Modularize add-log-current-defun.

Suggested by Jari Aalto.

* lisp/emacs-lisp/lisp-mode.el (lisp-current-defun-name): New.
(lisp-mode-variables): Use it.

* lisp/progmodes/cc-mode.el (c-common-init):
* lisp/progmodes/cperl-mode.el (cperl-mode): Set a value for
add-log-current-defun-function.

* lisp/progmodes/m4-mode.el (m4-current-defun-name): New function.
(m4-mode): Use it.

* lisp/progmodes/perl-mode.el (perl-current-defun-name): New.
(perl-mode): Use it.

* lisp/progmodes/scheme.el (scheme-mode-variables, dsssl-mode): Use
lisp-current-defun-name.

* lisp/textmodes/tex-mode.el (tex-current-defun-name): New.
(tex-common-initialization): Use it.

* lisp/textmodes/texinfo.el (texinfo-current-defun-name): New.
(texinfo-mode): Use it.

* lisp/vc/add-log.el (add-log-current-defun-function): Doc fix.
(add-log-current-defun): Move mode-specific code to other files.
(add-log-lisp-like-modes, add-log-c-like-modes)
(add-log-tex-like-modes): Variables deleted.

Fixes: debbugs:2224

1 files changed, 26 insertions, 0 deletions

diff --git a/lisp/emacs-lisp/lisp-mode.el b/lisp/emacs-lisp/lisp-mode.el
index 81adab53c93..11dd6dc6ee2 100644
--- a/lisp/emacs-lisp/lisp-mode.el
+++ b/lisp/emacs-lisp/lisp-mode.el
@@ -209,6 +209,7 @@ font-lock keywords will not be case sensitive."
   (setq-local indent-line-function 'lisp-indent-line)
   (setq-local outline-regexp ";;;\\(;* [^ \t\n]\\|###autoload\\)\\|(")
   (setq-local outline-level 'lisp-outline-level)
+  (setq-local add-log-current-defun-function #'lisp-current-defun-name)
   (setq-local comment-start ";")
   ;; Look within the line for a ; following an even number of backslashes
   ;; after either a non-backslash or the line beginning.
@@ -237,6 +238,31 @@ font-lock keywords will not be case sensitive."
 	1000
       len)))
 
+(defun lisp-current-defun-name ()
+  "Return the name of the defun at point, or nil."
+  (let ((location (point)))
+    ;; If we are now precisely at the beginning of a defun, make sure
+    ;; beginning-of-defun finds that one rather than the previous one.
+    (or (eobp) (forward-char 1))
+    (beginning-of-defun)
+    ;; Make sure we are really inside the defun found, not after it.
+    (when (and (looking-at "\\s(")
+	       (progn (end-of-defun)
+		      (< location (point)))
+	       (progn (forward-sexp -1)
+		      (>= location (point))))
+      (if (looking-at "\\s(")
+	  (forward-char 1))
+      ;; Skip the defining construct name, typically "defun" or
+      ;; "defvar".
+      (forward-sexp 1)
+      ;; The second element is usually a symbol being defined.  If it
+      ;; is not, use the first symbol in it.
+      (skip-chars-forward " \t\n'(")
+      (buffer-substring-no-properties (point)
+				      (progn (forward-sexp 1)
+					     (point))))))
+
 (defvar lisp-mode-shared-map
   (let ((map (make-sparse-keymap)))
     (define-key map "\e\C-q" 'indent-sexp)