bug#22828: 25.1.50; Mark symlinks whose target matches regexp

bug#22828: 25.1.50; Mark symlinks whose target matches regexp

[Tino Calancha]

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dired-mark-files-regexp checks the NAME of a symbolic link.
Its useful to introduce one function which look for a match
in the TARGET of the symbolic links.
Such function could be bound to '%@'.

In GNU Emacs 25.1.50.1 (x86_64-pc-linux-gnu, GTK+ Version 2.24.29)
Repository revision: 25c5651951ef39f650927652dac8b4bbfccb60fa

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diff --git a/lisp/dired.el b/lisp/dired.el
index 6c7445c..5f7a484 100644
--- a/lisp/dired.el
+++ b/lisp/dired.el
@@ -1493,6 +1493,7 @@ dired-mode-map
     (define-key map "%d" 'dired-flag-files-regexp)
     (define-key map "%g" 'dired-mark-files-containing-regexp)
     (define-key map "%m" 'dired-mark-files-regexp)
+    (define-key map "%@" 'dired-mark-symlinks-regexp)
     (define-key map "%r" 'dired-do-rename-regexp)
     (define-key map "%C" 'dired-do-copy-regexp)
     (define-key map "%H" 'dired-do-hardlink-regexp)
@@ -1730,6 +1731,9 @@ dired-mode-map
     (define-key map [menu-bar regexp flag]
       '(menu-item "Flag..." dired-flag-files-regexp
 		  :help "Flag files matching regexp for deletion"))
+    (define-key map [menu-bar regexp mark-sym]
+      '(menu-item "Mark Symlinks Target..." dired-mark-symlinks-regexp
+		  :help "Mark symbolic links whose target matches regexp for future operations"))
     (define-key map [menu-bar regexp mark]
       '(menu-item "Mark..." dired-mark-files-regexp
 		  :help "Mark files matching regexp for future operations"))
@@ -3345,6 +3349,31 @@ dired-mark-files-regexp
 	    (and fn (string-match-p regexp fn))))
      "matching file")))
 
+(defun dired-mark-symlinks-regexp (regexp &optional marker-char)
+  "Mark all symbolic links whose target file matches REGEXP
+for use in later commands.
+A prefix argument means to unmark them instead.
+
+REGEXP is an Emacs regexp, not a shell wildcard.  Thus, use ‘\.o$’ for
+object files--just ‘.o’ will mark more than you might think."
+  (interactive
+   (list (read-regexp (concat (if current-prefix-arg "Unmark" "Mark")
+                              " symlinks target (regexp): ")
+                      nil 'dired-regexp-history)
+		 (if current-prefix-arg ?\040)))
+  (let ((dired-marker-char (or marker-char dired-marker-char)))
+    (dired-mark-if
+     (and (looking-at-p dired-re-sym)
+		  (not (looking-at-p dired-re-dot))
+		  (not (eolp))			; empty line
+		  
+		  (let* ((eol (line-end-position))
+				 (fn (save-excursion
+					   (search-forward " -> " eol t)
+					   (buffer-substring-no-properties (point) eol))))
+			(and fn (string-match-p regexp fn))))
+			"matching symbolic link")))
+
 (defun dired-mark-files-containing-regexp (regexp &optional marker-char)
   "Mark all files with contents containing REGEXP for use in later commands.
 A prefix argument means to unmark them instead.

bug#22828: 25.1.50; Mark symlinks whose target matches regexp

[Lars Ingebrigtsen]

Tino Calancha <f92capac@gmail.com> writes:

> dired-mark-files-regexp checks the NAME of a symbolic link.
> Its useful to introduce one function which look for a match
> in the TARGET of the symbolic links.
> Such function could be bound to '%@'.

I'm not sure whether that's generally useful enough to include in
dired...  I can't say that I remember ever wanting something like that.


[...]

> +    (dired-mark-if
> +     (and (looking-at-p dired-re-sym)
> +		  (not (looking-at-p dired-re-dot))
> +		  (not (eolp))			; empty line
> +		  
> +		  (let* ((eol (line-end-position))
> +				 (fn (save-excursion
> +					   (search-forward " -> " eol t)
> +					   (buffer-substring-no-properties (point) eol))))
> +			(and fn (string-match-p regexp fn))))
> +			"matching symbolic link")))

And this implementation also seems quite fragile.  Will symlinks always
be presented as " -> "?  And can " -> " be a valid part of a file name.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#22828: 25.1.50; Mark symlinks whose target matches regexp

[Tino Calancha]

> I'm not sure whether that's generally useful enough to include in
> dired...  I can't say that I remember ever wanting something like that.
Sometimes the meaninful part of the symbolic link is in the target.
Let's say you have a lot of files (thousands of them), in different 
locations and you create links to them:
t1
t2
...
ti
...
to all those files under the same directory for whatever 
processing/editing that you have in mind.
In such case, the only mark which has sense to pick up some
particular files with a regexp is something like the proposed
command in this thread.

> And this implementation also seems quite fragile.  Will symlinks always
> be presented as " -> "?  And can " -> " be a valid part of a file name.
Good point. I agree with this.

bug#22828: 25.1.50; Mark symlinks whose target matches regexp

[Andreas Schwab]

Tino Calancha <f92capac@gmail.com> writes:

>> And this implementation also seems quite fragile.  Will symlinks always
>> be presented as " -> "?  And can " -> " be a valid part of a file name.
> Good point. I agree with this.

Use dired-move-to-end-of-filename to find the proper place.

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."

bug#22828: 25.1.50; Mark symlinks whose target matches regexp

[Tino Calancha]

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> Use dired-move-to-end-of-filename to find the proper place.
I see, this way we forget about the '@ -> ' or ' -> ' 
(or any other?).

Do you think is ok that fn contains such ' -> ' thing?
I would prefer if fn doesn't contain that.
So, the question is:
do we have a portable way to get the target of one link?
We may introduce something like:
dired-symlink-target (if doesn't exist)

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diff --git a/lisp/dired.el b/lisp/dired.el
index 6c7445c..6e70cd9 100644
--- a/lisp/dired.el
+++ b/lisp/dired.el
@@ -1493,6 +1493,7 @@ dired-mode-map
     (define-key map "%d" 'dired-flag-files-regexp)
     (define-key map "%g" 'dired-mark-files-containing-regexp)
     (define-key map "%m" 'dired-mark-files-regexp)
+    (define-key map "%@" 'dired-mark-symlinks-regexp)
     (define-key map "%r" 'dired-do-rename-regexp)
     (define-key map "%C" 'dired-do-copy-regexp)
     (define-key map "%H" 'dired-do-hardlink-regexp)
@@ -1730,6 +1731,9 @@ dired-mode-map
     (define-key map [menu-bar regexp flag]
       '(menu-item "Flag..." dired-flag-files-regexp
 		  :help "Flag files matching regexp for deletion"))
+    (define-key map [menu-bar regexp mark-sym]
+      '(menu-item "Mark Symlinks Target..." dired-mark-symlinks-regexp
+		  :help "Mark symbolic links whose target matches regexp for future operations"))
     (define-key map [menu-bar regexp mark]
       '(menu-item "Mark..." dired-mark-files-regexp
 		  :help "Mark files matching regexp for future operations"))
@@ -3345,6 +3349,31 @@ dired-mark-files-regexp
 	    (and fn (string-match-p regexp fn))))
      "matching file")))
 
+(defun dired-mark-symlinks-regexp (regexp &optional marker-char)
+  "Mark all symbolic links whose target file matches REGEXP
+for use in later commands.
+A prefix argument means to unmark them instead.
+
+REGEXP is an Emacs regexp, not a shell wildcard.  Thus, use ‘\.o$’ for
+object files--just ‘.o’ will mark more than you might think."
+  (interactive
+   (list (read-regexp (concat (if current-prefix-arg "Unmark" "Mark")
+                              " symlinks target (regexp): ")
+                      nil 'dired-regexp-history)
+         (if current-prefix-arg ?\040)))
+  (let ((dired-marker-char (or marker-char dired-marker-char)))
+    (dired-mark-if
+     (and (looking-at-p dired-re-sym)
+          (not (looking-at-p dired-re-dot))
+          (not (eolp))			; empty line
+          
+          (let* ((eol (line-end-position))
+                 (fn (save-excursion
+                       (and (dired-move-to-end-of-filename 'noerror)
+                            (buffer-substring-no-properties (point) eol)))))
+            (and fn (string-match-p regexp fn))))
+     "matching symbolic link")))
+
 (defun dired-mark-files-containing-regexp (regexp &optional marker-char)
   "Mark all files with contents containing REGEXP for use in later commands.
 A prefix argument means to unmark them instead.

bug#22828: 25.1.50; Mark symlinks whose target matches regexp

[Lars Ingebrigtsen]

Tino Calancha <f92capac@gmail.com> writes:

>> Use dired-move-to-end-of-filename to find the proper place.
> I see, this way we forget about the '@ -> ' or ' -> ' (or any other?).
>
> Do you think is ok that fn contains such ' -> ' thing?
> I would prefer if fn doesn't contain that.
> So, the question is:
> do we have a portable way to get the target of one link?
> We may introduce something like:
> dired-symlink-target (if doesn't exist)

I thin kyou should just call `(dired-get-filename nil t)' on each line
to get the file names, and then call `file-truename' to get the name of
the target.  Inspecting the text in the buffer with regexps is bound to
be fragile.

But I'm still not sure this is a function that would be generally
useful.  :-)

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#22828: 25.1.50; Mark symlinks whose target matches regexp

[Constantino Calancha]

> I thin kyou should just call `(dired-get-filename nil t)' on each line
> to get the file names, and then call `file-truename' to get the name of
> the target.
Very good. I wasn't aware about this function.

> But I'm still not sure this is a function that would be generally
> useful.  :-)
In that case let's forget about it and let's close this thread. No problem.