ceph/src/boost/boost/algorithm/clamp.hpp

   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