;; A major mode for editing scripts written in Deelang

(add-to-list 'auto-mode-alist '("\\.dee\\'" . dee-mode))

(defcustom dee-indent-offset 4
  "Default indentation offset for Deelang."
  :group 'dee
  :type 'integer
  :safe 'integerp)

(defvar dee-mode-map
  (let ((map (make-sparse-keymap)))
    map)
  "Keymap for Deelang files")

(defvar dee-mode-syntax-table
  (let ((table (make-syntax-table)))
    (modify-syntax-entry ?# "<" table)
    (modify-syntax-entry ?\n ">" table)
    (modify-syntax-entry ?- "w" table)
    (modify-syntax-entry ?? "w" table)
    table)
  "Syntax table for Deelang files")

(defvar dee-font-lock-id-re
  (rx (seq alpha (* (any alnum ?- ??)))))

(defvar dee-font-lock-keywords
  `(,(rx symbol-start
	 (or
	  "if" "elif" "else" "loop" "until" "over" "in" "")
	 symbol-end)
    (,(rx (group (regexp dee-font-lock-id-re)) (* space) "<-")
     (1 font-lock-variable-name-face))
    (,(rx (group (regexp dee-font-lock-id-re)) (* space) "(")
     (1 font-lock-function-name-face))
    (,(rx (group (regexp dee-font-lock-id-re)) (* space) "->")
     (1 font-lock-constant-face))))

(defun dee-indent-line-function ()
  'noindent) ;TODO

(define-derived-mode dee-mode prog-mode "Dee"
  "Major mode for editing scripts written in Deelang.

\\{dee-mode-map}"
  (set (make-local-variable 'indent-line-function)
       #'dee-indent-line-function)
  (set (make-local-variable 'font-lock-defaults)
       `(,dee-font-lock-keywords
	 nil nil nil nil)))

(provide 'dee)