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Re-did implementation

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[SVN r47408]
This commit is contained in:
Daryle Walker
2008-07-13 23:30:18 +00:00
parent 422ef1ebe6
commit 2f91e69629
1 changed files with 102 additions and 46 deletions
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148
include/boost/integer.hpp
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@ -7,6 +7,7 @@
// See http://www.boost.org/libs/integer for documentation.
// Revision History
// 13 Jul 08 Redid implmentation. (Daryle Walker)
// 22 Sep 01 Added value-based integer templates. (Daryle Walker)
// 01 Apr 01 Modified to use new <boost/limits.hpp> header. (John Maddock)
// 30 Jul 00 Add typename syntax fix (Jens Maurer)
@ -17,33 +18,105 @@
#include <boost/integer_fwd.hpp> // self include
#include <boost/config.hpp> // for BOOST_STATIC_CONSTANT
#include <boost/integer_traits.hpp> // for boost::integer_traits
#include <boost/limits.hpp> // for std::numeric_limits
namespace boost
{
// Helper templates ------------------------------------------------------//
// integer template mapping a type to its processor-optimized analog -----//
// fast integers from least integers
// int_fast_t<> works correctly for unsigned too, in spite of the name.
template< typename LeastInt >
struct int_fast_t { typedef LeastInt fast; }; // imps may specialize
// convert category to type
template< int Category > struct int_least_helper {}; // default is empty
namespace detail
{
// specializatons: 1=long, 2=int, 3=short, 4=signed char,
// 6=unsigned long, 7=unsigned int, 8=unsigned short, 9=unsigned char
// no specializations for 0 and 5: requests for a type > long are in error
template<> struct int_least_helper<1> { typedef long least; };
template<> struct int_least_helper<2> { typedef int least; };
template<> struct int_least_helper<3> { typedef short least; };
template<> struct int_least_helper<4> { typedef signed char least; };
template<> struct int_least_helper<6> { typedef unsigned long least; };
template<> struct int_least_helper<7> { typedef unsigned int least; };
template<> struct int_least_helper<8> { typedef unsigned short least; };
template<> struct int_least_helper<9> { typedef unsigned char least; };
// Helper templates ------------------------------------------------------//
// convert integer category to type ; default is empty
template< int Rank, typename Signedness > struct int_least_helper {};
// specializatons: 1=(unsigned) long, 2=unsigned/int, 3=(unsigned) short,
// 4=(un)signed char
// no specializations for 0: requests for a type > (unsigned) long are in
// error
template<> struct int_least_helper<1, signed> { typedef long least; };
template<> struct int_least_helper<1, unsigned>
{ typedef unsigned long least; };
template<> struct int_least_helper<2, signed> { typedef int least; };
template<> struct int_least_helper<2, unsigned>
{ typedef unsigned int least; };
template<> struct int_least_helper<3, signed> { typedef short least; };
template<> struct int_least_helper<3, unsigned>
{ typedef unsigned short least; };
template<> struct int_least_helper<4, signed> { typedef signed char least; };
template<> struct int_least_helper<4, unsigned>
{ typedef unsigned char least; };
// category bounds
enum
{
lowest_integral_rank = 1,
highest_integral_rank = 4
};
// map a bit count to a category
template < int BitsIncludingSign >
struct int_rank_helper
{
BOOST_STATIC_CONSTANT( int, rank =
(BitsIncludingSign - 1 <= std::numeric_limits< long >::digits) +
(BitsIncludingSign - 1 <= std::numeric_limits< int >::digits) +
(BitsIncludingSign - 1 <= std::numeric_limits< short >::digits) +
(BitsIncludingSign - 1 <= std::numeric_limits< signed char >::digits) );
};
template < int Bits >
struct uint_rank_helper
{
BOOST_STATIC_CONSTANT( int, rank =
(Bits <= std::numeric_limits< unsigned long >::digits) +
(Bits <= std::numeric_limits< unsigned int >::digits) +
(Bits <= std::numeric_limits< unsigned short >::digits) +
(Bits <= std::numeric_limits< unsigned char >::digits) );
};
// map an extreme value to a category
template < long MaxValue >
struct int_max_rank_helper
{
BOOST_STATIC_CONSTANT( int, rank =
(MaxValue <= integer_traits< long >::const_max) +
(MaxValue <= integer_traits< int >::const_max) +
(MaxValue <= integer_traits< short >::const_max) +
(MaxValue <= integer_traits< signed char >::const_max) );
};
template < long MinValue >
struct int_min_rank_helper
{
BOOST_STATIC_CONSTANT( int, rank =
(MinValue >= integer_traits< long >::const_min) +
(MinValue >= integer_traits< int >::const_min) +
(MinValue >= integer_traits< short >::const_min) +
(MinValue >= integer_traits< signed char >::const_min) );
};
template < unsigned long Value >
struct uint_max_rank_helper
{
BOOST_STATIC_CONSTANT( int, rank =
(Value <= integer_traits< unsigned long >::const_max) +
(Value <= integer_traits< unsigned int >::const_max) +
(Value <= integer_traits< unsigned short >::const_max) +
(Value <= integer_traits< unsigned char >::const_max) );
};
} // namespace detail
// integer templates specifying number of bits ---------------------------//
@ -51,13 +124,10 @@ namespace boost
template< int Bits > // bits (including sign) required
struct int_t
{
typedef typename int_least_helper
typedef typename detail::int_least_helper
<
(Bits-1 <= std::numeric_limits<long>::digits) +
(Bits-1 <= std::numeric_limits<int>::digits) +
(Bits-1 <= std::numeric_limits<short>::digits) +
(Bits-1 <= std::numeric_limits<signed char>::digits)
>::least least;
detail::int_rank_helper<Bits>::rank,
signed>::least least;
typedef typename int_fast_t<least>::fast fast;
};
@ -65,14 +135,10 @@ namespace boost
template< int Bits > // bits required
struct uint_t
{
typedef typename int_least_helper
typedef typename detail::int_least_helper
<
5 +
(Bits <= std::numeric_limits<unsigned long>::digits) +
(Bits <= std::numeric_limits<unsigned int>::digits) +
(Bits <= std::numeric_limits<unsigned short>::digits) +
(Bits <= std::numeric_limits<unsigned char>::digits)
>::least least;
detail::uint_rank_helper<Bits>::rank,
unsigned>::least least;
typedef typename int_fast_t<least>::fast fast;
// int_fast_t<> works correctly for unsigned too, in spite of the name.
};
@ -83,26 +149,20 @@ namespace boost
template< long MaxValue > // maximum value to require support
struct int_max_value_t
{
typedef typename int_least_helper
typedef typename detail::int_least_helper
<
(MaxValue <= integer_traits<long>::const_max) +
(MaxValue <= integer_traits<int>::const_max) +
(MaxValue <= integer_traits<short>::const_max) +
(MaxValue <= integer_traits<signed char>::const_max)
>::least least;
detail::int_max_rank_helper<MaxValue>::rank,
signed>::least least;
typedef typename int_fast_t<least>::fast fast;
};
template< long MinValue > // minimum value to require support
struct int_min_value_t
{
typedef typename int_least_helper
typedef typename detail::int_least_helper
<
(MinValue >= integer_traits<long>::const_min) +
(MinValue >= integer_traits<int>::const_min) +
(MinValue >= integer_traits<short>::const_min) +
(MinValue >= integer_traits<signed char>::const_min)
>::least least;
detail::int_min_rank_helper<MinValue>::rank,
signed>::least least;
typedef typename int_fast_t<least>::fast fast;
};
@ -110,14 +170,10 @@ namespace boost
template< unsigned long Value > // maximum value to require support
struct uint_value_t
{
typedef typename int_least_helper
typedef typename detail::int_least_helper
<
5 +
(Value <= integer_traits<unsigned long>::const_max) +
(Value <= integer_traits<unsigned int>::const_max) +
(Value <= integer_traits<unsigned short>::const_max) +
(Value <= integer_traits<unsigned char>::const_max)
>::least least;
detail::uint_max_rank_helper<Value>::rank,
unsigned>::least least;
typedef typename int_fast_t<least>::fast fast;
};