class Sass::Script::Operation

def _perform(environment)
  literal1 = @operand1.perform(environment)
  # Special-case :and and :or to support short-circuiting.
  if @operator == :and
    return literal1.to_bool ? @operand2.perform(environment) : literal1
  elsif @operator == :or
    return literal1.to_bool ? literal1 : @operand2.perform(environment)
  end
  literal2 = @operand2.perform(environment)
  if (literal1.is_a?(Null) || literal2.is_a?(Null)) && @operator != :eq && @operator != :neq
    raise Sass::SyntaxError.new("Invalid null operation: \"#{literal1.inspect} #{@operator} #{literal2.inspect}\".")
  end
  begin
    opts(literal1.send(@operator, literal2))
  rescue NoMethodError => e
    raise e unless e.name.to_s == @operator.to_s
    raise Sass::SyntaxError.new("Undefined operation: \"#{literal1} #{@operator} #{literal2}\".")
  end
end

def children
  [@operand1, @operand2]
end

def deep_copy
  node = dup
  node.instance_variable_set('@operand1', @operand1.deep_copy)
  node.instance_variable_set('@operand2', @operand2.deep_copy)
  node
end

def initialize(operand1, operand2, operator)
  @operand1 = operand1
  @operand2 = operand2
  @operator = operator
  super()
end

def inspect
  "(#{@operator.inspect} #{@operand1.inspect} #{@operand2.inspect})"
end

def operand_to_sass(op, side, opts)
  return "(#{op.to_sass(opts)})" if op.is_a?(List)
  return op.to_sass(opts) unless op.is_a?(Operation)
  pred = Sass::Script::Parser.precedence_of(@operator)
  sub_pred = Sass::Script::Parser.precedence_of(op.operator)
  assoc = Sass::Script::Parser.associative?(@operator)
  return "(#{op.to_sass(opts)})" if sub_pred < pred ||
    (side == :right && sub_pred == pred && !assoc)
  op.to_sass(opts)
end

def to_sass(opts = {})
  o1 = operand_to_sass @operand1, :left, opts
  o2 = operand_to_sass @operand2, :right, opts
  sep =
    case @operator
    when :comma; ", "
    when :space; " "
    else; " #{Lexer::OPERATORS_REVERSE[@operator]} "
    end
  "#{o1}#{sep}#{o2}"
end