[Boost-users] [spirit] error removal

From: Aaron Griffin (aaronmgriffin_at_[hidden])
Date: 2005-10-13 10:13:06

Hi all,

This is a contrived example, but the solution should be the same.

Assuming I have two rules, like so:
section = identifier >> ch_p('{') >> *setting >> ch_p('}');
setting = identifier >> ch_p('=') >> value;
// identifier and value are simple, but left off for brevity

This should parse something like:
somesettings
{
   a = 12
   b = "hello whirled"
}

Now, what I am looking to do is, if the parser fails parsing a value
inside a "section", the parsing itself does not fail, but that section
itself does.  So if I also had:
moresettings
{
   this_is_valid = 12345
   bigfaterror = 12"hi there"4.3"fewewfewfw"
}
Then the "somesettings" section would exist in the final AST, but
"moresettings" would not.  The error handling docs are a bit unclear
to me, bit if I were to make a generic functor_parser which kept an
error flag, how would I conditionally remove the section based on that
value, seeing as it will already be mid-parse (I don't think something
like if_p will work).

Thanks in advance for any advice.

On a side note, if I have a rule similar to (keyword >> identifier),
the skip_parser will translate "somekeyword a" into "somekeyworda" and
will parse it fine.  However, what is to stop someone from removing
the whitespace in the original code.  With a quick glance, it appears
the example c grammar from the spirit site will parse "voidfoo()" just
fine due to this.  Is there anyway I can tell the skip grammar to
force a seperation?

Thanks again,
Aaron Griffin