traverse a directory

traverse a directory

[Xah Lee]

if i want to recurse into a directory, do i have to write my own?

e.g. i want to apply a file processing function to all files in a dir
and subdirs. Somethnig like

(apply 'process-my-file "/Users/xah/emacs/" "\.html$")

I noticed that directory-files only list the dir file. Someone told me
there's a directory-files-recur but that doesn't seems to be in emacs.

thx in advance.

  Xah
  xah@xahlee.org
\xAD\xF4 http://xahlee.org/

Re: traverse a directory

[Eli Zaretskii]

> From: Xah Lee <xah@xahlee.org>
> Date: Tue, 1 Jan 2008 08:51:33 -0800 (PST)
> 
> if i want to recurse into a directory, do i have to write my own?

Take a look at the package find-lisp.el, which is bundled with Emacs
22.  It has infrastructure for what you want.  In particular, there's
the `find-lisp-find-files-internal' function that recursively
traverses a directory.

Re: traverse a directory

[Mike Mattie]

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On Tue, 1 Jan 2008 08:51:33 -0800 (PST)
Xah Lee <xah@xahlee.org> wrote:

> if i want to recurse into a directory, do i have to write my own?
> 
> e.g. i want to apply a file processing function to all files in a dir
> and subdirs. Somethnig like
> 
> (apply 'process-my-file "/Users/xah/emacs/" "\.html$")
> 
> I noticed that directory-files only list the dir file. Someone told me
> there's a directory-files-recur but that doesn't seems to be in emacs.
> 
> thx in advance.

here is something kinda related that I recently hacked up. I needed to be able to
filter the results of a directory list. The first hack started off as a plain
defun but I encountered variations so I made a macro. it may duplicate existing
emacs code.

the elisp-in-path defun shows how the form is used. It's uncommented, and
relies upon map-filter-nil which needs to be non-recursive for general use.

It is pretty easy to extend for filtering on either the path or the mode string.
Writing a general tree recursion is trivial, it shouldn't even be file specific.
this defun may help tailor such a recursion towards a fs tree.

(defun filter-ls-attributes ( filter-form )
  "implement the various attribute filters for the filter-ls form"
  (lexical-let
    ((attr-name (symbol-name (car filter-form)))
      (attr-match (cadr filter-form)))

    (cond
      ((string-equal "type" attr-name) (list 'char-equal attr-match  '(aref (cdr path-pair) 0)))
      ((string-equal "path" attr-name) (list 'string-match-p attr-match '(car path-pair)))
    ;; error path
    )))

(defmacro filter-ls (path path-type &rest filters)
  "a form for flexibly filtering the result of listing a directory with attributes"
  `(apply 'map-filter-nil
     (lambda ( path-pair )
       (if ,(cons 'and (mapcar 'filter-ls-attributes filters))
         (car path-pair)))

     ;; reduce the attributes to a pair of the path, and the mode string
     (mapcar (lambda ( attr-list )
               (cons (car attr-list) (nth 9 attr-list)))
       ;; get the list of files.
       (directory-files-and-attributes ,path ,path-type))
     ))

;; path-type is t absolute, nil relative.

(defun elisp-in-path ( path path-type )
  "return a list of elisp files in the path"

  (filter-ls path path-type
    (type ?-)
    (path "\\.el$")))

P.S

here is map-filter-nil. use at your own risk.

(defun map-filter-nil ( func &rest seq )
  "map-filter-nil. apply the function to the arguements ala mapcar.
   Filter any nil elements of the sequence before the function is
   applied, and after the function is applied."

  (if (car seq)
    (let
      ((result (funcall func (car seq))))
      (if result
        (cons result (apply 'map-filter-nil func (cdr seq)))
        (apply 'map-filter-nil func (cdr seq))
        ))
    (if (cdr seq)
      (apply 'map-filter-nil func (cdr seq)))
    ))

>   Xah
>   xah@xahlee.org
> ∑ http://xahlee.org/
> 
> _______________________________________________
> help-gnu-emacs mailing list
> help-gnu-emacs@gnu.org
> http://lists.gnu.org/mailman/listinfo/help-gnu-emacs

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Re: traverse a directory

[Joel J. Adamson]

Mike Mattie <codermattie@gmail.com> writes:

> On Tue, 1 Jan 2008 08:51:33 -0800 (PST)
> Xah Lee <xah@xahlee.org> wrote:
>
>> if i want to recurse into a directory, do i have to write my own?

I know that doing this in Emacs is especially cool, but "find ... exec {}\;"
should do the trick.

Joel

-- 
Joel J. Adamson
Biostatistician
Pediatric Psychopharmacology Research Unit
Massachusetts General Hospital
Boston, MA  02114
(617) 643-1432
(303) 880-3109

Re: traverse a directory

[Mike Mattie]

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On Wed, 02 Jan 2008 13:03:39 -0500
jadamson@partners.org (Joel J. Adamson) wrote:

> Mike Mattie <codermattie@gmail.com> writes:
> 
> > On Tue, 1 Jan 2008 08:51:33 -0800 (PST)
> > Xah Lee <xah@xahlee.org> wrote:
> >
> >> if i want to recurse into a directory, do i have to write my own?
> 
> I know that doing this in Emacs is especially cool, but "find ...
> exec {}\;" should do the trick.
> 
> Joel
> 

cool maybe, but portable was my reason for doing it this way. BSD find is very different from gnu find. 
some systems don't even have find. exec is a jungle, posix a mirage :)

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Re: traverse a directory

[Joel J. Adamson]

Mike Mattie <codermattie@gmail.com> writes:

> On Wed, 02 Jan 2008 13:03:39 -0500
> jadamson@partners.org (Joel J. Adamson) wrote:
>
>> Mike Mattie <codermattie@gmail.com> writes:
>> 
>> > On Tue, 1 Jan 2008 08:51:33 -0800 (PST)
>> > Xah Lee <xah@xahlee.org> wrote:
>> >
>> >> if i want to recurse into a directory, do i have to write my own?
>> 
>> I know that doing this in Emacs is especially cool, but "find ...
>> exec {}\;" should do the trick.
>> 
>> Joel
>> 
>
> cool maybe, but portable was my reason for doing it this way. BSD find
> is very different from gnu find.

So I've heard: should I go ahead with installing FreeBSD?

> some systems don't even have find. exec is a jungle, posix a mirage :)

Some systems I've found aren't systematic.

Joel

-- 
Joel J. Adamson
Biostatistician
Pediatric Psychopharmacology Research Unit
Massachusetts General Hospital
Boston, MA  02114
(617) 643-1432
(303) 880-3109

Re: traverse a directory

[Xah Lee]

Xah Lee wrote:
「if i want to recurse into a directory, do i have to write my own?」

Eli Zaretskii <e...@gnu.org> wrote:
「Take a look at the package find-lisp.el, which is bundled with Emacs
22.  It has infrastructure for what you want.  In particular, there's
the `find-lisp-find-files-internal' function that recursively
traverses a directory.」

Thanks. That does it.

(require 'find-lisp)
(find-lisp-find-files "~/web/" "\\.html$")

  Xah
  xah@xahlee.org
\xAD\xF4 http://xahlee.org/

Re: traverse a directory

[Xah Lee]

about traversing a dir tree...

In Python, it's done with “walk”, like this:
os.path.walk(mydir, myfun, 'somenull')

In Perl, it's done with File::Find qw(find), like this:
find(\&myfun, $mydir);

which is quite fucked up.

For details on Python and Perl's dir traverse, see

★ Perl-Python Tutorial: Traverse A Directory
http://xahlee.org/perl-python/traverse_dir.html

For unix, as you said, is “find” (with exec or xargs), which is the
most fucking fuck demented twisted crippled shit in the entire
universe. (This point is particularly interesting because most senior
unix sys admins and don't realize it but actually thought its godsend)
For more, see:

★ Unix Command Line Tools Tips
http://xahlee.org/UnixResource_dir/unix_tips.html

Emacs lisp's
(require 'find-lisp)
(mapcar 'myfun (find-lisp-find-files mydir))
Is the most beautiful among these.

For a general treatise on sorting tree nodes (i.e. the order of
visiting), see:

★ Sorting Tree Indexes
http://xahlee.org/tree/a-IndexSetSort.html

  Xah
  xah@xahlee.org
\xAD\xF4 http://xahlee.org/


On Jan 2, 11:25 am, jadam...@partners.org (Joel J. Adamson) wrote:
>...
> > cool maybe, but portable was my reason for doing it this way. BSD find
> > is very different from gnu find.
>
> So I've heard: should I go ahead with installing FreeBSD?
>
> > some systems don't even have find. exec is a jungle, posix a mirage :)
>
> Some systems I've found aren't systematic.

Re: traverse a directory

[Alexey Pustyntsev]

Xah Lee <xah@xahlee.org> writes:

> For unix, as you said, is “find” (with exec or xargs), which is the
> most fucking fuck demented twisted crippled shit in the entire
> universe. (This point is particularly interesting because most senior
> unix sys admins and don't realize it but actually thought its godsend)
> For more, see:
>
> ★ Unix Command Line Tools Tips
> http://xahlee.org/UnixResource_dir/unix_tips.html
>
> Emacs lisp's
> (require 'find-lisp)
> (mapcar 'myfun (find-lisp-find-files mydir))
> Is the most beautiful among these.
>
> For a general treatise on sorting tree nodes (i.e. the order of
> visiting), see:

Dude, please, calm down. Relax. 

-- 
Rgds
Alexey

Happy New Year!

Re: traverse a directory

[Joel J. Adamson]

Xah Lee <xah@xahlee.org> writes:

> For unix, as you said, is “find” (with exec or xargs), which is the
> most fucking fuck demented twisted crippled shit in the entire
> universe.

Really?  I was unaware of that fact.  Thanks for letting me know.  I'll
keep it in mind.

Any other fucking fuck demented twisted crippled shit in the entire
universe you'd like to let me know about?

Thanks,
Joel
-- 
Joel J. Adamson
Biostatistician
Pediatric Psychopharmacology Research Unit
Massachusetts General Hospital
Boston, MA  02114
(617) 643-1432
(303) 880-3109

Re: traverse a directory

[Mike Mattie]

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On Wed, 02 Jan 2008 14:25:04 -0500
jadamson@partners.org (Joel J. Adamson) wrote:

> Mike Mattie <codermattie@gmail.com> writes:
> 
> > On Wed, 02 Jan 2008 13:03:39 -0500
> > jadamson@partners.org (Joel J. Adamson) wrote:
> >
> >> Mike Mattie <codermattie@gmail.com> writes:
> >> 
> >> > On Tue, 1 Jan 2008 08:51:33 -0800 (PST)
> >> > Xah Lee <xah@xahlee.org> wrote:
> >> >
> >> >> if i want to recurse into a directory, do i have to write my
> >> >> own?
> >> 
> >> I know that doing this in Emacs is especially cool, but "find ...
> >> exec {}\;" should do the trick.
> >> 
> >> Joel
> >> 
> >
> > cool maybe, but portable was my reason for doing it this way. BSD
> > find is very different from gnu find.
> 
> So I've heard: should I go ahead with installing FreeBSD?

I sure don't know. Whatever you like the best. I just post
code if I think it's apropos. Sometimes it is, and when
it isn't someone usually mentions where the canonical
implementation is located within the Emacs distribution.
 
> > some systems don't even have find. exec is a jungle, posix a
> > mirage :)
> 
> Some systems I've found aren't systematic.
> 
> Joel
> 

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OT: Re: traverse a directory

[Johan Lindström]

At 04:51 2008-01-03, Xah Lee wrote:
>In Perl, it's done with File::Find qw(find), like this:
>find(\&myfun, $mydir);
>
>which is quite fucked up.

Yes, that interface surely shows its age. For a nicer experience, try:
http://search.cpan.org/perldoc?File::Find::Rule
or possibly
http://search.cpan.org/perldoc?File::Finder


/J