class Syntax::Javascript

def step
  case
  when scan(/\s+/)
    start_group :normal, matched
  when scan(/\\u[0-9a-f]{4}/i)
    start_group :unicode, matched
  when scan(/0[xX][0-9A-Fa-f]+/)
    start_group :hex, matched
  when scan(/(?:0[0-7]+)(?![89.eEfF])/)
    start_group :oct, matched
  when scan(/(?:\d+)(?![.eEfF])/)
    start_group :integer, matched
  when scan(/\d[fF]?|\d*\.\d+(?:[eE][+-]?\d+)?[fF]?|\d+[eE][+-]?\d+[fF]?/)
    start_group :float, matched
  when (scan(/"(?:[^"\\]|\\.)*"/) or scan(/'(?:[^'\\]|\\.)*'/) )
    start_group :string, matched
  when scan(/[a-z_$][a-z_\d]*/i)
    if JAVASCRIPT_KEYWORDS.include?( matched )
      start_group :keyword, matched
    elsif JAVASCRIPT_PREDEFINED_TYPES.include?( matched )
      start_group :predefined_types, matched
    else
      start_group :ident, matched
    end
  when scan(%r! // [^\n\\]* (?: \\. [^\n\\]* )* | /\* (?: .*? \*/ | .* ) !mx)
    start_group :comment, matched
  else
    start_group :other, scan(/./x)
  end
end