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# Author: Steven J. Bethard <steven.bethard@gmail.com>.
"""Command-line parsing library
This module is an optparse-inspired command-line parsing library that:
- handles both optional and positional arguments - produces highly informative usage messages - supports parsers that dispatch to sub-parsers
The following is a simple usage example that sums integers from thecommand-line and writes the result to a file::
parser = argparse.ArgumentParser( description='sum the integers at the command line') parser.add_argument( 'integers', metavar='int', nargs='+', type=int, help='an integer to be summed') parser.add_argument( '--log', default=sys.stdout, type=argparse.FileType('w'), help='the file where the sum should be written') args = parser.parse_args() args.log.write('%s' % sum(args.integers)) args.log.close()
The module contains the following public classes:
- ArgumentParser -- The main entry point for command-line parsing. As the example above shows, the add_argument() method is used to populate the parser with actions for optional and positional arguments. Then the parse_args() method is invoked to convert the args at the command-line into an object with attributes.
- ArgumentError -- The exception raised by ArgumentParser objects when there are errors with the parser's actions. Errors raised while parsing the command-line are caught by ArgumentParser and emitted as command-line messages.
- FileType -- A factory for defining types of files to be created. As the example above shows, instances of FileType are typically passed as the type= argument of add_argument() calls.
- Action -- The base class for parser actions. Typically actions are selected by passing strings like 'store_true' or 'append_const' to the action= argument of add_argument(). However, for greater customization of ArgumentParser actions, subclasses of Action may be defined and passed as the action= argument.
- HelpFormatter, RawDescriptionHelpFormatter, RawTextHelpFormatter, ArgumentDefaultsHelpFormatter -- Formatter classes which may be passed as the formatter_class= argument to the ArgumentParser constructor. HelpFormatter is the default, RawDescriptionHelpFormatter and RawTextHelpFormatter tell the parser not to change the formatting for help text, and ArgumentDefaultsHelpFormatter adds information about argument defaults to the help.
All other classes in this module are considered implementation details.(Also note that HelpFormatter and RawDescriptionHelpFormatter are onlyconsidered public as object names -- the API of the formatter objects isstill considered an implementation detail.)"""
__version__ = '1.1'__all__ = [ 'ArgumentParser', 'ArgumentError', 'ArgumentTypeError', 'FileType', 'HelpFormatter', 'ArgumentDefaultsHelpFormatter', 'RawDescriptionHelpFormatter', 'RawTextHelpFormatter', 'MetavarTypeHelpFormatter', 'Namespace', 'Action', 'ONE_OR_MORE', 'OPTIONAL', 'PARSER', 'REMAINDER', 'SUPPRESS', 'ZERO_OR_MORE',]
import collections as _collectionsimport copy as _copyimport os as _osimport re as _reimport sys as _sysimport textwrap as _textwrap
from gettext import gettext as _, ngettext
SUPPRESS = '==SUPPRESS=='
OPTIONAL = '?'ZERO_OR_MORE = '*'ONE_OR_MORE = '+'PARSER = 'A...'REMAINDER = '...'_UNRECOGNIZED_ARGS_ATTR = '_unrecognized_args'
# =============================# Utility functions and classes# =============================
class _AttributeHolder(object): """Abstract base class that provides __repr__.
The __repr__ method returns a string in the format:: ClassName(attr=name, attr=name, ...) The attributes are determined either by a class-level attribute, '_kwarg_names', or by inspecting the instance __dict__. """
def __repr__(self): type_name = type(self).__name__ arg_strings = [] star_args = {} for arg in self._get_args(): arg_strings.append(repr(arg)) for name, value in self._get_kwargs(): if name.isidentifier(): arg_strings.append('%s=%r' % (name, value)) else: star_args[name] = value if star_args: arg_strings.append('**%s' % repr(star_args)) return '%s(%s)' % (type_name, ', '.join(arg_strings))
def _get_kwargs(self): return sorted(self.__dict__.items())
def _get_args(self): return []
def _ensure_value(namespace, name, value): if getattr(namespace, name, None) is None: setattr(namespace, name, value) return getattr(namespace, name)
# ===============# Formatting Help# ===============
class HelpFormatter(object): """Formatter for generating usage messages and argument help strings.
Only the name of this class is considered a public API. All the methods provided by the class are considered an implementation detail. """
def __init__(self, prog, indent_increment=2, max_help_position=24, width=None):
# default setting for width if width is None: try: width = int(_os.environ['COLUMNS']) except (KeyError, ValueError): width = 80 width -= 2
self._prog = prog self._indent_increment = indent_increment self._max_help_position = max_help_position self._max_help_position = min(max_help_position, max(width - 20, indent_increment * 2)) self._width = width
self._current_indent = 0 self._level = 0 self._action_max_length = 0
self._root_section = self._Section(self, None) self._current_section = self._root_section
self._whitespace_matcher = _re.compile(r'\s+', _re.ASCII) self._long_break_matcher = _re.compile(r'\n\n\n+')
# =============================== # Section and indentation methods # =============================== def _indent(self): self._current_indent += self._indent_increment self._level += 1
def _dedent(self): self._current_indent -= self._indent_increment assert self._current_indent >= 0, 'Indent decreased below 0.' self._level -= 1
class _Section(object):
def __init__(self, formatter, parent, heading=None): self.formatter = formatter self.parent = parent self.heading = heading self.items = []
def format_help(self): # format the indented section if self.parent is not None: self.formatter._indent() join = self.formatter._join_parts item_help = join([func(*args) for func, args in self.items]) if self.parent is not None: self.formatter._dedent()
# return nothing if the section was empty if not item_help: return ''
# add the heading if the section was non-empty if self.heading is not SUPPRESS and self.heading is not None: current_indent = self.formatter._current_indent heading = '%*s%s:\n' % (current_indent, '', self.heading) else: heading = ''
# join the section-initial newline, the heading and the help return join(['\n', heading, item_help, '\n'])
def _add_item(self, func, args): self._current_section.items.append((func, args))
# ======================== # Message building methods # ======================== def start_section(self, heading): self._indent() section = self._Section(self, self._current_section, heading) self._add_item(section.format_help, []) self._current_section = section
def end_section(self): self._current_section = self._current_section.parent self._dedent()
def add_text(self, text): if text is not SUPPRESS and text is not None: self._add_item(self._format_text, [text])
def add_usage(self, usage, actions, groups, prefix=None): if usage is not SUPPRESS: args = usage, actions, groups, prefix self._add_item(self._format_usage, args)
def add_argument(self, action): if action.help is not SUPPRESS:
# find all invocations get_invocation = self._format_action_invocation invocations = [get_invocation(action)] for subaction in self._iter_indented_subactions(action): invocations.append(get_invocation(subaction))
# update the maximum item length invocation_length = max([len(s) for s in invocations]) action_length = invocation_length + self._current_indent self._action_max_length = max(self._action_max_length, action_length)
# add the item to the list self._add_item(self._format_action, [action])
def add_arguments(self, actions): for action in actions: self.add_argument(action)
# ======================= # Help-formatting methods # ======================= def format_help(self): help = self._root_section.format_help() if help: help = self._long_break_matcher.sub('\n\n', help) help = help.strip('\n') + '\n' return help
def _join_parts(self, part_strings): return ''.join([part for part in part_strings if part and part is not SUPPRESS])
def _format_usage(self, usage, actions, groups, prefix): if prefix is None: prefix = _('usage: ')
# if usage is specified, use that if usage is not None: usage = usage % dict(prog=self._prog)
# if no optionals or positionals are available, usage is just prog elif usage is None and not actions: usage = '%(prog)s' % dict(prog=self._prog)
# if optionals and positionals are available, calculate usage elif usage is None: prog = '%(prog)s' % dict(prog=self._prog)
# split optionals from positionals optionals = [] positionals = [] for action in actions: if action.option_strings: optionals.append(action) else: positionals.append(action)
# build full usage string format = self._format_actions_usage action_usage = format(optionals + positionals, groups) usage = ' '.join([s for s in [prog, action_usage] if s])
# wrap the usage parts if it's too long text_width = self._width - self._current_indent if len(prefix) + len(usage) > text_width:
# break usage into wrappable parts part_regexp = r'\(.*?\)+|\[.*?\]+|\S+' opt_usage = format(optionals, groups) pos_usage = format(positionals, groups) opt_parts = _re.findall(part_regexp, opt_usage) pos_parts = _re.findall(part_regexp, pos_usage) assert ' '.join(opt_parts) == opt_usage assert ' '.join(pos_parts) == pos_usage
# helper for wrapping lines def get_lines(parts, indent, prefix=None): lines = [] line = [] if prefix is not None: line_len = len(prefix) - 1 else: line_len = len(indent) - 1 for part in parts: if line_len + 1 + len(part) > text_width and line: lines.append(indent + ' '.join(line)) line = [] line_len = len(indent) - 1 line.append(part) line_len += len(part) + 1 if line: lines.append(indent + ' '.join(line)) if prefix is not None: lines[0] = lines[0][len(indent):] return lines
# if prog is short, follow it with optionals or positionals if len(prefix) + len(prog) <= 0.75 * text_width: indent = ' ' * (len(prefix) + len(prog) + 1) if opt_parts: lines = get_lines([prog] + opt_parts, indent, prefix) lines.extend(get_lines(pos_parts, indent)) elif pos_parts: lines = get_lines([prog] + pos_parts, indent, prefix) else: lines = [prog]
# if prog is long, put it on its own line else: indent = ' ' * len(prefix) parts = opt_parts + pos_parts lines = get_lines(parts, indent) if len(lines) > 1: lines = [] lines.extend(get_lines(opt_parts, indent)) lines.extend(get_lines(pos_parts, indent)) lines = [prog] + lines
# join lines into usage usage = '\n'.join(lines)
# prefix with 'usage:' return '%s%s\n\n' % (prefix, usage)
def _format_actions_usage(self, actions, groups): # find group indices and identify actions in groups group_actions = set() inserts = {} for group in groups: try: start = actions.index(group._group_actions[0]) except ValueError: continue else: end = start + len(group._group_actions) if actions[start:end] == group._group_actions: for action in group._group_actions: group_actions.add(action) if not group.required: if start in inserts: inserts[start] += ' [' else: inserts[start] = '[' inserts[end] = ']' else: if start in inserts: inserts[start] += ' (' else: inserts[start] = '(' inserts[end] = ')' for i in range(start + 1, end): inserts[i] = '|'
# collect all actions format strings parts = [] for i, action in enumerate(actions):
# suppressed arguments are marked with None # remove | separators for suppressed arguments if action.help is SUPPRESS: parts.append(None) if inserts.get(i) == '|': inserts.pop(i) elif inserts.get(i + 1) == '|': inserts.pop(i + 1)
# produce all arg strings elif not action.option_strings: default = self._get_default_metavar_for_positional(action) part = self._format_args(action, default)
# if it's in a group, strip the outer [] if action in group_actions: if part[0] == '[' and part[-1] == ']': part = part[1:-1]
# add the action string to the list parts.append(part)
# produce the first way to invoke the option in brackets else: option_string = action.option_strings[0]
# if the Optional doesn't take a value, format is: # -s or --long if action.nargs == 0: part = '%s' % option_string
# if the Optional takes a value, format is: # -s ARGS or --long ARGS else: default = self._get_default_metavar_for_optional(action) args_string = self._format_args(action, default) part = '%s %s' % (option_string, args_string)
# make it look optional if it's not required or in a group if not action.required and action not in group_actions: part = '[%s]' % part
# add the action string to the list parts.append(part)
# insert things at the necessary indices for i in sorted(inserts, reverse=True): parts[i:i] = [inserts[i]]
# join all the action items with spaces text = ' '.join([item for item in parts if item is not None])
# clean up separators for mutually exclusive groups open = r'[\[(]' close = r'[\])]' text = _re.sub(r'(%s) ' % open, r'\1', text) text = _re.sub(r' (%s)' % close, r'\1', text) text = _re.sub(r'%s *%s' % (open, close), r'', text) text = _re.sub(r'\(([^|]*)\)', r'\1', text) text = text.strip()
# return the text return text
def _format_text(self, text): if '%(prog)' in text: text = text % dict(prog=self._prog) text_width = max(self._width - self._current_indent, 11) indent = ' ' * self._current_indent return self._fill_text(text, text_width, indent) + '\n\n'
def _format_action(self, action): # determine the required width and the entry label help_position = min(self._action_max_length + 2, self._max_help_position) help_width = max(self._width - help_position, 11) action_width = help_position - self._current_indent - 2 action_header = self._format_action_invocation(action)
# no help; start on same line and add a final newline if not action.help: tup = self._current_indent, '', action_header action_header = '%*s%s\n' % tup
# short action name; start on the same line and pad two spaces elif len(action_header) <= action_width: tup = self._current_indent, '', action_width, action_header action_header = '%*s%-*s ' % tup indent_first = 0
# long action name; start on the next line else: tup = self._current_indent, '', action_header action_header = '%*s%s\n' % tup indent_first = help_position
# collect the pieces of the action help parts = [action_header]
# if there was help for the action, add lines of help text if action.help: help_text = self._expand_help(action) help_lines = self._split_lines(help_text, help_width) parts.append('%*s%s\n' % (indent_first, '', help_lines[0])) for line in help_lines[1:]: parts.append('%*s%s\n' % (help_position, '', line))
# or add a newline if the description doesn't end with one elif not action_header.endswith('\n'): parts.append('\n')
# if there are any sub-actions, add their help as well for subaction in self._iter_indented_subactions(action): parts.append(self._format_action(subaction))
# return a single string return self._join_parts(parts)
def _format_action_invocation(self, action): if not action.option_strings: default = self._get_default_metavar_for_positional(action) metavar, = self._metavar_formatter(action, default)(1) return metavar
else: parts = []
# if the Optional doesn't take a value, format is: # -s, --long if action.nargs == 0: parts.extend(action.option_strings)
# if the Optional takes a value, format is: # -s ARGS, --long ARGS else: default = self._get_default_metavar_for_optional(action) args_string = self._format_args(action, default) for option_string in action.option_strings: parts.append('%s %s' % (option_string, args_string))
return ', '.join(parts)
def _metavar_formatter(self, action, default_metavar): if action.metavar is not None: result = action.metavar elif action.choices is not None: choice_strs = [str(choice) for choice in action.choices] result = '{%s}' % ','.join(choice_strs) else: result = default_metavar
def format(tuple_size): if isinstance(result, tuple): return result else: return (result, ) * tuple_size return format
def _format_args(self, action, default_metavar): get_metavar = self._metavar_formatter(action, default_metavar) if action.nargs is None: result = '%s' % get_metavar(1) elif action.nargs == OPTIONAL: result = '[%s]' % get_metavar(1) elif action.nargs == ZERO_OR_MORE: result = '[%s [%s ...]]' % get_metavar(2) elif action.nargs == ONE_OR_MORE: result = '%s [%s ...]' % get_metavar(2) elif action.nargs == REMAINDER: result = '...' elif action.nargs == PARSER: result = '%s ...' % get_metavar(1) else: formats = ['%s' for _ in range(action.nargs)] result = ' '.join(formats) % get_metavar(action.nargs) return result
def _expand_help(self, action): params = dict(vars(action), prog=self._prog) for name in list(params): if params[name] is SUPPRESS: del params[name] for name in list(params): if hasattr(params[name], '__name__'): params[name] = params[name].__name__ if params.get('choices') is not None: choices_str = ', '.join([str(c) for c in params['choices']]) params['choices'] = choices_str return self._get_help_string(action) % params
def _iter_indented_subactions(self, action): try: get_subactions = action._get_subactions except AttributeError: pass else: self._indent() yield from get_subactions() self._dedent()
def _split_lines(self, text, width): text = self._whitespace_matcher.sub(' ', text).strip() return _textwrap.wrap(text, width)
def _fill_text(self, text, width, indent): text = self._whitespace_matcher.sub(' ', text).strip() return _textwrap.fill(text, width, initial_indent=indent, subsequent_indent=indent)
def _get_help_string(self, action): return action.help
def _get_default_metavar_for_optional(self, action): return action.dest.upper()
def _get_default_metavar_for_positional(self, action): return action.dest
class RawDescriptionHelpFormatter(HelpFormatter): """Help message formatter which retains any formatting in descriptions.
Only the name of this class is considered a public API. All the methods provided by the class are considered an implementation detail. """
def _fill_text(self, text, width, indent): return ''.join(indent + line for line in text.splitlines(keepends=True))
class RawTextHelpFormatter(RawDescriptionHelpFormatter): """Help message formatter which retains formatting of all help text.
Only the name of this class is considered a public API. All the methods provided by the class are considered an implementation detail. """
def _split_lines(self, text, width): return text.splitlines()
class ArgumentDefaultsHelpFormatter(HelpFormatter): """Help message formatter which adds default values to argument help.
Only the name of this class is considered a public API. All the methods provided by the class are considered an implementation detail. """
def _get_help_string(self, action): help = action.help if '%(default)' not in action.help: if action.default is not SUPPRESS: defaulting_nargs = [OPTIONAL, ZERO_OR_MORE] if action.option_strings or action.nargs in defaulting_nargs: help += ' (default: %(default)s)' return help
class MetavarTypeHelpFormatter(HelpFormatter): """Help message formatter which uses the argument 'type' as the default
metavar value (instead of the argument 'dest')
Only the name of this class is considered a public API. All the methods provided by the class are considered an implementation detail. """
def _get_default_metavar_for_optional(self, action): return action.type.__name__
def _get_default_metavar_for_positional(self, action): return action.type.__name__
# =====================# Options and Arguments# =====================
def _get_action_name(argument): if argument is None: return None elif argument.option_strings: return '/'.join(argument.option_strings) elif argument.metavar not in (None, SUPPRESS): return argument.metavar elif argument.dest not in (None, SUPPRESS): return argument.dest else: return None
class ArgumentError(Exception): """An error from creating or using an argument (optional or positional).
The string value of this exception is the message, augmented with information about the argument that caused it. """
def __init__(self, argument, message): self.argument_name = _get_action_name(argument) self.message = message
def __str__(self): if self.argument_name is None: format = '%(message)s' else: format = 'argument %(argument_name)s: %(message)s' return format % dict(message=self.message, argument_name=self.argument_name)
class ArgumentTypeError(Exception): """An error from trying to convert a command line string to a type.""" pass
# ==============# Action classes# ==============
class Action(_AttributeHolder): """Information about how to convert command line strings to Python objects.
Action objects are used by an ArgumentParser to represent the information needed to parse a single argument from one or more strings from the command line. The keyword arguments to the Action constructor are also all attributes of Action instances.
Keyword Arguments:
- option_strings -- A list of command-line option strings which should be associated with this action.
- dest -- The name of the attribute to hold the created object(s)
- nargs -- The number of command-line arguments that should be consumed. By default, one argument will be consumed and a single value will be produced. Other values include: - N (an integer) consumes N arguments (and produces a list) - '?' consumes zero or one arguments - '*' consumes zero or more arguments (and produces a list) - '+' consumes one or more arguments (and produces a list) Note that the difference between the default and nargs=1 is that with the default, a single value will be produced, while with nargs=1, a list containing a single value will be produced.
- const -- The value to be produced if the option is specified and the option uses an action that takes no values.
- default -- The value to be produced if the option is not specified.
- type -- A callable that accepts a single string argument, and returns the converted value. The standard Python types str, int, float, and complex are useful examples of such callables. If None, str is used.
- choices -- A container of values that should be allowed. If not None, after a command-line argument has been converted to the appropriate type, an exception will be raised if it is not a member of this collection.
- required -- True if the action must always be specified at the command line. This is only meaningful for optional command-line arguments.
- help -- The help string describing the argument.
- metavar -- The name to be used for the option's argument with the help string. If None, the 'dest' value will be used as the name. """
def __init__(self, option_strings, dest, nargs=None, const=None, default=None, type=None, choices=None, required=False, help=None, metavar=None): self.option_strings = option_strings self.dest = dest self.nargs = nargs self.const = const self.default = default self.type = type self.choices = choices self.required = required self.help = help self.metavar = metavar
def _get_kwargs(self): names = [ 'option_strings', 'dest', 'nargs', 'const', 'default', 'type', 'choices', 'help', 'metavar', ] return [(name, getattr(self, name)) for name in names]
def __call__(self, parser, namespace, values, option_string=None): raise NotImplementedError(_('.__call__() not defined'))
class _StoreAction(Action):
def __init__(self, option_strings, dest, nargs=None, const=None, default=None, type=None, choices=None, required=False, help=None, metavar=None): if nargs == 0: raise ValueError('nargs for store actions must be > 0; if you ' 'have nothing to store, actions such as store ' 'true or store const may be more appropriate') if const is not None and nargs != OPTIONAL: raise ValueError('nargs must be %r to supply const' % OPTIONAL) super(_StoreAction, self).__init__( option_strings=option_strings, dest=dest, nargs=nargs, const=const, default=default, type=type, choices=choices, required=required, help=help, metavar=metavar)
def __call__(self, parser, namespace, values, option_string=None): setattr(namespace, self.dest, values)
class _StoreConstAction(Action):
def __init__(self, option_strings, dest, const, default=None, required=False, help=None, metavar=None): super(_StoreConstAction, self).__init__( option_strings=option_strings, dest=dest, nargs=0, const=const, default=default, required=required, help=help)
def __call__(self, parser, namespace, values, option_string=None): setattr(namespace, self.dest, self.const)
class _StoreTrueAction(_StoreConstAction):
def __init__(self, option_strings, dest, default=False, required=False, help=None): super(_StoreTrueAction, self).__init__( option_strings=option_strings, dest=dest, const=True, default=default, required=required, help=help)
class _StoreFalseAction(_StoreConstAction):
def __init__(self, option_strings, dest, default=True, required=False, help=None): super(_StoreFalseAction, self).__init__( option_strings=option_strings, dest=dest, const=False, default=default, required=required, help=help)
class _AppendAction(Action):
def __init__(self, option_strings, dest, nargs=None, const=None, default=None, type=None, choices=None, required=False, help=None, metavar=None): if nargs == 0: raise ValueError('nargs for append actions must be > 0; if arg ' 'strings are not supplying the value to append, ' 'the append const action may be more appropriate') if const is not None and nargs != OPTIONAL: raise ValueError('nargs must be %r to supply const' % OPTIONAL) super(_AppendAction, self).__init__( option_strings=option_strings, dest=dest, nargs=nargs, const=const, default=default, type=type, choices=choices, required=required, help=help, metavar=metavar)
def __call__(self, parser, namespace, values, option_string=None): items = _copy.copy(_ensure_value(namespace, self.dest, [])) items.append(values) setattr(namespace, self.dest, items)
class _AppendConstAction(Action):
def __init__(self, option_strings, dest, const, default=None, required=False, help=None, metavar=None): super(_AppendConstAction, self).__init__( option_strings=option_strings, dest=dest, nargs=0, const=const, default=default, required=required, help=help, metavar=metavar)
def __call__(self, parser, namespace, values, option_string=None): items = _copy.copy(_ensure_value(namespace, self.dest, [])) items.append(self.const) setattr(namespace, self.dest, items)
class _CountAction(Action):
def __init__(self, option_strings, dest, default=None, required=False, help=None): super(_CountAction, self).__init__( option_strings=option_strings, dest=dest, nargs=0, default=default, required=required, help=help)
def __call__(self, parser, namespace, values, option_string=None): new_count = _ensure_value(namespace, self.dest, 0) + 1 setattr(namespace, self.dest, new_count)
class _HelpAction(Action):
def __init__(self, option_strings, dest=SUPPRESS, default=SUPPRESS, help=None): super(_HelpAction, self).__init__( option_strings=option_strings, dest=dest, default=default, nargs=0, help=help)
def __call__(self, parser, namespace, values, option_string=None): parser.print_help() parser.exit()
class _VersionAction(Action):
def __init__(self, option_strings, version=None, dest=SUPPRESS, default=SUPPRESS, help="show program's version number and exit"): super(_VersionAction, self).__init__( option_strings=option_strings, dest=dest, default=default, nargs=0, help=help) self.version = version
def __call__(self, parser, namespace, values, option_string=None): version = self.version if version is None: version = parser.version formatter = parser._get_formatter() formatter.add_text(version) parser._print_message(formatter.format_help(), _sys.stdout) parser.exit()
class _SubParsersAction(Action):
class _ChoicesPseudoAction(Action):
def __init__(self, name, aliases, help): metavar = dest = name if aliases: metavar += ' (%s)' % ', '.join(aliases) sup = super(_SubParsersAction._ChoicesPseudoAction, self) sup.__init__(option_strings=[], dest=dest, help=help, metavar=metavar)
def __init__(self, option_strings, prog, parser_class, dest=SUPPRESS, help=None, metavar=None):
self._prog_prefix = prog self._parser_class = parser_class self._name_parser_map = _collections.OrderedDict() self._choices_actions = []
super(_SubParsersAction, self).__init__( option_strings=option_strings, dest=dest, nargs=PARSER, choices=self._name_parser_map, help=help, metavar=metavar)
def add_parser(self, name, **kwargs): # set prog from the existing prefix if kwargs.get('prog') is None: kwargs['prog'] = '%s %s' % (self._prog_prefix, name)
aliases = kwargs.pop('aliases', ())
# create a pseudo-action to hold the choice help if 'help' in kwargs: help = kwargs.pop('help') choice_action = self._ChoicesPseudoAction(name, aliases, help) self._choices_actions.append(choice_action)
# create the parser and add it to the map parser = self._parser_class(**kwargs) self._name_parser_map[name] = parser
# make parser available under aliases also for alias in aliases: self._name_parser_map[alias] = parser
return parser
def _get_subactions(self): return self._choices_actions
def __call__(self, parser, namespace, values, option_string=None): parser_name = values[0] arg_strings = values[1:]
# set the parser name if requested if self.dest is not SUPPRESS: setattr(namespace, self.dest, parser_name)
# select the parser try: parser = self._name_parser_map[parser_name] except KeyError: args = {'parser_name': parser_name, 'choices': ', '.join(self._name_parser_map)} msg = _('unknown parser %(parser_name)r (choices: %(choices)s)') % args raise ArgumentError(self, msg)
# parse all the remaining options into the namespace # store any unrecognized options on the object, so that the top # level parser can decide what to do with them
# In case this subparser defines new defaults, we parse them # in a new namespace object and then update the original # namespace for the relevant parts. subnamespace, arg_strings = parser.parse_known_args(arg_strings, None) for key, value in vars(subnamespace).items(): setattr(namespace, key, value)
if arg_strings: vars(namespace).setdefault(_UNRECOGNIZED_ARGS_ATTR, []) getattr(namespace, _UNRECOGNIZED_ARGS_ATTR).extend(arg_strings)
# ==============# Type classes# ==============
class FileType(object): """Factory for creating file object types
Instances of FileType are typically passed as type= arguments to the ArgumentParser add_argument() method.
Keyword Arguments: - mode -- A string indicating how the file is to be opened. Accepts the same values as the builtin open() function. - bufsize -- The file's desired buffer size. Accepts the same values as the builtin open() function. - encoding -- The file's encoding. Accepts the same values as the builtin open() function. - errors -- A string indicating how encoding and decoding errors are to be handled. Accepts the same value as the builtin open() function. """
def __init__(self, mode='r', bufsize=-1, encoding=None, errors=None): self._mode = mode self._bufsize = bufsize self._encoding = encoding self._errors = errors
def __call__(self, string): # the special argument "-" means sys.std{in,out} if string == '-': if 'r' in self._mode: return _sys.stdin elif 'w' in self._mode: return _sys.stdout else: msg = _('argument "-" with mode %r') % self._mode raise ValueError(msg)
# all other arguments are used as file names try: return open(string, self._mode, self._bufsize, self._encoding, self._errors) except OSError as e: message = _("can't open '%s': %s") raise ArgumentTypeError(message % (string, e))
def __repr__(self): args = self._mode, self._bufsize kwargs = [('encoding', self._encoding), ('errors', self._errors)] args_str = ', '.join([repr(arg) for arg in args if arg != -1] + ['%s=%r' % (kw, arg) for kw, arg in kwargs if arg is not None]) return '%s(%s)' % (type(self).__name__, args_str)
# ===========================# Optional and Positional Parsing# ===========================
class Namespace(_AttributeHolder): """Simple object for storing attributes.
Implements equality by attribute names and values, and provides a simple string representation. """
def __init__(self, **kwargs): for name in kwargs: setattr(self, name, kwargs[name])
def __eq__(self, other): if not isinstance(other, Namespace): return NotImplemented return vars(self) == vars(other)
def __contains__(self, key): return key in self.__dict__
class _ActionsContainer(object):
def __init__(self, description, prefix_chars, argument_default, conflict_handler): super(_ActionsContainer, self).__init__()
self.description = description self.argument_default = argument_default self.prefix_chars = prefix_chars self.conflict_handler = conflict_handler
# set up registries self._registries = {}
# register actions self.register('action', None, _StoreAction) self.register('action', 'store', _StoreAction) self.register('action', 'store_const', _StoreConstAction) self.register('action', 'store_true', _StoreTrueAction) self.register('action', 'store_false', _StoreFalseAction) self.register('action', 'append', _AppendAction) self.register('action', 'append_const', _AppendConstAction) self.register('action', 'count', _CountAction) self.register('action', 'help', _HelpAction) self.register('action', 'version', _VersionAction) self.register('action', 'parsers', _SubParsersAction)
# raise an exception if the conflict handler is invalid self._get_handler()
# action storage self._actions = [] self._option_string_actions = {}
# groups self._action_groups = [] self._mutually_exclusive_groups = []
# defaults storage self._defaults = {}
# determines whether an "option" looks like a negative number self._negative_number_matcher = _re.compile(r'^-\d+$|^-\d*\.\d+$')
# whether or not there are any optionals that look like negative # numbers -- uses a list so it can be shared and edited self._has_negative_number_optionals = []
# ==================== # Registration methods # ==================== def register(self, registry_name, value, object): registry = self._registries.setdefault(registry_name, {}) registry[value] = object
def _registry_get(self, registry_name, value, default=None): return self._registries[registry_name].get(value, default)
# ================================== # Namespace default accessor methods # ================================== def set_defaults(self, **kwargs): self._defaults.update(kwargs)
# if these defaults match any existing arguments, replace # the previous default on the object with the new one for action in self._actions: if action.dest in kwargs: action.default = kwargs[action.dest]
def get_default(self, dest): for action in self._actions: if action.dest == dest and action.default is not None: return action.default return self._defaults.get(dest, None)
# ======================= # Adding argument actions # ======================= def add_argument(self, *args, **kwargs): """
add_argument(dest, ..., name=value, ...) add_argument(option_string, option_string, ..., name=value, ...) """
# if no positional args are supplied or only one is supplied and # it doesn't look like an option string, parse a positional # argument chars = self.prefix_chars if not args or len(args) == 1 and args[0][0] not in chars: if args and 'dest' in kwargs: raise ValueError('dest supplied twice for positional argument') kwargs = self._get_positional_kwargs(*args, **kwargs)
# otherwise, we're adding an optional argument else: kwargs = self._get_optional_kwargs(*args, **kwargs)
# if no default was supplied, use the parser-level default if 'default' not in kwargs: dest = kwargs['dest'] if dest in self._defaults: kwargs['default'] = self._defaults[dest] elif self.argument_default is not None: kwargs['default'] = self.argument_default
# create the action object, and add it to the parser action_class = self._pop_action_class(kwargs) if not callable(action_class): raise ValueError('unknown action "%s"' % (action_class,)) action = action_class(**kwargs)
# raise an error if the action type is not callable type_func = self._registry_get('type', action.type, action.type) if not callable(type_func): raise ValueError('%r is not callable' % (type_func,))
# raise an error if the metavar does not match the type if hasattr(self, "_get_formatter"): try: self._get_formatter()._format_args(action, None) except TypeError: raise ValueError("length of metavar tuple does not match nargs")
return self._add_action(action)
def add_argument_group(self, *args, **kwargs): group = _ArgumentGroup(self, *args, **kwargs) self._action_groups.append(group) return group
def add_mutually_exclusive_group(self, **kwargs): group = _MutuallyExclusiveGroup(self, **kwargs) self._mutually_exclusive_groups.append(group) return group
def _add_action(self, action): # resolve any conflicts self._check_conflict(action)
# add to actions list self._actions.append(action) action.container = self
# index the action by any option strings it has for option_string in action.option_strings: self._option_string_actions[option_string] = action
# set the flag if any option strings look like negative numbers for option_string in action.option_strings: if self._negative_number_matcher.match(option_string): if not self._has_negative_number_optionals: self._has_negative_number_optionals.append(True)
# return the created action return action
def _remove_action(self, action): self._actions.remove(action)
def _add_container_actions(self, container): # collect groups by titles title_group_map = {} for group in self._action_groups: if group.title in title_group_map: msg = _('cannot merge actions - two groups are named %r') raise ValueError(msg % (group.title)) title_group_map[group.title] = group
# map each action to its group group_map = {} for group in container._action_groups:
# if a group with the title exists, use that, otherwise # create a new group matching the container's group if group.title not in title_group_map: title_group_map[group.title] = self.add_argument_group( title=group.title, description=group.description, conflict_handler=group.conflict_handler)
# map the actions to their new group for action in group._group_actions: group_map[action] = title_group_map[group.title]
# add container's mutually exclusive groups # NOTE: if add_mutually_exclusive_group ever gains title= and # description= then this code will need to be expanded as above for group in container._mutually_exclusive_groups: mutex_group = self.add_mutually_exclusive_group( required=group.required)
# map the actions to their new mutex group for action in group._group_actions: group_map[action] = mutex_group
# add all actions to this container or their group for action in container._actions: group_map.get(action, self)._add_action(action)
def _get_positional_kwargs(self, dest, **kwargs): # make sure required is not specified if 'required' in kwargs: msg = _("'required' is an invalid argument for positionals") raise TypeError(msg)
# mark positional arguments as required if at least one is # always required if kwargs.get('nargs') not in [OPTIONAL, ZERO_OR_MORE]: kwargs['required'] = True if kwargs.get('nargs') == ZERO_OR_MORE and 'default' not in kwargs: kwargs['required'] = True
# return the keyword arguments with no option strings return dict(kwargs, dest=dest, option_strings=[])
def _get_optional_kwargs(self, *args, **kwargs): # determine short and long option strings option_strings = [] long_option_strings = [] for option_string in args: # error on strings that don't start with an appropriate prefix if not option_string[0] in self.prefix_chars: args = {'option': option_string, 'prefix_chars': self.prefix_chars} msg = _('invalid option string %(option)r: ' 'must start with a character %(prefix_chars)r') raise ValueError(msg % args)
# strings starting with two prefix characters are long options option_strings.append(option_string) if option_string[0] in self.prefix_chars: if len(option_string) > 1: if option_string[1] in self.prefix_chars: long_option_strings.append(option_string)
# infer destination, '--foo-bar' -> 'foo_bar' and '-x' -> 'x' dest = kwargs.pop('dest', None) if dest is None: if long_option_strings: dest_option_string = long_option_strings[0] else: dest_option_string = option_strings[0] dest = dest_option_string.lstrip(self.prefix_chars) if not dest: msg = _('dest= is required for options like %r') raise ValueError(msg % option_string) dest = dest.replace('-', '_')
# return the updated keyword arguments return dict(kwargs, dest=dest, option_strings=option_strings)
def _pop_action_class(self, kwargs, default=None): action = kwargs.pop('action', default) return self._registry_get('action', action, action)
def _get_handler(self): # determine function from conflict handler string handler_func_name = '_handle_conflict_%s' % self.conflict_handler try: return getattr(self, handler_func_name) except AttributeError: msg = _('invalid conflict_resolution value: %r') raise ValueError(msg % self.conflict_handler)
def _check_conflict(self, action):
# find all options that conflict with this option confl_optionals = [] for option_string in action.option_strings: if option_string in self._option_string_actions: confl_optional = self._option_string_actions[option_string] confl_optionals.append((option_string, confl_optional))
# resolve any conflicts if confl_optionals: conflict_handler = self._get_handler() conflict_handler(action, confl_optionals)
def _handle_conflict_error(self, action, conflicting_actions): message = ngettext('conflicting option string: %s', 'conflicting option strings: %s', len(conflicting_actions)) conflict_string = ', '.join([option_string for option_string, action in conflicting_actions]) raise ArgumentError(action, message % conflict_string)
def _handle_conflict_resolve(self, action, conflicting_actions):
# remove all conflicting options for option_string, action in conflicting_actions:
# remove the conflicting option action.option_strings.remove(option_string) self._option_string_actions.pop(option_string, None)
# if the option now has no option string, remove it from the # container holding it if not action.option_strings: action.container._remove_action(action)
class _ArgumentGroup(_ActionsContainer):
def __init__(self, container, title=None, description=None, **kwargs): # add any missing keyword arguments by checking the container update = kwargs.setdefault update('conflict_handler', container.conflict_handler) update('prefix_chars', container.prefix_chars) update('argument_default', container.argument_default) super_init = super(_ArgumentGroup, self).__init__ super_init(description=description, **kwargs)
# group attributes self.title = title self._group_actions = []
# share most attributes with the container self._registries = container._registries self._actions = container._actions self._option_string_actions = container._option_string_actions self._defaults = container._defaults self._has_negative_number_optionals = \ container._has_negative_number_optionals self._mutually_exclusive_groups = container._mutually_exclusive_groups
def _add_action(self, action): action = super(_ArgumentGroup, self)._add_action(action) self._group_actions.append(action) return action
def _remove_action(self, action): super(_ArgumentGroup, self)._remove_action(action) self._group_actions.remove(action)
class _MutuallyExclusiveGroup(_ArgumentGroup):
def __init__(self, container, required=False): super(_MutuallyExclusiveGroup, self).__init__(container) self.required = required self._container = container
def _add_action(self, action): if action.required: msg = _('mutually exclusive arguments must be optional') raise ValueError(msg) action = self._container._add_action(action) self._group_actions.append(action) return action
def _remove_action(self, action): self._container._remove_action(action) self._group_actions.remove(action)
class ArgumentParser(_AttributeHolder, _ActionsContainer): """Object for parsing command line strings into Python objects.
Keyword Arguments: - prog -- The name of the program (default: sys.argv[0]) - usage -- A usage message (default: auto-generated from arguments) - description -- A description of what the program does - epilog -- Text following the argument descriptions - parents -- Parsers whose arguments should be copied into this one - formatter_class -- HelpFormatter class for printing help messages - prefix_chars -- Characters that prefix optional arguments - fromfile_prefix_chars -- Characters that prefix files containing additional arguments - argument_default -- The default value for all arguments - conflict_handler -- String indicating how to handle conflicts - add_help -- Add a -h/-help option - allow_abbrev -- Allow long options to be abbreviated unambiguously """
def __init__(self, prog=None, usage=None, description=None, epilog=None, parents=[], formatter_class=HelpFormatter, prefix_chars='-', fromfile_prefix_chars=None, argument_default=None, conflict_handler='error', add_help=True, allow_abbrev=True):
superinit = super(ArgumentParser, self).__init__ superinit(description=description, prefix_chars=prefix_chars, argument_default=argument_default, conflict_handler=conflict_handler)
# default setting for prog if prog is None: prog = _os.path.basename(_sys.argv[0])
self.prog = prog self.usage = usage self.epilog = epilog self.formatter_class = formatter_class self.fromfile_prefix_chars = fromfile_prefix_chars self.add_help = add_help self.allow_abbrev = allow_abbrev
add_group = self.add_argument_group self._positionals = add_group(_('positional arguments')) self._optionals = add_group(_('optional arguments')) self._subparsers = None
# register types def identity(string): return string self.register('type', None, identity)
# add help argument if necessary # (using explicit default to override global argument_default) default_prefix = '-' if '-' in prefix_chars else prefix_chars[0] if self.add_help: self.add_argument( default_prefix+'h', default_prefix*2+'help', action='help', default=SUPPRESS, help=_('show this help message and exit'))
# add parent arguments and defaults for parent in parents: self._add_container_actions(parent) try: defaults = parent._defaults except AttributeError: pass else: self._defaults.update(defaults)
# ======================= # Pretty __repr__ methods # ======================= def _get_kwargs(self): names = [ 'prog', 'usage', 'description', 'formatter_class', 'conflict_handler', 'add_help', ] return [(name, getattr(self, name)) for name in names]
# ================================== # Optional/Positional adding methods # ================================== def add_subparsers(self, **kwargs): if self._subparsers is not None: self.error(_('cannot have multiple subparser arguments'))
# add the parser class to the arguments if it's not present kwargs.setdefault('parser_class', type(self))
if 'title' in kwargs or 'description' in kwargs: title = _(kwargs.pop('title', 'subcommands')) description = _(kwargs.pop('description', None)) self._subparsers = self.add_argument_group(title, description) else: self._subparsers = self._positionals
# prog defaults to the usage message of this parser, skipping # optional arguments and with no "usage:" prefix if kwargs.get('prog') is None: formatter = self._get_formatter() positionals = self._get_positional_actions() groups = self._mutually_exclusive_groups formatter.add_usage(self.usage, positionals, groups, '') kwargs['prog'] = formatter.format_help().strip()
# create the parsers action and add it to the positionals list parsers_class = self._pop_action_class(kwargs, 'parsers') action = parsers_class(option_strings=[], **kwargs) self._subparsers._add_action(action)
# return the created parsers action return action
def _add_action(self, action): if action.option_strings: self._optionals._add_action(action) else: self._positionals._add_action(action) return action
def _get_optional_actions(self): return [action for action in self._actions if action.option_strings]
def _get_positional_actions(self): return [action for action in self._actions if not action.option_strings]
# ===================================== # Command line argument parsing methods # ===================================== def parse_args(self, args=None, namespace=None): args, argv = self.parse_known_args(args, namespace) if argv: msg = _('unrecognized arguments: %s') self.error(msg % ' '.join(argv)) return args
def parse_known_args(self, args=None, namespace=None): if args is None: # args default to the system args args = _sys.argv[1:] else: # make sure that args are mutable args = list(args)
# default Namespace built from parser defaults if namespace is None: namespace = Namespace()
# add any action defaults that aren't present for action in self._actions: if action.dest is not SUPPRESS: if not hasattr(namespace, action.dest): if action.default is not SUPPRESS: setattr(namespace, action.dest, action.default)
# add any parser defaults that aren't present for dest in self._defaults: if not hasattr(namespace, dest): setattr(namespace, dest, self._defaults[dest])
# parse the arguments and exit if there are any errors try: namespace, args = self._parse_known_args(args, namespace) if hasattr(namespace, _UNRECOGNIZED_ARGS_ATTR): args.extend(getattr(namespace, _UNRECOGNIZED_ARGS_ATTR)) delattr(namespace, _UNRECOGNIZED_ARGS_ATTR) return namespace, args except ArgumentError: err = _sys.exc_info()[1] self.error(str(err))
def _parse_known_args(self, arg_strings, namespace): # replace arg strings that are file references if self.fromfile_prefix_chars is not None: arg_strings = self._read_args_from_files(arg_strings)
# map all mutually exclusive arguments to the other arguments # they can't occur with action_conflicts = {} for mutex_group in self._mutually_exclusive_groups: group_actions = mutex_group._group_actions for i, mutex_action in enumerate(mutex_group._group_actions): conflicts = action_conflicts.setdefault(mutex_action, []) conflicts.extend(group_actions[:i]) conflicts.extend(group_actions[i + 1:])
# find all option indices, and determine the arg_string_pattern # which has an 'O' if there is an option at an index, # an 'A' if there is an argument, or a '-' if there is a '--' option_string_indices = {} arg_string_pattern_parts = [] arg_strings_iter = iter(arg_strings) for i, arg_string in enumerate(arg_strings_iter):
# all args after -- are non-options if arg_string == '--': arg_string_pattern_parts.append('-') for arg_string in arg_strings_iter: arg_string_pattern_parts.append('A')
# otherwise, add the arg to the arg strings # and note the index if it was an option else: option_tuple = self._parse_optional(arg_string) if option_tuple is None: pattern = 'A' else: option_string_indices[i] = option_tuple pattern = 'O' arg_string_pattern_parts.append(pattern)
# join the pieces together to form the pattern arg_strings_pattern = ''.join(arg_string_pattern_parts)
# converts arg strings to the appropriate and then takes the action seen_actions = set() seen_non_default_actions = set()
def take_action(action, argument_strings, option_string=None): seen_actions.add(action) argument_values = self._get_values(action, argument_strings)
# error if this argument is not allowed with other previously # seen arguments, assuming that actions that use the default # value don't really count as "present" if argument_values is not action.default: seen_non_default_actions.add(action) for conflict_action in action_conflicts.get(action, []): if conflict_action in seen_non_default_actions: msg = _('not allowed with argument %s') action_name = _get_action_name(conflict_action) raise ArgumentError(action, msg % action_name)
# take the action if we didn't receive a SUPPRESS value # (e.g. from a default) if argument_values is not SUPPRESS: action(self, namespace, argument_values, option_string)
# function to convert arg_strings into an optional action def consume_optional(start_index):
# get the optional identified at this index option_tuple = option_string_indices[start_index] action, option_string, explicit_arg = option_tuple
# identify additional optionals in the same arg string # (e.g. -xyz is the same as -x -y -z if no args are required) match_argument = self._match_argument action_tuples = [] while True:
# if we found no optional action, skip it if action is None: extras.append(arg_strings[start_index]) return start_index + 1
# if there is an explicit argument, try to match the # optional's string arguments to only this if explicit_arg is not None: arg_count = match_argument(action, 'A')
# if the action is a single-dash option and takes no # arguments, try to parse more single-dash options out # of the tail of the option string chars = self.prefix_chars if arg_count == 0 and option_string[1] not in chars: action_tuples.append((action, [], option_string)) char = option_string[0] option_string = char + explicit_arg[0] new_explicit_arg = explicit_arg[1:] or None optionals_map = self._option_string_actions if option_string in optionals_map: action = optionals_map[option_string] explicit_arg = new_explicit_arg else: msg = _('ignored explicit argument %r') raise ArgumentError(action, msg % explicit_arg)
# if the action expect exactly one argument, we've # successfully matched the option; exit the loop elif arg_count == 1: stop = start_index + 1 args = [explicit_arg] action_tuples.append((action, args, option_string)) break
# error if a double-dash option did not use the # explicit argument else: msg = _('ignored explicit argument %r') raise ArgumentError(action, msg % explicit_arg)
# if there is no explicit argument, try to match the # optional's string arguments with the following strings # if successful, exit the loop else: start = start_index + 1 selected_patterns = arg_strings_pattern[start:] arg_count = match_argument(action, selected_patterns) stop = start + arg_count args = arg_strings[start:stop] action_tuples.append((action, args, option_string)) break
# add the Optional to the list and return the index at which # the Optional's string args stopped assert action_tuples for action, args, option_string in action_tuples: take_action(action, args, option_string) return stop
# the list of Positionals left to be parsed; this is modified # by consume_positionals() positionals = self._get_positional_actions()
# function to convert arg_strings into positional actions def consume_positionals(start_index): # match as many Positionals as possible match_partial = self._match_arguments_partial selected_pattern = arg_strings_pattern[start_index:] arg_counts = match_partial(positionals, selected_pattern)
# slice off the appropriate arg strings for each Positional # and add the Positional and its args to the list for action, arg_count in zip(positionals, arg_counts): args = arg_strings[start_index: start_index + arg_count] start_index += arg_count take_action(action, args)
# slice off the Positionals that we just parsed and return the # index at which the Positionals' string args stopped positionals[:] = positionals[len(arg_counts):] return start_index
# consume Positionals and Optionals alternately, until we have # passed the last option string extras = [] start_index = 0 if option_string_indices: max_option_string_index = max(option_string_indices) else: max_option_string_index = -1 while start_index <= max_option_string_index:
# consume any Positionals preceding the next option next_option_string_index = min([ index for index in option_string_indices if index >= start_index]) if start_index != next_option_string_index: positionals_end_index = consume_positionals(start_index)
# only try to parse the next optional if we didn't consume # the option string during the positionals parsing if positionals_end_index > start_index: start_index = positionals_end_index continue else: start_index = positionals_end_index
# if we consumed all the positionals we could and we're not # at the index of an option string, there were extra arguments if start_index not in option_string_indices: strings = arg_strings[start_index:next_option_string_index] extras.extend(strings) start_index = next_option_string_index
# consume the next optional and any arguments for it start_index = consume_optional(start_index)
# consume any positionals following the last Optional stop_index = consume_positionals(start_index)
# if we didn't consume all the argument strings, there were extras extras.extend(arg_strings[stop_index:])
# make sure all required actions were present and also convert # action defaults which were not given as arguments required_actions = [] for action in self._actions: if action not in seen_actions: if action.required: required_actions.append(_get_action_name(action)) else: # Convert action default now instead of doing it before # parsing arguments to avoid calling convert functions # twice (which may fail) if the argument was given, but # only if it was defined already in the namespace if (action.default is not None and isinstance(action.default, str) and hasattr(namespace, action.dest) and action.default is getattr(namespace, action.dest)): setattr(namespace, action.dest, self._get_value(action, action.default))
if required_actions: self.error(_('the following arguments are required: %s') % ', '.join(required_actions))
# make sure all required groups had one option present for group in self._mutually_exclusive_groups: if group.required: for action in group._group_actions: if action in seen_non_default_actions: break
# if no actions were used, report the error else: names = [_get_action_name(action) for action in group._group_actions if action.help is not SUPPRESS] msg = _('one of the arguments %s is required') self.error(msg % ' '.join(names))
# return the updated namespace and the extra arguments return namespace, extras
def _read_args_from_files(self, arg_strings): # expand arguments referencing files new_arg_strings = [] for arg_string in arg_strings:
# for regular arguments, just add them back into the list if not arg_string or arg_string[0] not in self.fromfile_prefix_chars: new_arg_strings.append(arg_string)
# replace arguments referencing files with the file content else: try: with open(arg_string[1:]) as args_file: arg_strings = [] for arg_line in args_file.read().splitlines(): for arg in self.convert_arg_line_to_args(arg_line): arg_strings.append(arg) arg_strings = self._read_args_from_files(arg_strings) new_arg_strings.extend(arg_strings) except OSError: err = _sys.exc_info()[1] self.error(str(err))
# return the modified argument list return new_arg_strings
def convert_arg_line_to_args(self, arg_line): return [arg_line]
def _match_argument(self, action, arg_strings_pattern): # match the pattern for this action to the arg strings nargs_pattern = self._get_nargs_pattern(action) match = _re.match(nargs_pattern, arg_strings_pattern)
# raise an exception if we weren't able to find a match if match is None: nargs_errors = { None: _('expected one argument'), OPTIONAL: _('expected at most one argument'), ONE_OR_MORE: _('expected at least one argument'), } default = ngettext('expected %s argument', 'expected %s arguments', action.nargs) % action.nargs msg = nargs_errors.get(action.nargs, default) raise ArgumentError(action, msg)
# return the number of arguments matched return len(match.group(1))
def _match_arguments_partial(self, actions, arg_strings_pattern): # progressively shorten the actions list by slicing off the # final actions until we find a match result = [] for i in range(len(actions), 0, -1): actions_slice = actions[:i] pattern = ''.join([self._get_nargs_pattern(action) for action in actions_slice]) match = _re.match(pattern, arg_strings_pattern) if match is not None: result.extend([len(string) for string in match.groups()]) break
# return the list of arg string counts return result
def _parse_optional(self, arg_string): # if it's an empty string, it was meant to be a positional if not arg_string: return None
# if it doesn't start with a prefix, it was meant to be positional if not arg_string[0] in self.prefix_chars: return None
# if the option string is present in the parser, return the action if arg_string in self._option_string_actions: action = self._option_string_actions[arg_string] return action, arg_string, None
# if it's just a single character, it was meant to be positional if len(arg_string) == 1: return None
# if the option string before the "=" is present, return the action if '=' in arg_string: option_string, explicit_arg = arg_string.split('=', 1) if option_string in self._option_string_actions: action = self._option_string_actions[option_string] return action, option_string, explicit_arg
if self.allow_abbrev: # search through all possible prefixes of the option string # and all actions in the parser for possible interpretations option_tuples = self._get_option_tuples(arg_string)
# if multiple actions match, the option string was ambiguous if len(option_tuples) > 1: options = ', '.join([option_string for action, option_string, explicit_arg in option_tuples]) args = {'option': arg_string, 'matches': options} msg = _('ambiguous option: %(option)s could match %(matches)s') self.error(msg % args)
# if exactly one action matched, this segmentation is good, # so return the parsed action elif len(option_tuples) == 1: option_tuple, = option_tuples return option_tuple
# if it was not found as an option, but it looks like a negative # number, it was meant to be positional # unless there are negative-number-like options if self._negative_number_matcher.match(arg_string): if not self._has_negative_number_optionals: return None
# if it contains a space, it was meant to be a positional if ' ' in arg_string: return None
# it was meant to be an optional but there is no such option # in this parser (though it might be a valid option in a subparser) return None, arg_string, None
def _get_option_tuples(self, option_string): result = []
# option strings starting with two prefix characters are only # split at the '=' chars = self.prefix_chars if option_string[0] in chars and option_string[1] in chars: if '=' in option_string: option_prefix, explicit_arg = option_string.split('=', 1) else: option_prefix = option_string explicit_arg = None for option_string in self._option_string_actions: if option_string.startswith(option_prefix): action = self._option_string_actions[option_string] tup = action, option_string, explicit_arg result.append(tup)
# single character options can be concatenated with their arguments # but multiple character options always have to have their argument # separate elif option_string[0] in chars and option_string[1] not in chars: option_prefix = option_string explicit_arg = None short_option_prefix = option_string[:2] short_explicit_arg = option_string[2:]
for option_string in self._option_string_actions: if option_string == short_option_prefix: action = self._option_string_actions[option_string] tup = action, option_string, short_explicit_arg result.append(tup) elif option_string.startswith(option_prefix): action = self._option_string_actions[option_string] tup = action, option_string, explicit_arg result.append(tup)
# shouldn't ever get here else: self.error(_('unexpected option string: %s') % option_string)
# return the collected option tuples return result
def _get_nargs_pattern(self, action): # in all examples below, we have to allow for '--' args # which are represented as '-' in the pattern nargs = action.nargs
# the default (None) is assumed to be a single argument if nargs is None: nargs_pattern = '(-*A-*)'
# allow zero or one arguments elif nargs == OPTIONAL: nargs_pattern = '(-*A?-*)'
# allow zero or more arguments elif nargs == ZERO_OR_MORE: nargs_pattern = '(-*[A-]*)'
# allow one or more arguments elif nargs == ONE_OR_MORE: nargs_pattern = '(-*A[A-]*)'
# allow any number of options or arguments elif nargs == REMAINDER: nargs_pattern = '([-AO]*)'
# allow one argument followed by any number of options or arguments elif nargs == PARSER: nargs_pattern = '(-*A[-AO]*)'
# all others should be integers else: nargs_pattern = '(-*%s-*)' % '-*'.join('A' * nargs)
# if this is an optional action, -- is not allowed if action.option_strings: nargs_pattern = nargs_pattern.replace('-*', '') nargs_pattern = nargs_pattern.replace('-', '')
# return the pattern return nargs_pattern
# ======================== # Value conversion methods # ======================== def _get_values(self, action, arg_strings): # for everything but PARSER, REMAINDER args, strip out first '--' if action.nargs not in [PARSER, REMAINDER]: try: arg_strings.remove('--') except ValueError: pass
# optional argument produces a default when not present if not arg_strings and action.nargs == OPTIONAL: if action.option_strings: value = action.const else: value = action.default if isinstance(value, str): value = self._get_value(action, value) self._check_value(action, value)
# when nargs='*' on a positional, if there were no command-line # args, use the default if it is anything other than None elif (not arg_strings and action.nargs == ZERO_OR_MORE and not action.option_strings): if action.default is not None: value = action.default else: value = arg_strings self._check_value(action, value)
# single argument or optional argument produces a single value elif len(arg_strings) == 1 and action.nargs in [None, OPTIONAL]: arg_string, = arg_strings value = self._get_value(action, arg_string) self._check_value(action, value)
# REMAINDER arguments convert all values, checking none elif action.nargs == REMAINDER: value = [self._get_value(action, v) for v in arg_strings]
# PARSER arguments convert all values, but check only the first elif action.nargs == PARSER: value = [self._get_value(action, v) for v in arg_strings] self._check_value(action, value[0])
# all other types of nargs produce a list else: value = [self._get_value(action, v) for v in arg_strings] for v in value: self._check_value(action, v)
# return the converted value return value
def _get_value(self, action, arg_string): type_func = self._registry_get('type', action.type, action.type) if not callable(type_func): msg = _('%r is not callable') raise ArgumentError(action, msg % type_func)
# convert the value to the appropriate type try: result = type_func(arg_string)
# ArgumentTypeErrors indicate errors except ArgumentTypeError: name = getattr(action.type, '__name__', repr(action.type)) msg = str(_sys.exc_info()[1]) raise ArgumentError(action, msg)
# TypeErrors or ValueErrors also indicate errors except (TypeError, ValueError): name = getattr(action.type, '__name__', repr(action.type)) args = {'type': name, 'value': arg_string} msg = _('invalid %(type)s value: %(value)r') raise ArgumentError(action, msg % args)
# return the converted value return result
def _check_value(self, action, value): # converted value must be one of the choices (if specified) if action.choices is not None and value not in action.choices: args = {'value': value, 'choices': ', '.join(map(repr, action.choices))} msg = _('invalid choice: %(value)r (choose from %(choices)s)') raise ArgumentError(action, msg % args)
# ======================= # Help-formatting methods # ======================= def format_usage(self): formatter = self._get_formatter() formatter.add_usage(self.usage, self._actions, self._mutually_exclusive_groups) return formatter.format_help()
def format_help(self): formatter = self._get_formatter()
# usage formatter.add_usage(self.usage, self._actions, self._mutually_exclusive_groups)
# description formatter.add_text(self.description)
# positionals, optionals and user-defined groups for action_group in self._action_groups: formatter.start_section(action_group.title) formatter.add_text(action_group.description) formatter.add_arguments(action_group._group_actions) formatter.end_section()
# epilog formatter.add_text(self.epilog)
# determine help from format above return formatter.format_help()
def _get_formatter(self): return self.formatter_class(prog=self.prog)
# ===================== # Help-printing methods # ===================== def print_usage(self, file=None): if file is None: file = _sys.stdout self._print_message(self.format_usage(), file)
def print_help(self, file=None): if file is None: file = _sys.stdout self._print_message(self.format_help(), file)
def _print_message(self, message, file=None): if message: if file is None: file = _sys.stderr file.write(message)
# =============== # Exiting methods # =============== def exit(self, status=0, message=None): if message: self._print_message(message, _sys.stderr) _sys.exit(status)
def error(self, message): """error(message: string)
Prints a usage message incorporating the message to stderr and exits.
If you override this in a subclass, it should not return -- it should either exit or raise an exception. """
self.print_usage(_sys.stderr) args = {'prog': self.prog, 'message': message} self.exit(2, _('%(prog)s: error: %(message)s\n') % args)
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