File name wild cards

File name wild cards

[Bill Findlay]

Can anyone point me to a portable way of doing wildcard filename lookups?

In Ada.Directories we have;

> type Search_Type is limited private;
> procedure Start_Search (Search: in out Search_Type;
> Directory: in String;
> Pattern: in String;
> Filter: in Filter_Type := (others =>  True));

etc
But the interpretation of Pattern is implementation defined.
Worse, I cannot find any interpretation in the GNAT documentation.

-- 
Bill Findlay

Re: File name wild cards

[Jeffrey R. Carter]

On 08/15/2018 10:45 PM, Bill Findlay wrote:
> Can anyone point me to a portable way of doing wildcard filename lookups?
> 
> In Ada.Directories we have;
> 
>> type Search_Type is limited private;
>> procedure Start_Search (Search: in out Search_Type;
>> Directory: in String;
>> Pattern: in String;
>> Filter: in Filter_Type := (others =>  True));
> 
> etc
> But the interpretation of Pattern is implementation defined.

I interpret this as being like the Form parameter for opening a file. It's 
whatever's meaningful for the actual platform being used.

There's no way to be completely portable, since even the way one specifies a 
directory can vary significantly between file systems.

Assuming you have a way of specifying the directory that is acceptably portable 
for your uses, one way to portably select only files that match some pattern is 
to pass Pattern => "" and select files that match your pattern internally, 
perhaps using a regular-expression pkg.

However, if by portable you mean between Unix-like and Windows systems, and you 
restrict yourself to the current directory (or directories you can construct 
from it using Hierarchical_File_Names), then I've found that '*' and '?' are 
portable enough for my needs.

For example, the program that selected the signature on this msg used Directory 
=> "." and Pattern => "signature???.txt".

-- 
Jeff Carter
"Have you gone berserk? Can't you see that that man is a ni?"
Blazing Saddles
38

Re: File name wild cards

[Dmitry A. Kazakov]

On 2018-08-15 22:45, Bill Findlay wrote:
> Can anyone point me to a portable way of doing wildcard filename lookups?
> 
> In Ada.Directories we have;
> 
>> type Search_Type is limited private;
>> procedure Start_Search (Search: in out Search_Type;
>> Directory: in String;
>> Pattern: in String;
>> Filter: in Filter_Type := (others =>  True));
> 
> etc
> But the interpretation of Pattern is implementation defined.
> Worse, I cannot find any interpretation in the GNAT documentation.

AFAIK Ada.Directories is non-portable anyway. I hope this will be fixed 
in Ada 2020 in a way that would abstract the file system as a set of 
nice ADTs.

I do portable file lookup this admittedly ugly way:

1. I use Ada bindings to GLib. GLib has portable directory walk, which 
maintains UTF-8 names regardless the underlying OS:

    http://www.dmitry-kazakov.de/ada/gtkada_contributions.htm#5

Dir_Open, Dir_Read_Name etc.

2. I check names for artifacts like "." and ".." and translate \ to /.

3. I use wild-card matcher for UTF-8 encoded strings:

    http://www.dmitry-kazakov.de/ada/strings_edit.htm#7.5

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de

Re: File name wild cards

[Bill Findlay]

On 16 Aug 2018, Jeffrey R. Carter wrote
(in article <pl3a5c$rre$1@dont-email.me>):

> On 08/15/2018 10:45 PM, Bill Findlay wrote:
> > Can anyone point me to a portable way of doing wildcard filename lookups?
> >
> > In Ada.Directories we have;
> >
> > > type Search_Type is limited private;
> > > procedure Start_Search (Search: in out Search_Type;
> > > Directory: in String;
> > > Pattern: in String;
> > > Filter: in Filter_Type := (others =>  True));
> >
> > etc
> > But the interpretation of Pattern is implementation defined.
>
> I interpret this as being like the Form parameter for opening a file. It's
> whatever's meaningful for the actual platform being used.
>
> There's no way to be completely portable, since even the way one specifies a
> directory can vary significantly between file systems.

I had been told that Java had a portable way of doing it, but was sceptical
for exactly the reason you state.

> Assuming you have a way of specifying the directory that is acceptably portable
> for your uses, one way to portably select only files that match some pattern is
> to pass Pattern =>  "" and select files that match your pattern internally,
> perhaps using a regular-expression pkg.

Simple, obvious, why didn't I think of that? 8-)

Thanks, Jeff.

-- 
Bill Findlay

Re: File name wild cards

[Bill Findlay]

On 16 Aug 2018, Dmitry A. Kazakov wrote
(in article <pl3a6i$15s1$1@gioia.aioe.org>):

> On 2018-08-15 22:45, Bill Findlay wrote:
> > Can anyone point me to a portable way of doing wildcard filename lookups?
> >
> > In Ada.Directories we have;
> >
> > > type Search_Type is limited private;
> > > procedure Start_Search (Search: in out Search_Type;
> > > Directory: in String;
> > > Pattern: in String;
> > > Filter: in Filter_Type := (others =>  True));
> >
> > etc
> > But the interpretation of Pattern is implementation defined.
> > Worse, I cannot find any interpretation in the GNAT documentation.
>
> AFAIK Ada.Directories is non-portable anyway. I hope this will be fixed
> in Ada 2020 in a way that would abstract the file system as a set of
> nice ADTs.
>
> I do portable file lookup this admittedly ugly way:
>
> 1. I use Ada bindings to GLib. GLib has portable directory walk, which
> maintains UTF-8 names regardless the underlying OS:
>
> http://www.dmitry-kazakov.de/ada/gtkada_contributions.htm#5
>
> Dir_Open, Dir_Read_Name etc.
>
> 2. I check names for artifacts like "." and ".." and translate \ to /.
>
> 3. I use wild-card matcher for UTF-8 encoded strings:
>
> http://www.dmitry-kazakov.de/ada/strings_edit.htm#7.5

Thanks for those suggestions, Dmitry.
My program is non-GUI, and I want to avoid using any non-Ada.* libraries.

-- 
Bill Findlay