176 lines
7.7 KiB
C++
176 lines
7.7 KiB
C++
/*
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Copyright (c) Marshall Clow 2008-2012.
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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Revision history:
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27 June 2009 mtc First version
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23 Oct 2010 mtc Added predicate version
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*/
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/// \file clamp.hpp
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/// \brief Clamp algorithm
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/// \author Marshall Clow
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///
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/// Suggested by olafvdspek in https://svn.boost.org/trac/boost/ticket/3215
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#ifndef BOOST_ALGORITHM_CLAMP_HPP
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#define BOOST_ALGORITHM_CLAMP_HPP
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#include <functional> // For std::less
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#include <iterator> // For std::iterator_traits
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#include <cassert>
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#include <boost/range/begin.hpp>
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#include <boost/range/end.hpp>
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#include <boost/mpl/identity.hpp> // for identity
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#include <boost/utility/enable_if.hpp> // for boost::disable_if
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namespace boost { namespace algorithm {
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/// \fn clamp ( T const& val,
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/// typename boost::mpl::identity<T>::type const & lo,
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/// typename boost::mpl::identity<T>::type const & hi, Pred p )
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/// \return the value "val" brought into the range [ lo, hi ]
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/// using the comparison predicate p.
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/// If p ( val, lo ) return lo.
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/// If p ( hi, val ) return hi.
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/// Otherwise, return the original value.
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///
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/// \param val The value to be clamped
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/// \param lo The lower bound of the range to be clamped to
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/// \param hi The upper bound of the range to be clamped to
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/// \param p A predicate to use to compare the values.
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/// p ( a, b ) returns a boolean.
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///
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template<typename T, typename Pred>
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T const & clamp ( T const& val,
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typename boost::mpl::identity<T>::type const & lo,
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typename boost::mpl::identity<T>::type const & hi, Pred p )
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{
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// assert ( !p ( hi, lo )); // Can't assert p ( lo, hi ) b/c they might be equal
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return p ( val, lo ) ? lo : p ( hi, val ) ? hi : val;
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}
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/// \fn clamp ( T const& val,
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/// typename boost::mpl::identity<T>::type const & lo,
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/// typename boost::mpl::identity<T>::type const & hi )
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/// \return the value "val" brought into the range [ lo, hi ].
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/// If the value is less than lo, return lo.
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/// If the value is greater than "hi", return hi.
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/// Otherwise, return the original value.
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///
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/// \param val The value to be clamped
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/// \param lo The lower bound of the range to be clamped to
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/// \param hi The upper bound of the range to be clamped to
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///
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template<typename T>
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T const& clamp ( const T& val,
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typename boost::mpl::identity<T>::type const & lo,
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typename boost::mpl::identity<T>::type const & hi )
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{
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return (clamp) ( val, lo, hi, std::less<T>());
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}
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/// \fn clamp_range ( InputIterator first, InputIterator last, OutputIterator out,
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/// std::iterator_traits<InputIterator>::value_type const & lo,
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/// std::iterator_traits<InputIterator>::value_type const & hi )
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/// \return clamp the sequence of values [first, last) into [ lo, hi ]
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///
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/// \param first The start of the range of values
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/// \param last One past the end of the range of input values
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/// \param out An output iterator to write the clamped values into
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/// \param lo The lower bound of the range to be clamped to
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/// \param hi The upper bound of the range to be clamped to
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///
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template<typename InputIterator, typename OutputIterator>
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OutputIterator clamp_range ( InputIterator first, InputIterator last, OutputIterator out,
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typename std::iterator_traits<InputIterator>::value_type const & lo,
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typename std::iterator_traits<InputIterator>::value_type const & hi )
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{
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// this could also be written with bind and std::transform
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while ( first != last )
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*out++ = clamp ( *first++, lo, hi );
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return out;
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}
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/// \fn clamp_range ( const Range &r, OutputIterator out,
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/// typename std::iterator_traits<typename boost::range_iterator<const Range>::type>::value_type const & lo,
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/// typename std::iterator_traits<typename boost::range_iterator<const Range>::type>::value_type const & hi )
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/// \return clamp the sequence of values [first, last) into [ lo, hi ]
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///
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/// \param r The range of values to be clamped
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/// \param out An output iterator to write the clamped values into
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/// \param lo The lower bound of the range to be clamped to
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/// \param hi The upper bound of the range to be clamped to
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///
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template<typename Range, typename OutputIterator>
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typename boost::disable_if_c<boost::is_same<Range, OutputIterator>::value, OutputIterator>::type
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clamp_range ( const Range &r, OutputIterator out,
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typename std::iterator_traits<typename boost::range_iterator<const Range>::type>::value_type const & lo,
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typename std::iterator_traits<typename boost::range_iterator<const Range>::type>::value_type const & hi )
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{
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return clamp_range ( boost::begin ( r ), boost::end ( r ), out, lo, hi );
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}
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/// \fn clamp_range ( InputIterator first, InputIterator last, OutputIterator out,
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/// std::iterator_traits<InputIterator>::value_type const & lo,
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/// std::iterator_traits<InputIterator>::value_type const & hi, Pred p )
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/// \return clamp the sequence of values [first, last) into [ lo, hi ]
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/// using the comparison predicate p.
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///
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/// \param first The start of the range of values
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/// \param last One past the end of the range of input values
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/// \param out An output iterator to write the clamped values into
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/// \param lo The lower bound of the range to be clamped to
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/// \param hi The upper bound of the range to be clamped to
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/// \param p A predicate to use to compare the values.
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/// p ( a, b ) returns a boolean.
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///
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template<typename InputIterator, typename OutputIterator, typename Pred>
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OutputIterator clamp_range ( InputIterator first, InputIterator last, OutputIterator out,
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typename std::iterator_traits<InputIterator>::value_type const & lo,
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typename std::iterator_traits<InputIterator>::value_type const & hi, Pred p )
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{
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// this could also be written with bind and std::transform
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while ( first != last )
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*out++ = clamp ( *first++, lo, hi, p );
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return out;
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}
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/// \fn clamp_range ( const Range &r, OutputIterator out,
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/// typename std::iterator_traits<typename boost::range_iterator<const Range>::type>::value_type const & lo,
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/// typename std::iterator_traits<typename boost::range_iterator<const Range>::type>::value_type const & hi,
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/// Pred p )
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/// \return clamp the sequence of values [first, last) into [ lo, hi ]
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/// using the comparison predicate p.
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///
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/// \param r The range of values to be clamped
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/// \param out An output iterator to write the clamped values into
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/// \param lo The lower bound of the range to be clamped to
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/// \param hi The upper bound of the range to be clamped to
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/// \param p A predicate to use to compare the values.
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/// p ( a, b ) returns a boolean.
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//
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// Disable this template if the first two parameters are the same type;
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// In that case, the user will get the two iterator version.
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template<typename Range, typename OutputIterator, typename Pred>
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typename boost::disable_if_c<boost::is_same<Range, OutputIterator>::value, OutputIterator>::type
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clamp_range ( const Range &r, OutputIterator out,
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typename std::iterator_traits<typename boost::range_iterator<const Range>::type>::value_type const & lo,
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typename std::iterator_traits<typename boost::range_iterator<const Range>::type>::value_type const & hi,
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Pred p )
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{
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return clamp_range ( boost::begin ( r ), boost::end ( r ), out, lo, hi, p );
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}
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}}
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#endif // BOOST_ALGORITHM_CLAMP_HPP
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