boost/log/utility/functional/logical.hpp
/*
* Copyright Andrey Semashev 2007 - 2015.
* 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)
*/
/*!
* \file logical.hpp
* \author Andrey Semashev
* \date 30.03.2008
*
* This header contains logical predicates for value comparison, analogous to \c std::less, \c std::greater
* and others. The main difference from the standard equivalents is that the predicates defined in this
* header are not templates and therefore do not require a fixed argument type. Furthermore, both arguments
* may have different types, in which case the comparison is performed without type conversion.
*
* \note In case if arguments are integral, the conversion is performed according to the standard C++ rules
* in order to avoid warnings from the compiler.
*/
#ifndef BOOST_LOG_UTILITY_FUNCTIONAL_LOGICAL_HPP_INCLUDED_
#define BOOST_LOG_UTILITY_FUNCTIONAL_LOGICAL_HPP_INCLUDED_
#include <boost/type_traits/is_integral.hpp>
#include <boost/type_traits/is_unsigned.hpp>
#include <boost/type_traits/conditional.hpp>
#include <boost/type_traits/integral_constant.hpp>
#include <boost/log/detail/config.hpp>
#include <boost/log/detail/header.hpp>
#ifdef BOOST_HAS_PRAGMA_ONCE
#pragma once
#endif
namespace boost {
BOOST_LOG_OPEN_NAMESPACE
namespace aux {
//! The trait creates a common integral type suitable for comparison. This is mostly to silence compiler warnings like 'signed/unsigned mismatch'.
template< typename T, typename U, unsigned int TSizeV = sizeof(T), unsigned int USizeV = sizeof(U), bool TSmallerThanU = (sizeof(T) < sizeof(U)) >
struct make_common_integral_type
{
typedef T type;
};
//! Specialization for case when \c T is smaller than \c U
template< typename T, typename U, unsigned int TSizeV, unsigned int USizeV >
struct make_common_integral_type< T, U, TSizeV, USizeV, true >
{
typedef U type;
};
//! Specialization for the case when both types have the same size
template< typename T, typename U, unsigned int SizeV >
struct make_common_integral_type< T, U, SizeV, SizeV, false > :
public boost::conditional<
is_unsigned< T >::value,
T,
U
>
{
};
} // namespace aux
//! Equality predicate
struct equal_to
{
typedef bool result_type;
template< typename T, typename U >
bool operator() (T const& left, U const& right) const
{
return op(left, right, integral_constant< bool, is_integral< T >::value && is_integral< U >::value >());
}
private:
template< typename T, typename U >
static bool op(T const& left, U const& right, false_type)
{
return (left == right);
}
template< typename T, typename U >
static bool op(T const& left, U const& right, true_type)
{
typedef typename aux::make_common_integral_type< T, U >::type common_integral_type;
return static_cast< common_integral_type >(left) == static_cast< common_integral_type >(right);
}
};
//! Inequality predicate
struct not_equal_to
{
typedef bool result_type;
template< typename T, typename U >
bool operator() (T const& left, U const& right) const
{
return op(left, right, integral_constant< bool, is_integral< T >::value && is_integral< U >::value >());
}
private:
template< typename T, typename U >
static bool op(T const& left, U const& right, false_type)
{
return (left != right);
}
template< typename T, typename U >
static bool op(T const& left, U const& right, true_type)
{
typedef typename aux::make_common_integral_type< T, U >::type common_integral_type;
return static_cast< common_integral_type >(left) != static_cast< common_integral_type >(right);
}
};
//! Less predicate
struct less
{
typedef bool result_type;
template< typename T, typename U >
bool operator() (T const& left, U const& right) const
{
return op(left, right, integral_constant< bool, is_integral< T >::value && is_integral< U >::value >());
}
private:
template< typename T, typename U >
static bool op(T const& left, U const& right, false_type)
{
return (left < right);
}
template< typename T, typename U >
static bool op(T const& left, U const& right, true_type)
{
typedef typename aux::make_common_integral_type< T, U >::type common_integral_type;
return static_cast< common_integral_type >(left) < static_cast< common_integral_type >(right);
}
};
//! Greater predicate
struct greater
{
typedef bool result_type;
template< typename T, typename U >
bool operator() (T const& left, U const& right) const
{
return op(left, right, integral_constant< bool, is_integral< T >::value && is_integral< U >::value >());
}
private:
template< typename T, typename U >
static bool op(T const& left, U const& right, false_type)
{
return (left > right);
}
template< typename T, typename U >
static bool op(T const& left, U const& right, true_type)
{
typedef typename aux::make_common_integral_type< T, U >::type common_integral_type;
return static_cast< common_integral_type >(left) > static_cast< common_integral_type >(right);
}
};
//! Less or equal predicate
struct less_equal
{
typedef bool result_type;
template< typename T, typename U >
bool operator() (T const& left, U const& right) const
{
return op(left, right, integral_constant< bool, is_integral< T >::value && is_integral< U >::value >());
}
private:
template< typename T, typename U >
static bool op(T const& left, U const& right, false_type)
{
return (left <= right);
}
template< typename T, typename U >
static bool op(T const& left, U const& right, true_type)
{
typedef typename aux::make_common_integral_type< T, U >::type common_integral_type;
return static_cast< common_integral_type >(left) <= static_cast< common_integral_type >(right);
}
};
//! Greater or equal predicate
struct greater_equal
{
typedef bool result_type;
template< typename T, typename U >
bool operator() (T const& left, U const& right) const
{
return op(left, right, integral_constant< bool, is_integral< T >::value && is_integral< U >::value >());
}
private:
template< typename T, typename U >
static bool op(T const& left, U const& right, false_type)
{
return (left >= right);
}
template< typename T, typename U >
static bool op(T const& left, U const& right, true_type)
{
typedef typename aux::make_common_integral_type< T, U >::type common_integral_type;
return static_cast< common_integral_type >(left) >= static_cast< common_integral_type >(right);
}
};
BOOST_LOG_CLOSE_NAMESPACE // namespace log
} // namespace boost
#include <boost/log/detail/footer.hpp>
#endif // BOOST_LOG_UTILITY_FUNCTIONAL_LOGICAL_HPP_INCLUDED_