Error found.
The problem was in the and_impl transform. It uses comma operator to
chain calls to each and_ alternatives.
However, when this is used in a grammar used as a Generator, it enters a
subtle infinite loop as each comma
want to build an expression with the newly generated expression.
I locally modified proto this way in boost/proto/matches.hpp :
template<BOOST_PP_ENUM_PARAMS(N, typename G), typename Expr, typename
State, typename Data>
struct _and_impl<proto::and_<BOOST_PP_ENUM_PARAMS(N, G)>, Expr, State, Data>
: proto::transform_impl<Expr, State, Data>
{
#define M0(Z, N,
DATA) \
typedef
\
typename proto::when<proto::_, BOOST_PP_CAT(G,
N)> \
::template impl<Expr, State,
Data> \
BOOST_PP_CAT(Gimpl,
N); \
/**/
BOOST_PP_REPEAT(N, M0, ~)
typedef typename BOOST_PP_CAT(Gimpl, BOOST_PP_DEC(N))::result_type
result_type;
result_type operator()(
typename _and_impl::expr_param e
, typename _and_impl::state_param s
, typename _and_impl::data_param d
) const
{
// Fix: jfalcou - 12/29/2010
// This allow and_ to be used in grammar used as generator
// by not using comma which caused an infinite loop
#define M1(Z,N,DATA) \
BOOST_PP_CAT(Gimpl,N)()(e,s,d);\
/**/
// expands to G0()(e,s,d); G1()(e,s,d); ... G{N-1}()(e,s,d);
BOOST_PP_REPEAT(BOOST_PP_DEC(N),M1,~)
return BOOST_PP_CAT(Gimpl,BOOST_PP_DEC(N))()(e,s,d);
}
#undef M1
#undef M0
};
instead of using comma, I just generate N-1 application of GimplN and
return the last Gimpl call.
Is this fix acceptable or am I doing something wrong all together ?
If yes, Eric, any objections that I merge this into trunk ?
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