[ragel-users] Re: Problem with long alphabet type

Adrian Thurston thurs... at cs.queensu.ca
Thu Sep 13 19:46:13 UTC 2007


Elmin wrote:
> It occurs to me that since Unicode doesn't (for now) take up the full
> 32-bit range, there might be an application for a kind of
> "intermediate" alphabet type between short and long -- that way the
> storage could still be long, and characters could be allocated in the
> range 0x10FFFF..0x8FFFFFFF or something.  Does that sound like it
> might work?

There is a half-implemented feature called "range" which could support
this. It allows you to define which characters in the input alphabet
that the machine can expect to see. It is assumed that the user of the
machine guarantees that no characters outside the range make it to the
state machine. I started on this thinking it would be useful, but never
had a use for it myself so it was not finished.

Though I should say that such a feature may not help as conditions can
eat up the remaining available characters pretty quickly. This is
especially true if you embed multiple conditions in the same transition.
In the end it depends on how you use them.

By the way, in the last email when I said "necessary changes" I was
referring to the warning about longs+conditions in the documentation and
the appropriate error message when the available characters run out.

-Adrian

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