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- // Copyright (C) 2004 Arkadiy Vertleyb
- // Use, modification and distribution is subject to the Boost Software
- // License, Version 1.0. (http://www.boost.org/LICENSE_1_0.txt)
- #ifndef BOOST_TYPEOF_INT_ENCODING_HPP_INCLUDED
- #define BOOST_TYPEOF_INT_ENCODING_HPP_INCLUDED
- #include <boost/config.hpp>
- #include <boost/typeof/constant.hpp>
- namespace boost { namespace type_of {
- template<class T> struct get_unsigned
- {
- typedef T type;
- };
- template<> struct get_unsigned<signed char>
- {
- typedef unsigned char type;
- };
- template<> struct get_unsigned<char>
- {
- typedef unsigned char type;
- };
- template<> struct get_unsigned<short>
- {
- typedef unsigned short type;
- };
- template<> struct get_unsigned<int>
- {
- typedef unsigned int type;
- };
- template<> struct get_unsigned<long>
- {
- typedef unsigned long type;
- };
- //////////////////////////
- template<std::size_t n, bool Overflow>
- struct pack
- {
- BOOST_STATIC_CONSTANT(std::size_t , value=((n + 1) * 2 + (Overflow ? 1 : 0)));
- };
- template<std::size_t m>
- struct unpack
- {
- BOOST_STATIC_CONSTANT(std::size_t, value = (m / 2) - 1);
- BOOST_STATIC_CONSTANT(std::size_t, overflow = (m % 2 == 1));
- };
- ////////////////////////////////
- template<class V, std::size_t n, bool overflow = (n >= 0x3fffffff)>
- struct encode_size_t : push_back<
- V,
- boost::type_of::constant<std::size_t,pack<n, false>::value>
- >
- {};
- template<class V, std::size_t n>
- struct encode_size_t<V, n, true> : push_back<typename push_back<
- V,
- boost::type_of::constant<std::size_t,pack<n % 0x3ffffffe, true>::value> >::type,
- boost::type_of::constant<std::size_t,n / 0x3ffffffe>
- >
- {};
- template<class V, class T, T n>
- struct encode_integral : encode_size_t< V, (typename get_unsigned<T>::type)n,(((typename get_unsigned<T>::type)n)>=0x3fffffff) >
- {};
- template<class V, bool b>
- struct encode_integral<V, bool, b> : encode_size_t< V, b?1:0, false>
- {};
- ///////////////////////////
- template<std::size_t n, class Iter, bool overflow>
- struct decode_size_t;
- template<std::size_t n, class Iter>
- struct decode_size_t<n, Iter, false>
- {
- BOOST_STATIC_CONSTANT(std::size_t,value = n);
- typedef Iter iter;
- };
- template<std::size_t n, class Iter>
- struct decode_size_t<n, Iter, true>
- {
- BOOST_STATIC_CONSTANT(std::size_t,m = Iter::type::value);
- BOOST_STATIC_CONSTANT(std::size_t,value = (std::size_t)m * 0x3ffffffe + n);
- typedef typename Iter::next iter;
- };
- template<class T, class Iter>
- struct decode_integral
- {
- typedef decode_integral<T,Iter> self_t;
- BOOST_STATIC_CONSTANT(std::size_t,m = Iter::type::value);
- BOOST_STATIC_CONSTANT(std::size_t,n = unpack<m>::value);
- BOOST_STATIC_CONSTANT(std::size_t,overflow = unpack<m>::overflow);
- typedef typename Iter::next nextpos;
- static const T value = (T)(std::size_t)decode_size_t<n, nextpos, overflow>::value;
- typedef typename decode_size_t<self_t::n, nextpos, self_t::overflow>::iter iter;
- };
- }}//namespace
- #endif//BOOST_TYPEOF_INT_ENCODING_HPP_INCLUDED
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