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> clamp(const T & val,typename boost::mpl::identity<T>::type const & lo,typename boost::mpl::identity<T>::type const & hi)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> clamp_range(InputIterator first,InputIterator last,OutputIterator out,typename std::iterator_traits<InputIterator>::value_type const & lo,typename std::iterator_traits<InputIterator>::value_type const & hi)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 clamp_range(const Range & r,OutputIterator out,typename std::iterator_traits<typename boost::range_iterator<const Range>::type>::value_type const & lo,typename std::iterator_traits<typename boost::range_iterator<const Range>::type>::value_type const & hi)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 clamp_range(const Range & r,OutputIterator out,typename std::iterator_traits<typename boost::range_iterator<const Range>::type>::value_type const & lo,typename std::iterator_traits<typename boost::range_iterator<const Range>::type>::value_type const & hi,Pred p)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