----- Original Message -----
From: <[EMAIL PROTECTED]>
> Hi,
>
> I was talking to you on the boost newsgroup about spirit being slow to compile
> Here is a standalone section of code, it'll compile but you can't do anything with it
> The compile takes about 15 mins on my machine
> (We are using spirit for a second file but that is smaller and only takes a minute
>or two)
>
> The Spec of my machine is P3 833, 512M RAM
> I'm using NT4 SP6a and VC6 SP4
>
> I split it into a lib and it works fine so the problem is less crucial than it was!
[]
> I have a feeling that the Grammar is just big so it's slow and there may not be
> any getting around that but let me know if you see anything we are doing wrong
[]
Indeed! I counted 25 grammars. Wow I'm amazed, some grammars are
quite elaborate, even :-)
After taking a peek at the grammars, I see one minor and one
major code tweaks that should improve both the actual code size
and compile time speed.
minor: use chlit<> or strlit<> rather than rule<ScannerT> whenever possible.
(e.g. m_CommaToken)
major: I see lots of code duplication. It would be best to factor out common
grammar definitions into base definition classes. Example:
template<class ScannerT>
struct basic_definition
{
template<class GrammarT>
basic_definition(GrammarT const& self)
{
// common definitions
}
};
Then subclass your grammar definition from this.
struct my_grammar : public spirit::grammar<grammar>
{
template<class ScannerT>
struct definition : basic_definition<ScannerT>
{
typedef basic_definition<ScannerT> base_t;
definition(my_grammar const& self)
: base_t(self)
{
}
};
};
It would help a lot to factor out the common grammars this way. You
can even use multiple inheritance where necessary.
I hope this helps. I took the liberty to re-post this to the list in the hope
that this simple tip might be useful to others.
BTW, in the near future, productions such as:
r = a | b | c | d | e...
where the alternatives have unambiguous prefixes, example:
a = "LINEDESC:" >> ...
b = "PAINTDESC:" >> ...
can be optimized through Spirit style syntactic predicates.
Ahh, finaly BTW, you do not need to wrap str_p("...") inside
a lexeme because strlits are implicit lexemes.
Regards,
Joel de Guzman
[EMAIL PROTECTED]
http://www.boost-consulting.com
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