1 files changed, 95 insertions, 0 deletions
diff --git a/misc/emacs/nix-mode.el b/misc/emacs/nix-mode.el
new file mode 100644
index 000000000000..790799d858cc
--- /dev/null
+++ b/misc/emacs/nix-mode.el
@@ -0,0 +1,95 @@
+;;; 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 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 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