compreCSSor

A CSS minifier built with Ruby — Work in progress.

Ways to minify the CSS

Combine selectors. (This will probably reduce the code more than anything else, so it has to be done really good.)
Optimize unnecessary specific selectors. E.g. body div #id to #id. Also remove the universal selector when it's not needed, e.g.: *.class to .class.
Combine properties into shorthand properties if possible. (E.g. margin-top, margin-right, margin-bottom and margin-left into margin.)
Remove all whitespace characters and /* */ comments if they are not inside a string. This will be done automatically because of the way the CSS is parsed and rearranged.
Omit the last semicolon as it's optional.
Replace none and 0 followed by a suffix (px, em and so on) with 0 as they do the same thing.
Replace the font-weight values normal and bold with their corresponding numeric values 400 and 700.
Replace rgb, hsl, rgba / hsla with 1 as the alpha value, cymk and the color keywords if they are longer than 4 or 7 characters with their corresponding HEX values. Use the color keywords if they are shorter than the corresponding HEX values. (E.g. red instead of #f00.)
Use shorthand HEX values if possible. (#f80 instead of #ff8800.)

API usage [draft]

require 'comprecssor'
compiler = comprecssor.new

compiler.minify('The CSS in a string', {}); # CSS in a string

file = File.open('file.css')
compiler.minify(file); # CSS in a file

file2 = File.open('file2.css')
compiler.minify([file, file2]) # Two CSS files

compiler.minify(file, {}) # Options in a hash

Parser [draft]

// Parser output:

{

  'at-rules' => {

    'charset' => '',

    'media' => [
      { 'conditions' => [], 'rules' => {} },
    ],

    'import' => [
      { 'url' => '', 'conditions': [] }
    ],

    'page': [
      { 'selector' => '', 'rules' => {} }
    ],

    'font-face': [
      { rules => {} }
    ],

    'namespace' => [], # ?

    'keyframe' => [
      { 'name' => '', 'rules' => {} }
    ]

  },

  'rules' => {

    'key:selector' => {
      'property' => 'value'
    }

  }

}

Parsing h1 { color: red; } should return a rules hash:

{
	'h1' => {
		'color' = 'red'
	}
}

Contributing

If you've found any bugs or have suggestions, let us know!
Or if you want, you can fork this project on GitHub and create a pull request.

Credits :)

Authors:
Florian H.
Mogria m0gr14@gmail.com