Lib/getopt.py

   1 """Parser for command line options.
   2
   3 This module helps scripts to parse the command line arguments in
   4 sys.argv.  It supports the same conventions as the Unix getopt()
   5 function (including the special meanings of arguments of the form `-'
   6 and `--').  Long options similar to those supported by GNU software
   7 may be used as well via an optional third argument.  This module
   8 provides a single function and an exception:
   9
  10 getopt() -- Parse command line options
  11 GetoptError -- exception (class) raised with 'opt' attribute, which is the
  12 option involved with the exception.
  13 """
  14
  15 # Long option support added by Lars Wirzenius <liw@iki.fi>.
  16
  17 # Gerrit Holl <gerrit@nl.linux.org> moved the string-based exceptions
  18 # to class-based exceptions.
  19
  20 __all__ = ["GetoptError","error","getopt"]
  21
  22 class GetoptError(Exception):
  23     opt = ''
  24     msg = ''
  25     def __init__(self, msg, opt):
  26         self.msg = msg
  27         self.opt = opt
  28         Exception.__init__(self, msg, opt)
  29
  30     def __str__(self):
  31         return self.msg
  32
  33 error = GetoptError # backward compatibility
  34
  35 def getopt(args, shortopts, longopts = []):
  36     """getopt(args, options[, long_options]) -> opts, args
  37
  38     Parses command line options and parameter list.  args is the
  39     argument list to be parsed, without the leading reference to the
  40     running program.  Typically, this means "sys.argv[1:]".  shortopts
  41     is the string of option letters that the script wants to
  42     recognize, with options that require an argument followed by a
  43     colon (i.e., the same format that Unix getopt() uses).  If
  44     specified, longopts is a list of strings with the names of the
  45     long options which should be supported.  The leading '--'
  46     characters should not be included in the option name.  Options
  47     which require an argument should be followed by an equal sign
  48     ('=').
  49
  50     The return value consists of two elements: the first is a list of
  51     (option, value) pairs; the second is the list of program arguments
  52     left after the option list was stripped (this is a trailing slice
  53     of the first argument).  Each option-and-value pair returned has
  54     the option as its first element, prefixed with a hyphen (e.g.,
  55     '-x'), and the option argument as its second element, or an empty
  56     string if the option has no argument.  The options occur in the
  57     list in the same order in which they were found, thus allowing
  58     multiple occurrences.  Long and short options may be mixed.
  59
  60     """
  61
  62     opts = []
  63     if type(longopts) == type(""):
  64         longopts = [longopts]
  65     else:
  66         longopts = list(longopts)
  67     while args and args[0].startswith('-') and args[0] != '-':
  68         if args[0] == '--':
  69             args = args[1:]
  70             break
  71         if args[0][:2] == '--':
  72             opts, args = do_longs(opts, args[0][2:], longopts, args[1:])
  73         else:
  74             opts, args = do_shorts(opts, args[0][1:], shortopts, args[1:])
  75
  76     return opts, args
  77
  78 def do_longs(opts, opt, longopts, args):
  79     try:
  80         i = opt.index('=')
  81     except ValueError:
  82         optarg = None
  83     else:
  84         opt, optarg = opt[:i], opt[i+1:]
  85
  86     has_arg, opt = long_has_args(opt, longopts)
  87     if has_arg:
  88         if optarg is None:
  89             if not args:
  90                 raise GetoptError('option --%s requires argument' % opt, opt)
  91             optarg, args = args[0], args[1:]
  92     elif optarg:
  93         raise GetoptError('option --%s must not have an argument' % opt, opt)
  94     opts.append(('--' + opt, optarg or ''))
  95     return opts, args
  96
  97 # Return:
  98 #   has_arg?
  99 #   full option name
 100 def long_has_args(opt, longopts):
 101     possibilities = [o for o in longopts if o.startswith(opt)]
 102     if not possibilities:
 103         raise GetoptError('option --%s not recognized' % opt, opt)
 104     # Is there an exact match?
 105     if opt in possibilities:
 106         return 0, opt
 107     elif opt + '=' in possibilities:
 108         return 1, opt
 109     # No exact match, so better be unique.
 110     if len(possibilities) > 1:
 111         # XXX since possibilities contains all valid continuations, might be
 112         # nice to work them into the error msg
 113         raise GetoptError('option --%s not a unique prefix' % opt, opt)
 114     assert len(possibilities) == 1
 115     unique_match = possibilities[0]
 116     has_arg = unique_match.endswith('=')
 117     if has_arg:
 118         unique_match = unique_match[:-1]
 119     return has_arg, unique_match
 120
 121 def do_shorts(opts, optstring, shortopts, args):
 122     while optstring != '':
 123         opt, optstring = optstring[0], optstring[1:]
 124         if short_has_arg(opt, shortopts):
 125             if optstring == '':
 126                 if not args:
 127                     raise GetoptError('option -%s requires argument' % opt, opt)
 128                 optstring, args = args[0], args[1:]
 129             optarg, optstring = optstring, ''
 130         else:
 131             optarg = ''
 132         opts.append(('-' + opt, optarg))
 133     return opts, args
 134
 135 def short_has_arg(opt, shortopts):
 136     for i in range(len(shortopts)):
 137         if opt == shortopts[i] != ':':
 138             return shortopts[i+1:i+2] == ':'
 139     raise GetoptError('option -%s not recognized' % opt, opt)
 140
 141 if __name__ == '__main__':
 142     import sys
 143     print getopt(sys.argv[1:], "a:b", ["alpha=", "beta"])