class Sass::Script::Tree::ListLiteral

def _perform(environment)
  list = Sass::Script::Value::List.new(
    elements.map {|e| e.perform(environment)},
    separator: separator,
    bracketed: bracketed)
  list.source_range = source_range
  list.options = options
  list
end

def children; elements; end

def deep_copy
  node = dup
  node.instance_variable_set('@elements', elements.map {|e| e.deep_copy})
  node
end

def element_needs_parens?(element)
  if element.is_a?(ListLiteral)
    return false if element.elements.length < 2
    return false if element.bracketed
    return Sass::Script::Parser.precedence_of(element.separator || :space) <=
           Sass::Script::Parser.precedence_of(separator || :space)
  end
  return false unless separator == :space
  if element.is_a?(UnaryOperation)
    return element.operator == :minus || element.operator == :plus
  end
  return false unless element.is_a?(Operation)
  return true unless element.operator == :div
  !(is_literal_number?(element.operand1) && is_literal_number?(element.operand2))
end

def force_division!
  # Do nothing. Lists prevent division propagation.
end

def initialize(elements, separator: nil, bracketed: false)
  @elements = elements
  @separator = separator
  @bracketed = bracketed
end

def inspect
  (bracketed ? '[' : '(') +
    elements.map {|e| e.inspect}.join(separator == :space ? ' ' : ', ') +
    (bracketed ? ']' : ')')
end

def is_literal_number?(value)
  value.is_a?(Literal) &&
    value.value.is_a?((Sass::Script::Value::Number)) &&
    !value.value.original.nil?
end

def sep_str(opts = options)
  return ' ' if separator == :space
  return ',' if opts && opts[:style] == :compressed
  ', '
end

def to_sass(opts = {})
  return bracketed ? "[]" : "()" if elements.empty?
  members = elements.map do |v|
    if element_needs_parens?(v)
      "(#{v.to_sass(opts)})"
    else
      v.to_sass(opts)
    end
  end
  if separator == :comma && members.length == 1
    return "#{bracketed ? '[' : '('}#{members.first},#{bracketed ? ']' : ')'}"
  end
  contents = members.join(sep_str(nil))
  bracketed ? "[#{contents}]" : contents
end