Implement a new function directory-files-recursively

* doc/lispref/files.texi (Contents of Directories): Document
directory-files-recursively.

* etc/NEWS: Mention directory-files-recursively.

* lisp/files.el (find-files): New function.

doc/lispref/ChangeLog

+2014-12-09  Lars Magne Ingebrigtsen  <larsi@gnus.org>
+
+	* files.texi (Contents of Directories): Document
+	directory-files-recursively.
+
 2014-12-04  Eli Zaretskii  <eliz@gnu.org>
 
 	* display.texi (Bidirectional Display): Document

doc/lispref/files.texi

@@ -2605,6 +2605,14 @@ An error is signaled if @var{directory} is not the name of a directory
 that can be read.
 @end defun
 
+@defun directory-files-recursively directory match &optional include-directories
+Return all files under @var{directory} whose file names match
+@var{match} recursively.  The file names are returned ``depth first'',
+meaning that contents of sub-directories are returned before contents
+of the directories.  If @var{include-directories} is non-@code{nil},
+also return directory names that have matching names.
+@end defun
+
 @defun directory-files-and-attributes directory &optional full-name match-regexp nosort id-format
 This is similar to @code{directory-files} in deciding which files
 to report on and how to report their names.  However, instead

etc/ChangeLog

+2014-12-09  Lars Magne Ingebrigtsen  <larsi@gnus.org>
+
+	* NEWS: Mention directory-files-recursively.
+
 2014-12-08  Lars Magne Ingebrigtsen  <larsi@gnus.org>
 
 	* NEWS: Mention the new eww `S' command.

etc/NEWS

@@ -137,6 +137,9 @@ buffers to allow certain parts of the text to be writable.
 to all the files and subdirectories of a directory, similarly to the C
 library function `ftw'.
 
+** A new function `directory-files-recursively' returns all matching
+files (recursively) under a directory.
+
 
 * Editing Changes in Emacs 25.1
 

lisp/ChangeLog

 2014-12-09  Lars Magne Ingebrigtsen  <larsi@gnus.org>
 
+	* files.el (find-files): New function.
+
 	* net/shr.el (shr-dom-print): Don't print comments.
 	(shr-tag-svg): Give inline SVG images the right type.
 

lisp/files.el

@@ -762,6 +762,27 @@ prevented.  Directory entries are sorted with string-lessp."
 		(file-name-nondirectory dir)
 		args))))
 
+(defun directory-files-recursively (dir match &optional include-directories)
+  "Return all files under DIR that have file names matching MATCH (a regexp).
+This function works recursively.  Files are returned in \"depth first\"
+and alphabetical order.
+If INCLUDE-DIRECTORIES, also include directories that have matching names."
+  (let ((result nil)
+	(files nil))
+    (dolist (file (directory-files dir t))
+      (let ((leaf (file-name-nondirectory file)))
+	(unless (member leaf '("." ".."))
+	  (if (file-directory-p file)
+	      (progn
+		(when (and include-directories
+			   (string-match match leaf))
+		  (push file files))
+		(setq result (nconc result (directory-files-recursively
+					    file match include-directories))))
+	    (when (string-match match leaf)
+	      (push file files))))))
+    (nconc result (nreverse files))))
+
 (defun load-file (file)
   "Load the Lisp file named FILE."
   ;; This is a case where .elc makes a lot of sense.