From: Freeman Gilmore <freeman.gilmore@gmail.com>
To: Mark H Weaver <mhw@netris.org>
Cc: guile-user@gnu.org
Subject: Re: Unicode numeric value
Date: Fri, 4 Jan 2019 20:07:34 -0500 [thread overview]
Message-ID: <CAM=7=uTB5UA3f8jDyQVEM_YWinhSQNZYDiVVZSu68wbojebczw@mail.gmail.com> (raw)
In-Reply-To: <87bm5kxae3.fsf@netris.org>
Mark:
I have been away and just getting back to email. Thank you for replying.
So it looks like the library is just a lookup table. I though it was
more complicated than that, reading from a Unicode data file. The hash
table may be better and more portable. I could also change the numeric
value for the given code points as needed. I do not know what " SRFI-4
homogeneous numeric vector" is, but I did google it, a lot there.
I am to new to this but I did copy your hash table that you made for me and
added the correction. Thanks for your time here. I will probably be using
it (if I learn enough).
You all have a good year.
ƒg
On Mon, Dec 17, 2018 at 1:43 PM Mark H Weaver <mhw@netris.org> wrote:
> Hi,
>
> Freeman Gilmore <freeman.gilmore@gmail.com> writes:
>
> > On Sun, Dec 16, 2018 at 3:15 AM Mark H Weaver <mhw@netris.org> wrote:
> >
> > Freeman Gilmore <freeman.gilmore@gmail.com> writes:
> >
> > > I am looking for a procedure that will read the numeric value, field
> 8, of
> > > an Unicode numeric character. Has anyone written this procedure or
> know
> > > where I can find it?
> >
> > The 'r7rs-wip' branch of the Guile git repository contains a procedure
> > that does this, with a lookup table derived from Unicode 6.3.0.
> >
> >
> https://git.savannah.gnu.org/cgit/guile.git/tree/module/scheme/char.scm?h=r7rs-wip
> >
> > The file is written as an R7RS library form, which won't work on current
> > releases of Guile, but for now you could simply extract the
> > 'digit-value' procedure from it, provided that you preserve the
> > copyright notice.
> >
> > Mark
> >
> > Thank you Mark:
> >
> > That is only half the battle, let me explain. I do not want to read
> > the standard Unicode table. I want to directly read field 8 of a
> > numeric character in the privet use area of the Unicode.
> >
> > This is not part of scheme. The other half, I need to finger out how
> > to put the numeric values in field 8 for the characters I want to use.
>
> If the mapping from code points to numeric values is static, then you
> could simply modify the lookup table in the code I suggested above.
>
> If the mapping is dynamic, then you'll need a different strategy. One
> simple approach would be to use a hash table mapping from characters to
> digit values:
>
> (define digit-value-table (make-hash-table))
>
> (define (set-digit-value! char value)
> (hashv-set! digit-value-table char value))
>
> (define (digit-value char)
> (hashv-ref digit-value-table char #f))
>
> If the range of relevant code points is small enough, another approach
> would be to use a vector:
>
> (define private-code-point-start #xE000)
> (define private-code-point-end #xF900)
>
> (define (code-point-in-range? cp)
> (<= private-code-point-start
> cp
> private-code-point-end))
>
> (define digit-value-table
> (make-vector (- private-code-point-end
> private-code-point-start)
> #f))
>
> (define (set-digit-value! char value)
> (let ((cp (char->integer char)))
> (unless (code-point-in-range? cp)
> (error "set-digit-value!: code point out of range:" cp))
> (vector-set! digit-value-table
> (- cp private-code-point-start)
> value)))
>
> (define (digit-value char)
> (let ((cp (char->integer char)))
> (and (code-point-in-range? cp)
> (vector-ref digit-value-table
> (- cp private-code-point-start)))))
>
> For a more compact representation, you could use a SRFI-4 homogeneous
> numeric vector instead, although you'd need to designate a special
> numeric value to represent "not a digit".
>
> Regards,
> Mark
>
prev parent reply other threads:[~2019-01-05 1:07 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-16 4:31 Unicode numeric value Freeman Gilmore
2018-12-16 6:11 ` John Cowan
2018-12-16 8:14 ` Mark H Weaver
2018-12-16 11:24 ` Freeman Gilmore
2018-12-17 18:42 ` Mark H Weaver
2018-12-17 18:52 ` Mark H Weaver
2019-01-05 1:07 ` Freeman Gilmore [this message]
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