added syntax highlighting for emacs

CONTRIBUTORS

@@ -9,6 +9,7 @@ Joshua Warner <joshuawarner32@gmail.com>: cmake build, AnyStruct/AnyList, other
 Scott Purdy <scott@fer.io>: kj/std iostream interface
 Bryan Borham <bjboreham@gmail.com>: Initial MSVC support
 Philip Quinn <p@partylemon.com>: cmake build and other assorted bits
+Brian Taylor <el.wubo@gmail.com>: emacs syntax highlighting
 
 This file does not list people who maintain their own Cap'n Proto
 implementations as separate projects.  Those people are awesome too!  :)

highlighting/emacs/README.md

+Syntax Coloring for Emacs
+=========================
+
+How to use:
+
+Add this to your .emacs file (altering the path to wherever your
+capnproto directory lives):
+
+```elisp
+(add-to-list 'load-path "~/src/capnproto/highlighting/emacs")
+(require 'capnp-mode)
+(add-to-list 'auto-mode-alist '("\\.capnp\\'" . capnp-mode))
+```

highlighting/emacs/capnp-mode.el

+;;; capnp-mode.el --- major mode for editing Capn' Proto Files
+
+;; This is free and unencumbered software released into the public domain.
+
+;; Author: Brian Taylor <el.wubo@gmail.com>
+;; Version: 1.0.0
+
+;;; Commentary:
+
+;; Provides basic syntax highlighting for capnp files.
+;;
+;; To use:
+;;
+;; Add something like this to your .emacs file:
+;;
+;; (add-to-list 'load-path "~/src/capnproto/highlighting/emacs")
+;; (require 'capnp-mode)
+;; (add-to-list 'auto-mode-alist '("\\.capnp\\'" . capnp-mode))
+;;
+
+;;; Code:
+
+;; command to comment/uncomment text
+(defun capnp-comment-dwim (arg)
+  "Comment or uncomment current line or region in a smart way.
+For detail, see `comment-dwim'."
+  (interactive "*P")
+  (require 'newcomment)
+  (let (
+        (comment-start "#") (comment-end "")
+        )
+    (comment-dwim arg)))
+
+(defvar capnp--syntax-table
+  (let ((syn-table (make-syntax-table)))
+
+    ;; bash style comment: “# …”
+    (modify-syntax-entry ?# "< b" syn-table)
+    (modify-syntax-entry ?\n "> b" syn-table)
+
+    syn-table)
+  "Syntax table for `capnp-mode'.")
+
+(defvar capnp--keywords
+  '("struct" "enum" "interface" "union" "import"
+    "using" "const" "annotation" "extends" "in"
+    "of" "on" "as" "with" "from" "fixed")
+  "Keywords in `capnp-mode'.")
+
+(defvar capnp--types
+  '("union" "group" "Void" "Bool" "Int8" "Int16"
+    "Int32" "Int64" "UInt8" "UInt16" "UInt32"
+    "UInt64" "Float32" "Float64" "Text" "Data"
+    "AnyPointer" "AnyStruct" "Capability" "List")
+  "Types in `capnp-mode'.")
+
+(defvar capnp--font-lock-keywords
+  `(
+    (,(regexp-opt capnp--keywords 'words) . font-lock-keyword-face)
+    (,(regexp-opt capnp--types 'words) . font-lock-type-face)
+    ("@\\w+" . font-lock-constant-face))
+  "Font lock definitions in `capnp-mode'.")
+
+;;;###autoload
+(define-derived-mode capnp-mode prog-mode
+  "capn-mode is a major mode for editing capnp protocol files"
+  :syntax-table capnp--syntax-table
+
+  (setq font-lock-defaults '((capnp--font-lock-keywords)))
+
+
+  (setq mode-name "capnp")
+  (define-key capnp-mode-map [remap comment-dwim] 'capnp-comment-dwim))
+
+(provide 'capnp-mode)