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|
;;; 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:
(defun nix-syntax-match-antiquote (limit)
(let ((pos (next-single-char-property-change (point) 'nix-syntax-antiquote
nil limit)))
(when (and pos (> pos (point)))
(goto-char pos)
(let ((char (char-after pos)))
(pcase char
(`?$
(forward-char 2))
(`?}
(forward-char 1)))
(set-match-data (list pos (point)))
t))))
(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)
(nix-syntax-match-antiquote 0 font-lock-preprocessor-face t))
"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-syntax-propertize-escaped-antiquote ()
"Set syntax properies for escaped antiquote marks."
nil)
(defun nix-syntax-propertize-multiline-string ()
"Set syntax properies for multiline string delimiters."
(let* ((start (match-beginning 0))
(end (match-end 0))
(context (save-excursion (save-match-data (syntax-ppss start))))
(string-type (nth 3 context)))
(pcase string-type
(`t
;; inside a multiline string
;; ending multi-line string delimiter
(put-text-property (1- end) end
'syntax-table (string-to-syntax "|")))
(`nil
;; beginning multi-line string delimiter
(put-text-property start (1+ start)
'syntax-table (string-to-syntax "|"))))))
(defun nix-syntax-propertize-antiquote ()
"Set syntax properties for antiquote marks."
(let* ((start (match-beginning 0)))
(put-text-property start (1+ start)
'syntax-table (string-to-syntax "|"))
(put-text-property start (+ start 2)
'nix-syntax-antiquote t)))
(defun nix-syntax-propertize-close-brace ()
"Set syntax properties for close braces.
If a close brace `}' ends an antiquote, the next character begins a string."
(let* ((start (match-beginning 0))
(end (match-end 0))
(context (save-excursion (save-match-data (syntax-ppss start))))
(open (nth 1 context)))
(when open ;; a corresponding open-brace was found
(let* ((antiquote (get-text-property open 'nix-syntax-antiquote)))
(when antiquote
(put-text-property (+ start 1) (+ start 2)
'syntax-table (string-to-syntax "|"))
(put-text-property start (1+ start)
'nix-syntax-antiquote t))))))
(defun nix-syntax-propertize (start end)
"Special syntax properties for Nix."
;; search for multi-line string delimiters
(goto-char start)
(remove-text-properties start end '(syntax-table nil nix-syntax-antiquote nil))
(funcall
(syntax-propertize-rules
("''\\${"
(0 (ignore (nix-syntax-propertize-escaped-antiquote))))
("''"
(0 (ignore (nix-syntax-propertize-multiline-string))))
("\\${"
(0 (ignore (nix-syntax-propertize-antiquote))))
("}"
(0 (ignore (nix-syntax-propertize-close-brace)))))
start end))
(defun nix-indent-line ()
"Indent current line in a Nix expression."
(interactive)
(indent-relative-maybe))
;;;###autoload
(define-derived-mode nix-mode prog-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-local font-lock-defaults '(nix-font-lock-keywords nil nil nil nil))
;; Special syntax properties for Nix
(setq-local syntax-propertize-function 'nix-syntax-propertize)
;; Look at text properties when parsing
(setq-local parse-sexp-lookup-properties t)
;; 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
|
