Re: [boost] [xpressive] Performance Tuning?

Subject: Re: [boost] [xpressive] Performance Tuning?
From: OvermindDL1 (overminddl1_at_[hidden])
Date: 2009-07-14 00:30:21

On Mon, Jul 13, 2009 at 10:22 PM, Michael
Caisse<boost_at_[hidden]> wrote:
> OvermindDL1 wrote:
>>
>> I find this quite interesting.  I wonder if I might have the time
>> tonight to make a Spirit2.1 version of this, the code would certainly
>> be a great deal shorter.
>> Just to make sure, from what I gathered looking at the code, you are
>> trying to parse out a number from an ascii string that could
>> potentially be an integer (64-bit, just digits, always base 10), a
>> double (digits as the integer, then a period, then more digits parsed
>> as the integer, OR a whole integer, then a space(s), followed by an
>> int then a / then an int), it looks like that a real number can have a
>> 'g' after it, but what is a g?  I know what e's means, but g?  I am
>> also confused, it seems your types support int64 as well as double,
>> but you only ever return an int64, why not a variant of both?  Should
>> I do this for Spirit2.1?  Spirit2.1 naturally wants to use such things
>> anyway so it is actually easier for me to do so, and the user would
>> have a more accurate value too as they would get either an int64 or a
>> double depending on what it parsed, I could also add in other
>> representations like a struct of two int64's for a
>> numerator/denominator as well for best accuracy.  What would you
>> prefer?
>> _______________________________________________
>>
>
> I have considered doing this myself on and off. I'm still learning
> Spirit 2.1 and if you were to throw this together it would be a great
> example of approaching the problem three different ways.
>
> I am looking forward to seeing your effort.

Spirit2.1 is by far the most easy Spirit to date, as well as the
fastest, beats out many hand-written and tuned parsers as well.
Should not be hard to do, and I think I would prefer to return a
variant of all possible types as I see no point cutting out
information, let the user decide what info they want, unless someone
tells me they only want anything/everything as an int64, then I can do
it that way too.

But still, what would the 'g' in a number like 2.4g5 do, I know what e
does, but g?