 | typename boost::mpl::identity<T>::type const & lo, | |
51 | typename boost::mpl::identity<T>::type const & hi, Pred p ) | |
52 | { | |
53 | // assert ( !p ( hi, lo )); // Can't assert p ( lo, hi ) b/c they might be equal | |
54 | return p ( val, lo ) ? lo : p ( hi, val ) ? hi : val; | |
55 | } | |
56 | ||
57 | ||
58 | /// \fn clamp ( T const& val, | |
59 | /// typename boost::mpl::identity<T>::type const & lo, | |
60 | /// typename boost::mpl::identity<T>::type const & hi ) | |
61 | /// \return the value "val" brought into the range [ lo, hi ]. | |
62 | /// If the value is less than lo, return lo. | |
63 | /// If the value is greater than "hi", return hi. | |
64 | /// Otherwise, return the original value. | |
65 | /// | |
66 | /// \param val The value to be clamped | |
67 | /// \param lo The lower bound of the range to be clamped to | |
68 | /// \param hi The upper bound of the range to be clamped to | |
69 | /// | |
70 | template<typename T> | |
71 | T const& clamp ( const T& val, | |
72 | typename boost::mpl::identity<T>::type const & lo, | |
73 | typename boost::mpl::identity<T>::type const & hi ) | |
74 | { | |
75 | return (clamp) ( val, lo, hi, std::less<T>()); | |
76 | } | |
77 | ||
78 | /// \fn clamp_range ( InputIterator first, InputIterator last, OutputIterator out, | |
79 | /// std::iterator_traits<InputIterator>::value_type const & lo, | |
80 | /// std::iterator_traits<InputIterator>::value_type const & hi ) | |
81 | /// \return clamp the sequence of values [first, last) into [ lo, hi ] | |
82 | /// | |
83 | /// \param first The start of the range of values | |
84 | /// \param last One past the end of the range of input values | |
85 | /// \param out An output iterator to write the clamped values into | |
86 | /// \param lo The lower bound of the range to be clamped to | |
87 | /// \param hi The upper bound of the range to be clamped to | |
88 | /// | |
89 | template<typename InputIterator, typename OutputIterator> | |
90 | OutputIterator clamp_range ( InputIterator first, InputIterator last, OutputIterator out, | |
91 | typename std::iterator_traits<InputIterator>::value_type const & lo, | |
92 | typename std::iterator_traits<InputIterator>::value_type const & hi ) | |
93 | { | |
94 | // this could also be written with bind and std::transform | |
95 | while ( first != last ) | |
96 | *out++ = clamp ( *first++, lo, hi ); | |
97 | return out; | |
98 | } | |
99 | ||
100 | /// \fn clamp_range ( const Range &r, OutputIterator out, | |
101 | /// typename std::iterator_traits<typename boost::range_iterator<const Range>::type>::value_type const & lo, | |
102 | /// typename std::iterator_traits<typename boost::range_iterator<const Range>::type>::value_type const & hi ) | |
103 | /// \return clamp the sequence of values [first, last) into [ lo, hi ] | |
104 | /// | |
105 | /// \param r The range of values to be clamped | |
106 | /// \param out An output iterator to write the clamped values into | |
107 | /// \param lo The lower bound of the range to be clamped to | |
108 | /// \param hi The upper bound of the range to be clamped to | |
109 | /// | |
110 | template<typename Range, typename OutputIterator> | |
111 | typename boost::disable_if_c<boost::is_same<Range, OutputIterator>::value, OutputIterator>::type | |
112 | clamp_range ( const Range &r, OutputIterator out, | |
113 | typename std::iterator_traits<typename boost::range_iterator<const Range>::type>::value_type const & lo, | |
114 | typename std::iterator_traits<typename boost::range_iterator<const Range>::type>::value_type const & hi ) | |
115 | { | |
116 | return clamp_range ( boost::begin ( r ), boost::end ( r ), out, lo, hi ); | |
117 | } | |
118 | ||
119 | ||
120 | /// \fn clamp_range ( InputIterator first, InputIterator last, OutputIterator out, | |
121 | /// std::iterator_traits<InputIterator>::value_type const & lo, | |
122 | /// std::iterator_traits<InputIterator>::value_type const & hi, Pred p ) | |
123 | /// \return clamp the sequence of values [first, last) into [ lo, hi ] | |
124 | /// using the comparison predicate p. | |
125 | /// | |
126 | /// \param first The start of the range of values | |
127 | /// \param last One past the end of the range of input values | |
128 | /// \param out An output iterator to write the clamped values into | |
129 | /// \param lo The lower bound of the range to be clamped to | |
130 | /// \param hi The upper bound of the range to be clamped to | |
131 | /// \param p A predicate to use to compare the values. | |
132 | /// p ( a, b ) returns a boolean. | |
133 | ||
134 | /// | |
135 | template<typename InputIterator, typename OutputIterator, typename Pred> | |
136 | OutputIterator clamp_range ( InputIterator first, InputIterator last, OutputIterator out, | |
137 | typename std::iterator_traits<InputIterator>::value_type const & lo, | |
138 | typename std::iterator_traits<InputIterator>::value_type const & hi, Pred p ) | |
139 | { | |
140 | // this could also be written with bind and std::transform | |
141 | while ( first != last ) | |
142 | *out++ = clamp ( *first++, lo, hi, p ); | |
143 | return out; | |
144 | } | |
145 | ||
146 | /// \fn clamp_range ( const Range &r, OutputIterator out, | |
147 | /// typename std::iterator_traits<typename boost::range_iterator<const Range>::type>::value_type const & lo, | |
148 | /// typename std::iterator_traits<typename boost::range_iterator<const Range>::type>::value_type const & hi, | |
149 | /// Pred p ) | |
150 | /// \return clamp the sequence of values [first, last) into [ lo, hi ] | |
151 | /// using the comparison predicate p. | |
152 | /// | |
153 | /// \param r The range of values to be clamped | |
154 | /// \param out An output iterator to write the clamped values into | |
155 | /// \param lo The lower bound of the range to be clamped to | |
156 | /// \param hi The upper bound of the range to be clamped to | |
157 | /// \param p A predicate to use to compare the values. | |
158 | /// p ( a, b ) returns a boolean. | |
159 | // | |
160 | // Disable this template if the first two parameters are the same type; | |
161 | // In that case, the user will get the two iterator version. | |
162 | template<typename Range, typename OutputIterator, typename Pred> | |
163 | typename boost::disable_if_c<boost::is_same<Range, OutputIterator>::value, OutputIterator>::type | |
164 | clamp_range ( const Range &r, OutputIterator out, | |
165 | typename std::iterator_traits<typename boost::range_iterator<const Range>::type>::value_type const & lo, | |
166 | typename std::iterator_traits<typename boost::range_iterator<const Range>::type>::value_type const & hi, | |
167 | Pred p ) | |
168 | { | |
169 | return clamp_range ( boost::begin ( r ), boost::end ( r ), out, lo, hi, p ); | |
170 | } | |
171 | ||
172 | ||
173 | }} | |
174 | ||
175 | #endif // BOOST_ALGORITHM_CLAMP_HPP |