* A Nix mode for Emacs.

2 files changed, 113 insertions, 0 deletions

diff --git a/misc/emacs/Makefile.am b/misc/emacs/Makefile.am
new file mode 100644
index 0000000000..9ca6ec9e3d
--- /dev/null
+++ b/misc/emacs/Makefile.am
@@ -0,0 +1,5 @@
+EXTRA_DIST = nix-mode.el
+
+install-data-local:
+	$(INSTALL) -d $(DESTDIR)$(datadir)/emacs/site-lisp
+	$(INSTALL_DATA) nix-mode.el $(DESTDIR)$(datadir)/emacs/site-lisp
diff --git a/misc/emacs/nix-mode.el b/misc/emacs/nix-mode.el
new file mode 100644
index 0000000000..9d9934ab45
--- /dev/null
+++ b/misc/emacs/nix-mode.el
@@ -0,0 +1,108 @@
+(defun nix-mode ()
+  "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}
+"
+
+  (interactive)
+  
+  (kill-all-local-variables)
+  
+  (setq major-mode 'nix-mode)
+  (setq mode-name "Nix")
+
+  (use-local-map nix-mode-map)
+
+  (set-syntax-table nix-mode-syntax-table)
+
+  ;; Font lock support.
+  (setq font-lock-defaults '(nix-keywords nil nil nil nil))
+
+  ;; Automatic indentation [C-j].
+  (make-local-variable 'indent-line-function)
+  (setq indent-line-function 'nix-indent-line)
+
+  ;; Indenting of comments.
+  (make-local-variable 'comment-start)
+  (setq comment-start "# ")
+  (make-local-variable 'comment-end)
+  (setq comment-end "")
+  (make-local-variable 'comment-start-skip)
+  (setq comment-start-skip "\\(^\\|\\s-\\);?#+ *")
+
+  ;; Filling of comments.
+  (make-local-variable 'adaptive-fill-mode)
+  (setq adaptive-fill-mode t)
+  (make-local-variable 'paragraph-start)
+  (setq paragraph-start "[ \t]*\\(#+[ \t]*\\)?$")
+  (make-local-variable 'paragraph-separate)
+  (setq paragraph-separate paragraph-start)
+  
+  (run-hooks 'nix-mode-hook)
+  )
+
+
+(defvar nix-mode-map nil
+  "Keymap for Nix mode.")
+
+(setq nix-mode-map (make-sparse-keymap))
+;(define-key nix-mode-map [tab] 'tab-to-tab-stop)
+
+
+(defvar nix-keywords
+  '("\\<if\\>" "\\<then\\>" "\\<else\\>" "\\<assert\\>"
+    "\\<let\\>" "\\<rec\\>" "\\<inherit\\>"
+    ("\\<true\\>" . font-lock-builtin-face)
+    ("\\<false\\>" . font-lock-builtin-face)
+    ("\\<null\\>" . font-lock-builtin-face)
+    ("\\<import\\>" . font-lock-builtin-face)
+    ("\\<derivation\\>" . font-lock-builtin-face)
+    ("\\<baseNameOf\\>" . font-lock-builtin-face)
+    ("\\<toString\\>" . font-lock-builtin-face)
+    ("\\<isNull\\>" . font-lock-builtin-face)
+    ("\\<\\([a-zA-Z_][a-zA-Z0-9_']*\\)[ \t]*="
+     (1 font-lock-variable-name-face nil nil))
+    ("[a-zA-Z][a-zA-Z0-9\\+-\\.]*:[a-zA-Z0-9%/\\?:@&=\\+\\$,_\\.!~\\*'-]+"
+     . font-lock-constant-face)
+    ("[a-zA-Z0-9._\\+-]*\\(/[a-zA-Z0-9._\\+-]+\\)+"
+     . font-lock-constant-face)
+    ))
+
+
+(defvar nix-mode-syntax-table nil
+  "Syntax table for Nix mode.")
+
+(if nix-mode-syntax-table
+    nil
+    (progn
+      (setq nix-mode-syntax-table (make-syntax-table))
+      (modify-syntax-entry ?/ ". 14" nix-mode-syntax-table)
+      (modify-syntax-entry ?* ". 23" nix-mode-syntax-table)
+      (modify-syntax-entry ?# "< b" nix-mode-syntax-table)
+      (modify-syntax-entry ?\n "> b" nix-mode-syntax-table)
+      ))
+
+
+(defun nix-indent-line ()
+  "Indent current line in a Nix expression."
+  (interactive)
+  (indent-relative-maybe))
+
+
+(setq auto-mode-alist (cons '("\\.nix\\'" . nix-mode) auto-mode-alist))