Name	Size	Mode	Actions
cast_char.hpp	2274	0644	editdlrm

/*============================================================================= Copyright (c) 2001-2014 Joel de Guzman Copyright (c) 2001-2011 Hartmut Kaiser Distributed under 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) =============================================================================*/ #if !defined(BOOST_SPIRIT_X3_CAST_CHAR_NOVEMBER_10_2006_0907AM) #define BOOST_SPIRIT_X3_CAST_CHAR_NOVEMBER_10_2006_0907AM #include #include #include namespace boost { namespace spirit { namespace x3 { namespace detail { // Here's the thing... typical encodings (except ASCII) deal with unsigned // integers > 127 (ASCII uses only 127). Yet, most char and wchar_t are signed. // Thus, a char with value > 127 is negative (e.g. char 233 is -23). When you // cast this to an unsigned int with 32 bits, you get 4294967273! // // The trick is to cast to an unsigned version of the source char first // before casting to the target. {P.S. Don't worry about the code, the // optimizer will optimize the if-else branches} template TargetChar cast_char(SourceChar ch) { #if defined(_MSC_VER) # pragma warning(push) # pragma warning(disable: 4127) // conditional expression is constant #endif if (is_signed::value != is_signed::value) { if (is_signed::value) { // source is signed, target is unsigned typedef typename make_unsigned::type USourceChar; return TargetChar(USourceChar(ch)); } else { // source is unsigned, target is signed typedef typename make_signed::type SSourceChar; return TargetChar(SSourceChar(ch)); } } else { // source and target has same signedness return TargetChar(ch); // just cast } #if defined(_MSC_VER) # pragma warning(pop) #endif } }}}} #endif