williamr@2: //  © Copyright Fernando Luis Cacciola Carballal 2000-2004
williamr@2: //  Use, modification, and distribution is subject to the Boost Software
williamr@2: //  License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
williamr@2: //  http://www.boost.org/LICENSE_1_0.txt)
williamr@2: 
williamr@2: //  See library home page at http://www.boost.org/libs/numeric/conversion
williamr@2: //
williamr@2: // Contact the author at: fernando_cacciola@hotmail.com
williamr@2: //
williamr@2: #ifndef BOOST_NUMERIC_CONVERSION_CONVERTER_POLICIES_FLC_12NOV2002_HPP
williamr@2: #define BOOST_NUMERIC_CONVERSION_CONVERTER_POLICIES_FLC_12NOV2002_HPP
williamr@2: 
williamr@2: #include <typeinfo> // for std::bad_cast
williamr@2: 
williamr@2: #include <cmath> // for std::floor and std::ceil
williamr@2: 
williamr@2: #include <functional>
williamr@2: 
williamr@2: #include "boost/type_traits/is_arithmetic.hpp"
williamr@2: 
williamr@2: #include "boost/mpl/if.hpp"
williamr@2: #include "boost/mpl/integral_c.hpp"
williamr@2: 
williamr@2: namespace boost { namespace numeric
williamr@2: {
williamr@2: 
williamr@2: template<class S>
williamr@2: struct Trunc
williamr@2: {
williamr@2:   typedef S source_type ;
williamr@2: 
williamr@2:   typedef typename mpl::if_< is_arithmetic<S>,S,S const&>::type argument_type ;
williamr@2: 
williamr@2:   static source_type nearbyint ( argument_type s )
williamr@2:   {
williamr@2: #if !defined(BOOST_NO_STDC_NAMESPACE)
williamr@2:     using std::floor ;
williamr@2:     using std::ceil  ;
williamr@2: #endif
williamr@2: 
williamr@2:     return s < static_cast<S>(0) ? ceil(s) : floor(s) ;
williamr@2:   }
williamr@2: 
williamr@2:   typedef mpl::integral_c< std::float_round_style, std::round_toward_zero> round_style ;
williamr@2: } ;
williamr@2: 
williamr@2: 
williamr@2: 
williamr@2: template<class S>
williamr@2: struct Floor
williamr@2: {
williamr@2:   typedef S source_type ;
williamr@2: 
williamr@2:   typedef typename mpl::if_< is_arithmetic<S>,S,S const&>::type argument_type ;
williamr@2: 
williamr@2:   static source_type nearbyint ( argument_type s )
williamr@2:   {
williamr@2: #if !defined(BOOST_NO_STDC_NAMESPACE)
williamr@2:     using std::floor ;
williamr@2: #endif
williamr@2: 
williamr@2:     return floor(s) ;
williamr@2:   }
williamr@2: 
williamr@2:   typedef mpl::integral_c< std::float_round_style, std::round_toward_neg_infinity> round_style ;
williamr@2: } ;
williamr@2: 
williamr@2: template<class S>
williamr@2: struct Ceil
williamr@2: {
williamr@2:   typedef S source_type ;
williamr@2: 
williamr@2:   typedef typename mpl::if_< is_arithmetic<S>,S,S const&>::type argument_type ;
williamr@2: 
williamr@2:   static source_type nearbyint ( argument_type s )
williamr@2:   {
williamr@2: #if !defined(BOOST_NO_STDC_NAMESPACE)
williamr@2:     using std::ceil ;
williamr@2: #endif
williamr@2: 
williamr@2:     return ceil(s) ;
williamr@2:   }
williamr@2: 
williamr@2:   typedef mpl::integral_c< std::float_round_style, std::round_toward_infinity> round_style ;
williamr@2: } ;
williamr@2: 
williamr@2: template<class S>
williamr@2: struct RoundEven
williamr@2: {
williamr@2:   typedef S source_type ;
williamr@2: 
williamr@2:   typedef typename mpl::if_< is_arithmetic<S>,S,S const&>::type argument_type ;
williamr@2: 
williamr@2:   static source_type nearbyint ( argument_type s )
williamr@2:   {
williamr@2:     // Algorithm contributed by Guillaume Melquiond
williamr@2: 
williamr@2: #if !defined(BOOST_NO_STDC_NAMESPACE)
williamr@2:     using std::floor ;
williamr@2:     using std::ceil  ;
williamr@2: #endif
williamr@2: 
williamr@2:     // only works inside the range not at the boundaries
williamr@2:     S prev = floor(s);
williamr@2:     S next = ceil(s);
williamr@2: 
williamr@2:     S rt = (s - prev) - (next - s); // remainder type
williamr@2: 
williamr@2:     S const zero(0.0);
williamr@2:     S const two(2.0);
williamr@2: 
williamr@2:     if ( rt < zero )
williamr@2:       return prev;
williamr@2:     else if ( rt > zero )
williamr@2:       return next;
williamr@2:     else
williamr@2:     {
williamr@2:       bool is_prev_even = two * floor(prev / two) == prev ;
williamr@2:       return ( is_prev_even ? prev : next ) ;
williamr@2:     }
williamr@2:   }
williamr@2: 
williamr@2:   typedef mpl::integral_c< std::float_round_style, std::round_to_nearest> round_style ;
williamr@2: } ;
williamr@2: 
williamr@2: 
williamr@2: enum range_check_result
williamr@2: {
williamr@2:   cInRange     = 0 ,
williamr@2:   cNegOverflow = 1 ,
williamr@2:   cPosOverflow = 2
williamr@2: } ;
williamr@2: 
williamr@2: class bad_numeric_cast : public std::bad_cast
williamr@2: {
williamr@2:   public:
williamr@2: 
williamr@2:     virtual const char * what() const throw()
williamr@2:       {  return "bad numeric conversion: overflow"; }
williamr@2: };
williamr@2: 
williamr@2: class negative_overflow : public bad_numeric_cast
williamr@2: {
williamr@2:   public:
williamr@2: 
williamr@2:     virtual const char * what() const throw()
williamr@2:       {  return "bad numeric conversion: negative overflow"; }
williamr@2: };
williamr@2: class positive_overflow : public bad_numeric_cast
williamr@2: {
williamr@2:   public:
williamr@2: 
williamr@2:     virtual const char * what() const throw()
williamr@2:       { return "bad numeric conversion: positive overflow"; }
williamr@2: };
williamr@2: 
williamr@2: struct def_overflow_handler
williamr@2: {
williamr@2:   void operator() ( range_check_result r ) // throw(negative_overflow,positive_overflow)
williamr@2:   {
williamr@2:     if ( r == cNegOverflow )
williamr@2:       throw negative_overflow() ;
williamr@2:     else if ( r == cPosOverflow )
williamr@2:            throw positive_overflow() ;
williamr@2:   }
williamr@2: } ;
williamr@2: 
williamr@2: struct silent_overflow_handler
williamr@2: {
williamr@2:   void operator() ( range_check_result ) {} // throw()
williamr@2: } ;
williamr@2: 
williamr@2: template<class Traits>
williamr@2: struct raw_converter
williamr@2: {
williamr@2:   typedef typename Traits::result_type   result_type   ;
williamr@2:   typedef typename Traits::argument_type argument_type ;
williamr@2: 
williamr@2:   static result_type low_level_convert ( argument_type s ) { return static_cast<result_type>(s) ; }
williamr@2: } ;
williamr@2: 
williamr@2: struct UseInternalRangeChecker {} ;
williamr@2: 
williamr@2: } } // namespace boost::numeric
williamr@2: 
williamr@2: #endif