(find-tag-default): Simplify using exclusively

skip-syntax-backward/-forward.

2 files changed, 28 insertions, 20 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 0673f5cb357..0b0a7dca4de 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,8 @@
+2008-01-26  Martin Rudalics  <rudalics@gmx.at>
+
+        * subr.el (find-tag-default): Simplify using exclusively
+        skip-syntax-backward/-forward.
+
 2008-01-26  Michael Albinus  <michael.albinus@gmx.de>
 
         * vc.el (vc-directory, vc-update-change-log): Remove check for
diff --git a/lisp/subr.el b/lisp/subr.el
index 5a7f88f76dd..f3579cc1fa6 100644
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -2127,26 +2127,29 @@ Note that this should end with a directory separator.")
 (defun find-tag-default ()
   "Determine default tag to search for, based on text at point.
 If there is no plausible default, return nil."
-  (save-excursion
-    (while (looking-at "\\sw\\|\\s_")
-      (forward-char 1))
-    (if (or (re-search-backward "\\sw\\|\\s_"
-                                (save-excursion (beginning-of-line) (point))
-                                t)
-            (re-search-forward "\\(\\sw\\|\\s_\\)+"
-                               (save-excursion (end-of-line) (point))
-                               t))
-        (progn
-          (goto-char (match-end 0))
-          (condition-case nil
-              (buffer-substring-no-properties
-               (point)
-               (progn (forward-sexp -1)
-                      (while (looking-at "\\s'")
-                        (forward-char 1))
-                      (point)))
-            (error nil)))
-      nil)))
+  (let (from to bound)
+    (when (or (progn
+                ;; Look at text around `point'.
+                (save-excursion
+                  (skip-syntax-backward "w_") (setq from (point)))
+                (save-excursion
+                  (skip-syntax-forward "w_") (setq to (point)))
+                (> to from))
+              ;; Look between `line-beginning-position' and `point'.
+              (save-excursion
+                (and (setq bound (line-beginning-position))
+                     (skip-syntax-backward "^w_" bound)
+                     (> (setq to (point)) bound)
+                     (skip-syntax-backward "w_")
+                     (setq from (point))))
+              ;; Look between `point' and `line-end-position'.
+              (save-excursion
+                (and (setq bound (line-end-position))
+                     (skip-syntax-forward "^w_" bound)
+                     (< (setq from (point)) bound)
+                     (skip-syntax-forward "w_")
+                     (setq to (point)))))
+      (buffer-substring-no-properties from to))))
 
 (defun play-sound (sound)
   "SOUND is a list of the form `(sound KEYWORD VALUE...)'.