getopt

const (
	// DoubleDashTerminatesOptions indicates that all elements after an argument
	// "--" are treated as arguments.
	DoubleDashTerminatesOptions Config = 1 << iota
	// FirstArgTerminatesOptions indicates that all elements after the first
	// argument are treated as arguments.
	FirstArgTerminatesOptions
	// LongOnly indicates that long options may be started by either one or two
	// dashes, and short options are not allowed. Should replicate the behavior
	// of getopt_long_only and the
	// flag package of the Go standard library.
	LongOnly
	// GNUGetoptLong is a configuration that should replicate the behavior of
	// GNU getopt_long.
	GNUGetoptLong = DoubleDashTerminatesOptions
	// POSIXGetopt is a configuration that should replicate the behavior of
	// POSIX getopt.
	POSIXGetopt = DoubleDashTerminatesOptions | FirstArgTerminatesOptions
)

const (
	// NewOptionOrArgument indicates that the last element may be either a new
	// option or a new argument. Returned when it is an empty string.
	NewOptionOrArgument ContextType = iota
	// NewOption indicates that the last element must be new option, short or
	// long. Returned when it is "-".
	NewOption
	// NewLongOption indicates that the last element must be a new long option.
	// Returned when it is "--".
	NewLongOption
	// 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 an argument. The partial
	// argument is stored in Context.Text.
	Argument
)

const (
	// NoArgument indicates that an option takes no argument.
	NoArgument HasArg = iota
	// RequiredArgument indicates that an option must take 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 subsequent
	// argument after the option (-o arg, --long arg).
	RequiredArgument
	// OptionalArgument indicates that an 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
)