[fpc-pascal] findfirst wildcards...

[waldo kitty]

On 12/3/2014 6:16 AM, Tomas Hajny wrote:
> Given the fact that OS/2 appeared in your listing, I can clarify the
> difference. It comes from the fact that in case of FindFirst/FindNext, the
> interpretation of wildcards is performed by the underlying operating
> system whereas the routine mentioned by Bart performs this interpretation
> inside the Pascal code. Equally to DOS (and actually implemented that way
> in an attempt to make OS/2 as compatible to DOS as possible), OS/2 is
> somewhat more "relaxed" in interpretation of question marks at the end of
> the file name (i.e. before the file extension) in the sense of evaluating
> question marks at that position (but not elsewhere) as either 1 _or_ no
> character.

right... i see this ""everywhere"" /except/ on native linux... even DOSEMU and 
similar that i have tested all see '?' as "0 or 1" character... even REGEX takes 
that approach :)

> You get the same behaviour under DOS (either compiled with TP/BP or FPC)
> and also e.g. under DosEmu under Linux, etc. I believe that the MS Windows
> NTVDM implementation would not behave that way (i.e. I believe that the
> DOS window simply passes the request to MS Windows which perform the
> evaluation differently), but I haven't tried it.

cmd and command both see '?' as "0 or 1" character...

C:\freepascal\projects\misc>command

C:\FREEPA~1\PROJECTS\MISC>ver

Microsoft Windows [Version 6.0.6002]

C:\FREEPA~1\PROJECTS\MISC>dir t?.txt
  Volume in drive C is SQ004512V04
  Volume Serial Number is DC02-9142

  Directory of C:\FREEPA~1\projects\misc

12/02/2014  11:31 PM                 2 t.txt
12/02/2014  11:31 PM                 2 t1.txt
                2 File(s)              4 bytes
                0 Dir(s)  51,110,965,248 bytes free

C:\FREEPA~1\PROJECTS\MISC>exit


C:\FREEPA~1\projects\misc>cmd
Microsoft Windows [Version 6.0.6002]
Copyright (c) 2006 Microsoft Corporation.  All rights reserved.

C:\FREEPA~1\projects\misc>dir t?.txt
  Volume in drive C is SQ004512V04
  Volume Serial Number is DC02-9142

  Directory of C:\FREEPA~1\projects\misc

12/02/2014  11:31 PM                 2 t.txt
12/02/2014  11:31 PM                 2 t1.txt
                2 File(s)              4 bytes
                0 Dir(s)  51,111,006,208 bytes free

C:\FREEPA~1\projects\misc>exit


> Now regarding your original question - I don't think that you can ask the
> operating system to search for multiple masks at the same time (and thus
> the RTL does not provide such functionality directly either).

understood...

> Scanning through all the files as suggested by Bart is the standard solution
> for that.

i didn't realize that that would be how it was done until after i started 
finding and reading relevant pages... when i started looking, i found nothing 
for plain FPC... everything was for delphi or lazarus...

> However, _if_ you have reasons to be concerned about the performance of
> scanning through all the files (e.g. if running over a slow network drive and
> having to work with directories containing _many_ files - read: thousands of
> files at least), it is possible to reduce the number of operating system
> calls and network transfers by using the OS/2 API directly and providing it
> with a buffer sufficient for returning information about many files at once
> (e.g. one hundred of them, or whatever).

the most i've had to wade through was ~40000 files but i don't think that that 
will be much of a problem... it wasn't a problem with my previous simplistic 
finding and processing methods but i've recently removed the ""artificial"" file 
limits i had when using arrays... now i'm loading matching filenames into 
stringlists and then processing from there ;)

> Obviously, your code would still need to go through all of them one by
> another, but it would decrease the overall time needed for processing this
> scan. Still, as already mentioned, this solution should not be necessary
> under normal conditions (and it would imply necessity of changing the
> implementation for other operating systems - unlike to using standard RTL
> functionality).

yeah, i'm looking for easy and simplistic cross-platform capability if i can get 
it... one of my projects is targetted at OS/2, winwhatever, and linux... they're 
all i can compile natively for... with that and the lack of lazarus on OS/2, i 
think the demo program i posted in my reply to jonas shows me the yellow brick 
road to follow to the emerald city... the hint came from bart and/or some older 
messages i found where it was stated that calling findfirst multiple times was a 
possibility... i think that (ff1) and/or the regex one i came up with (ff3) will 
work best for my needs...

i do also greatly appreciate bart's initial post and the subsequent ones from 
others... they got me started thinking clearer when i was blind and stuck before ;)


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