;;; delight.el - A dimmer switch for your lighter text.
;;
;; Author: Phil S.
;; URL: http://www.emacswiki.org/emacs/DelightedModes
;; Version: 1.01

;; Commentary:
;;
;; Enables you to customise the mode names displayed in the mode line.
;;
;; For major modes, the buffer-local `mode-name' variable is modified.
;; For minor modes, the associated value in `minor-mode-alist' is set.
;;
;; Example usage:
;;
;; (require 'delight)
;;
;; (delight 'abbrev-mode " Abv" "abbrev")
;;
;; (delight '((abbrev-mode " Abv" "abbrev")
;;            (smart-tab-mode " \\t" "smart-tab")
;;            (eldoc-mode nil "eldoc")
;;            (rainbow-mode)
;;            (emacs-lisp-mode "Elisp" :major)))
;;
;; Important note:
;;
;; Although strings are common, any mode-line construct is permitted
;; as the value (for both minor and major modes); so before you
;; override a value you should check the existing one, as you may
;; want to replicate any structural elements in your replacement
;; if it turns out not to be a simple string.
;;
;; For major modes, M-: mode-name
;; For minor modes, M-: (cadr (assq 'MODE minor-mode-alist))
;; for the minor MODE in question.
;;
;; Conversely, you may incorporate additional mode-line constructs in
;; your replacement values, if you so wish. e.g.:
;;
;; (delight 'emacs-lisp-mode
;;          '("Elisp" (lexical-binding ":Lex" ":Dyn"))
;;          :major)
;;
;; See `mode-line-format' for information about mode-line constructs,
;; and M-: (info "(elisp) Mode Line Format") for further details.
;;
;; Also bear in mind that some modes may dynamically update these
;; values themselves (for instance dired-mode updates mode-name if
;; you change the sorting criteria) in which cases this library may
;; prove inadequate.

;;; Changelog:
;;
;; 1.01 - Added support for using the keyword :major as the FILE argument
;;        for major modes, to avoid also processing them as minor modes.

;;; Code:

(defvar delighted-modes ()
  "List of specs for modifying the display of mode names in the mode line.

See `delight'.")

;;;###autoload
(defun delight (spec &optional value file)
  "Modify the lighter value displayed in the mode line for the given mode SPEC
if and when the mode is loaded.

SPEC can be either a mode symbol, or a list containing multiple elements of
the form (MODE VALUE FILE). In the latter case the two optional arguments are
omitted, as they are instead specified for each element of the list.

For minor modes, VALUE is the replacement lighter value (or nil to disable)
to set in the `minor-mode-alist' variable. For major modes VALUE is the
replacement buffer-local `mode-name' value to use when a buffer changes to
that mode.

In both cases VALUE is commonly a string, but may in fact contain any valid
mode-line construct. See `mode-line-format' for details.

The FILE argument is passed through to `eval-after-load'. If FILE is nil then
the mode symbol is passed as the required feature. Both of these cases are
relevant to minor modes only.

For major modes you should specify the keyword :major as the value of FILE,
to prevent the mode being treated as a minor mode."
  (add-hook 'after-change-major-mode-hook 'delight-major-mode)
  (let ((glum (if (consp spec) spec (list (list spec value file)))))
    (while glum
      (destructuring-bind (mode &optional value file) (pop glum)
        (assq-delete-all mode delighted-modes)
        (add-to-list 'delighted-modes (list mode value file))
        (unless (eq file :major)
          (eval-after-load (or file mode)
            `(let ((minor-delight (assq ',mode minor-mode-alist)))
               (when minor-delight
                 (setcar (cdr minor-delight) ',value)))))))))

(defun delight-major-mode ()
  "Delight the 'pretty name' of the current buffer's major mode
when displayed in the mode-line.

When `mode-name' is displayed in other contexts (such as in the
`describe-mode' help buffer), its original value will be used."
  (let ((major-delight (assq major-mode delighted-modes)))
    (when major-delight
      (setq mode-name `(inhibit-mode-name-delight
                        ,mode-name ;; glum
                        ,(cadr major-delight)))))) ;; delighted

(defadvice format-mode-line (around delighted-modes-are-glum activate)
  "Delighted modes should exhibit their original `mode-name' when
`format-mode-line' is called. See `delight-major-mode'."
  (let ((inhibit-mode-name-delight t))
    ad-do-it))

(provide 'delight)