Source code for argparse
# 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 the
command-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 only
considered public as object names -- the API of the formatter objects is
still 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 _collections
import copy as _copy
import os as _os
import re as _re
import sys as _sys
import textwrap as _textwrap
try:
from gettext import gettext as _, ngettext
except ImportError:
def _(message):
return message
def ngettext(singular,plural,n):
if n == 1:
return singular
else:
return plural
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 = []
for arg in self._get_args():
arg_strings.append(repr(arg))
for name, value in self._get_kwargs():
arg_strings.append('%s=%r' % (name, value))
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+')
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
for func, args in self.items:
func(*args)
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 __ne__(self, other):
if not isinstance(other, Namespace):
return NotImplemented
return not (self == 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
"""
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):
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
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
# 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)