sl@0: // Copyright David Abrahams 2002.
sl@0: // Distributed under the Boost Software License, Version 1.0. (See
sl@0: // accompanying file LICENSE_1_0.txt or copy at
sl@0: // http://www.boost.org/LICENSE_1_0.txt)
sl@0: #ifndef WORKAROUND_DWA2002126_HPP
sl@0: # define WORKAROUND_DWA2002126_HPP
sl@0: 
sl@0: // Compiler/library version workaround macro
sl@0: //
sl@0: // Usage:
sl@0: //
sl@0: //     #if BOOST_WORKAROUND(BOOST_MSVC, < 1300)
sl@0: //        // workaround for eVC4 and VC6
sl@0: //        ... // workaround code here
sl@0: //     #endif
sl@0: //
sl@0: // When BOOST_STRICT_CONFIG is defined, expands to 0. Otherwise, the
sl@0: // first argument must be undefined or expand to a numeric
sl@0: // value. The above expands to:
sl@0: //
sl@0: //     (BOOST_MSVC) != 0 && (BOOST_MSVC) < 1300
sl@0: //
sl@0: // When used for workarounds that apply to the latest known version 
sl@0: // and all earlier versions of a compiler, the following convention 
sl@0: // should be observed:
sl@0: //
sl@0: //     #if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1301))
sl@0: //
sl@0: // The version number in this case corresponds to the last version in
sl@0: // which the workaround was known to have been required. When
sl@0: // BOOST_DETECT_OUTDATED_WORKAROUNDS is not the defined, the macro
sl@0: // BOOST_TESTED_AT(x) expands to "!= 0", which effectively activates
sl@0: // the workaround for any version of the compiler. When
sl@0: // BOOST_DETECT_OUTDATED_WORKAROUNDS is defined, a compiler warning or
sl@0: // error will be issued if the compiler version exceeds the argument
sl@0: // to BOOST_TESTED_AT().  This can be used to locate workarounds which
sl@0: // may be obsoleted by newer versions.
sl@0: 
sl@0: # ifndef BOOST_STRICT_CONFIG
sl@0: 
sl@0: #  define BOOST_WORKAROUND(symbol, test)                \
sl@0:         ((symbol != 0) && (1 % (( (symbol test) ) + 1)))
sl@0: //                              ^ ^           ^ ^
sl@0: // The extra level of parenthesis nesting above, along with the
sl@0: // BOOST_OPEN_PAREN indirection below, is required to satisfy the
sl@0: // broken preprocessor in MWCW 8.3 and earlier.
sl@0: //
sl@0: // The basic mechanism works as follows:
sl@0: //      (symbol test) + 1        =>   if (symbol test) then 2 else 1
sl@0: //      1 % ((symbol test) + 1)  =>   if (symbol test) then 1 else 0
sl@0: //
sl@0: // The complication with % is for cooperation with BOOST_TESTED_AT().
sl@0: // When "test" is BOOST_TESTED_AT(x) and
sl@0: // BOOST_DETECT_OUTDATED_WORKAROUNDS is #defined,
sl@0: //
sl@0: //      symbol test              =>   if (symbol <= x) then 1 else -1
sl@0: //      (symbol test) + 1        =>   if (symbol <= x) then 2 else 0
sl@0: //      1 % ((symbol test) + 1)  =>   if (symbol <= x) then 1 else divide-by-zero
sl@0: //
sl@0: 
sl@0: #  ifdef BOOST_DETECT_OUTDATED_WORKAROUNDS
sl@0: #   define BOOST_OPEN_PAREN (
sl@0: #   define BOOST_TESTED_AT(value)  > value) ?(-1): BOOST_OPEN_PAREN 1
sl@0: #  else
sl@0: #   define BOOST_TESTED_AT(value) != ((value)-(value))
sl@0: #  endif
sl@0: 
sl@0: # else
sl@0: 
sl@0: #  define BOOST_WORKAROUND(symbol, test) 0
sl@0: 
sl@0: # endif 
sl@0: 
sl@0: #endif // WORKAROUND_DWA2002126_HPP