class Crass::Parser

def consume_at_rule(input = @tokens)
  rule = {}
  rule[:tokens] = input.collect do
    rule[:name]    = input.consume[:value]
    rule[:prelude] = []
    while token = input.consume
      node = token[:node]
      if node == :comment # Non-standard.
        next
      elsif node == :semicolon
        break
      elsif node === :'{'
        # Note: The spec says the block should _be_ the consumed simple
        # block, but Simon Sapin's CSS parsing tests and tinycss2 expect
        # only the _value_ of the consumed simple block here. I assume I'm
        # interpreting the spec too literally, so I'm going with the
        # tinycss2 behavior.
        rule[:block] = consume_simple_block(input)[:value]
        break
      elsif node == :simple_block && token[:start] == '{'
        # Note: The spec says the block should _be_ the simple block, but
        # Simon Sapin's CSS parsing tests and tinycss2 expect only the
        # _value_ of the simple block here. I assume I'm interpreting the
        # spec too literally, so I'm going with the tinycss2 behavior.
        rule[:block] = token[:value]
        break
      else
        input.reconsume
        rule[:prelude] << consume_component_value(input)
      end
    end
  end
  create_node(:at_rule, rule)
end