projects / ceph.git / blame
| Commit | Line | Data |
|---|---|---|
| 7c673cae FG |
1 | /*============================================================================= |
| 2 | Copyright (c) 2001-2014 Joel de Guzman | |
| 3 | Copyright (c) 2001-2011 Hartmut Kaiser | |
| 4 | ||
| 5 | Distributed under the Boost Software License, Version 1.0. (See accompanying | |
| 6 | file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) | |
| 7 | =============================================================================*/ | |
| 8 | #if !defined(BOOST_SPIRIT_X3_CAST_CHAR_NOVEMBER_10_2006_0907AM) | |
| 9 | #define BOOST_SPIRIT_X3_CAST_CHAR_NOVEMBER_10_2006_0907AM | |
| 10 | ||
| 11 | #include <boost/type_traits/is_signed.hpp> | |
| 12 | #include <boost/type_traits/make_unsigned.hpp> | |
| 13 | #include <boost/type_traits/make_signed.hpp> | |
| 14 | ||
| 15 | namespace boost { namespace spirit { namespace x3 { namespace detail | |
| 16 | { | |
| 17 | // Here's the thing... typical encodings (except ASCII) deal with unsigned | |
| 18 | // integers > 127 (ASCII uses only 127). Yet, most char and wchar_t are signed. | |
| 19 | // Thus, a char with value > 127 is negative (e.g. char 233 is -23). When you | |
| 20 | // cast this to an unsigned int with 32 bits, you get 4294967273! | |
| 21 | // | |
| 22 | // The trick is to cast to an unsigned version of the source char first | |
| 23 | // before casting to the target. {P.S. Don't worry about the code, the | |
| 24 | // optimizer will optimize the if-else branches} | |
| 25 | ||
| 26 | template <typename TargetChar, typename SourceChar> | |
| 27 | TargetChar cast_char(SourceChar ch) | |
| 28 | { | |
| 29 | if (is_signed<TargetChar>::value != is_signed<SourceChar>::value) | |
| 30 | { | |
| 31 | if (is_signed<SourceChar>::value) | |
| 32 | { | |
| 33 | // source is signed, target is unsigned | |
| 34 | typedef typename make_unsigned<SourceChar>::type USourceChar; | |
| 35 | return TargetChar(USourceChar(ch)); | |
| 36 | } | |
| 37 | else | |
| 38 | { | |
| 39 | // source is unsigned, target is signed | |
| 40 | typedef typename make_signed<SourceChar>::type SSourceChar; | |
| 41 | return TargetChar(SSourceChar(ch)); | |
| 42 | } | |
| 43 | } | |
| 44 | else | |
| 45 | { | |
| 46 | // source and target has same signedness | |
| 47 | return TargetChar(ch); // just cast | |
| 48 | } | |
| 49 | } | |
| 50 | }}}} | |
| 51 | ||
| 52 | #endif | |
| 53 | ||
| 54 |