(interpreter-mode-alist): New variable.

(set-auto-mode): Use that for chosing a mode.

1 files changed, 33 insertions, 1 deletions

diff --git a/lisp/files.el b/lisp/files.el
index d441cafcb56..00cc617d927 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -839,6 +839,20 @@ If the element has the form (REGEXP FUNCTION), then after calling
 FUNCTION, we delete the suffix that matched REGEXP and search the list
 again for another match.")
 
+(defconst interpreter-mode-alist
+  '(("perl" . perl-mode)
+    ("scope" . tcl-mode)
+    ("wish" . tcl-mode)
+    ("shell" . tcl-mode)
+    ("form" . tcl-mode)
+    ("tcl" . tcl-mode))
+  "Alist mapping interpreter names to major modes.
+This alist applies to files whose first line starts with `#!'.
+Each element looks like (INTERPRETER . MODE).
+The car of each element is compared with
+the name of the interpreter specified in the first line.
+If it matches, mode MODE is selected.")
+
 (defconst inhibit-local-variables-regexps '("\\.tar$")
   "List of regexps; if one matches a file name, don't look for local vars.")
 
@@ -928,7 +942,25 @@ If `enable-local-variables' is nil, this function does not check for a
                         (setq mode (cdr (car alist))
                               keep-going nil)))
                   (setq alist (cdr alist)))
-                (if mode (funcall mode)))))))))
+                (if mode
+                    (funcall mode)
+                  ;; If we can't deduce a mode from the file name,
+                  ;; look for an interpreter specified in the first line.
+                  (let ((interpreter
+                         (save-excursion
+                           (goto-char (point-min))
+                           (if (looking-at "#! *")
+                               (progn
+                                 (goto-char (match-end 0))
+                                 (buffer-substring (point)
+                                                   (progn (end-of-line) (point))))
+                             "")))
+                        elt)
+                    ;; Map interpreter name to a mode.
+                    (setq elt (assoc (file-name-nondirectory interpreter)
+                                     interpreter-mode-alist))
+                    (if elt
+                        (funcall (cdr elt))))))))))))
 
 (defun hack-local-variables-prop-line ()
   ;; Set local variables specified in the -*- line.