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author | DongHun Kwak <dh0128.kwak@samsung.com> | 2017-09-13 11:24:46 +0900 |
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committer | DongHun Kwak <dh0128.kwak@samsung.com> | 2017-09-13 11:25:39 +0900 |
commit | 4fadd968fa12130524c8380f33fcfe25d4de79e5 (patch) | |
tree | fd26a490cd15388d42fc6652b3c5c13012e7f93e /boost/next_prior.hpp | |
parent | b5c87084afaef42b2d058f68091be31988a6a874 (diff) | |
download | boost-upstream/1.65.0.tar.gz boost-upstream/1.65.0.tar.bz2 boost-upstream/1.65.0.zip |
Imported Upstream version 1.65.0upstream/1.65.0
Change-Id: Icf8400b375482cb11bcf77440a6934ba360d6ba4
Signed-off-by: DongHun Kwak <dh0128.kwak@samsung.com>
Diffstat (limited to 'boost/next_prior.hpp')
-rw-r--r-- | boost/next_prior.hpp | 125 |
1 files changed, 70 insertions, 55 deletions
diff --git a/boost/next_prior.hpp b/boost/next_prior.hpp index 7854ec436a..bad46ed654 100644 --- a/boost/next_prior.hpp +++ b/boost/next_prior.hpp @@ -1,8 +1,11 @@ // Boost next_prior.hpp header file ---------------------------------------// -// (C) Copyright Dave Abrahams and Daniel Walker 1999-2003. 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) +// (C) Copyright Dave Abrahams and Daniel Walker 1999-2003. +// Copyright (c) Andrey Semashev 2017 +// +// 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) // See http://www.boost.org/libs/utility for documentation. @@ -13,17 +16,14 @@ #define BOOST_NEXT_PRIOR_HPP_INCLUDED #include <iterator> -#if defined(_MSC_VER) && _MSC_VER <= 1310 -#include <boost/mpl/and.hpp> -#include <boost/type_traits/is_integral.hpp> -#endif -#include <boost/type_traits/is_unsigned.hpp> -#include <boost/type_traits/integral_promotion.hpp> -#include <boost/type_traits/make_signed.hpp> +#include <boost/config.hpp> +#include <boost/core/enable_if.hpp> #include <boost/type_traits/has_plus.hpp> #include <boost/type_traits/has_plus_assign.hpp> #include <boost/type_traits/has_minus.hpp> #include <boost/type_traits/has_minus_assign.hpp> +#include <boost/iterator/advance.hpp> +#include <boost/iterator/reverse_iterator.hpp> namespace boost { @@ -39,18 +39,36 @@ namespace boost { namespace next_prior_detail { -template< typename T, typename Distance, bool HasPlus = has_plus< T, Distance >::value > -struct next_impl2 +// The trait attempts to detect if the T type is an iterator. Class-type iterators are assumed +// to have the nested type iterator_category. Strictly speaking, this is not required to be the +// case (e.g. a user can specialize iterator_traits for T without defining T::iterator_category). +// Still, this is a good heuristic in practice, and we can't do anything better anyway. +// Since C++17 we can test for iterator_traits<T>::iterator_category presence instead as it is +// required to be only present for iterators. +template< typename T, typename Void = void > +struct is_iterator { - static T call(T x, Distance n) - { - std::advance(x, n); - return x; - } + static BOOST_CONSTEXPR_OR_CONST bool value = false; +}; + +template< typename T > +struct is_iterator< T, typename enable_if_has_type< typename T::iterator_category >::type > +{ + static BOOST_CONSTEXPR_OR_CONST bool value = true; }; +template< typename T > +struct is_iterator< T*, void > +{ + static BOOST_CONSTEXPR_OR_CONST bool value = true; +}; + + +template< typename T, typename Distance, bool HasPlus = has_plus< T, Distance >::value > +struct next_plus_impl; + template< typename T, typename Distance > -struct next_impl2< T, Distance, true > +struct next_plus_impl< T, Distance, true > { static T call(T x, Distance n) { @@ -58,15 +76,14 @@ struct next_impl2< T, Distance, true > } }; - template< typename T, typename Distance, bool HasPlusAssign = has_plus_assign< T, Distance >::value > -struct next_impl1 : - public next_impl2< T, Distance > +struct next_plus_assign_impl : + public next_plus_impl< T, Distance > { }; template< typename T, typename Distance > -struct next_impl1< T, Distance, true > +struct next_plus_assign_impl< T, Distance, true > { static T call(T x, Distance n) { @@ -75,47 +92,28 @@ struct next_impl1< T, Distance, true > } }; - -template< - typename T, - typename Distance, - typename PromotedDistance = typename integral_promotion< Distance >::type, -#if !defined(_MSC_VER) || _MSC_VER > 1310 - bool IsUInt = is_unsigned< PromotedDistance >::value -#else - // MSVC 7.1 has problems with applying is_unsigned to non-integral types - bool IsUInt = mpl::and_< is_integral< PromotedDistance >, is_unsigned< PromotedDistance > >::value -#endif -> -struct prior_impl3 +template< typename T, typename Distance, bool IsIterator = is_iterator< T >::value > +struct next_advance_impl : + public next_plus_assign_impl< T, Distance > { - static T call(T x, Distance n) - { - std::advance(x, -n); - return x; - } }; -template< typename T, typename Distance, typename PromotedDistance > -struct prior_impl3< T, Distance, PromotedDistance, true > +template< typename T, typename Distance > +struct next_advance_impl< T, Distance, true > { static T call(T x, Distance n) { - typedef typename make_signed< PromotedDistance >::type signed_distance; - std::advance(x, -static_cast< signed_distance >(static_cast< PromotedDistance >(n))); + boost::iterators::advance(x, n); return x; } }; template< typename T, typename Distance, bool HasMinus = has_minus< T, Distance >::value > -struct prior_impl2 : - public prior_impl3< T, Distance > -{ -}; +struct prior_minus_impl; template< typename T, typename Distance > -struct prior_impl2< T, Distance, true > +struct prior_minus_impl< T, Distance, true > { static T call(T x, Distance n) { @@ -123,15 +121,14 @@ struct prior_impl2< T, Distance, true > } }; - template< typename T, typename Distance, bool HasMinusAssign = has_minus_assign< T, Distance >::value > -struct prior_impl1 : - public prior_impl2< T, Distance > +struct prior_minus_assign_impl : + public prior_minus_impl< T, Distance > { }; template< typename T, typename Distance > -struct prior_impl1< T, Distance, true > +struct prior_minus_assign_impl< T, Distance, true > { static T call(T x, Distance n) { @@ -140,6 +137,24 @@ struct prior_impl1< T, Distance, true > } }; +template< typename T, typename Distance, bool IsIterator = is_iterator< T >::value > +struct prior_advance_impl : + public prior_minus_assign_impl< T, Distance > +{ +}; + +template< typename T, typename Distance > +struct prior_advance_impl< T, Distance, true > +{ + static T call(T x, Distance n) + { + // Avoid negating n to sidestep possible integer overflow + boost::iterators::reverse_iterator< T > rx(x); + boost::iterators::advance(rx, n); + return rx.base(); + } +}; + } // namespace next_prior_detail template <class T> @@ -148,7 +163,7 @@ inline T next(T x) { return ++x; } template <class T, class Distance> inline T next(T x, Distance n) { - return next_prior_detail::next_impl1< T, Distance >::call(x, n); + return next_prior_detail::next_advance_impl< T, Distance >::call(x, n); } template <class T> @@ -157,7 +172,7 @@ inline T prior(T x) { return --x; } template <class T, class Distance> inline T prior(T x, Distance n) { - return next_prior_detail::prior_impl1< T, Distance >::call(x, n); + return next_prior_detail::prior_advance_impl< T, Distance >::call(x, n); } } // namespace boost |