# An option to choose from an enumeration
#
# Declare an enumeration option with all its possible values as an array.
# Once the arguments are processed, `value` is set as the index of the selected value, if any.
class OptionEnum
	super OptionParameter
	redef type VALUE: Int

	# Values in the enumeration.
	var values: Array[String]

	# Init a new OptionEnum from `values` with a `help` message and `names`.
	#
	# `default` is the index of the default value in `values`.
	init(values: Array[String], help: String, default: Int, names: String...) is old_style_init do
		assert values.length > 0
		self.values = values.to_a
		super("{help} <{values.join(", ")}>", default, names)
	end

	redef fun convert(str)
	do
		var id = values.index_of(str)
		if id == -1 then
			var e = "Unrecognized value for option {names.join(", ")}.\n"
			e += "Expected values are: {values.join(", ")}."
			errors.add(e)
		end
		return id
	end

	# Get the value name from `values`.
	fun value_name: String do return values[value]

	redef fun pretty_default
	do
		return " ({values[default_value]})"
	end
end