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Subject: Re: [boost] [xpressive] Performance Tuning?
From: Stewart, Robert (Robert.Stewart_at_[hidden])
Date: 2009-07-02 08:21:14

Matthew Chambers wrote:
> Why is Xpressive more readable than using lexical_cast or your
> numeric_cast? I've implemented specializations of lexical_cast
> for string->numeric conversions using strto[ld]. It is a vast
> speed improvement of course, and since those specializations
> are hidden away in a header, readability is the same as with
> normal lexical_casts. Maybe I'm misunderstanding your use case?
> Do you not know ahead of time what the type of the number will
> be?

If you'll have a look at my first post in this thread, you'll see the Xpressive code and the grammar I've implemented. A later post shows the string-based parsing logic that uses string-to-number conversions similar to what you suggest. (Indeed, the Xpressive semantic actions involve the same sorts of conversions.) As you'll see, the code must parse whole numbers, fractions, mixed numbers, and real numbers.

Rob Stewart robert.stewart_at_[hidden]
Software Engineer, Core Software using std::disclaimer;
Susquehanna International Group, LLP

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