--- /dev/null
+// (c) Copyright Fernando Luis Cacciola Carballal 2000-2004
+// Use, modification, and distribution is subject to 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 library home page at http://www.boost.org/libs/numeric/conversion
+//
+// Contact the author at: fernando_cacciola@hotmail.com
+//
+#ifndef BOOST_NUMERIC_CONVERSION_DETAIL_IS_SUBRANGED_FLC_12NOV2002_HPP
+#define BOOST_NUMERIC_CONVERSION_DETAIL_IS_SUBRANGED_FLC_12NOV2002_HPP
+
+#include "boost/config.hpp"
+#include "boost/limits.hpp"
+
+#include "boost/mpl/int.hpp"
+#include "boost/mpl/multiplies.hpp"
+#include "boost/mpl/less.hpp"
+#include "boost/mpl/equal_to.hpp"
+
+#include "boost/type_traits/is_same.hpp"
+
+#include "boost/numeric/conversion/detail/meta.hpp"
+#include "boost/numeric/conversion/detail/int_float_mixture.hpp"
+#include "boost/numeric/conversion/detail/sign_mixture.hpp"
+#include "boost/numeric/conversion/detail/udt_builtin_mixture.hpp"
+
+namespace boost { namespace numeric { namespace convdetail
+{
+ //---------------------------------------------------------------
+ // Implementations of the compile time predicate "T is subranged"
+ //---------------------------------------------------------------
+
+ // for integral to integral conversions
+ template<class T,class S>
+ struct subranged_Sig2Unsig
+ {
+ // Signed to unsigned conversions are 'subranged' because of possible loose
+ // of negative values.
+ typedef mpl::true_ type ;
+ } ;
+
+ // for unsigned integral to signed integral conversions
+ template<class T,class S>
+ struct subranged_Unsig2Sig
+ {
+ // IMPORTANT NOTE:
+ //
+ // This code assumes that signed/unsigned integral values are represented
+ // such that:
+ //
+ // numeric_limits<signed T>::digits + 1 == numeric_limits<unsigned T>::digits
+ //
+ // The '+1' is required since numeric_limits<>::digits gives 1 bit less for signed integral types.
+ //
+ // This fact is used by the following logic:
+ //
+ // if ( (numeric_limits<T>::digits+1) < (2*numeric_limits<S>::digits) )
+ // then the conversion is subranged.
+ //
+
+ typedef mpl::int_< ::std::numeric_limits<S>::digits > S_digits ;
+ typedef mpl::int_< ::std::numeric_limits<T>::digits > T_digits ;
+
+ // T is signed, so take digits+1
+ typedef typename T_digits::next u_T_digits ;
+
+ typedef mpl::int_<2> Two ;
+
+ typedef typename mpl::multiplies<S_digits,Two>::type S_digits_times_2 ;
+
+ typedef typename mpl::less<u_T_digits,S_digits_times_2>::type type ;
+ } ;
+
+ // for integral to integral conversions of the same sign.
+ template<class T,class S>
+ struct subranged_SameSign
+ {
+ // An integral conversion of the same sign is subranged if digits(T) < digits(S).
+
+ typedef mpl::int_< ::std::numeric_limits<S>::digits > S_digits ;
+ typedef mpl::int_< ::std::numeric_limits<T>::digits > T_digits ;
+
+ typedef typename mpl::less<T_digits,S_digits>::type type ;
+ } ;
+
+ // for integral to float conversions
+ template<class T,class S>
+ struct subranged_Int2Float
+ {
+ typedef mpl::false_ type ;
+ } ;
+
+ // for float to integral conversions
+ template<class T,class S>
+ struct subranged_Float2Int
+ {
+ typedef mpl::true_ type ;
+ } ;
+
+ // for float to float conversions
+ template<class T,class S>
+ struct subranged_Float2Float
+ {
+ // If both T and S are floats,
+ // compare exponent bits and if they match, mantisa bits.
+
+ typedef mpl::int_< ::std::numeric_limits<S>::digits > S_mantisa ;
+ typedef mpl::int_< ::std::numeric_limits<T>::digits > T_mantisa ;
+
+ typedef mpl::int_< ::std::numeric_limits<S>::max_exponent > S_exponent ;
+ typedef mpl::int_< ::std::numeric_limits<T>::max_exponent > T_exponent ;
+
+ typedef typename mpl::less<T_exponent,S_exponent>::type T_smaller_exponent ;
+
+ typedef typename mpl::equal_to<T_exponent,S_exponent>::type equal_exponents ;
+
+ typedef mpl::less<T_mantisa,S_mantisa> T_smaller_mantisa ;
+
+ typedef mpl::eval_if<equal_exponents,T_smaller_mantisa,mpl::false_> not_bigger_exponent_case ;
+
+ typedef typename
+ mpl::eval_if<T_smaller_exponent,mpl::true_,not_bigger_exponent_case>::type
+ type ;
+ } ;
+
+ // for Udt to built-in conversions
+ template<class T,class S>
+ struct subranged_Udt2BuiltIn
+ {
+ typedef mpl::true_ type ;
+ } ;
+
+ // for built-in to Udt conversions
+ template<class T,class S>
+ struct subranged_BuiltIn2Udt
+ {
+ typedef mpl::false_ type ;
+ } ;
+
+ // for Udt to Udt conversions
+ template<class T,class S>
+ struct subranged_Udt2Udt
+ {
+ typedef mpl::false_ type ;
+ } ;
+
+ //-------------------------------------------------------------------
+ // Selectors for the implementations of the subranged predicate
+ //-------------------------------------------------------------------
+
+ template<class T,class S>
+ struct get_subranged_Int2Int
+ {
+ typedef subranged_SameSign<T,S> Sig2Sig ;
+ typedef subranged_Sig2Unsig<T,S> Sig2Unsig ;
+ typedef subranged_Unsig2Sig<T,S> Unsig2Sig ;
+ typedef Sig2Sig Unsig2Unsig ;
+
+ typedef typename get_sign_mixture<T,S>::type sign_mixture ;
+
+ typedef typename
+ for_sign_mixture<sign_mixture, Sig2Sig, Sig2Unsig, Unsig2Sig, Unsig2Unsig>::type
+ type ;
+ } ;
+
+ template<class T,class S>
+ struct get_subranged_BuiltIn2BuiltIn
+ {
+ typedef get_subranged_Int2Int<T,S> Int2IntQ ;
+
+ typedef subranged_Int2Float <T,S> Int2Float ;
+ typedef subranged_Float2Int <T,S> Float2Int ;
+ typedef subranged_Float2Float<T,S> Float2Float ;
+
+ typedef mpl::identity<Int2Float > Int2FloatQ ;
+ typedef mpl::identity<Float2Int > Float2IntQ ;
+ typedef mpl::identity<Float2Float> Float2FloatQ ;
+
+ typedef typename get_int_float_mixture<T,S>::type int_float_mixture ;
+
+ typedef for_int_float_mixture<int_float_mixture, Int2IntQ, Int2FloatQ, Float2IntQ, Float2FloatQ> for_ ;
+
+ typedef typename for_::type selected ;
+
+ typedef typename selected::type type ;
+ } ;
+
+ template<class T,class S>
+ struct get_subranged
+ {
+ typedef get_subranged_BuiltIn2BuiltIn<T,S> BuiltIn2BuiltInQ ;
+
+ typedef subranged_BuiltIn2Udt<T,S> BuiltIn2Udt ;
+ typedef subranged_Udt2BuiltIn<T,S> Udt2BuiltIn ;
+ typedef subranged_Udt2Udt<T,S> Udt2Udt ;
+
+ typedef mpl::identity<BuiltIn2Udt> BuiltIn2UdtQ ;
+ typedef mpl::identity<Udt2BuiltIn> Udt2BuiltInQ ;
+ typedef mpl::identity<Udt2Udt > Udt2UdtQ ;
+
+ typedef typename get_udt_builtin_mixture<T,S>::type udt_builtin_mixture ;
+
+ typedef typename
+ for_udt_builtin_mixture<udt_builtin_mixture, BuiltIn2BuiltInQ, BuiltIn2UdtQ, Udt2BuiltInQ, Udt2UdtQ>::type
+ selected ;
+
+ typedef typename selected::type selected2 ;
+
+ typedef typename selected2::type type ;
+ } ;
+
+
+ //-------------------------------------------------------------------
+ // Top level implementation selector.
+ //-------------------------------------------------------------------
+ template<class T, class S>
+ struct get_is_subranged
+ {
+ typedef get_subranged<T,S> non_trivial_case ;
+ typedef mpl::identity<mpl::false_> trivial_case ;
+
+ typedef is_same<T,S> is_trivial ;
+
+ typedef typename mpl::if_<is_trivial,trivial_case,non_trivial_case>::type selected ;
+
+ typedef typename selected::type type ;
+ } ;
+
+} } } // namespace boost::numeric::convdetail
+
+#endif
+
+
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