;;
;; Adds command M-X make-guard
;; this function inserts the standard C header
;; guard in an .h file around any existing text
;; for example if the file 
;; is foo-bar_baz.h
;; ---------------------------
;; #ifndef __FOO_BAR_BAZ_H__
;; #define __FOO_BAR_BAZ_H__
;;
;;
;; #ifdef __cplusplus
;; extern "C" {
;; #endif
;;
;; existing code
;;                                                                
;;                                                                            
;; #ifdef __cplusplus
;; } /* extern "C" */
;; #endif
;; #endif /* __FOO_BAR_BAZ_H__*/
;; 
;; ----------------------------------


(defun make-guard ()

  (interactive)
  (let ((buffer-name (buffer-name (current-buffer))))
    (if (eq (compare-strings buffer-name
			     (- (length buffer-name) 2) nil
			    ".h" 0 nil t) t)
	(insert-header-guard buffer-name)
      (message "File must be a header file (.h)"))))



(defun insert-header-guard (buffer-name)
  (let* ((split-name (split-string buffer-name "[-_.]"))
	 (guard-def (concat "__" 
			    (mapconcat (lambda (x) (upcase x)) 
				       split-name  "_")
			    "__")))
    (save-excursion
      (progn
	(goto-char 0)
	(insert "#ifndef ")
	(insert guard-def)
	(insert "\n")
	(insert "#define ")
	(insert guard-def)
	(insert "\n\n\n")
	(insert "#ifdef __cplusplus
extern \"C\" { 
#endif\n\n")

	
	(goto-char (point-max))
	(insert "\n\n#ifdef __cplusplus
} /* extern \"C\" */
#endif\n\n")
	(insert "\n\n#endif /* ")
	(insert guard-def)
	(insert "*/\n")))))