1 # Context Coloring [![Build Status](https://travis-ci.org/jacksonrayhamilton/context-coloring.png?branch=master)](https://travis-ci.org/jacksonrayhamilton/context-coloring) [![Coverage Status](https://coveralls.io/repos/jacksonrayhamilton/context-coloring/badge.svg?branch=master)](https://coveralls.io/r/jacksonrayhamilton/context-coloring?branch=master)
4 <img alt="Screenshot of JavaScript code highlighted by context." src="screenshot.png" title="Screenshot">
7 Highlights code by scope. Top-level scopes are one color, second-level scopes
8 are another color, and so on. Variables retain the color of the scope in which
9 they are defined. A variable defined in an outer scope referenced by an inner
10 scope is colored the same as the outer scope.
12 By default, comments and strings are still highlighted syntactically.
16 - Light and dark (customizable) color schemes.
18 - Very fast for files under 1000 lines.
19 - Script, function and block scopes (and even `catch` block scopes).
21 - `defun`, `lambda`, `let`, `let*`, quotes, backticks, commas.
27 JavaScript language support requires either [js2-mode][], or
28 [Node.js 0.10+][node] and the [scopifier][] executable.
32 - `M-x package-install RET context-coloring RET`
36 - Clone this repository.
40 git clone https://github.com/jacksonrayhamilton/context-coloring.git
43 - Byte-compile the package for improved speed.
50 - Add the following to your init file:
53 (add-to-list 'load-path "~/.emacs.d/context-coloring")
54 (require 'context-coloring)
57 ### Dependencies (js-mode)
60 npm install -g scopifier
65 Add the following to your init file:
69 (add-hook 'js-mode-hook 'context-coloring-mode)
72 (add-to-list 'auto-mode-alist '("\\.js\\'" . js2-mode))
73 (add-hook 'js2-mode-hook 'context-coloring-mode)
76 (add-hook 'emacs-lisp-mode-hook 'context-coloring-mode)
83 - `context-coloring-syntactic-comments` (default: `t`): If non-nil, also color
84 comments using `font-lock`.
85 - `context-coloring-syntactic-strings` (default: `t`): If non-nil, also color
86 strings using `font-lock`.
87 - `context-coloring-delay` (default: `0.25`; supported modes: `js-mode`,
88 `js3-mode`, `emacs-lisp-mode`): Delay between a buffer update and
90 - `context-coloring-js-block-scopes` (default: `nil`; supported modes:
91 `js2-mode`): If non-nil, also color block scopes in the scope hierarchy in
96 Color schemes for custom themes are automatically applied when those themes are
97 active. Built-in theme support is available for: `ample`, `anti-zenburn`,
98 `grandshell`, `leuven`, `monokai`, `solarized`, `spacegray`, `tango` and
101 You can define your own theme colors too:
104 (context-coloring-define-theme
119 See `C-h f context-coloring-define-theme` for more info on theme parameters.
123 To add support for a new language, write a "scopifier" for it, and define a new
124 coloring dispatch strategy with `context-coloring-define-dispatch`. Then the
125 plugin should handle the rest. (See `C-h f context-coloring-define-dispatch`
126 for more info on dispatch strategies.)
128 A "scopifier" is a CLI program that reads a buffer's contents from stdin and
129 writes a JSON array of numbers to stdout. Every three numbers in the array
130 represent a range of color. For instance, if I fed the following string of
131 JavaScript code to a scopifier
134 var a = function () {};
137 then the scopifier would produce the following array
143 where, for every three numbers, the first number is a 1-indexed start [point][],
144 the second number is an exclusive end point, and the third number is a scope
145 level. The result of applying level 0 coloring to the range [1, 24) and
146 then applying level 1 coloring to the range [9, 23) would result in the
150 <img alt="Screenshot of ranges [1, 24) and [9, 23)." src="scopifier.png" title="Screenshot">
153 If there is an abstract syntax tree generator for your language, you can walk
154 the syntax tree, find variables and scopes, and build their positions and levels
155 into an array like the one above.
157 For example, a Ruby scopifier might be defined and implemented like this:
160 (context-coloring-define-dispatch
164 :command "/home/username/scopifier")
173 print scopifier ARGF.read
176 When a `--version` argument is passed, a scopifier should print its version
177 number and exit. This allows context-coloring to determine if an update is
180 Alternatively, you could implement a "colorizer" in Emacs Lisp. A colorizer
181 also handles the job of calling `context-coloring-colorize-region` to apply
182 colors to a buffer. A colorizer may have better performance than a scopifier
183 when parsing and coloring can be performed in the same pass.
185 [js2-mode]: https://github.com/mooz/js2-mode
186 [node]: http://nodejs.org/download/
187 [scopifier]: https://github.com/jacksonrayhamilton/scopifier
188 [point]: http://www.gnu.org/software/emacs/manual/html_node/elisp/Point.html