Joel de Guzman wrote:
----- 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
I'll give it a go :-)
Thanks, Vin
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