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lix/misc/emacs/nix-mode.el
Steve Purcell 61c464f252 Add autoloads, make code more concise & idiomatic
- Use define-derived-mode to declare nix-mode
- Use autoloads to ensure nix-mode is usable (and enabled) without needing `require`
- Use set + make-local-variable instead of longer 2-step equivalent
2014-06-12 12:34:58 +02:00

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EmacsLisp

;;; nix-mode.el --- Major mode for editing Nix expressions
;; Author: Eelco Dolstra
;; URL: https://github.com/NixOS/nix/tree/master/misc/emacs
;; Version: 1.0
;;; Commentary:
;;; Code:
(defconst nix-font-lock-keywords
'("\\<if\\>" "\\<then\\>" "\\<else\\>" "\\<assert\\>" "\\<with\\>"
"\\<let\\>" "\\<in\\>" "\\<rec\\>" "\\<inherit\\>" "\\<or\\>"
("\\<true\\>" . font-lock-builtin-face)
("\\<false\\>" . font-lock-builtin-face)
("\\<null\\>" . font-lock-builtin-face)
("\\<import\\>" . font-lock-builtin-face)
("\\<derivation\\>" . font-lock-builtin-face)
("\\<baseNameOf\\>" . font-lock-builtin-face)
("\\<toString\\>" . font-lock-builtin-face)
("\\<isNull\\>" . font-lock-builtin-face)
("[a-zA-Z][a-zA-Z0-9\\+-\\.]*:[a-zA-Z0-9%/\\?:@&=\\+\\$,_\\.!~\\*'-]+"
. font-lock-constant-face)
("\\<\\([a-zA-Z_][a-zA-Z0-9_'\-\.]*\\)[ \t]*="
(1 font-lock-variable-name-face nil nil))
("<[a-zA-Z0-9._\\+-]+\\(/[a-zA-Z0-9._\\+-]+\\)*>"
. font-lock-constant-face)
("[a-zA-Z0-9._\\+-]*\\(/[a-zA-Z0-9._\\+-]+\\)+"
. font-lock-constant-face))
"Font lock keywords for nix.")
(defvar nix-mode-syntax-table
(let ((table (make-syntax-table)))
(modify-syntax-entry ?/ ". 14" table)
(modify-syntax-entry ?* ". 23" table)
(modify-syntax-entry ?# "< b" table)
(modify-syntax-entry ?\n "> b" table)
table)
"Syntax table for Nix mode.")
(defun nix-indent-line ()
"Indent current line in a Nix expression."
(interactive)
(indent-relative-maybe))
;;;###autoload
(define-derived-mode nix-mode fundamental-mode "Nix"
"Major mode for editing Nix expressions.
The following commands may be useful:
'\\[newline-and-indent]'
Insert a newline and move the cursor to align with the previous
non-empty line.
'\\[fill-paragraph]'
Refill a paragraph so that all lines are at most `fill-column'
lines long. This should do the right thing for comments beginning
with `#'. However, this command doesn't work properly yet if the
comment is adjacent to code (i.e., no intervening empty lines).
In that case, select the text to be refilled and use
`\\[fill-region]' instead.
The hook `nix-mode-hook' is run when Nix mode is started.
\\{nix-mode-map}
"
(set-syntax-table nix-mode-syntax-table)
;; Font lock support.
(setq font-lock-defaults '(nix-font-lock-keywords nil nil nil nil))
;; Automatic indentation [C-j].
(set (make-local-variable 'indent-line-function) 'nix-indent-line)
;; Indenting of comments.
(set (make-local-variable 'comment-start) "# ")
(set (make-local-variable 'comment-end) "")
(set (make-local-variable 'comment-start-skip) "\\(^\\|\\s-\\);?#+ *")
;; Filling of comments.
(set (make-local-variable 'adaptive-fill-mode) t)
(set (make-local-variable 'paragraph-start) "[ \t]*\\(#+[ \t]*\\)?$")
(set (make-local-variable 'paragraph-separate) paragraph-start))
;;;###autoload
(progn
(add-to-list 'auto-mode-alist '("\\.nix\\'" . nix-mode))
(add-to-list 'auto-mode-alist '("\\.nix.in\\'" . nix-mode)))
(provide 'nix-mode)
;;; nix-mode.el ends here