Ticket #2297: template_arity.patch

File template_arity.patch, 2.0 KB (added by Dave Abrahams, 9 years ago)

The correct improved patch

  • template_arity.hpp

     
    6464namespace boost { namespace mpl { namespace aux {
    6565
    6666template< BOOST_MPL_AUX_NTTP_DECL(int, N) > struct arity_tag
     67  : arity_tag<N-1>
    6768{
    68     typedef char (&type)[N + 1];
     69    typedef char (&type)[N + 2];
    6970};
    7071
    71 #   define AUX778076_MAX_ARITY_OP(unused, state, i_) \
    72     ( BOOST_PP_CAT(C,i_) > 0 ? BOOST_PP_CAT(C,i_) : state ) \
    73 /**/
    74 
    75 template<
    76       BOOST_MPL_PP_PARAMS(AUX778076_ARITY, BOOST_MPL_AUX_NTTP_DECL(int, C))
    77     >
    78 struct max_arity
     72template <>
     73struct arity_tag<0>
    7974{
    80     BOOST_STATIC_CONSTANT(int, value =
    81           BOOST_PP_SEQ_FOLD_LEFT(
    82               AUX778076_MAX_ARITY_OP
    83             , -1
    84             , BOOST_MPL_PP_RANGE(1, AUX778076_ARITY)
    85             )
    86         );
     75    typedef char type;
    8776};
    8877
    89 #   undef AUX778076_MAX_ARITY_OP
    90 
    9178arity_tag<0>::type arity_helper(...);
    9279
    9380#   define BOOST_PP_ITERATION_LIMITS (1, AUX778076_ARITY)
    9481#   define BOOST_PP_FILENAME_1 <boost/mpl/aux_/template_arity.hpp>
    9582#   include BOOST_PP_ITERATE()
    9683
    97 template< typename F, BOOST_MPL_AUX_NTTP_DECL(int, N) >
    98 struct template_arity_impl
    99 {
    100     BOOST_STATIC_CONSTANT(int, value =
    101           sizeof(arity_helper(type_wrapper<F>(),arity_tag<N>())) - 1
    102         );
    103 };
    104 
    105 #   define AUX778076_TEMPLATE_ARITY_IMPL_INVOCATION(unused, i_, F) \
    106     BOOST_PP_COMMA_IF(i_) template_arity_impl<F,BOOST_PP_INC(i_)>::value \
    107 /**/
    108 
    10984template< typename F >
    11085struct template_arity
     86  : mpl::int_<
     87        (sizeof(arity_helper(type_wrapper<F>(), arity_tag<AUX778076_ARITY>())) - 2)
     88    >
    11189{
    112     BOOST_STATIC_CONSTANT(int, value = (
    113           max_arity< BOOST_MPL_PP_REPEAT(
    114               AUX778076_ARITY
    115             , AUX778076_TEMPLATE_ARITY_IMPL_INVOCATION
    116             , F
    117             ) >::value
    118         ));
    119        
    120     typedef mpl::int_<value> type;
    12190};
    12291
    12392#   undef AUX778076_TEMPLATE_ARITY_IMPL_INVOCATION