Implement a new function `directory-name-p'

* doc/lispref/files.texi (Relative File Names): Mention
`directory-name-p'.

* etc/NEWS: Mention directory-name-p.

(directory-name-p): New function.
(directory-files-recursively): Use it.

doc/lispref/ChangeLog

+2014-12-13  Lars Magne Ingebrigtsen  <larsi@gnus.org>
+
+	* files.texi (Relative File Names): Mention `directory-name-p'.
+
 2014-12-13  Eli Zaretskii  <eliz@gnu.org>
 
 	* text.texi (Comparing Text): Prevent a text string from being

doc/lispref/files.texi

@@ -2020,6 +2020,11 @@ form.
 @end example
 @end defun
 
+@defun directory-name-p filename
+This function returns non-@code{nil} if @var{filename} ends with a
+forward slash (@samp{/}) character.
+@end defun
+
 @node Directory Names
 @subsection Directory Names
 @cindex directory name

etc/ChangeLog

+2014-12-13  Lars Magne Ingebrigtsen  <larsi@gnus.org>
+
+	* NEWS: Mention directory-name-p.
+
 2014-12-09  Lars Magne Ingebrigtsen  <larsi@gnus.org>
 
 	* NEWS: Mention directory-files-recursively.

etc/NEWS

@@ -140,6 +140,11 @@ library function `ftw'.
 ** A new function `directory-files-recursively' returns all matching
 files (recursively) under a directory.
 
+** The new `directory-name-p' can be used to check whether a file
+name (as returned from, for instance, `file-name-all-completions' is
+a directory file name.  It returns non-nil if the last character in
+the name is a forward slash.
+
 
 * Editing Changes in Emacs 25.1
 

lisp/ChangeLog

@@ -2,6 +2,8 @@
 	* files.el (directory-files-recursively): Really check whether
 	files are symlinks.
+	(directory-name-p): New function.
+	(directory-files-recursively): Use it.
 2014-12-13  Artur Malabarba  <bruce.connor.am@gmail.com>

lisp/files.el

@@ -761,6 +761,11 @@ prevented.  Directory entries are sorted with string-lessp."
 		(file-name-nondirectory dir)
 		args))))
 
+(defsubst directory-name-p (name)
+  "Return non-nil if NAME ends with a slash character."
+  (and (> (length name) 0)
+       (char-equal (aref name (1- (length name))) ?/)))
+
 (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\"
@@ -771,7 +776,7 @@ If INCLUDE-DIRECTORIES, also include directories that have matching names."
     (dolist (file (sort (file-name-all-completions "" dir)
 			'string<))
       (unless (member file '("./" "../"))
-	(if (= (aref file (1- (length file))) ?/)
+	(if (directory-name-p file)
 	    (let* ((leaf (substring file 0 (1- (length file))))
 		   (path (expand-file-name leaf dir)))
 	      ;; Don't follow symlinks to other directories.