[M3devel] Text processing

[Mika Nystrom]

I think whenever Modula-3 TEXTs are represented as arrays (including
*all* m3 TEXTs in SRC and P M3), there's a null at the end.

It's not included in the "length of the string" but obviously it
*is* included in the "length of the array".  That's precisely the
source of the bug.  The old version allocates "length of string
plus one", which is the wrong number to pass to the new interfaces
(which don't expose the trailing zero, but keep it, just the same).

Yes, the idea is you can pass Modula-3 TEXTs freely (cheaply) to C
routines.  Well, you used to be able to, before TEXTs were "improved"
by Critical Mass.  The code would have been something like this...?

IMPORT TextF;

    VAR txt : TEXT;
    ...
    some_c_function(ADR(txt[0]))
    ...

No I don't miss this feature much.  There are other improvements that
bug me a lot more.  But this is all about to be fixed with the new
Text implementation, right? :-)

     Mika

Jay writes:
>
>Are the nulls included in the length?
> 
>If so, that'd be a likely bug. If not, it'd be a /possible/ feature. Seriously
>.
>I deal with "lengthed" strings a lot, but my "duplicate" and "concat" function
>s add them, and don't put them in the length, for interop with all the other c
>ode out there..
>But it is a little sleazy my pattern and we do have explicit functions for C i
>nterop.
> 
> 
> - Jay
>
>
>----------------------------------------
>> To: rcoleburn at scires.com
>> Date: Tue, 28 Apr 2009 09:26:24 -0700
>> From: mika at async.caltech.edu
>> CC: m3devel at elegosoft.com
>> Subject: Re: [M3devel] Text processing
>>
>> Hmm cm3ide has its own Wx. It doesn't use that? It looks different
>> from the standard one in cm3.
>>
>> In the *standard* one, that is, m3-libs/libbuf/src/Wx.m3,
>> the fix is the following:
>>
>> PROCEDURE ToText (t: T): TEXT =
>> VAR txt := Text8.Create(t.nFull * ChunkSize + t.next);
>> c := t.head; n := 0;
>> BEGIN
>>
>> There used to be a "+ 1" in the call to Text8.Create. It's crud
>> from converting from the old array TEXTs.
>>
>> I've already checked this in to the cm3 distribution.
>>
>> Mika
>>
>> "Randy Coleburn" writes:
>>>This is a MIME message. If you are reading this text, you may want to
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>>>--=__Part6C44DF9F.0__=
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>>>There is a bug in CM3IDE that may be the result of this problem. I'll =
>>>need to get your fix and try it.
>>>--Randy
>>>
>>>>>> Mika Nystrom 4/28/2009 11:36 AM>>>
>>>
>>>Speaking of text processing, I was very surprised at the bug I found
>>>in Wx the other day (and checked in a fix for). I'm 99% certain my
>>>fix is correct, but I'm very surprised no one found this bug before.
>>>
>>>Wx was inserting spurious nulls at the end of every generated TEXT.
>>>
>>>Is it possible someone is using this interface and depending on the
>>>buggy behavior? m3ide and m3browser import it.
>>>
>>> Mika
>>>
>>>
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>>>>>">
>>>
>
>>>
>>>
>There is a bug in CM3IDE that may be the result of this problem. =
>>> I'll need to get your fix and try it.
>>>
>--Randy
>
>>>> Mika Nystrom =
>>>; 4/28/2009 11:36 AM>>>
>
>Speaking of text processing, I =
>>>was very surprised at the bug I found
>in Wx the other day (and checked =
>>>in a fix for).  I'm 99% certain my
>fix is correct, but I'm very =
>>>surprised no one found this bug before.
>
>Wx was inserting spurious =
>>>nulls at the end of every generated TEXT.
>
>Is it possible someone is =
>>>using this interface and depending on the
>buggy behavior?  m3ide =
>>>and m3browser import it.
>
>     Mika
>
>=
>>>
>>>
>>>--=__Part6C44DF9F.0__=--