Re: [Boost-users] [Wave] advanced preprocessing hooks

From: Andreas Sæbjørnsen (andreas.saebjoernsen_at_[hidden])
Date: 2006-06-16 21:18:20

>
> Hmmm. The 'warning_directive' preprocess_exception is recoverable. That
> means you may simply continue to iterate after catching this type of
> exception (see the wave driver how this may be achieved). That's the
> reason
> why I made the warning to throw an exception (same as #error). I'm not
> sure
> if we really should change this behaviour (even more as the driver
> currently
> depends on that).
>
> OTOH I like your idea to add a on_warning() pp hook function (same should
> be
> added for #error as well). What do you think, what if we use the return
> value of the on_warning() pp hook to decide, whether to throw the
> exception?
> This way we could keep the default behaviour (throwing) but you could
> enforce the non-throwing behaviour simply by returning false.

I think using the return value form on_warning() or on_hook() to decide if
an exception
should be thrown is an excellent idea. That would fit very well with my
needs.

Regards
Andreas

>
> > Thanks
> > Andreas
> >
> >
> > #if BOOST_WAVE_SUPPORT_WARNING_DIRECTIVE != 0
> > //////////////////////////////////////////////////////////////
> > /////////////////
> > //
> > //  on_warning(): handle #warning directives
> > //
> > //////////////////////////////////////////////////////////////
> > /////////////////
> > template <typename ContextT>
> > inline void
> > pp_iterator_functor<ContextT>::on_warning(
> >     typename parse_tree_type::const_iterator const &begin,
> >     typename parse_tree_type::const_iterator const &end)
> > {
> >     BOOST_ASSERT(ctx.get_if_block_status());
> >
> >
> >
> > // preprocess the given sequence into the provided list
> > token_sequence_type expanded;
> > get_token_value<result_type, parse_node_type> get_value;
> >
> >
> >
> > typename ref_transform_iterator_generator<
> >         get_token_value<result_type, parse_node_type>,
> >         typename parse_tree_type::const_iterator
> >     >::type first = make_ref_transform_iterator(begin, get_value);
> >
> >
> >
> > #if BOOST_WAVE_PREPROCESS_ERROR_MESSAGE_BODY != 0
> > // preprocess the body of this #warning message
> > token_sequence_type toexpand;
> >
> >
> >
> >     std::copy(first, make_ref_transform_iterator(end, get_value),
> >         std::inserter(toexpand, toexpand.end()));
> >
> >
> >
> >     typename token_sequence_type::iterator begin2 = toexpand.begin();
> >     ctx.expand_whole_tokensequence(begin2, toexpand.end(), expanded,
> >         false);
> > #else
> > // simply copy the body of this #warning message to the
> > issued diagnostic
> > // message
> >     std::copy(first, make_ref_transform_iterator(end, get_value),
> >        std::inserter(expanded, expanded.end()));
> > #endif
> >     //AS(051706) Added an extra hook to send the warning directive
> >     std::cout << "The warning is: " <<
> > boost::wave::util::impl::as_string(expanded).c_str()
> >               << std::endl;
> >     ctx.get_hooks().on_warning(toexpand);
> >
> >
> >
> > //AS(051606) Do not treat warning directives as errors
> > #if 0
> > // report the corresponding error
> >     BOOST_WAVE_THROW(preprocess_exception, warning_directive,
> >         boost::wave::util::impl::as_string(expanded).c_str(),
> > act_pos);
> > #endif
> >
> >
> >
> > }
> > #endif // BOOST_WAVE_SUPPORT_WARNING_DIRECTIVE != 0
> >
> >
> >
> >
> >
> >
> >
> >
> >       Regards Hartmut
> >
> >
> >       _______________________________________________
> >       Boost-users mailing list
> >       Boost-users_at_[hidden]
> >       http://lists.boost.org/mailman/listinfo.cgi/boost-users
> >
> >
> >
> >
>
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