Added file-tree-walk to files.el.

2 files changed, 30 insertions, 0 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 10d48884b2e..b79b918dc77 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,7 @@
+2014-12-03  Eric S. Raymond  <esr@snark.thyrsus.com>
+
+	* files.el (file-tree-walk): Lisp translation of ANSI ftw(3).
+
 2014-12-02  Glenn Morris  <rgm@gnu.org>
 
 	* whitespace.el (whitespace-big-indent-regexp): Add :version.
diff --git a/lisp/files.el b/lisp/files.el
index c9d1d2da3b8..720a633761a 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -729,6 +729,32 @@ The path separator is colon in GNU and GNU-like systems."
                     (lambda (f) (and (file-directory-p f) 'dir-ok)))
        (error "No such directory found via CDPATH environment variable"))))
 
+(defun file-tree-walk (dir action &rest args)
+  "Walk DIR executing ACTION.  Each call gets as arguments DIR, a file path,
+and optional ARGS. The ACTION is applied to each subdirectory
+before descending into it, and if nil is returned at that point
+the descent will be prevented.  Directory entries are sorted with
+string-lessp"
+  (cond ((file-directory-p dir)
+	 (or (char-equal ?/ (aref dir (1- (length dir))))
+	     (setq dir (file-name-as-directory dir)))
+	 (let ((lst (directory-files dir nil nil t))
+	       fullname file)
+	   (while lst
+	     (setq file (car lst))
+	     (setq lst (cdr lst))
+	     (cond ((member file '("." "..")))
+		   (t
+		    (and (apply action dir file args)
+			 (setq fullname (concat dir file))
+			 (file-directory-p fullname)
+			 (apply 'file-tree-walk fullname action args)))))))
+	(t
+	 (apply action
+		(file-name-directory dir)
+		(file-name-nondirectory dir)
+		args))))
+
 (defun load-file (file)
   "Load the Lisp file named FILE."
   ;; This is a case where .elc makes a lot of sense.