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134 lines
3.6 KiB
134 lines
3.6 KiB
// Copyright David Abrahams 2004. Use, modification and distribution is |
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// subject to 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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#ifndef IS_INCREMENTABLE_DWA200415_HPP |
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# define IS_INCREMENTABLE_DWA200415_HPP |
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# include <boost/type_traits/detail/template_arity_spec.hpp> |
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# include <boost/type_traits/remove_cv.hpp> |
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# include <boost/mpl/aux_/lambda_support.hpp> |
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# include <boost/mpl/bool.hpp> |
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# include <boost/detail/workaround.hpp> |
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// Must be the last include |
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# include <boost/type_traits/detail/bool_trait_def.hpp> |
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namespace boost { namespace detail { |
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// is_incrementable<T> metafunction |
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// |
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// Requires: Given x of type T&, if the expression ++x is well-formed |
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// it must have complete type; otherwise, it must neither be ambiguous |
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// nor violate access. |
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// This namespace ensures that ADL doesn't mess things up. |
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namespace is_incrementable_ |
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{ |
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// a type returned from operator++ when no increment is found in the |
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// type's own namespace |
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struct tag {}; |
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// any soaks up implicit conversions and makes the following |
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// operator++ less-preferred than any other such operator that |
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// might be found via ADL. |
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struct any { template <class T> any(T const&); }; |
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// This is a last-resort operator++ for when none other is found |
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# if BOOST_WORKAROUND(__GNUC__, == 4) && __GNUC_MINOR__ == 0 && __GNUC_PATCHLEVEL__ == 2 |
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} |
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namespace is_incrementable_2 |
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{ |
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is_incrementable_::tag operator++(is_incrementable_::any const&); |
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is_incrementable_::tag operator++(is_incrementable_::any const&,int); |
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} |
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using namespace is_incrementable_2; |
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namespace is_incrementable_ |
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{ |
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# else |
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tag operator++(any const&); |
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tag operator++(any const&,int); |
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# endif |
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# if BOOST_WORKAROUND(__MWERKS__, BOOST_TESTED_AT(0x3202)) \ |
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|| BOOST_WORKAROUND(BOOST_MSVC, <= 1300) |
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# define BOOST_comma(a,b) (a) |
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# else |
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// In case an operator++ is found that returns void, we'll use ++x,0 |
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tag operator,(tag,int); |
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# define BOOST_comma(a,b) (a,b) |
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# endif |
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# if defined(BOOST_MSVC) |
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# pragma warning(push) |
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# pragma warning(disable:4913) // Warning about operator, |
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# endif |
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// two check overloads help us identify which operator++ was picked |
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char (& check_(tag) )[2]; |
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template <class T> |
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char check_(T const&); |
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template <class T> |
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struct impl |
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{ |
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static typename boost::remove_cv<T>::type& x; |
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BOOST_STATIC_CONSTANT( |
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bool |
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, value = sizeof(is_incrementable_::check_(BOOST_comma(++x,0))) == 1 |
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); |
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}; |
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template <class T> |
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struct postfix_impl |
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{ |
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static typename boost::remove_cv<T>::type& x; |
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BOOST_STATIC_CONSTANT( |
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bool |
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, value = sizeof(is_incrementable_::check_(BOOST_comma(x++,0))) == 1 |
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); |
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}; |
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# if defined(BOOST_MSVC) |
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# pragma warning(pop) |
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# endif |
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} |
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# undef BOOST_comma |
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template<typename T> |
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struct is_incrementable |
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BOOST_TT_AUX_BOOL_C_BASE(::boost::detail::is_incrementable_::impl<T>::value) |
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{ |
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BOOST_TT_AUX_BOOL_TRAIT_VALUE_DECL(::boost::detail::is_incrementable_::impl<T>::value) |
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BOOST_MPL_AUX_LAMBDA_SUPPORT(1,is_incrementable,(T)) |
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}; |
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template<typename T> |
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struct is_postfix_incrementable |
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BOOST_TT_AUX_BOOL_C_BASE(::boost::detail::is_incrementable_::impl<T>::value) |
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{ |
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BOOST_TT_AUX_BOOL_TRAIT_VALUE_DECL(::boost::detail::is_incrementable_::postfix_impl<T>::value) |
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BOOST_MPL_AUX_LAMBDA_SUPPORT(1,is_postfix_incrementable,(T)) |
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}; |
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} // namespace detail |
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BOOST_TT_AUX_TEMPLATE_ARITY_SPEC(1, ::boost::detail::is_incrementable) |
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BOOST_TT_AUX_TEMPLATE_ARITY_SPEC(1, ::boost::detail::is_postfix_incrementable) |
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} // namespace boost |
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# include <boost/type_traits/detail/bool_trait_undef.hpp> |
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#endif // IS_INCREMENTABLE_DWA200415_HPP
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