Re: [proto] Adding stuff in proto operator
OK, small road bump.
I tried a simple grammar as geenrator thingy but using the idea that i
didnt wanted to replicate all possible generator out there.
So i made a template grammar taking a Generator and doing thing around:
struct print_tag : proto::callable
{
typedef void result_type;
templateclass X void operator()(X const) const
{
std::cout typeid(typename proto::tag_ofX::type).name() \n;
}
};
templateclass Generator
struct debug_generator
: proto::when proto::_
, proto::and_ print_tag(proto::_)
, Generator(proto::_)
{};
I then took the Calc2 example and changed the calculator_domain to be :
struct calculator_domain
:
proto::domaindebug_generatorproto::generatorcalculator_expression
{};
Boost version is 1.45
The full modified code is : http://codepad.org/41nnNNwf
Alas, I got a lump of errors as specified here : http://codepad.org/4hnylfvQ
Am I missing something or is the and_ not working like I thougt it was
as a transform.
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Re: [proto] Adding stuff in proto operator
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 :
templateBOOST_PP_ENUM_PARAMS(N, typename G), typename Expr, typename
State, typename Data
struct _and_implproto::and_BOOST_PP_ENUM_PARAMS(N, G), Expr, State, Data
: proto::transform_implExpr, State, Data
{
#define M0(Z, N,
DATA)\
typedef
\
typename proto::whenproto::_, BOOST_PP_CAT(G,
N)\
::template implExpr, 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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Re: [proto] Adding stuff in proto operator
On 12/29/2010 5:40 AM, Joel Falcou wrote: 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. snip The problem is that in this expression, Proto's overloaded comma operator is considered. It shouldn't be. I was being a little too cute when I used the comma operator like this. Is this fix acceptable or am I doing something wrong all together ? If yes, Eric, any objections that I merge this into trunk ? I made a few adjustments and committed it myself. Thanks, Joel! -- Eric Niebler BoostPro Computing http://www.boostpro.com ___ proto mailing list proto@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/proto
