getopt

const (
	// The option takes no argument.
	NoArgument Arity = iota
	// The option requires an argument. The argument can come either directly
	// after a short option (-oarg), after a long option followed by an equal
	// sign (--long=arg), or as a separate argument after the option (-o arg,
	// --long arg).
	RequiredArgument
	// The option takes an optional argument. The argument can come either
	// directly after a short option (-oarg) or after a long option followed by
	// an equal sign (--long=arg).
	OptionalArgument
)

const (
	// Stop parsing options after "--".
	StopAfterDoubleDash Config = 1 << iota
	// Stop parsing options before the first non-option argument.
	StopBeforeFirstNonOption
	// Allow long options to start with "-", and disallow short options.
	// Replicates the behavior of getopt_long_only and the flag package.
	LongOnly

	// Config to replicate the behavior of GNU's getopt_long.
	GNU = StopAfterDoubleDash
	// Config to replicate the behavior of BSD's getopt_long.
	BSD = StopAfterDoubleDash | StopBeforeFirstNonOption
)

const (
	// OptionOrArgument indicates that the last element may be either a new
	// option or a new argument. Returned when it is an empty string.
	OptionOrArgument ContextType = iota
	// AnyOption indicates that the last element must be new option, short or
	// long. Returned when it is "-".
	AnyOption
	// LongOption indicates that the last element is a long option (but not its
	// argument). The partial name of the long option is stored in Context.Text.
	LongOption
	// ChainShortOption indicates that a new short option may be chained.
	// Returned when the last element consists of a chain of options that take
	// no arguments.
	ChainShortOption
	// OptionArgument indicates that the last element list must be an argument
	// to an option. The option in question is stored in Context.Option.
	OptionArgument
	// Argument indicates that the last element is a non-option argument. The
	// partial argument is stored in Context.Text.
	Argument
)