# module getopt -- Standard command line processing.

# Function getopt.getopt() has a different interface but provides the
# similar functionality to the Unix getopt() function, with the
# addition of long-option support.  (Long option support added by Lars
# Wirzenius <liw@iki.fi>.)

# It has two required arguments: the first should be argv[1:] (it
# doesn't want the script name), the second the string of option
# letters as passed to Unix getopt() (i.e., a string of allowable
# option letters, with options requiring an argument followed by a
# colon).

# The optional third argument, if present, getopt.getopt works similar
# to the GNU getopt_long function (but optional arguments are not
# supported).  The third argument should be a list of strings that
# name the long options.  If the name ends '=', the argument requires
# an argument.

# It raises the exception getopt.error with a string argument if it
# detects an error.

# It returns two values:
# (1)   a list of pairs (option, option_argument) giving the options in
#       the order in which they were specified.  (I'd use a dictionary
#       but applications may depend on option order or multiple
#       occurrences.)  Boolean options have '' as option_argument.
# (2)   the list of remaining arguments (may be empty).

import string

error = 'getopt.error'

def getopt(args, shortopts, longopts = []):
	list = []
	longopts = longopts[:]
	longopts.sort()
	while args and args[0][:1] == '-' and args[0] != '-':
		if args[0] == '--':
			args = args[1:]
			break
		if args[0][:2] == '--':
			list, args = do_longs(list, args[0][2:], longopts, args[1:])
		else:
			list, args = do_shorts(list, args[0][1:], shortopts, args[1:])
 
	return list, args

def do_longs(list, opt, longopts, args):
	try:
		i = string.index(opt, '=')
		opt, optarg = opt[:i], opt[i+1:]
	except ValueError:
		optarg = None
 
	has_arg, opt = long_has_args(opt, longopts)
	if has_arg:
		if optarg is None:
			if not args:
				raise error, 'option --%s requires argument' % opt
			optarg, args = args[0], args[1:]
	elif optarg:
		raise error, 'option --%s must not have an argument' % opt
	list.append(('--' + opt, optarg or ''))
	return list, args

# Return:
#   has_arg?
#   full option name
def long_has_args(opt, longopts):
	optlen = len(opt)
	for i in range(len(longopts)):
		x, y = longopts[i][:optlen], longopts[i][optlen:]
		if opt != x:
			continue
		if y != '' and y != '=' and i+1 < len(longopts):
			if opt == longopts[i+1][:optlen]:
				raise error, 'option --%s not a unique prefix' % opt
		if longopts[i][-1:] in ('=', ):
			return 1, longopts[i][:-1]
		return 0, longopts[i]
	raise error, 'option --' + opt + ' not recognized'

def do_shorts(list, optstring, shortopts, args):
	while optstring != '':
		opt, optstring = optstring[0], optstring[1:]
		if short_has_arg(opt, shortopts):
			if optstring == '':
				if not args:
					raise error, 'option -%s requires argument' % opt
				optstring, args = args[0], args[1:]
			optarg, optstring = optstring, ''
		else:
			optarg = ''
		list.append(('-' + opt, optarg))
	return list, args

def short_has_arg(opt, shortopts):
	for i in range(len(shortopts)):
		if opt == shortopts[i] != ':':
			return shortopts[i+1:i+2] == ':'
	raise error, 'option -%s not recognized' % opt

if __name__ == '__main__':
	import sys
	print getopt(sys.argv[1:], "a:b", ["alpha=", "beta"])
