class RSpec::Mocks::ArityCalculator

def self.supports_optional_and_splat_args?
  Method.method_defined?(:parameters)
end

def initialize(method)
  @method = method
end

def max_arity
  params = method.parameters
  if params.any? {|(type, _)| type == :rest }
    # Method takes a splat argument
    return INFINITY
  else
    params.count {|(type, _)| type != :block }
  end
end

def max_arity
  # On 1.8, Method#parameters does not exist.  There is no way to
  # distinguish between default and splat args, so there is no way to
  # have it work correctly for both default and splat args, as far as I
  # can tell. The best we can do is consider it INFINITY (to be
  # tolerant of splat args).
  method.arity < 0 ? INFINITY : method.arity
end

def method
  @method
end

def min_arity
  return method.arity if method.arity >= 0
  # `~` inverts the one's complement and gives us the number of
  # required arguments.
  ~method.arity
end

def range_description
  return min_arity.to_s if min_arity == max_arity
  return "#{min_arity} or more" if max_arity == INFINITY
  "#{min_arity} to #{max_arity}"
end

def within_range?(actual)
  min_arity <= actual && actual <= max_arity
end