(help-C-source-directory): New var.

(help-subr-name, help-C-file-name, help-find-C-source): New funs.
(describe-function-1, describe-variable): Use them.

diff --git a/lisp/help-fns.el b/lisp/help-fns.el
index 4201a3de1a5357c57fdf54e3fece06156559c98d..ab76b5eb2327f7cc1d8e60371601e9633537d833 100644 (file)
--- a/lisp/help-fns.el
+++ b/lisp/help-fns.el
@@ -1,6 +1,6 @@
 ;;; help-fns.el --- Complex help functions
 
-;; Copyright (C) 1985, 1986, 1993, 1994, 1998, 1999, 2000, 2001, 2002, 2003
+;; Copyright (C) 1985, 86, 93, 94, 98, 1999, 2000, 01, 02, 03, 2004
 ;;   Free Software Foundation, Inc.
 
 ;; Maintainer: FSF
@@ -215,6 +215,61 @@ ARGLIST can also be t or a string of the form \"(fun ARG1 ARG2 ...)\"."
                        (intern (upcase name))))))
                arglist)))
 
+(defvar help-C-source-directory
+  (let ((dir (expand-file-name "src" source-directory)))
+    (when (and (file-directory-p dir) (file-readable-p dir))
+      dir))
+  "Directory where the C source files of Emacs can be found.
+If nil, do not try to find the source code of functions and variables
+defined in C.")
+
+(defun help-subr-name (subr)
+  (let ((name (prin1-to-string subr)))
+    (if (string-match "\\`#<subr \\(.*\\)>\\'" name)
+       (match-string 1 name)
+      (error "Unexpected subroutine print name: %s" name))))
+
+(defun help-C-file-name (subr-or-var kind)
+  "Return the name of the C file where SUBR-OR-VAR is defined.
+KIND should be `var' for a variable or `subr' for a subroutine."
+  (let ((docbuf (get-buffer-create " *DOC*"))
+       (name (if (eq 'var kind)
+                 (concat "V" (symbol-name subr-or-var))
+               (concat "F" (help-subr-name subr-or-var)))))
+    (with-current-buffer docbuf
+      (goto-char (point-min))
+      (if (eobp)
+         (insert-file-contents-literally
+          (expand-file-name internal-doc-file-name doc-directory)))
+      (search-forward (concat "\1f" name "\n"))
+      (re-search-backward "\1fS\\(.*\\)")
+      (let ((file (match-string 1)))
+       (if (string-match "\\.\\(o\\|obj\\)\\'" file)
+           (replace-match ".c" t t file)
+         file)))))
+
+(defun help-find-C-source (fun-or-var file kind)
+  "Find the source location where SUBR-OR-VAR is defined in FILE.
+KIND should be `var' for a variable or `subr' for a subroutine."
+  (setq file (expand-file-name file help-C-source-directory))
+  (unless (file-readable-p file)
+    (error "The C source file %s is not available"
+          (file-name-nondirectory file)))
+  (if (eq 'fun kind)
+      (setq fun-or-var (indirect-function fun-or-var)))
+  (with-current-buffer (find-file-noselect file)
+    (goto-char (point-min))
+    (unless (re-search-forward
+            (if (eq 'fun kind)
+                (concat "DEFUN[ \t\n]*([ \t\n]*\""
+                        (regexp-quote (help-subr-name fun-or-var))
+                        "\"")
+              (concat "DEFVAR[A-Z_]*[ \t\n]*([ \t\n]*\""
+                      (regexp-quote (symbol-name fun-or-var))))
+            nil t)
+      (error "Can't find source for %s" fun))
+    (cons (current-buffer) (match-beginning 0))))
+
 ;;;###autoload
 (defun describe-function-1 (function)
   (let* ((def (if (symbolp function)
@@ -280,8 +335,10 @@ ARGLIST can also be t or a string of the form \"(fun ARG1 ARG2 ...)\"."
            (when (re-search-backward
                   "^;;; Generated autoloads from \\(.*\\)" nil t)
              (setq file-name (match-string 1)))))))
-    (cond
-     (file-name
+    (when (and (null file-name) (subrp def) help-C-source-directory)
+      ;; Find the C source file name.
+      (setq file-name (concat "src/" (help-C-file-name def 'subr))))
+    (when file-name
       (princ " in `")
       ;; We used to add .el to the file name,
       ;; but that's completely wrong when the user used load-file.
@@ -289,9 +346,9 @@ ARGLIST can also be t or a string of the form \"(fun ARG1 ARG2 ...)\"."
       (princ "'")
       ;; Make a hyperlink to the library.
       (with-current-buffer standard-output
-       (save-excursion
+        (save-excursion
          (re-search-backward "`\\([^`']+\\)'" nil t)
-         (help-xref-button 1 'help-function-def function file-name)))))
+         (help-xref-button 1 'help-function-def function file-name))))
     (princ ".")
     (terpri)
     (when (commandp function)
@@ -500,6 +557,13 @@ it is displayed along with the global value."
                      (when (re-search-backward
                             "^;;; Generated autoloads from \\(.*\\)" nil t)
                        (setq file-name (match-string 1)))))))
+             (when (and (null file-name)
+                        (integerp (get variable 'variable-documentation)))
+               ;; It's a variable not defined in Elisp but in C.
+               (if help-C-source-directory
+                   (setq file-name
+                         (concat "src/" (help-C-file-name variable 'var)))
+                 (princ "\n\nDefined in core C code.")))
              (when file-name
                (princ "\n\nDefined in `")
                (princ file-name)