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Added true_type and false_type to make user-defined specialisations easier to write.

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[SVN r21268]
This commit is contained in:
John Maddock
2003-12-15 11:58:20 +00:00
parent 9c45fdc67a
commit 8aaa85b7c3
1 changed files with 29 additions and 0 deletions
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29
include/boost/type_traits/detail/bool_trait_def.hpp
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@@ -149,3 +149,32 @@ template< param > struct trait##_impl< sp1,sp2 > \
BOOST_TT_AUX_BOOL_TRAIT_SPEC1(trait,sp,value) \
/**/
#endif
#ifndef BOOST_TT_INTEGRAL_CONSTANT
#define BOOST_TT_INTEGRAL_CONSTANT
//
// this is not a TR1 conforming integral_constant,
// but it is a first start:
//
namespace boost{
template <class T, T val>
struct integral_constant
{
typedef T value_type;
typedef integral_constant<T, val> type;
BOOST_STATIC_CONSTANT(value_type, value = val);
};
BOOST_TT_AUX_BOOL_TRAIT_SPEC2(integral_constant, bool, true, true);
BOOST_TT_AUX_BOOL_TRAIT_SPEC2(integral_constant, bool, false, false);
typedef integral_constant<bool, true> true_type;
typedef integral_constant<bool, false> false_type;
}
#endif