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 |
176 | |