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: `ample`, `anti-zenburn`,
  94 `grandshell`, `leuven`, `monokai`, `solarized`, `spacegray`, `tango` and
  95 `zenburn`.
  96
  97 You can define your own theme colors too:
  98
  99 ```lisp
 100 (context-coloring-define-theme
 101  'zenburn
 102  :colors '("#DCDCCC"
 103            "#93E0E3"
 104            "#BFEBBF"
 105            "#F0DFAF"
 106            "#DFAF8F"
 107            "#CC9393"
 108            "#DC8CC3"
 109            "#94BFF3"
 110            "#9FC59F"
 111            "#D0BF8F"
 112            "#DCA3A3"))
 113 ```
 114
 115 See `C-h f context-coloring-define-theme` for more info on theme parameters.
 116
 117 ## Extending
 118
 119 To add support for a new language, write a "scopifier" for it, and define a new
 120 coloring dispatch strategy with `context-coloring-define-dispatch`. Then the
 121 plugin should handle the rest. (See `C-h f context-coloring-define-dispatch` for
 122 more info on dispatch strategies.)
 123
 124 A "scopifier" is a CLI program that reads a buffer's contents from stdin and
 125 writes a JSON array of numbers to stdout. Every three numbers in the array
 126 represent a range of color. For instance, if I fed the following string of
 127 JavaScript code to a scopifier:
 128
 129 ```js
 130 var a = function () {};
 131 ```
 132
 133 Then the scopifier would produce the following array:
 134
 135 ```js
 136 [1,24,0,9,23,1]
 137 ```
 138
 139 Where, for every three numbers, the first number is a 1-indexed start [point][],
 140 the second number is an exclusive end point, and the third number is a scope
 141 level. The result of applying level 0 coloring to the range &#91;1, 24) and then
 142 applying level 1 coloring to the range &#91;9, 23) would result in the following
 143 coloring:
 144
 145 <p align="center">
 146   <img alt="Screenshot of ranges &#91;1, 24) and &#91;9, 23)." src="scopifier.png" title="Screenshot">
 147 </p>
 148
 149 If there is an abstract syntax tree generator for your language, you can walk
 150 the syntax tree, find variables and scopes, and build their positions and levels
 151 into an array like the one above.
 152
 153 For example, a Ruby scopifier might be defined and implemented like this:
 154
 155 ```lisp
 156 (context-coloring-define-dispatch
 157  'ruby
 158  :modes '(ruby-mode)
 159  :executable "ruby"
 160  :command "/home/username/scopifier")
 161 ```
 162
 163 ```ruby
 164 #!/usr/bin/env ruby
 165 def scopifier(code)
 166     # Parse code.
 167     # Return an array.
 168 end
 169 print scopifier ARGF.read
 170 ```
 171
 172 When a `--version` argument is passed, a scopifier should print its version
 173 number and exit. This allows context-coloring to determine if an update is
 174 required.
 175
 176 [linter]: http://jshint.com/about/
 177 [flycheck]: http://www.flycheck.org/
 178 [js2-mode]: https://github.com/mooz/js2-mode
 179 [node]: http://nodejs.org/download/
 180 [scopifier]: https://github.com/jacksonrayhamilton/scopifier
 181 [point]: http://www.gnu.org/software/emacs/manual/html_node/elisp/Point.html