@subsection Selecting a Tags Table
@findex visit-tags-table
- Emacs has at any time at most one @dfn{selected} tags table. All the
-commands for working with tags tables use the selected one. To select
-a tags table, type @kbd{M-x visit-tags-table}, which reads the tags
-table file name as an argument, with @file{TAGS} in the default
-directory as the default.
+ Emacs has at any time at most one @dfn{selected} tags table. All
+the commands for working with tags tables use the selected one. To
+select a tags table, type @kbd{M-x visit-tags-table}, which reads the
+tags table file name as an argument, with @file{TAGS} defaulting to
+the first directory that contains a file named @file{TAGS} encountered
+when recursively searching upward from the default directory.
@vindex tags-file-name
Emacs does not actually read in the tags table contents until you
(setq buffer-undo-list t)
(initialize-new-tags-table))
+(defun tags--find-default-tags-dir-recursively (current-dir)
+ "Find the directory in which the default TAGS file lives.
+It is the first directory that contains a file named TAGS
+encountered when recursively searching upward from CURRENT-DIR."
+ (let ((tag-filename (expand-file-name "TAGS" current-dir)))
+ (if (file-exists-p tag-filename)
+ current-dir
+ (let ((parent-dir
+ (file-name-directory (directory-file-name current-dir))))
+ (if (string= parent-dir current-dir) ;; root dir is reached
+ nil
+ (tags--find-default-tags-dir-recursively parent-dir))))))
+
;;;###autoload
(defun visit-tags-table (file &optional local)
"Tell tags commands to use tags table file FILE.
When you find a tag with \\[find-tag], the buffer it finds the tag
in is given a local value of this variable which is the name of the tags
file the tag was in."
- (interactive (list (read-file-name "Visit tags table (default TAGS): "
- default-directory
- (expand-file-name "TAGS"
- default-directory)
- t)
- current-prefix-arg))
+ (interactive
+ (let ((default-tag-dir
+ (or (tags--find-default-tags-dir-recursively default-directory)
+ default-directory)))
+ (list (read-file-name
+ "Visit tags table (default TAGS): "
+ ;; default to TAGS from default-directory up to root.
+ default-tag-dir
+ (expand-file-name "TAGS" default-tag-dir)
+ t)
+ current-prefix-arg)))
+
(or (stringp file) (signal 'wrong-type-argument (list 'stringp file)))
;; Bind tags-file-name so we can control below whether the local or
;; global value gets set.