;;; plist-mode.el --- Plist major mode

;; Author: wiml <wiml@omnigroup.com>
;; Maintainer: wiml


;; This file may be distributed under the terms of the GNU General Public
;; License. You will find a copy of the General Public License in your
;; emacs distribution. If you don't have emacs this file won't be very
;; useful to you.

;; History:
;;   November, 1998 (wiml):
;;      Created. Does paren-balancing and indentation. 
;;

;; Things to do:
;;
;; Font lock isn't very useful with this mode because plist semantics are
;; so arbitrary. Perhaps minor modes should define the keys that are
;; useful and/or valid in each dictionary (i.e., provide a schema).
;; Or (less complicated) plist-mode could understand that a string 
;; to the left of an equals sign is probably a dictionary key, and
;; therefore should have a different face, and possibly be matched against
;; a list of known dictionary keys for a given kind of plist (a simpler
;; sort of schema).
;;
;; Font-lock doesn't understand that barewords are strings too.
;;
;; Would it be useful to automatically add and remove doublequotes around
;; strings when the user puts an invalid character in the middle? This is
;; the second most common cause of unparsable plists (after unmatched 
;; braces and incorrect semicolons --- okay, make that the third most
;; common cause).
;;
;; Indentation doesn't understand multiline comments.


(defvar plist-mode-syntax-table nil 
  "syntax table used in plist-mode")
(if plist-mode-syntax-table
    ()
  (setq plist-mode-syntax-table (make-syntax-table))
  (modify-syntax-entry ?{ "(}" plist-mode-syntax-table)
  (modify-syntax-entry ?} "){" plist-mode-syntax-table)
  (modify-syntax-entry ?/ "  14" plist-mode-syntax-table)
  (modify-syntax-entry ?* "  23" plist-mode-syntax-table))

(defvar plist-mode-map nil "Keymap for plist-mode.")
(if plist-mode-map
    ()
  (setq plist-mode-map (make-sparse-keymap))
  (define-key plist-mode-map "\t" 'plist-indent-line)
)

(defvar plist-indentation 4 "Amount to indent nested items in plist mode.")
(defvar plist-mode-hook nil "Hooks to run on entry to plist mode.")

(defun plist-mode ()
  "Major mode for editing plist files as used by OpenStep and its
descendants (Rhapsody, MacOS X, etc.).

A plist consists of one toplevel item. Items are strings, arrays, and
dictionaries. A string is a sequence of characters between
double-quotes. A string containing no special characters need not be
quoted. An array consists of a number of items, separated by commas,
surrounded by parentheses. A dictionary is delimited by curly braces
and has entries of the form STRING = ITEM ;.

The following keys are active in plist-mode:
\\{plist-mode-map}"
  (interactive)
  (kill-all-local-variables)
  (use-local-map plist-mode-map)
  (set-syntax-table plist-mode-syntax-table)
  (setq mode-name "Plist")
  (setq major-mode 'plist-mode)
  (run-hooks 'plist-mode-hook))

(defun calculate-plist-indent ()
  (save-excursion
    (beginning-of-line)
    (if (< (point) 2)
	0
      (skip-chars-forward " \t")
      (let ((indent-above (if (eq (char-syntax (following-char)) ?\) )
			      0
			    plist-indentation)))
	(up-list -1)
	(+ (current-indentation) indent-above)))))

(defun plist-indent-line ()
  (interactive)
  (let ((level (calculate-plist-indent))
	(pos (- (point-max) (point)))
	beg)
    (beginning-of-line)
    (setq beg (point))
    (skip-chars-forward " \t")
    (if (equal level (current-column))
	nil
      (delete-region beg (point))
      (indent-to level)
      ;; ???
)))