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