Sync to HEAD

1 files changed, 28 insertions, 13 deletions

diff --git a/lisp/emacs-lisp/eldoc.el b/lisp/emacs-lisp/eldoc.el
index cbcd5b2a555..bc868759d92 100644
--- a/lisp/emacs-lisp/eldoc.el
+++ b/lisp/emacs-lisp/eldoc.el
@@ -7,8 +7,6 @@
 ;; Keywords: extensions
 ;; Created: 1995-10-06
 
-;; $Id: eldoc.el,v 1.24 2003/02/11 00:11:55 monnier Exp $
-
 ;; This file is part of GNU Emacs.
 
 ;; GNU Emacs is free software; you can redistribute it and/or modify
@@ -40,11 +38,14 @@
 ;; One useful way to enable this minor mode is to put the following in your
 ;; .emacs:
 ;;
-;;      (autoload 'turn-on-eldoc-mode "eldoc" nil t)
 ;;      (add-hook 'emacs-lisp-mode-hook 'turn-on-eldoc-mode)
 ;;      (add-hook 'lisp-interaction-mode-hook 'turn-on-eldoc-mode)
 ;;      (add-hook 'ielm-mode-hook 'turn-on-eldoc-mode)
 
+;; Major modes for other languages may use Eldoc by defining an
+;; appropriate function as the buffer-local value of
+;; `eldoc-print-current-symbol-info-function'.
+
 ;;; Code:
 
 (require 'help-fns)		       ;For fundoc-usage handling functions.
@@ -233,19 +234,32 @@ With prefix ARG, turn ElDoc mode on if and only if ARG is positive."
        (not (eq (selected-window) (minibuffer-window)))))
 
 
+(defvar eldoc-print-current-symbol-info-function nil
+  "If non-nil, function to call to return doc string.
+The function of no args should return a one-line string for displaying
+doc about a function etc. appropriate to the context around point.
+It should return nil if there's no doc appropriate for the context.
+Typically doc is returned if point is on a function-like name or in its
+arg list.
+
+This variable is expected to be made buffer-local by modes (other than
+Emacs Lisp mode) that support Eldoc.")
+
 (defun eldoc-print-current-symbol-info ()
   (condition-case err
       (and (eldoc-display-message-p)
-	   (let* ((current-symbol (eldoc-current-symbol))
-		  (current-fnsym  (eldoc-fnsym-in-current-sexp))
-		  (doc (cond
-			((eq current-symbol current-fnsym)
-			 (or (eldoc-get-fnsym-args-string current-fnsym)
-			     (eldoc-get-var-docstring current-symbol)))
-			(t
-			 (or (eldoc-get-var-docstring current-symbol)
-			     (eldoc-get-fnsym-args-string current-fnsym))))))
-	     (eldoc-message doc)))
+	   (if eldoc-print-current-symbol-info-function
+	       (eldoc-message (funcall eldoc-print-current-symbol-info-function))
+	     (let* ((current-symbol (eldoc-current-symbol))
+		    (current-fnsym  (eldoc-fnsym-in-current-sexp))
+		    (doc (cond
+			  ((eq current-symbol current-fnsym)
+			   (or (eldoc-get-fnsym-args-string current-fnsym)
+			       (eldoc-get-var-docstring current-symbol)))
+			  (t
+			   (or (eldoc-get-var-docstring current-symbol)
+			       (eldoc-get-fnsym-args-string current-fnsym))))))
+	       (eldoc-message doc))))
     ;; This is run from post-command-hook or some idle timer thing,
     ;; so we need to be careful that errors aren't ignored.
     (error (message "eldoc error: %s" err))))
@@ -451,4 +465,5 @@ With prefix ARG, turn ElDoc mode on if and only if ARG is positive."
 
 (provide 'eldoc)
 
+;;; arch-tag: c9a58f9d-2055-46c1-9b82-7248b71a8375
 ;;; eldoc.el ends here