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.

6 files changed, 26 insertions, 1 deletions

diff --git a/doc/lispref/ChangeLog b/doc/lispref/ChangeLog
index 8f06881adc4..0d8458fabd1 100644
--- a/doc/lispref/ChangeLog
+++ b/doc/lispref/ChangeLog
@@ -1,3 +1,7 @@
+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
diff --git a/doc/lispref/files.texi b/doc/lispref/files.texi
index 92bb718e46a..b79d5df67c8 100644
--- a/doc/lispref/files.texi
+++ b/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
diff --git a/etc/ChangeLog b/etc/ChangeLog
index f56fb4ea683..5e02fced672 100644
--- a/etc/ChangeLog
+++ b/etc/ChangeLog
@@ -1,3 +1,7 @@
+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.
diff --git a/etc/NEWS b/etc/NEWS
index 58a5836a1c0..58e4b0e2cf1 100644
--- a/etc/NEWS
+++ b/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
 
diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index bc757189f60..6955c3c6cca 100644
--- a/lisp/ChangeLog
+++ b/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>
 
diff --git a/lisp/files.el b/lisp/files.el
index 2ab740d4a7f..d55ef1ad538 100644
--- a/lisp/files.el
+++ b/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.