code.delx.au - gnu-emacs-elpa/blob - README.md

   1 # Context Coloring [![Build Status](https://travis-ci.org/jacksonrayhamilton/context-coloring.png?branch=develop)](https://travis-ci.org/jacksonrayhamilton/context-coloring)
   2
   3 <p align="center">
   4   <img alt="Screenshot of JavaScript code highlighted by context." src="screenshot.png" title="Screenshot">
   5 </p>
   6
   7 Highlights code according to function context.
   8
   9 - Code in the global scope is one color. Code in functions within the global
  10   scope is a different color, and code within such functions is another color,
  11   and so on.
  12 - Identifiers retain the color of the scope in which they are declared.
  13
  14 Lexical scope information at-a-glance can assist a programmer in understanding
  15 the overall structure of a program. It can help to curb nasty bugs like name
  16 shadowing. A rainbow can indicate excessive complexity. State change within a
  17 closure is easily monitored.
  18
  19 By default, context-coloring still highlights comments and strings
  20 syntactically. It is still easy to differentiate code from non-code, and strings
  21 cannot be confused for variables.
  22
  23 This coloring strategy is probably more useful than conventional syntax
  24 highlighting. Highlighting keywords can help one to detect spelling errors, but
  25 a [linter][] could also spot those errors, and if integrated with [flycheck][],
  26 an extra spot opens up in your editing toolbelt.
  27
  28 Give context-coloring a try; you may find that it *changes the way you write
  29 code*.
  30
  31 ## Features
  32
  33 - Supported languages: JavaScript
  34 - Light and dark (customizable) color schemes.
  35 - Very fast for files under 1000 lines.
  36
  37 ## Installation
  38
  39 Requires Emacs 24+.
  40
  41 JavaScript language support requires either [js2-mode][], or
  42 [Node.js 0.10+][node] and the [scopifier][] executable.
  43
  44 ### ELPA
  45
  46 - `M-x package-install RET context-coloring RET`
  47
  48 ### Git
  49
  50 - Clone this repository.
  51
  52 ```bash
  53 cd ~/.emacs.d/
  54 git clone https://github.com/jacksonrayhamilton/context-coloring.git
  55 ```
  56
  57 - Byte-compile the package for improved speed.
  58
  59 ```bash
  60 cd context-coloring/
  61 make compile
  62 ```
  63
  64 - Add the following to your `~/.emacs` file:
  65
  66 ```lisp
  67 (add-to-list 'load-path "~/.emacs.d/context-coloring")
  68 (require 'context-coloring)
  69 ```
  70
  71 ### scopifier (for non-js2-mode users)
  72
  73 ```bash
  74 npm install -g scopifier
  75 ```
  76
  77 ## Usage
  78
  79 Add the following to your `~/.emacs` file:
  80
  81 ```lisp
  82 ;; non-js2-mode users:
  83 (add-hook 'js-mode-hook 'context-coloring-mode)
  84
  85 ;; js2-mode users:
  86 (add-to-list 'auto-mode-alist '("\\.js\\'" . js2-mode))
  87 (add-hook 'js2-mode-hook 'context-coloring-mode)
  88 ```
  89
  90 ## Customizing
  91
  92 Color schemes for custom themes are automatically applied when those themes are
  93 active. Built-in theme support is available for: `leuven`, `monokai`,
  94 `solarized`, `tango` and `zenburn`.
  95
  96 You can define your own theme colors too:
  97
  98 ```lisp
  99 (context-coloring-define-theme
 100  'zenburn
 101  :colors '("#DCDCCC"
 102            "#93E0E3"
 103            "#BFEBBF"
 104            "#F0DFAF"
 105            "#DFAF8F"
 106            "#CC9393"
 107            "#DC8CC3"
 108            "#94BFF3"
 109            "#9FC59F"
 110            "#D0BF8F"
 111            "#DCA3A3"))
 112 ```
 113
 114 ## Extending
 115
 116 To add support for a new language, write a "scopifier" for it, and define a new
 117 coloring dispatch strategy with `context-coloring-define-dispatch`. Then the
 118 plugin should handle the rest.
 119
 120 A "scopifier" is a CLI program that reads a buffer's contents from stdin and
 121 writes a JSON array of numbers to stdout. Every three numbers in the array
 122 represent a range of color. For instance, if I fed the following string of
 123 JavaScript code to a scopifier,
 124
 125 ```js
 126 var a = function () {};
 127 ```
 128
 129 then the scopifier would produce the following array:
 130
 131 ```js
 132 [1,24,0,9,23,1]
 133 ```
 134
 135 Where, for every three numbers, the first number is a 1-indexed start [point][],
 136 the second number is an exclusive end point, and the third number is a scope
 137 level. The result of applying level 0 coloring to the range &#91;1, 24) and then
 138 applying level 1 coloring to the range &#91;9, 23) would result in the following
 139 coloring:
 140
 141 <p align="center">
 142   <img alt="Screenshot of ranges &#91;1, 24) and &#91;9, 23)." src="scopifier.png" title="Screenshot">
 143 </p>
 144
 145 If there is an abstract syntax tree generator for your language, you can walk
 146 the syntax tree, find variables and scopes, and build their positions and levels
 147 into an array like the one above.
 148
 149 For example, a Ruby scopifier might be defined and implemented like this:
 150
 151 ```lisp
 152 (context-coloring-define-dispatch
 153  'ruby
 154  :modes '(ruby-mode)
 155  :executable "ruby"
 156  :command "/home/username/scopifier")
 157 ```
 158
 159 ```ruby
 160 #!/usr/bin/env ruby
 161 def scopifier(code)
 162     # Parse code.
 163     # Return an array.
 164 end
 165 print scopifier ARGF.read
 166 ```
 167
 168 When a `--version` argument is passed, a scopifier should print its version
 169 number and exit. This allows context-coloring to determine if an update is
 170 required.
 171
 172 [linter]: http://jshint.com/about/
 173 [flycheck]: http://www.flycheck.org/
 174 [zenburn]: http://github.com/bbatsov/zenburn-emacs
 175 [point]: http://www.gnu.org/software/emacs/manual/html_node/elisp/Point.html
 176 [js2-mode]: https://github.com/mooz/js2-mode
 177 [node]: http://nodejs.org/download/
 178 [scopifier]: https://github.com/jacksonrayhamilton/scopifier
 179 [load path]: https://www.gnu.org/software/emacs/manual/html_node/emacs/Lisp-Libraries.html