scripts/argparse.py

   1 # This is a local copy of the standard library argparse module taken from PyPI.
   2 # It is licensed under the Python Software Foundation License.  This is a
   3 # fallback for Python 2.6 which does not include this module.  Python 2.7+ and
   4 # 3+ will never load this module because built-in modules are loaded before
   5 # anything in sys.path.
   6 #
   7 # If your script is not located in the same directory as this file, import it
   8 # like this:
   9 #
  10 #   import os
  11 #   import sys
  12 #   sys.path.append(os.path.join(os.path.dirname(__file__), ..., 'scripts'))
  13 #   import argparse
  14
  15 # Author: Steven J. Bethard <steven.bethard@gmail.com>.
  16 # Maintainer: Thomas Waldmann <tw@waldmann-edv.de>
  17
  18 """Command-line parsing library
  19
  20 This module is an optparse-inspired command-line parsing library that:
  21
  22     - handles both optional and positional arguments
  23     - produces highly informative usage messages
  24     - supports parsers that dispatch to sub-parsers
  25
  26 The following is a simple usage example that sums integers from the
  27 command-line and writes the result to a file::
  28
  29     parser = argparse.ArgumentParser(
  30         description='sum the integers at the command line')
  31     parser.add_argument(
  32         'integers', metavar='int', nargs='+', type=int,
  33         help='an integer to be summed')
  34     parser.add_argument(
  35         '--log', default=sys.stdout, type=argparse.FileType('w'),
  36         help='the file where the sum should be written')
  37     args = parser.parse_args()
  38     args.log.write('%s' % sum(args.integers))
  39     args.log.close()
  40
  41 The module contains the following public classes:
  42
  43     - ArgumentParser -- The main entry point for command-line parsing. As the
  44         example above shows, the add_argument() method is used to populate
  45         the parser with actions for optional and positional arguments. Then
  46         the parse_args() method is invoked to convert the args at the
  47         command-line into an object with attributes.
  48
  49     - ArgumentError -- The exception raised by ArgumentParser objects when
  50         there are errors with the parser's actions. Errors raised while
  51         parsing the command-line are caught by ArgumentParser and emitted
  52         as command-line messages.
  53
  54     - FileType -- A factory for defining types of files to be created. As the
  55         example above shows, instances of FileType are typically passed as
  56         the type= argument of add_argument() calls.
  57
  58     - Action -- The base class for parser actions. Typically actions are
  59         selected by passing strings like 'store_true' or 'append_const' to
  60         the action= argument of add_argument(). However, for greater
  61         customization of ArgumentParser actions, subclasses of Action may
  62         be defined and passed as the action= argument.
  63
  64     - HelpFormatter, RawDescriptionHelpFormatter, RawTextHelpFormatter,
  65         ArgumentDefaultsHelpFormatter -- Formatter classes which
  66         may be passed as the formatter_class= argument to the
  67         ArgumentParser constructor. HelpFormatter is the default,
  68         RawDescriptionHelpFormatter and RawTextHelpFormatter tell the parser
  69         not to change the formatting for help text, and
  70         ArgumentDefaultsHelpFormatter adds information about argument defaults
  71         to the help.
  72
  73 All other classes in this module are considered implementation details.
  74 (Also note that HelpFormatter and RawDescriptionHelpFormatter are only
  75 considered public as object names -- the API of the formatter objects is
  76 still considered an implementation detail.)
  77 """
  78
  79 __version__ = '1.4.0'  # we use our own version number independent of the
  80                        # one in stdlib and we release this on pypi.
  81
  82 __external_lib__ = True  # to make sure the tests really test THIS lib,
  83                          # not the builtin one in Python stdlib
  84
  85 __all__ = [
  86     'ArgumentParser',
  87     'ArgumentError',
  88     'ArgumentTypeError',
  89     'FileType',
  90     'HelpFormatter',
  91     'ArgumentDefaultsHelpFormatter',
  92     'RawDescriptionHelpFormatter',
  93     'RawTextHelpFormatter',
  94     'Namespace',
  95     'Action',
  96     'ONE_OR_MORE',
  97     'OPTIONAL',
  98     'PARSER',
  99     'REMAINDER',
 100     'SUPPRESS',
 101     'ZERO_OR_MORE',
 102 ]
 103
 104
 105 import copy as _copy
 106 import os as _os
 107 import re as _re
 108 import sys as _sys
 109 import textwrap as _textwrap
 110
 111 from gettext import gettext as _
 112
 113 try:
 114     set
 115 except NameError:
 116     # for python < 2.4 compatibility (sets module is there since 2.3):
 117     from sets import Set as set
 118
 119 try:
 120     basestring
 121 except NameError:
 122     basestring = str
 123
 124 try:
 125     sorted
 126 except NameError:
 127     # for python < 2.4 compatibility:
 128     def sorted(iterable, reverse=False):
 129         result = list(iterable)
 130         result.sort()
 131         if reverse:
 132             result.reverse()
 133         return result
 134
 135
 136 def _callable(obj):
 137     return hasattr(obj, '__call__') or hasattr(obj, '__bases__')
 138
 139
 140 SUPPRESS = '==SUPPRESS=='
 141
 142 OPTIONAL = '?'
 143 ZERO_OR_MORE = '*'
 144 ONE_OR_MORE = '+'
 145 PARSER = 'A...'
 146 REMAINDER = '...'
 147 _UNRECOGNIZED_ARGS_ATTR = '_unrecognized_args'
 148
 149 # =============================
 150 # Utility functions and classes
 151 # =============================
 152
 153 class _AttributeHolder(object):
 154     """Abstract base class that provides __repr__.
 155
 156     The __repr__ method returns a string in the format::
 157         ClassName(attr=name, attr=name, ...)
 158     The attributes are determined either by a class-level attribute,
 159     '_kwarg_names', or by inspecting the instance __dict__.
 160     """
 161
 162     def __repr__(self):
 163         type_name = type(self).__name__
 164         arg_strings = []
 165         for arg in self._get_args():
 166             arg_strings.append(repr(arg))
 167         for name, value in self._get_kwargs():
 168             arg_strings.append('%s=%r' % (name, value))
 169         return '%s(%s)' % (type_name, ', '.join(arg_strings))
 170
 171     def _get_kwargs(self):
 172         return sorted(self.__dict__.items())
 173
 174     def _get_args(self):
 175         return []
 176
 177
 178 def _ensure_value(namespace, name, value):
 179     if getattr(namespace, name, None) is None:
 180         setattr(namespace, name, value)
 181     return getattr(namespace, name)
 182
 183
 184 # ===============
 185 # Formatting Help
 186 # ===============
 187
 188 class HelpFormatter(object):
 189     """Formatter for generating usage messages and argument help strings.
 190
 191     Only the name of this class is considered a public API. All the methods
 192     provided by the class are considered an implementation detail.
 193     """
 194
 195     def __init__(self,
 196                  prog,
 197                  indent_increment=2,
 198                  max_help_position=24,
 199                  width=None):
 200
 201         # default setting for width
 202         if width is None:
 203             try:
 204                 width = int(_os.environ['COLUMNS'])
 205             except (KeyError, ValueError):
 206                 width = 80
 207             width -= 2
 208
 209         self._prog = prog
 210         self._indent_increment = indent_increment
 211         self._max_help_position = max_help_position
 212         self._width = width
 213
 214         self._current_indent = 0
 215         self._level = 0
 216         self._action_max_length = 0
 217
 218         self._root_section = self._Section(self, None)
 219         self._current_section = self._root_section
 220
 221         self._whitespace_matcher = _re.compile(r'\s+')
 222         self._long_break_matcher = _re.compile(r'\n\n\n+')
 223
 224     # ===============================
 225     # Section and indentation methods
 226     # ===============================
 227     def _indent(self):
 228         self._current_indent += self._indent_increment
 229         self._level += 1
 230
 231     def _dedent(self):
 232         self._current_indent -= self._indent_increment
 233         assert self._current_indent >= 0, 'Indent decreased below 0.'
 234         self._level -= 1
 235
 236     class _Section(object):
 237
 238         def __init__(self, formatter, parent, heading=None):
 239             self.formatter = formatter
 240             self.parent = parent
 241             self.heading = heading
 242             self.items = []
 243
 244         def format_help(self):
 245             # format the indented section
 246             if self.parent is not None:
 247                 self.formatter._indent()
 248             join = self.formatter._join_parts
 249             for func, args in self.items:
 250                 func(*args)
 251             item_help = join([func(*args) for func, args in self.items])
 252             if self.parent is not None:
 253                 self.formatter._dedent()
 254
 255             # return nothing if the section was empty
 256             if not item_help:
 257                 return ''
 258
 259             # add the heading if the section was non-empty
 260             if self.heading is not SUPPRESS and self.heading is not None:
 261                 current_indent = self.formatter._current_indent
 262                 heading = '%*s%s:\n' % (current_indent, '', self.heading)
 263             else:
 264                 heading = ''
 265
 266             # join the section-initial newline, the heading and the help
 267             return join(['\n', heading, item_help, '\n'])
 268
 269     def _add_item(self, func, args):
 270         self._current_section.items.append((func, args))
 271
 272     # ========================
 273     # Message building methods
 274     # ========================
 275     def start_section(self, heading):
 276         self._indent()
 277         section = self._Section(self, self._current_section, heading)
 278         self._add_item(section.format_help, [])
 279         self._current_section = section
 280
 281     def end_section(self):
 282         self._current_section = self._current_section.parent
 283         self._dedent()
 284
 285     def add_text(self, text):
 286         if text is not SUPPRESS and text is not None:
 287             self._add_item(self._format_text, [text])
 288
 289     def add_usage(self, usage, actions, groups, prefix=None):
 290         if usage is not SUPPRESS:
 291             args = usage, actions, groups, prefix
 292             self._add_item(self._format_usage, args)
 293
 294     def add_argument(self, action):
 295         if action.help is not SUPPRESS:
 296
 297             # find all invocations
 298             get_invocation = self._format_action_invocation
 299             invocations = [get_invocation(action)]
 300             for subaction in self._iter_indented_subactions(action):
 301                 invocations.append(get_invocation(subaction))
 302
 303             # update the maximum item length
 304             invocation_length = max([len(s) for s in invocations])
 305             action_length = invocation_length + self._current_indent
 306             self._action_max_length = max(self._action_max_length,
 307                                           action_length)
 308
 309             # add the item to the list
 310             self._add_item(self._format_action, [action])
 311
 312     def add_arguments(self, actions):
 313         for action in actions:
 314             self.add_argument(action)
 315
 316     # =======================
 317     # Help-formatting methods
 318     # =======================
 319     def format_help(self):
 320         help = self._root_section.format_help()
 321         if help:
 322             help = self._long_break_matcher.sub('\n\n', help)
 323             help = help.strip('\n') + '\n'
 324         return help
 325
 326     def _join_parts(self, part_strings):
 327         return ''.join([part
 328                         for part in part_strings
 329                         if part and part is not SUPPRESS])
 330
 331     def _format_usage(self, usage, actions, groups, prefix):
 332         if prefix is None:
 333             prefix = _('usage: ')
 334
 335         # if usage is specified, use that
 336         if usage is not None:
 337             usage = usage % dict(prog=self._prog)
 338
 339         # if no optionals or positionals are available, usage is just prog
 340         elif usage is None and not actions:
 341             usage = '%(prog)s' % dict(prog=self._prog)
 342
 343         # if optionals and positionals are available, calculate usage
 344         elif usage is None:
 345             prog = '%(prog)s' % dict(prog=self._prog)
 346
 347             # split optionals from positionals
 348             optionals = []
 349             positionals = []
 350             for action in actions:
 351                 if action.option_strings:
 352                     optionals.append(action)
 353                 else:
 354                     positionals.append(action)
 355
 356             # build full usage string
 357             format = self._format_actions_usage
 358             action_usage = format(optionals + positionals, groups)
 359             usage = ' '.join([s for s in [prog, action_usage] if s])
 360
 361             # wrap the usage parts if it's too long
 362             text_width = self._width - self._current_indent
 363             if len(prefix) + len(usage) > text_width:
 364
 365                 # break usage into wrappable parts
 366                 part_regexp = r'\(.*?\)+|\[.*?\]+|\S+'
 367                 opt_usage = format(optionals, groups)
 368                 pos_usage = format(positionals, groups)
 369                 opt_parts = _re.findall(part_regexp, opt_usage)
 370                 pos_parts = _re.findall(part_regexp, pos_usage)
 371                 assert ' '.join(opt_parts) == opt_usage
 372                 assert ' '.join(pos_parts) == pos_usage
 373
 374                 # helper for wrapping lines
 375                 def get_lines(parts, indent, prefix=None):
 376                     lines = []
 377                     line = []
 378                     if prefix is not None:
 379                         line_len = len(prefix) - 1
 380                     else:
 381                         line_len = len(indent) - 1
 382                     for part in parts:
 383                         if line_len + 1 + len(part) > text_width:
 384                             lines.append(indent + ' '.join(line))
 385                             line = []
 386                             line_len = len(indent) - 1
 387                         line.append(part)
 388                         line_len += len(part) + 1
 389                     if line:
 390                         lines.append(indent + ' '.join(line))
 391                     if prefix is not None:
 392                         lines[0] = lines[0][len(indent):]
 393                     return lines
 394
 395                 # if prog is short, follow it with optionals or positionals
 396                 if len(prefix) + len(prog) <= 0.75 * text_width:
 397                     indent = ' ' * (len(prefix) + len(prog) + 1)
 398                     if opt_parts:
 399                         lines = get_lines([prog] + opt_parts, indent, prefix)
 400                         lines.extend(get_lines(pos_parts, indent))
 401                     elif pos_parts:
 402                         lines = get_lines([prog] + pos_parts, indent, prefix)
 403                     else:
 404                         lines = [prog]
 405
 406                 # if prog is long, put it on its own line
 407                 else:
 408                     indent = ' ' * len(prefix)
 409                     parts = opt_parts + pos_parts
 410                     lines = get_lines(parts, indent)
 411                     if len(lines) > 1:
 412                         lines = []
 413                         lines.extend(get_lines(opt_parts, indent))
 414                         lines.extend(get_lines(pos_parts, indent))
 415                     lines = [prog] + lines
 416
 417                 # join lines into usage
 418                 usage = '\n'.join(lines)
 419
 420         # prefix with 'usage:'
 421         return '%s%s\n\n' % (prefix, usage)
 422
 423     def _format_actions_usage(self, actions, groups):
 424         # find group indices and identify actions in groups
 425         group_actions = set()
 426         inserts = {}
 427         for group in groups:
 428             try:
 429                 start = actions.index(group._group_actions[0])
 430             except ValueError:
 431                 continue
 432             else:
 433                 end = start + len(group._group_actions)
 434                 if actions[start:end] == group._group_actions:
 435                     for action in group._group_actions:
 436                         group_actions.add(action)
 437                     if not group.required:
 438                         if start in inserts:
 439                             inserts[start] += ' ['
 440                         else:
 441                             inserts[start] = '['
 442                         inserts[end] = ']'
 443                     else:
 444                         if start in inserts:
 445                             inserts[start] += ' ('
 446                         else:
 447                             inserts[start] = '('
 448                         inserts[end] = ')'
 449                     for i in range(start + 1, end):
 450                         inserts[i] = '|'
 451
 452         # collect all actions format strings
 453         parts = []
 454         for i, action in enumerate(actions):
 455
 456             # suppressed arguments are marked with None
 457             # remove | separators for suppressed arguments
 458             if action.help is SUPPRESS:
 459                 parts.append(None)
 460                 if inserts.get(i) == '|':
 461                     inserts.pop(i)
 462                 elif inserts.get(i + 1) == '|':
 463                     inserts.pop(i + 1)
 464
 465             # produce all arg strings
 466             elif not action.option_strings:
 467                 part = self._format_args(action, action.dest)
 468
 469                 # if it's in a group, strip the outer []
 470                 if action in group_actions:
 471                     if part[0] == '[' and part[-1] == ']':
 472                         part = part[1:-1]
 473
 474                 # add the action string to the list
 475                 parts.append(part)
 476
 477             # produce the first way to invoke the option in brackets
 478             else:
 479                 option_string = action.option_strings[0]
 480
 481                 # if the Optional doesn't take a value, format is:
 482                 #    -s or --long
 483                 if action.nargs == 0:
 484                     part = '%s' % option_string
 485
 486                 # if the Optional takes a value, format is:
 487                 #    -s ARGS or --long ARGS
 488                 else:
 489                     default = action.dest.upper()
 490                     args_string = self._format_args(action, default)
 491                     part = '%s %s' % (option_string, args_string)
 492
 493                 # make it look optional if it's not required or in a group
 494                 if not action.required and action not in group_actions:
 495                     part = '[%s]' % part
 496
 497                 # add the action string to the list
 498                 parts.append(part)
 499
 500         # insert things at the necessary indices
 501         for i in sorted(inserts, reverse=True):
 502             parts[i:i] = [inserts[i]]
 503
 504         # join all the action items with spaces
 505         text = ' '.join([item for item in parts if item is not None])
 506
 507         # clean up separators for mutually exclusive groups
 508         open = r'[\[(]'
 509         close = r'[\])]'
 510         text = _re.sub(r'(%s) ' % open, r'\1', text)
 511         text = _re.sub(r' (%s)' % close, r'\1', text)
 512         text = _re.sub(r'%s *%s' % (open, close), r'', text)
 513         text = _re.sub(r'\(([^|]*)\)', r'\1', text)
 514         text = text.strip()
 515
 516         # return the text
 517         return text
 518
 519     def _format_text(self, text):
 520         if '%(prog)' in text:
 521             text = text % dict(prog=self._prog)
 522         text_width = self._width - self._current_indent
 523         indent = ' ' * self._current_indent
 524         return self._fill_text(text, text_width, indent) + '\n\n'
 525
 526     def _format_action(self, action):
 527         # determine the required width and the entry label
 528         help_position = min(self._action_max_length + 2,
 529                             self._max_help_position)
 530         help_width = self._width - help_position
 531         action_width = help_position - self._current_indent - 2
 532         action_header = self._format_action_invocation(action)
 533
 534         # ho nelp; start on same line and add a final newline
 535         if not action.help:
 536             tup = self._current_indent, '', action_header
 537             action_header = '%*s%s\n' % tup
 538
 539         # short action name; start on the same line and pad two spaces
 540         elif len(action_header) <= action_width:
 541             tup = self._current_indent, '', action_width, action_header
 542             action_header = '%*s%-*s  ' % tup
 543             indent_first = 0
 544
 545         # long action name; start on the next line
 546         else:
 547             tup = self._current_indent, '', action_header
 548             action_header = '%*s%s\n' % tup
 549             indent_first = help_position
 550
 551         # collect the pieces of the action help
 552         parts = [action_header]
 553
 554         # if there was help for the action, add lines of help text
 555         if action.help:
 556             help_text = self._expand_help(action)
 557             help_lines = self._split_lines(help_text, help_width)
 558             parts.append('%*s%s\n' % (indent_first, '', help_lines[0]))
 559             for line in help_lines[1:]:
 560                 parts.append('%*s%s\n' % (help_position, '', line))
 561
 562         # or add a newline if the description doesn't end with one
 563         elif not action_header.endswith('\n'):
 564             parts.append('\n')
 565
 566         # if there are any sub-actions, add their help as well
 567         for subaction in self._iter_indented_subactions(action):
 568             parts.append(self._format_action(subaction))
 569
 570         # return a single string
 571         return self._join_parts(parts)
 572
 573     def _format_action_invocation(self, action):
 574         if not action.option_strings:
 575             metavar, = self._metavar_formatter(action, action.dest)(1)
 576             return metavar
 577
 578         else:
 579             parts = []
 580
 581             # if the Optional doesn't take a value, format is:
 582             #    -s, --long
 583             if action.nargs == 0:
 584                 parts.extend(action.option_strings)
 585
 586             # if the Optional takes a value, format is:
 587             #    -s ARGS, --long ARGS
 588             else:
 589                 default = action.dest.upper()
 590                 args_string = self._format_args(action, default)
 591                 for option_string in action.option_strings:
 592                     parts.append('%s %s' % (option_string, args_string))
 593
 594             return ', '.join(parts)
 595
 596     def _metavar_formatter(self, action, default_metavar):
 597         if action.metavar is not None:
 598             result = action.metavar
 599         elif action.choices is not None:
 600             choice_strs = [str(choice) for choice in action.choices]
 601             result = '{%s}' % ','.join(choice_strs)
 602         else:
 603             result = default_metavar
 604
 605         def format(tuple_size):
 606             if isinstance(result, tuple):
 607                 return result
 608             else:
 609                 return (result, ) * tuple_size
 610         return format
 611
 612     def _format_args(self, action, default_metavar):
 613         get_metavar = self._metavar_formatter(action, default_metavar)
 614         if action.nargs is None:
 615             result = '%s' % get_metavar(1)
 616         elif action.nargs == OPTIONAL:
 617             result = '[%s]' % get_metavar(1)
 618         elif action.nargs == ZERO_OR_MORE:
 619             result = '[%s [%s ...]]' % get_metavar(2)
 620         elif action.nargs == ONE_OR_MORE:
 621             result = '%s [%s ...]' % get_metavar(2)
 622         elif action.nargs == REMAINDER:
 623             result = '...'
 624         elif action.nargs == PARSER:
 625             result = '%s ...' % get_metavar(1)
 626         else:
 627             formats = ['%s' for _ in range(action.nargs)]
 628             result = ' '.join(formats) % get_metavar(action.nargs)
 629         return result
 630
 631     def _expand_help(self, action):
 632         params = dict(vars(action), prog=self._prog)
 633         for name in list(params):
 634             if params[name] is SUPPRESS:
 635                 del params[name]
 636         for name in list(params):
 637             if hasattr(params[name], '__name__'):
 638                 params[name] = params[name].__name__
 639         if params.get('choices') is not None:
 640             choices_str = ', '.join([str(c) for c in params['choices']])
 641             params['choices'] = choices_str
 642         return self._get_help_string(action) % params
 643
 644     def _iter_indented_subactions(self, action):
 645         try:
 646             get_subactions = action._get_subactions
 647         except AttributeError:
 648             pass
 649         else:
 650             self._indent()
 651             for subaction in get_subactions():
 652                 yield subaction
 653             self._dedent()
 654
 655     def _split_lines(self, text, width):
 656         text = self._whitespace_matcher.sub(' ', text).strip()
 657         return _textwrap.wrap(text, width)
 658
 659     def _fill_text(self, text, width, indent):
 660         text = self._whitespace_matcher.sub(' ', text).strip()
 661         return _textwrap.fill(text, width, initial_indent=indent,
 662                                            subsequent_indent=indent)
 663
 664     def _get_help_string(self, action):
 665         return action.help
 666
 667
 668 class RawDescriptionHelpFormatter(HelpFormatter):
 669     """Help message formatter which retains any formatting in descriptions.
 670
 671     Only the name of this class is considered a public API. All the methods
 672     provided by the class are considered an implementation detail.
 673     """
 674
 675     def _fill_text(self, text, width, indent):
 676         return ''.join([indent + line for line in text.splitlines(True)])
 677
 678
 679 class RawTextHelpFormatter(RawDescriptionHelpFormatter):
 680     """Help message formatter which retains formatting of all help text.
 681
 682     Only the name of this class is considered a public API. All the methods
 683     provided by the class are considered an implementation detail.
 684     """
 685
 686     def _split_lines(self, text, width):
 687         return text.splitlines()
 688
 689
 690 class ArgumentDefaultsHelpFormatter(HelpFormatter):
 691     """Help message formatter which adds default values to argument help.
 692
 693     Only the name of this class is considered a public API. All the methods
 694     provided by the class are considered an implementation detail.
 695     """
 696
 697     def _get_help_string(self, action):
 698         help = action.help
 699         if '%(default)' not in action.help:
 700             if action.default is not SUPPRESS:
 701                 defaulting_nargs = [OPTIONAL, ZERO_OR_MORE]
 702                 if action.option_strings or action.nargs in defaulting_nargs:
 703                     help += ' (default: %(default)s)'
 704         return help
 705
 706
 707 # =====================
 708 # Options and Arguments
 709 # =====================
 710
 711 def _get_action_name(argument):
 712     if argument is None:
 713         return None
 714     elif argument.option_strings:
 715         return  '/'.join(argument.option_strings)
 716     elif argument.metavar not in (None, SUPPRESS):
 717         return argument.metavar
 718     elif argument.dest not in (None, SUPPRESS):
 719         return argument.dest
 720     else:
 721         return None
 722
 723
 724 class ArgumentError(Exception):
 725     """An error from creating or using an argument (optional or positional).
 726
 727     The string value of this exception is the message, augmented with
 728     information about the argument that caused it.
 729     """
 730
 731     def __init__(self, argument, message):
 732         self.argument_name = _get_action_name(argument)
 733         self.message = message
 734
 735     def __str__(self):
 736         if self.argument_name is None:
 737             format = '%(message)s'
 738         else:
 739             format = 'argument %(argument_name)s: %(message)s'
 740         return format % dict(message=self.message,
 741                              argument_name=self.argument_name)
 742
 743
 744 class ArgumentTypeError(Exception):
 745     """An error from trying to convert a command line string to a type."""
 746     pass
 747
 748
 749 # ==============
 750 # Action classes
 751 # ==============
 752
 753 class Action(_AttributeHolder):
 754     """Information about how to convert command line strings to Python objects.
 755
 756     Action objects are used by an ArgumentParser to represent the information
 757     needed to parse a single argument from one or more strings from the
 758     command line. The keyword arguments to the Action constructor are also
 759     all attributes of Action instances.
 760
 761     Keyword Arguments:
 762
 763         - option_strings -- A list of command-line option strings which
 764             should be associated with this action.
 765
 766         - dest -- The name of the attribute to hold the created object(s)
 767
 768         - nargs -- The number of command-line arguments that should be
 769             consumed. By default, one argument will be consumed and a single
 770             value will be produced.  Other values include:
 771                 - N (an integer) consumes N arguments (and produces a list)
 772                 - '?' consumes zero or one arguments
 773                 - '*' consumes zero or more arguments (and produces a list)
 774                 - '+' consumes one or more arguments (and produces a list)
 775             Note that the difference between the default and nargs=1 is that
 776             with the default, a single value will be produced, while with
 777             nargs=1, a list containing a single value will be produced.
 778
 779         - const -- The value to be produced if the option is specified and the
 780             option uses an action that takes no values.
 781
 782         - default -- The value to be produced if the option is not specified.
 783
 784         - type -- The type which the command-line arguments should be converted
 785             to, should be one of 'string', 'int', 'float', 'complex' or a
 786             callable object that accepts a single string argument. If None,
 787             'string' is assumed.
 788
 789         - choices -- A container of values that should be allowed. If not None,
 790             after a command-line argument has been converted to the appropriate
 791             type, an exception will be raised if it is not a member of this
 792             collection.
 793
 794         - required -- True if the action must always be specified at the
 795             command line. This is only meaningful for optional command-line
 796             arguments.
 797
 798         - help -- The help string describing the argument.
 799
 800         - metavar -- The name to be used for the option's argument with the
 801             help string. If None, the 'dest' value will be used as the name.
 802     """
 803
 804     def __init__(self,
 805                  option_strings,
 806                  dest,
 807                  nargs=None,
 808                  const=None,
 809                  default=None,
 810                  type=None,
 811                  choices=None,
 812                  required=False,
 813                  help=None,
 814                  metavar=None):
 815         self.option_strings = option_strings
 816         self.dest = dest
 817         self.nargs = nargs
 818         self.const = const
 819         self.default = default
 820         self.type = type
 821         self.choices = choices
 822         self.required = required
 823         self.help = help
 824         self.metavar = metavar
 825
 826     def _get_kwargs(self):
 827         names = [
 828             'option_strings',
 829             'dest',
 830             'nargs',
 831             'const',
 832             'default',
 833             'type',
 834             'choices',
 835             'help',
 836             'metavar',
 837         ]
 838         return [(name, getattr(self, name)) for name in names]
 839
 840     def __call__(self, parser, namespace, values, option_string=None):
 841         raise NotImplementedError(_('.__call__() not defined'))
 842
 843
 844 class _StoreAction(Action):
 845
 846     def __init__(self,
 847                  option_strings,
 848                  dest,
 849                  nargs=None,
 850                  const=None,
 851                  default=None,
 852                  type=None,
 853                  choices=None,
 854                  required=False,
 855                  help=None,
 856                  metavar=None):
 857         if nargs == 0:
 858             raise ValueError('nargs for store actions must be > 0; if you '
 859                              'have nothing to store, actions such as store '
 860                              'true or store const may be more appropriate')
 861         if const is not None and nargs != OPTIONAL:
 862             raise ValueError('nargs must be %r to supply const' % OPTIONAL)
 863         super(_StoreAction, self).__init__(
 864             option_strings=option_strings,
 865             dest=dest,
 866             nargs=nargs,
 867             const=const,
 868             default=default,
 869             type=type,
 870             choices=choices,
 871             required=required,
 872             help=help,
 873             metavar=metavar)
 874
 875     def __call__(self, parser, namespace, values, option_string=None):
 876         setattr(namespace, self.dest, values)
 877
 878
 879 class _StoreConstAction(Action):
 880
 881     def __init__(self,
 882                  option_strings,
 883                  dest,
 884                  const,
 885                  default=None,
 886                  required=False,
 887                  help=None,
 888                  metavar=None):
 889         super(_StoreConstAction, self).__init__(
 890             option_strings=option_strings,
 891             dest=dest,
 892             nargs=0,
 893             const=const,
 894             default=default,
 895             required=required,
 896             help=help)
 897
 898     def __call__(self, parser, namespace, values, option_string=None):
 899         setattr(namespace, self.dest, self.const)
 900
 901
 902 class _StoreTrueAction(_StoreConstAction):
 903
 904     def __init__(self,
 905                  option_strings,
 906                  dest,
 907                  default=False,
 908                  required=False,
 909                  help=None):
 910         super(_StoreTrueAction, self).__init__(
 911             option_strings=option_strings,
 912             dest=dest,
 913             const=True,
 914             default=default,
 915             required=required,
 916             help=help)
 917
 918
 919 class _StoreFalseAction(_StoreConstAction):
 920
 921     def __init__(self,
 922                  option_strings,
 923                  dest,
 924                  default=True,
 925                  required=False,
 926                  help=None):
 927         super(_StoreFalseAction, self).__init__(
 928             option_strings=option_strings,
 929             dest=dest,
 930             const=False,
 931             default=default,
 932             required=required,
 933             help=help)
 934
 935
 936 class _AppendAction(Action):
 937
 938     def __init__(self,
 939                  option_strings,
 940                  dest,
 941                  nargs=None,
 942                  const=None,
 943                  default=None,
 944                  type=None,
 945                  choices=None,
 946                  required=False,
 947                  help=None,
 948                  metavar=None):
 949         if nargs == 0:
 950             raise ValueError('nargs for append actions must be > 0; if arg '
 951                              'strings are not supplying the value to append, '
 952                              'the append const action may be more appropriate')
 953         if const is not None and nargs != OPTIONAL:
 954             raise ValueError('nargs must be %r to supply const' % OPTIONAL)
 955         super(_AppendAction, self).__init__(
 956             option_strings=option_strings,
 957             dest=dest,
 958             nargs=nargs,
 959             const=const,
 960             default=default,
 961             type=type,
 962             choices=choices,
 963             required=required,
 964             help=help,
 965             metavar=metavar)
 966
 967     def __call__(self, parser, namespace, values, option_string=None):
 968         items = _copy.copy(_ensure_value(namespace, self.dest, []))
 969         items.append(values)
 970         setattr(namespace, self.dest, items)
 971
 972
 973 class _AppendConstAction(Action):
 974
 975     def __init__(self,
 976                  option_strings,
 977                  dest,
 978                  const,
 979                  default=None,
 980                  required=False,
 981                  help=None,
 982                  metavar=None):
 983         super(_AppendConstAction, self).__init__(
 984             option_strings=option_strings,
 985             dest=dest,
 986             nargs=0,
 987             const=const,
 988             default=default,
 989             required=required,
 990             help=help,
 991             metavar=metavar)
 992
 993     def __call__(self, parser, namespace, values, option_string=None):
 994         items = _copy.copy(_ensure_value(namespace, self.dest, []))
 995         items.append(self.const)
 996         setattr(namespace, self.dest, items)
 997
 998
 999 class _CountAction(Action):
1000
1001     def __init__(self,
1002                  option_strings,
1003                  dest,
1004                  default=None,
1005                  required=False,
1006                  help=None):
1007         super(_CountAction, self).__init__(
1008             option_strings=option_strings,
1009             dest=dest,
1010             nargs=0,
1011             default=default,
1012             required=required,
1013             help=help)
1014
1015     def __call__(self, parser, namespace, values, option_string=None):
1016         new_count = _ensure_value(namespace, self.dest, 0) + 1
1017         setattr(namespace, self.dest, new_count)
1018
1019
1020 class _HelpAction(Action):
1021
1022     def __init__(self,
1023                  option_strings,
1024                  dest=SUPPRESS,
1025                  default=SUPPRESS,
1026                  help=None):
1027         super(_HelpAction, self).__init__(
1028             option_strings=option_strings,
1029             dest=dest,
1030             default=default,
1031             nargs=0,
1032             help=help)
1033
1034     def __call__(self, parser, namespace, values, option_string=None):
1035         parser.print_help()
1036         parser.exit()
1037
1038
1039 class _VersionAction(Action):
1040
1041     def __init__(self,
1042                  option_strings,
1043                  version=None,
1044                  dest=SUPPRESS,
1045                  default=SUPPRESS,
1046                  help="show program's version number and exit"):
1047         super(_VersionAction, self).__init__(
1048             option_strings=option_strings,
1049             dest=dest,
1050             default=default,
1051             nargs=0,
1052             help=help)
1053         self.version = version
1054
1055     def __call__(self, parser, namespace, values, option_string=None):
1056         version = self.version
1057         if version is None:
1058             version = parser.version
1059         formatter = parser._get_formatter()
1060         formatter.add_text(version)
1061         parser.exit(message=formatter.format_help())
1062
1063
1064 class _SubParsersAction(Action):
1065
1066     class _ChoicesPseudoAction(Action):
1067
1068         def __init__(self, name, aliases, help):
1069             metavar = dest = name
1070             if aliases:
1071                 metavar += ' (%s)' % ', '.join(aliases)
1072             sup = super(_SubParsersAction._ChoicesPseudoAction, self)
1073             sup.__init__(option_strings=[], dest=dest, help=help,
1074                         metavar=metavar)
1075
1076     def __init__(self,
1077                  option_strings,
1078                  prog,
1079                  parser_class,
1080                  dest=SUPPRESS,
1081                  help=None,
1082                  metavar=None):
1083
1084         self._prog_prefix = prog
1085         self._parser_class = parser_class
1086         self._name_parser_map = {}
1087         self._choices_actions = []
1088
1089         super(_SubParsersAction, self).__init__(
1090             option_strings=option_strings,
1091             dest=dest,
1092             nargs=PARSER,
1093             choices=self._name_parser_map,
1094             help=help,
1095             metavar=metavar)
1096
1097     def add_parser(self, name, **kwargs):
1098         # set prog from the existing prefix
1099         if kwargs.get('prog') is None:
1100             kwargs['prog'] = '%s %s' % (self._prog_prefix, name)
1101
1102         aliases = kwargs.pop('aliases', ())
1103
1104         # create a pseudo-action to hold the choice help
1105         if 'help' in kwargs:
1106             help = kwargs.pop('help')
1107             choice_action = self._ChoicesPseudoAction(name, aliases, help)
1108             self._choices_actions.append(choice_action)
1109
1110         # create the parser and add it to the map
1111         parser = self._parser_class(**kwargs)
1112         self._name_parser_map[name] = parser
1113
1114         # make parser available under aliases also
1115         for alias in aliases:
1116             self._name_parser_map[alias] = parser
1117
1118         return parser
1119
1120     def _get_subactions(self):
1121         return self._choices_actions
1122
1123     def __call__(self, parser, namespace, values, option_string=None):
1124         parser_name = values[0]
1125         arg_strings = values[1:]
1126
1127         # set the parser name if requested
1128         if self.dest is not SUPPRESS:
1129             setattr(namespace, self.dest, parser_name)
1130
1131         # select the parser
1132         try:
1133             parser = self._name_parser_map[parser_name]
1134         except KeyError:
1135             tup = parser_name, ', '.join(self._name_parser_map)
1136             msg = _('unknown parser %r (choices: %s)' % tup)
1137             raise ArgumentError(self, msg)
1138
1139         # parse all the remaining options into the namespace
1140         # store any unrecognized options on the object, so that the top
1141         # level parser can decide what to do with them
1142         namespace, arg_strings = parser.parse_known_args(arg_strings, namespace)
1143         if arg_strings:
1144             vars(namespace).setdefault(_UNRECOGNIZED_ARGS_ATTR, [])
1145             getattr(namespace, _UNRECOGNIZED_ARGS_ATTR).extend(arg_strings)
1146
1147
1148 # ==============
1149 # Type classes
1150 # ==============
1151
1152 class FileType(object):
1153     """Factory for creating file object types
1154
1155     Instances of FileType are typically passed as type= arguments to the
1156     ArgumentParser add_argument() method.
1157
1158     Keyword Arguments:
1159         - mode -- A string indicating how the file is to be opened. Accepts the
1160             same values as the builtin open() function.
1161         - bufsize -- The file's desired buffer size. Accepts the same values as
1162             the builtin open() function.
1163     """
1164
1165     def __init__(self, mode='r', bufsize=None):
1166         self._mode = mode
1167         self._bufsize = bufsize
1168
1169     def __call__(self, string):
1170         # the special argument "-" means sys.std{in,out}
1171         if string == '-':
1172             if 'r' in self._mode:
1173                 return _sys.stdin
1174             elif 'w' in self._mode:
1175                 return _sys.stdout
1176             else:
1177                 msg = _('argument "-" with mode %r' % self._mode)
1178                 raise ValueError(msg)
1179
1180         try:
1181             # all other arguments are used as file names
1182             if self._bufsize:
1183                 return open(string, self._mode, self._bufsize)
1184             else:
1185                 return open(string, self._mode)
1186         except IOError:
1187             err = _sys.exc_info()[1]
1188             message = _("can't open '%s': %s")
1189             raise ArgumentTypeError(message % (string, err))
1190
1191     def __repr__(self):
1192         args = [self._mode, self._bufsize]
1193         args_str = ', '.join([repr(arg) for arg in args if arg is not None])
1194         return '%s(%s)' % (type(self).__name__, args_str)
1195
1196 # ===========================
1197 # Optional and Positional Parsing
1198 # ===========================
1199
1200 class Namespace(_AttributeHolder):
1201     """Simple object for storing attributes.
1202
1203     Implements equality by attribute names and values, and provides a simple
1204     string representation.
1205     """
1206
1207     def __init__(self, **kwargs):
1208         for name in kwargs:
1209             setattr(self, name, kwargs[name])
1210
1211     __hash__ = None
1212
1213     def __eq__(self, other):
1214         return vars(self) == vars(other)
1215
1216     def __ne__(self, other):
1217         return not (self == other)
1218
1219     def __contains__(self, key):
1220         return key in self.__dict__
1221
1222
1223 class _ActionsContainer(object):
1224
1225     def __init__(self,
1226                  description,
1227                  prefix_chars,
1228                  argument_default,
1229                  conflict_handler):
1230         super(_ActionsContainer, self).__init__()
1231
1232         self.description = description
1233         self.argument_default = argument_default
1234         self.prefix_chars = prefix_chars
1235         self.conflict_handler = conflict_handler
1236
1237         # set up registries
1238         self._registries = {}
1239
1240         # register actions
1241         self.register('action', None, _StoreAction)
1242         self.register('action', 'store', _StoreAction)
1243         self.register('action', 'store_const', _StoreConstAction)
1244         self.register('action', 'store_true', _StoreTrueAction)
1245         self.register('action', 'store_false', _StoreFalseAction)
1246         self.register('action', 'append', _AppendAction)
1247         self.register('action', 'append_const', _AppendConstAction)
1248         self.register('action', 'count', _CountAction)
1249         self.register('action', 'help', _HelpAction)
1250         self.register('action', 'version', _VersionAction)
1251         self.register('action', 'parsers', _SubParsersAction)
1252
1253         # raise an exception if the conflict handler is invalid
1254         self._get_handler()
1255
1256         # action storage
1257         self._actions = []
1258         self._option_string_actions = {}
1259
1260         # groups
1261         self._action_groups = []
1262         self._mutually_exclusive_groups = []
1263
1264         # defaults storage
1265         self._defaults = {}
1266
1267         # determines whether an "option" looks like a negative number
1268         self._negative_number_matcher = _re.compile(r'^-\d+$|^-\d*\.\d+$')
1269
1270         # whether or not there are any optionals that look like negative
1271         # numbers -- uses a list so it can be shared and edited
1272         self._has_negative_number_optionals = []
1273
1274     # ====================
1275     # Registration methods
1276     # ====================
1277     def register(self, registry_name, value, object):
1278         registry = self._registries.setdefault(registry_name, {})
1279         registry[value] = object
1280
1281     def _registry_get(self, registry_name, value, default=None):
1282         return self._registries[registry_name].get(value, default)
1283
1284     # ==================================
1285     # Namespace default accessor methods
1286     # ==================================
1287     def set_defaults(self, **kwargs):
1288         self._defaults.update(kwargs)
1289
1290         # if these defaults match any existing arguments, replace
1291         # the previous default on the object with the new one
1292         for action in self._actions:
1293             if action.dest in kwargs:
1294                 action.default = kwargs[action.dest]
1295
1296     def get_default(self, dest):
1297         for action in self._actions:
1298             if action.dest == dest and action.default is not None:
1299                 return action.default
1300         return self._defaults.get(dest, None)
1301
1302
1303     # =======================
1304     # Adding argument actions
1305     # =======================
1306     def add_argument(self, *args, **kwargs):
1307         """
1308         add_argument(dest, ..., name=value, ...)
1309         add_argument(option_string, option_string, ..., name=value, ...)
1310         """
1311
1312         # if no positional args are supplied or only one is supplied and
1313         # it doesn't look like an option string, parse a positional
1314         # argument
1315         chars = self.prefix_chars
1316         if not args or len(args) == 1 and args[0][0] not in chars:
1317             if args and 'dest' in kwargs:
1318                 raise ValueError('dest supplied twice for positional argument')
1319             kwargs = self._get_positional_kwargs(*args, **kwargs)
1320
1321         # otherwise, we're adding an optional argument
1322         else:
1323             kwargs = self._get_optional_kwargs(*args, **kwargs)
1324
1325         # if no default was supplied, use the parser-level default
1326         if 'default' not in kwargs:
1327             dest = kwargs['dest']
1328             if dest in self._defaults:
1329                 kwargs['default'] = self._defaults[dest]
1330             elif self.argument_default is not None:
1331                 kwargs['default'] = self.argument_default
1332
1333         # create the action object, and add it to the parser
1334         action_class = self._pop_action_class(kwargs)
1335         if not _callable(action_class):
1336             raise ValueError('unknown action "%s"' % action_class)
1337         action = action_class(**kwargs)
1338
1339         # raise an error if the action type is not callable
1340         type_func = self._registry_get('type', action.type, action.type)
1341         if not _callable(type_func):
1342             raise ValueError('%r is not callable' % type_func)
1343
1344         return self._add_action(action)
1345
1346     def add_argument_group(self, *args, **kwargs):
1347         group = _ArgumentGroup(self, *args, **kwargs)
1348         self._action_groups.append(group)
1349         return group
1350
1351     def add_mutually_exclusive_group(self, **kwargs):
1352         group = _MutuallyExclusiveGroup(self, **kwargs)
1353         self._mutually_exclusive_groups.append(group)
1354         return group
1355
1356     def _add_action(self, action):
1357         # resolve any conflicts
1358         self._check_conflict(action)
1359
1360         # add to actions list
1361         self._actions.append(action)
1362         action.container = self
1363
1364         # index the action by any option strings it has
1365         for option_string in action.option_strings:
1366             self._option_string_actions[option_string] = action
1367
1368         # set the flag if any option strings look like negative numbers
1369         for option_string in action.option_strings:
1370             if self._negative_number_matcher.match(option_string):
1371                 if not self._has_negative_number_optionals:
1372                     self._has_negative_number_optionals.append(True)
1373
1374         # return the created action
1375         return action
1376
1377     def _remove_action(self, action):
1378         self._actions.remove(action)
1379
1380     def _add_container_actions(self, container):
1381         # collect groups by titles
1382         title_group_map = {}
1383         for group in self._action_groups:
1384             if group.title in title_group_map:
1385                 msg = _('cannot merge actions - two groups are named %r')
1386                 raise ValueError(msg % (group.title))
1387             title_group_map[group.title] = group
1388
1389         # map each action to its group
1390         group_map = {}
1391         for group in container._action_groups:
1392
1393             # if a group with the title exists, use that, otherwise
1394             # create a new group matching the container's group
1395             if group.title not in title_group_map:
1396                 title_group_map[group.title] = self.add_argument_group(
1397                     title=group.title,
1398                     description=group.description,
1399                     conflict_handler=group.conflict_handler)
1400
1401             # map the actions to their new group
1402             for action in group._group_actions:
1403                 group_map[action] = title_group_map[group.title]
1404
1405         # add container's mutually exclusive groups
1406         # NOTE: if add_mutually_exclusive_group ever gains title= and
1407         # description= then this code will need to be expanded as above
1408         for group in container._mutually_exclusive_groups:
1409             mutex_group = self.add_mutually_exclusive_group(
1410                 required=group.required)
1411
1412             # map the actions to their new mutex group
1413             for action in group._group_actions:
1414                 group_map[action] = mutex_group
1415
1416         # add all actions to this container or their group
1417         for action in container._actions:
1418             group_map.get(action, self)._add_action(action)
1419
1420     def _get_positional_kwargs(self, dest, **kwargs):
1421         # make sure required is not specified
1422         if 'required' in kwargs:
1423             msg = _("'required' is an invalid argument for positionals")
1424             raise TypeError(msg)
1425
1426         # mark positional arguments as required if at least one is
1427         # always required
1428         if kwargs.get('nargs') not in [OPTIONAL, ZERO_OR_MORE]:
1429             kwargs['required'] = True
1430         if kwargs.get('nargs') == ZERO_OR_MORE and 'default' not in kwargs:
1431             kwargs['required'] = True
1432
1433         # return the keyword arguments with no option strings
1434         return dict(kwargs, dest=dest, option_strings=[])
1435
1436     def _get_optional_kwargs(self, *args, **kwargs):
1437         # determine short and long option strings
1438         option_strings = []
1439         long_option_strings = []
1440         for option_string in args:
1441             # error on strings that don't start with an appropriate prefix
1442             if not option_string[0] in self.prefix_chars:
1443                 msg = _('invalid option string %r: '
1444                         'must start with a character %r')
1445                 tup = option_string, self.prefix_chars
1446                 raise ValueError(msg % tup)
1447
1448             # strings starting with two prefix characters are long options
1449             option_strings.append(option_string)
1450             if option_string[0] in self.prefix_chars:
1451                 if len(option_string) > 1:
1452                     if option_string[1] in self.prefix_chars:
1453                         long_option_strings.append(option_string)
1454
1455         # infer destination, '--foo-bar' -> 'foo_bar' and '-x' -> 'x'
1456         dest = kwargs.pop('dest', None)
1457         if dest is None:
1458             if long_option_strings:
1459                 dest_option_string = long_option_strings[0]
1460             else:
1461                 dest_option_string = option_strings[0]
1462             dest = dest_option_string.lstrip(self.prefix_chars)
1463             if not dest:
1464                 msg = _('dest= is required for options like %r')
1465                 raise ValueError(msg % option_string)
1466             dest = dest.replace('-', '_')
1467
1468         # return the updated keyword arguments
1469         return dict(kwargs, dest=dest, option_strings=option_strings)
1470
1471     def _pop_action_class(self, kwargs, default=None):
1472         action = kwargs.pop('action', default)
1473         return self._registry_get('action', action, action)
1474
1475     def _get_handler(self):
1476         # determine function from conflict handler string
1477         handler_func_name = '_handle_conflict_%s' % self.conflict_handler
1478         try:
1479             return getattr(self, handler_func_name)
1480         except AttributeError:
1481             msg = _('invalid conflict_resolution value: %r')
1482             raise ValueError(msg % self.conflict_handler)
1483
1484     def _check_conflict(self, action):
1485
1486         # find all options that conflict with this option
1487         confl_optionals = []
1488         for option_string in action.option_strings:
1489             if option_string in self._option_string_actions:
1490                 confl_optional = self._option_string_actions[option_string]
1491                 confl_optionals.append((option_string, confl_optional))
1492
1493         # resolve any conflicts
1494         if confl_optionals:
1495             conflict_handler = self._get_handler()
1496             conflict_handler(action, confl_optionals)
1497
1498     def _handle_conflict_error(self, action, conflicting_actions):
1499         message = _('conflicting option string(s): %s')
1500         conflict_string = ', '.join([option_string
1501                                      for option_string, action
1502                                      in conflicting_actions])
1503         raise ArgumentError(action, message % conflict_string)
1504
1505     def _handle_conflict_resolve(self, action, conflicting_actions):
1506
1507         # remove all conflicting options
1508         for option_string, action in conflicting_actions:
1509
1510             # remove the conflicting option
1511             action.option_strings.remove(option_string)
1512             self._option_string_actions.pop(option_string, None)
1513
1514             # if the option now has no option string, remove it from the
1515             # container holding it
1516             if not action.option_strings:
1517                 action.container._remove_action(action)
1518
1519
1520 class _ArgumentGroup(_ActionsContainer):
1521
1522     def __init__(self, container, title=None, description=None, **kwargs):
1523         # add any missing keyword arguments by checking the container
1524         update = kwargs.setdefault
1525         update('conflict_handler', container.conflict_handler)
1526         update('prefix_chars', container.prefix_chars)
1527         update('argument_default', container.argument_default)
1528         super_init = super(_ArgumentGroup, self).__init__
1529         super_init(description=description, **kwargs)
1530
1531         # group attributes
1532         self.title = title
1533         self._group_actions = []
1534
1535         # share most attributes with the container
1536         self._registries = container._registries
1537         self._actions = container._actions
1538         self._option_string_actions = container._option_string_actions
1539         self._defaults = container._defaults
1540         self._has_negative_number_optionals = \
1541             container._has_negative_number_optionals
1542
1543     def _add_action(self, action):
1544         action = super(_ArgumentGroup, self)._add_action(action)
1545         self._group_actions.append(action)
1546         return action
1547
1548     def _remove_action(self, action):
1549         super(_ArgumentGroup, self)._remove_action(action)
1550         self._group_actions.remove(action)
1551
1552
1553 class _MutuallyExclusiveGroup(_ArgumentGroup):
1554
1555     def __init__(self, container, required=False):
1556         super(_MutuallyExclusiveGroup, self).__init__(container)
1557         self.required = required
1558         self._container = container
1559
1560     def _add_action(self, action):
1561         if action.required:
1562             msg = _('mutually exclusive arguments must be optional')
1563             raise ValueError(msg)
1564         action = self._container._add_action(action)
1565         self._group_actions.append(action)
1566         return action
1567
1568     def _remove_action(self, action):
1569         self._container._remove_action(action)
1570         self._group_actions.remove(action)
1571
1572
1573 class ArgumentParser(_AttributeHolder, _ActionsContainer):
1574     """Object for parsing command line strings into Python objects.
1575
1576     Keyword Arguments:
1577         - prog -- The name of the program (default: sys.argv[0])
1578         - usage -- A usage message (default: auto-generated from arguments)
1579         - description -- A description of what the program does
1580         - epilog -- Text following the argument descriptions
1581         - parents -- Parsers whose arguments should be copied into this one
1582         - formatter_class -- HelpFormatter class for printing help messages
1583         - prefix_chars -- Characters that prefix optional arguments
1584         - fromfile_prefix_chars -- Characters that prefix files containing
1585             additional arguments
1586         - argument_default -- The default value for all arguments
1587         - conflict_handler -- String indicating how to handle conflicts
1588         - add_help -- Add a -h/-help option
1589     """
1590
1591     def __init__(self,
1592                  prog=None,
1593                  usage=None,
1594                  description=None,
1595                  epilog=None,
1596                  version=None,
1597                  parents=[],
1598                  formatter_class=HelpFormatter,
1599                  prefix_chars='-',
1600                  fromfile_prefix_chars=None,
1601                  argument_default=None,
1602                  conflict_handler='error',
1603                  add_help=True):
1604
1605         if version is not None:
1606             import warnings
1607             warnings.warn(
1608                 """The "version" argument to ArgumentParser is deprecated. """
1609                 """Please use """
1610                 """"add_argument(..., action='version', version="N", ...)" """
1611                 """instead""", DeprecationWarning)
1612
1613         superinit = super(ArgumentParser, self).__init__
1614         superinit(description=description,
1615                   prefix_chars=prefix_chars,
1616                   argument_default=argument_default,
1617                   conflict_handler=conflict_handler)
1618
1619         # default setting for prog
1620         if prog is None:
1621             prog = _os.path.basename(_sys.argv[0])
1622
1623         self.prog = prog
1624         self.usage = usage
1625         self.epilog = epilog
1626         self.version = version
1627         self.formatter_class = formatter_class
1628         self.fromfile_prefix_chars = fromfile_prefix_chars
1629         self.add_help = add_help
1630
1631         add_group = self.add_argument_group
1632         self._positionals = add_group(_('positional arguments'))
1633         self._optionals = add_group(_('optional arguments'))
1634         self._subparsers = None
1635
1636         # register types
1637         def identity(string):
1638             return string
1639         self.register('type', None, identity)
1640
1641         # add help and version arguments if necessary
1642         # (using explicit default to override global argument_default)
1643         if '-' in prefix_chars:
1644             default_prefix = '-'
1645         else:
1646             default_prefix = prefix_chars[0]
1647         if self.add_help:
1648             self.add_argument(
1649                 default_prefix+'h', default_prefix*2+'help',
1650                 action='help', default=SUPPRESS,
1651                 help=_('show this help message and exit'))
1652         if self.version:
1653             self.add_argument(
1654                 default_prefix+'v', default_prefix*2+'version',
1655                 action='version', default=SUPPRESS,
1656                 version=self.version,
1657                 help=_("show program's version number and exit"))
1658
1659         # add parent arguments and defaults
1660         for parent in parents:
1661             self._add_container_actions(parent)
1662             try:
1663                 defaults = parent._defaults
1664             except AttributeError:
1665                 pass
1666             else:
1667                 self._defaults.update(defaults)
1668
1669     # =======================
1670     # Pretty __repr__ methods
1671     # =======================
1672     def _get_kwargs(self):
1673         names = [
1674             'prog',
1675             'usage',
1676             'description',
1677             'version',
1678             'formatter_class',
1679             'conflict_handler',
1680             'add_help',
1681         ]
1682         return [(name, getattr(self, name)) for name in names]
1683
1684     # ==================================
1685     # Optional/Positional adding methods
1686     # ==================================
1687     def add_subparsers(self, **kwargs):
1688         if self._subparsers is not None:
1689             self.error(_('cannot have multiple subparser arguments'))
1690
1691         # add the parser class to the arguments if it's not present
1692         kwargs.setdefault('parser_class', type(self))
1693
1694         if 'title' in kwargs or 'description' in kwargs:
1695             title = _(kwargs.pop('title', 'subcommands'))
1696             description = _(kwargs.pop('description', None))
1697             self._subparsers = self.add_argument_group(title, description)
1698         else:
1699             self._subparsers = self._positionals
1700
1701         # prog defaults to the usage message of this parser, skipping
1702         # optional arguments and with no "usage:" prefix
1703         if kwargs.get('prog') is None:
1704             formatter = self._get_formatter()
1705             positionals = self._get_positional_actions()
1706             groups = self._mutually_exclusive_groups
1707             formatter.add_usage(self.usage, positionals, groups, '')
1708             kwargs['prog'] = formatter.format_help().strip()
1709
1710         # create the parsers action and add it to the positionals list
1711         parsers_class = self._pop_action_class(kwargs, 'parsers')
1712         action = parsers_class(option_strings=[], **kwargs)
1713         self._subparsers._add_action(action)
1714
1715         # return the created parsers action
1716         return action
1717
1718     def _add_action(self, action):
1719         if action.option_strings:
1720             self._optionals._add_action(action)
1721         else:
1722             self._positionals._add_action(action)
1723         return action
1724
1725     def _get_optional_actions(self):
1726         return [action
1727                 for action in self._actions
1728                 if action.option_strings]
1729
1730     def _get_positional_actions(self):
1731         return [action
1732                 for action in self._actions
1733                 if not action.option_strings]
1734
1735     # =====================================
1736     # Command line argument parsing methods
1737     # =====================================
1738     def parse_args(self, args=None, namespace=None):
1739         args, argv = self.parse_known_args(args, namespace)
1740         if argv:
1741             msg = _('unrecognized arguments: %s')
1742             self.error(msg % ' '.join(argv))
1743         return args
1744
1745     def parse_known_args(self, args=None, namespace=None):
1746         # args default to the system args
1747         if args is None:
1748             args = _sys.argv[1:]
1749
1750         # default Namespace built from parser defaults
1751         if namespace is None:
1752             namespace = Namespace()
1753
1754         # add any action defaults that aren't present
1755         for action in self._actions:
1756             if action.dest is not SUPPRESS:
1757                 if not hasattr(namespace, action.dest):
1758                     if action.default is not SUPPRESS:
1759                         setattr(namespace, action.dest, action.default)
1760
1761         # add any parser defaults that aren't present
1762         for dest in self._defaults:
1763             if not hasattr(namespace, dest):
1764                 setattr(namespace, dest, self._defaults[dest])
1765
1766         # parse the arguments and exit if there are any errors
1767         try:
1768             namespace, args = self._parse_known_args(args, namespace)
1769             if hasattr(namespace, _UNRECOGNIZED_ARGS_ATTR):
1770                 args.extend(getattr(namespace, _UNRECOGNIZED_ARGS_ATTR))
1771                 delattr(namespace, _UNRECOGNIZED_ARGS_ATTR)
1772             return namespace, args
1773         except ArgumentError:
1774             err = _sys.exc_info()[1]
1775             self.error(str(err))
1776
1777     def _parse_known_args(self, arg_strings, namespace):
1778         # replace arg strings that are file references
1779         if self.fromfile_prefix_chars is not None:
1780             arg_strings = self._read_args_from_files(arg_strings)
1781
1782         # map all mutually exclusive arguments to the other arguments
1783         # they can't occur with
1784         action_conflicts = {}
1785         for mutex_group in self._mutually_exclusive_groups:
1786             group_actions = mutex_group._group_actions
1787             for i, mutex_action in enumerate(mutex_group._group_actions):
1788                 conflicts = action_conflicts.setdefault(mutex_action, [])
1789                 conflicts.extend(group_actions[:i])
1790                 conflicts.extend(group_actions[i + 1:])
1791
1792         # find all option indices, and determine the arg_string_pattern
1793         # which has an 'O' if there is an option at an index,
1794         # an 'A' if there is an argument, or a '-' if there is a '--'
1795         option_string_indices = {}
1796         arg_string_pattern_parts = []
1797         arg_strings_iter = iter(arg_strings)
1798         for i, arg_string in enumerate(arg_strings_iter):
1799
1800             # all args after -- are non-options
1801             if arg_string == '--':
1802                 arg_string_pattern_parts.append('-')
1803                 for arg_string in arg_strings_iter:
1804                     arg_string_pattern_parts.append('A')
1805
1806             # otherwise, add the arg to the arg strings
1807             # and note the index if it was an option
1808             else:
1809                 option_tuple = self._parse_optional(arg_string)
1810                 if option_tuple is None:
1811                     pattern = 'A'
1812                 else:
1813                     option_string_indices[i] = option_tuple
1814                     pattern = 'O'
1815                 arg_string_pattern_parts.append(pattern)
1816
1817         # join the pieces together to form the pattern
1818         arg_strings_pattern = ''.join(arg_string_pattern_parts)
1819
1820         # converts arg strings to the appropriate and then takes the action
1821         seen_actions = set()
1822         seen_non_default_actions = set()
1823
1824         def take_action(action, argument_strings, option_string=None):
1825             seen_actions.add(action)
1826             argument_values = self._get_values(action, argument_strings)
1827
1828             # error if this argument is not allowed with other previously
1829             # seen arguments, assuming that actions that use the default
1830             # value don't really count as "present"
1831             if argument_values is not action.default:
1832                 seen_non_default_actions.add(action)
1833                 for conflict_action in action_conflicts.get(action, []):
1834                     if conflict_action in seen_non_default_actions:
1835                         msg = _('not allowed with argument %s')
1836                         action_name = _get_action_name(conflict_action)
1837                         raise ArgumentError(action, msg % action_name)
1838
1839             # take the action if we didn't receive a SUPPRESS value
1840             # (e.g. from a default)
1841             if argument_values is not SUPPRESS:
1842                 action(self, namespace, argument_values, option_string)
1843
1844         # function to convert arg_strings into an optional action
1845         def consume_optional(start_index):
1846
1847             # get the optional identified at this index
1848             option_tuple = option_string_indices[start_index]
1849             action, option_string, explicit_arg = option_tuple
1850
1851             # identify additional optionals in the same arg string
1852             # (e.g. -xyz is the same as -x -y -z if no args are required)
1853             match_argument = self._match_argument
1854             action_tuples = []
1855             while True:
1856
1857                 # if we found no optional action, skip it
1858                 if action is None:
1859                     extras.append(arg_strings[start_index])
1860                     return start_index + 1
1861
1862                 # if there is an explicit argument, try to match the
1863                 # optional's string arguments to only this
1864                 if explicit_arg is not None:
1865                     arg_count = match_argument(action, 'A')
1866
1867                     # if the action is a single-dash option and takes no
1868                     # arguments, try to parse more single-dash options out
1869                     # of the tail of the option string
1870                     chars = self.prefix_chars
1871                     if arg_count == 0 and option_string[1] not in chars:
1872                         action_tuples.append((action, [], option_string))
1873                         char = option_string[0]
1874                         option_string = char + explicit_arg[0]
1875                         new_explicit_arg = explicit_arg[1:] or None
1876                         optionals_map = self._option_string_actions
1877                         if option_string in optionals_map:
1878                             action = optionals_map[option_string]
1879                             explicit_arg = new_explicit_arg
1880                         else:
1881                             msg = _('ignored explicit argument %r')
1882                             raise ArgumentError(action, msg % explicit_arg)
1883
1884                     # if the action expect exactly one argument, we've
1885                     # successfully matched the option; exit the loop
1886                     elif arg_count == 1:
1887                         stop = start_index + 1
1888                         args = [explicit_arg]
1889                         action_tuples.append((action, args, option_string))
1890                         break
1891
1892                     # error if a double-dash option did not use the
1893                     # explicit argument
1894                     else:
1895                         msg = _('ignored explicit argument %r')
1896                         raise ArgumentError(action, msg % explicit_arg)
1897
1898                 # if there is no explicit argument, try to match the
1899                 # optional's string arguments with the following strings
1900                 # if successful, exit the loop
1901                 else:
1902                     start = start_index + 1
1903                     selected_patterns = arg_strings_pattern[start:]
1904                     arg_count = match_argument(action, selected_patterns)
1905                     stop = start + arg_count
1906                     args = arg_strings[start:stop]
1907                     action_tuples.append((action, args, option_string))
1908                     break
1909
1910             # add the Optional to the list and return the index at which
1911             # the Optional's string args stopped
1912             assert action_tuples
1913             for action, args, option_string in action_tuples:
1914                 take_action(action, args, option_string)
1915             return stop
1916
1917         # the list of Positionals left to be parsed; this is modified
1918         # by consume_positionals()
1919         positionals = self._get_positional_actions()
1920
1921         # function to convert arg_strings into positional actions
1922         def consume_positionals(start_index):
1923             # match as many Positionals as possible
1924             match_partial = self._match_arguments_partial
1925             selected_pattern = arg_strings_pattern[start_index:]
1926             arg_counts = match_partial(positionals, selected_pattern)
1927
1928             # slice off the appropriate arg strings for each Positional
1929             # and add the Positional and its args to the list
1930             for action, arg_count in zip(positionals, arg_counts):
1931                 args = arg_strings[start_index: start_index + arg_count]
1932                 start_index += arg_count
1933                 take_action(action, args)
1934
1935             # slice off the Positionals that we just parsed and return the
1936             # index at which the Positionals' string args stopped
1937             positionals[:] = positionals[len(arg_counts):]
1938             return start_index
1939
1940         # consume Positionals and Optionals alternately, until we have
1941         # passed the last option string
1942         extras = []
1943         start_index = 0
1944         if option_string_indices:
1945             max_option_string_index = max(option_string_indices)
1946         else:
1947             max_option_string_index = -1
1948         while start_index <= max_option_string_index:
1949
1950             # consume any Positionals preceding the next option
1951             next_option_string_index = min([
1952                 index
1953                 for index in option_string_indices
1954                 if index >= start_index])
1955             if start_index != next_option_string_index:
1956                 positionals_end_index = consume_positionals(start_index)
1957
1958                 # only try to parse the next optional if we didn't consume
1959                 # the option string during the positionals parsing
1960                 if positionals_end_index > start_index:
1961                     start_index = positionals_end_index
1962                     continue
1963                 else:
1964                     start_index = positionals_end_index
1965
1966             # if we consumed all the positionals we could and we're not
1967             # at the index of an option string, there were extra arguments
1968             if start_index not in option_string_indices:
1969                 strings = arg_strings[start_index:next_option_string_index]
1970                 extras.extend(strings)
1971                 start_index = next_option_string_index
1972
1973             # consume the next optional and any arguments for it
1974             start_index = consume_optional(start_index)
1975
1976         # consume any positionals following the last Optional
1977         stop_index = consume_positionals(start_index)
1978
1979         # if we didn't consume all the argument strings, there were extras
1980         extras.extend(arg_strings[stop_index:])
1981
1982         # if we didn't use all the Positional objects, there were too few
1983         # arg strings supplied.
1984         if positionals:
1985             self.error(_('too few arguments'))
1986
1987         # make sure all required actions were present, and convert defaults.
1988         for action in self._actions:
1989             if action not in seen_actions:
1990                 if action.required:
1991                     name = _get_action_name(action)
1992                     self.error(_('argument %s is required') % name)
1993                 else:
1994                     # Convert action default now instead of doing it before
1995                     # parsing arguments to avoid calling convert functions
1996                     # twice (which may fail) if the argument was given, but
1997                     # only if it was defined already in the namespace
1998                     if (action.default is not None and
1999                             isinstance(action.default, basestring) and
2000                             hasattr(namespace, action.dest) and
2001                             action.default is getattr(namespace, action.dest)):
2002                         setattr(namespace, action.dest,
2003                                 self._get_value(action, action.default))
2004
2005         # make sure all required groups had one option present
2006         for group in self._mutually_exclusive_groups:
2007             if group.required:
2008                 for action in group._group_actions:
2009                     if action in seen_non_default_actions:
2010                         break
2011
2012                 # if no actions were used, report the error
2013                 else:
2014                     names = [_get_action_name(action)
2015                              for action in group._group_actions
2016                              if action.help is not SUPPRESS]
2017                     msg = _('one of the arguments %s is required')
2018                     self.error(msg % ' '.join(names))
2019
2020         # return the updated namespace and the extra arguments
2021         return namespace, extras
2022
2023     def _read_args_from_files(self, arg_strings):
2024         # expand arguments referencing files
2025         new_arg_strings = []
2026         for arg_string in arg_strings:
2027
2028             # for regular arguments, just add them back into the list
2029             if arg_string[0] not in self.fromfile_prefix_chars:
2030                 new_arg_strings.append(arg_string)
2031
2032             # replace arguments referencing files with the file content
2033             else:
2034                 try:
2035                     args_file = open(arg_string[1:])
2036                     try:
2037                         arg_strings = []
2038                         for arg_line in args_file.read().splitlines():
2039                             for arg in self.convert_arg_line_to_args(arg_line):
2040                                 arg_strings.append(arg)
2041                         arg_strings = self._read_args_from_files(arg_strings)
2042                         new_arg_strings.extend(arg_strings)
2043                     finally:
2044                         args_file.close()
2045                 except IOError:
2046                     err = _sys.exc_info()[1]
2047                     self.error(str(err))
2048
2049         # return the modified argument list
2050         return new_arg_strings
2051
2052     def convert_arg_line_to_args(self, arg_line):
2053         return [arg_line]
2054
2055     def _match_argument(self, action, arg_strings_pattern):
2056         # match the pattern for this action to the arg strings
2057         nargs_pattern = self._get_nargs_pattern(action)
2058         match = _re.match(nargs_pattern, arg_strings_pattern)
2059
2060         # raise an exception if we weren't able to find a match
2061         if match is None:
2062             nargs_errors = {
2063                 None: _('expected one argument'),
2064                 OPTIONAL: _('expected at most one argument'),
2065                 ONE_OR_MORE: _('expected at least one argument'),
2066             }
2067             default = _('expected %s argument(s)') % action.nargs
2068             msg = nargs_errors.get(action.nargs, default)
2069             raise ArgumentError(action, msg)
2070
2071         # return the number of arguments matched
2072         return len(match.group(1))
2073
2074     def _match_arguments_partial(self, actions, arg_strings_pattern):
2075         # progressively shorten the actions list by slicing off the
2076         # final actions until we find a match
2077         result = []
2078         for i in range(len(actions), 0, -1):
2079             actions_slice = actions[:i]
2080             pattern = ''.join([self._get_nargs_pattern(action)
2081                                for action in actions_slice])
2082             match = _re.match(pattern, arg_strings_pattern)
2083             if match is not None:
2084                 result.extend([len(string) for string in match.groups()])
2085                 break
2086
2087         # return the list of arg string counts
2088         return result
2089
2090     def _parse_optional(self, arg_string):
2091         # if it's an empty string, it was meant to be a positional
2092         if not arg_string:
2093             return None
2094
2095         # if it doesn't start with a prefix, it was meant to be positional
2096         if not arg_string[0] in self.prefix_chars:
2097             return None
2098
2099         # if the option string is present in the parser, return the action
2100         if arg_string in self._option_string_actions:
2101             action = self._option_string_actions[arg_string]
2102             return action, arg_string, None
2103
2104         # if it's just a single character, it was meant to be positional
2105         if len(arg_string) == 1:
2106             return None
2107
2108         # if the option string before the "=" is present, return the action
2109         if '=' in arg_string:
2110             option_string, explicit_arg = arg_string.split('=', 1)
2111             if option_string in self._option_string_actions:
2112                 action = self._option_string_actions[option_string]
2113                 return action, option_string, explicit_arg
2114
2115         # search through all possible prefixes of the option string
2116         # and all actions in the parser for possible interpretations
2117         option_tuples = self._get_option_tuples(arg_string)
2118
2119         # if multiple actions match, the option string was ambiguous
2120         if len(option_tuples) > 1:
2121             options = ', '.join([option_string
2122                 for action, option_string, explicit_arg in option_tuples])
2123             tup = arg_string, options
2124             self.error(_('ambiguous option: %s could match %s') % tup)
2125
2126         # if exactly one action matched, this segmentation is good,
2127         # so return the parsed action
2128         elif len(option_tuples) == 1:
2129             option_tuple, = option_tuples
2130             return option_tuple
2131
2132         # if it was not found as an option, but it looks like a negative
2133         # number, it was meant to be positional
2134         # unless there are negative-number-like options
2135         if self._negative_number_matcher.match(arg_string):
2136             if not self._has_negative_number_optionals:
2137                 return None
2138
2139         # if it contains a space, it was meant to be a positional
2140         if ' ' in arg_string:
2141             return None
2142
2143         # it was meant to be an optional but there is no such option
2144         # in this parser (though it might be a valid option in a subparser)
2145         return None, arg_string, None
2146
2147     def _get_option_tuples(self, option_string):
2148         result = []
2149
2150         # option strings starting with two prefix characters are only
2151         # split at the '='
2152         chars = self.prefix_chars
2153         if option_string[0] in chars and option_string[1] in chars:
2154             if '=' in option_string:
2155                 option_prefix, explicit_arg = option_string.split('=', 1)
2156             else:
2157                 option_prefix = option_string
2158                 explicit_arg = None
2159             for option_string in self._option_string_actions:
2160                 if option_string.startswith(option_prefix):
2161                     action = self._option_string_actions[option_string]
2162                     tup = action, option_string, explicit_arg
2163                     result.append(tup)
2164
2165         # single character options can be concatenated with their arguments
2166         # but multiple character options always have to have their argument
2167         # separate
2168         elif option_string[0] in chars and option_string[1] not in chars:
2169             option_prefix = option_string
2170             explicit_arg = None
2171             short_option_prefix = option_string[:2]
2172             short_explicit_arg = option_string[2:]
2173
2174             for option_string in self._option_string_actions:
2175                 if option_string == short_option_prefix:
2176                     action = self._option_string_actions[option_string]
2177                     tup = action, option_string, short_explicit_arg
2178                     result.append(tup)
2179                 elif option_string.startswith(option_prefix):
2180                     action = self._option_string_actions[option_string]
2181                     tup = action, option_string, explicit_arg
2182                     result.append(tup)
2183
2184         # shouldn't ever get here
2185         else:
2186             self.error(_('unexpected option string: %s') % option_string)
2187
2188         # return the collected option tuples
2189         return result
2190
2191     def _get_nargs_pattern(self, action):
2192         # in all examples below, we have to allow for '--' args
2193         # which are represented as '-' in the pattern
2194         nargs = action.nargs
2195
2196         # the default (None) is assumed to be a single argument
2197         if nargs is None:
2198             nargs_pattern = '(-*A-*)'
2199
2200         # allow zero or one arguments
2201         elif nargs == OPTIONAL:
2202             nargs_pattern = '(-*A?-*)'
2203
2204         # allow zero or more arguments
2205         elif nargs == ZERO_OR_MORE:
2206             nargs_pattern = '(-*[A-]*)'
2207
2208         # allow one or more arguments
2209         elif nargs == ONE_OR_MORE:
2210             nargs_pattern = '(-*A[A-]*)'
2211
2212         # allow any number of options or arguments
2213         elif nargs == REMAINDER:
2214             nargs_pattern = '([-AO]*)'
2215
2216         # allow one argument followed by any number of options or arguments
2217         elif nargs == PARSER:
2218             nargs_pattern = '(-*A[-AO]*)'
2219
2220         # all others should be integers
2221         else:
2222             nargs_pattern = '(-*%s-*)' % '-*'.join('A' * nargs)
2223
2224         # if this is an optional action, -- is not allowed
2225         if action.option_strings:
2226             nargs_pattern = nargs_pattern.replace('-*', '')
2227             nargs_pattern = nargs_pattern.replace('-', '')
2228
2229         # return the pattern
2230         return nargs_pattern
2231
2232     # ========================
2233     # Value conversion methods
2234     # ========================
2235     def _get_values(self, action, arg_strings):
2236         # for everything but PARSER args, strip out '--'
2237         if action.nargs not in [PARSER, REMAINDER]:
2238             arg_strings = [s for s in arg_strings if s != '--']
2239
2240         # optional argument produces a default when not present
2241         if not arg_strings and action.nargs == OPTIONAL:
2242             if action.option_strings:
2243                 value = action.const
2244             else:
2245                 value = action.default
2246             if isinstance(value, basestring):
2247                 value = self._get_value(action, value)
2248                 self._check_value(action, value)
2249
2250         # when nargs='*' on a positional, if there were no command-line
2251         # args, use the default if it is anything other than None
2252         elif (not arg_strings and action.nargs == ZERO_OR_MORE and
2253               not action.option_strings):
2254             if action.default is not None:
2255                 value = action.default
2256             else:
2257                 value = arg_strings
2258             self._check_value(action, value)
2259
2260         # single argument or optional argument produces a single value
2261         elif len(arg_strings) == 1 and action.nargs in [None, OPTIONAL]:
2262             arg_string, = arg_strings
2263             value = self._get_value(action, arg_string)
2264             self._check_value(action, value)
2265
2266         # REMAINDER arguments convert all values, checking none
2267         elif action.nargs == REMAINDER:
2268             value = [self._get_value(action, v) for v in arg_strings]
2269
2270         # PARSER arguments convert all values, but check only the first
2271         elif action.nargs == PARSER:
2272             value = [self._get_value(action, v) for v in arg_strings]
2273             self._check_value(action, value[0])
2274
2275         # all other types of nargs produce a list
2276         else:
2277             value = [self._get_value(action, v) for v in arg_strings]
2278             for v in value:
2279                 self._check_value(action, v)
2280
2281         # return the converted value
2282         return value
2283
2284     def _get_value(self, action, arg_string):
2285         type_func = self._registry_get('type', action.type, action.type)
2286         if not _callable(type_func):
2287             msg = _('%r is not callable')
2288             raise ArgumentError(action, msg % type_func)
2289
2290         # convert the value to the appropriate type
2291         try:
2292             result = type_func(arg_string)
2293
2294         # ArgumentTypeErrors indicate errors
2295         except ArgumentTypeError:
2296             name = getattr(action.type, '__name__', repr(action.type))
2297             msg = str(_sys.exc_info()[1])
2298             raise ArgumentError(action, msg)
2299
2300         # TypeErrors or ValueErrors also indicate errors
2301         except (TypeError, ValueError):
2302             name = getattr(action.type, '__name__', repr(action.type))
2303             msg = _('invalid %s value: %r')
2304             raise ArgumentError(action, msg % (name, arg_string))
2305
2306         # return the converted value
2307         return result
2308
2309     def _check_value(self, action, value):
2310         # converted value must be one of the choices (if specified)
2311         if action.choices is not None and value not in action.choices:
2312             tup = value, ', '.join(map(repr, action.choices))
2313             msg = _('invalid choice: %r (choose from %s)') % tup
2314             raise ArgumentError(action, msg)
2315
2316     # =======================
2317     # Help-formatting methods
2318     # =======================
2319     def format_usage(self):
2320         formatter = self._get_formatter()
2321         formatter.add_usage(self.usage, self._actions,
2322                             self._mutually_exclusive_groups)
2323         return formatter.format_help()
2324
2325     def format_help(self):
2326         formatter = self._get_formatter()
2327
2328         # usage
2329         formatter.add_usage(self.usage, self._actions,
2330                             self._mutually_exclusive_groups)
2331
2332         # description
2333         formatter.add_text(self.description)
2334
2335         # positionals, optionals and user-defined groups
2336         for action_group in self._action_groups:
2337             formatter.start_section(action_group.title)
2338             formatter.add_text(action_group.description)
2339             formatter.add_arguments(action_group._group_actions)
2340             formatter.end_section()
2341
2342         # epilog
2343         formatter.add_text(self.epilog)
2344
2345         # determine help from format above
2346         return formatter.format_help()
2347
2348     def format_version(self):
2349         import warnings
2350         warnings.warn(
2351             'The format_version method is deprecated -- the "version" '
2352             'argument to ArgumentParser is no longer supported.',
2353             DeprecationWarning)
2354         formatter = self._get_formatter()
2355         formatter.add_text(self.version)
2356         return formatter.format_help()
2357
2358     def _get_formatter(self):
2359         return self.formatter_class(prog=self.prog)
2360
2361     # =====================
2362     # Help-printing methods
2363     # =====================
2364     def print_usage(self, file=None):
2365         if file is None:
2366             file = _sys.stdout
2367         self._print_message(self.format_usage(), file)
2368
2369     def print_help(self, file=None):
2370         if file is None:
2371             file = _sys.stdout
2372         self._print_message(self.format_help(), file)
2373
2374     def print_version(self, file=None):
2375         import warnings
2376         warnings.warn(
2377             'The print_version method is deprecated -- the "version" '
2378             'argument to ArgumentParser is no longer supported.',
2379             DeprecationWarning)
2380         self._print_message(self.format_version(), file)
2381
2382     def _print_message(self, message, file=None):
2383         if message:
2384             if file is None:
2385                 file = _sys.stderr
2386             file.write(message)
2387
2388     # ===============
2389     # Exiting methods
2390     # ===============
2391     def exit(self, status=0, message=None):
2392         if message:
2393             self._print_message(message, _sys.stderr)
2394         _sys.exit(status)
2395
2396     def error(self, message):
2397         """error(message: string)
2398
2399         Prints a usage message incorporating the message to stderr and
2400         exits.
2401
2402         If you override this in a subclass, it should not return -- it
2403         should either exit or raise an exception.
2404         """
2405         self.print_usage(_sys.stderr)
2406         self.exit(2, _('%s: error: %s\n') % (self.prog, message))