parser.js

var regexp = LSD.RegExp({
  'fn_tail': '\\.',
  'fn_arguments': '\\g<inside_round>',
  'fn_name': '\\g<unicode>',
  'fn': '\\g<fn_tail>?\\g<fn_name>\\(\\g<fn_arguments>\\)',
  
  'block_arguments': '\\g<inside_curly>',
  'block_body': '\\g<inside_curly>',
  'block': '\\{\\g<block_arguments>?\\g<block_body>\\}',
  
  'double_string': '"((?:[^"]|\\")*)"/',
  'single_string': "'((?:[^']|\\')*)'",
  'string': '\\g<double_string>|\\g<single_string>'
  
  'whitespace': '\\s+',
  'comma': ',',
  'semicolon': ';',
  'separator': '(\\g<whitespace>|\\g<comma>|\\g<semicolon>)'
  
  'index': '\\[\\s*\\g<inside_square>\\s*\\]',
  
  'token_tail': '\\.',
  'token_name': '\\g<unicode>',
  'token': '\\g<token_tail>?\\g<token_name>',
  
  'length_number': '[-+]?(?:\\d+\\.\\d*|\\d*\\.\\d+)'
  'length_unit': 'em|px|pt|%|fr|deg|(?=$|[^a-zA-Z0-9.])'
  'length': '\\g<length_number>\\g<length_unit>',
  
  'operator': '([-+]|[\\/%^~=><*\\^!|&$]+)'
}, {
  fn: function(tail, name, args) {

  },

  block: function(args, body) {

  },

  index: function(content) {

  },

  token: function(name) {

  },

  length: function(number, unit) {

  },

  operator: function(name) {

  },
  
  separator: function(token) {
    switch (token) {
      case ';':
        break;
      case ',':
        break;
    }
  }
})

var results = regexp.exec(string);