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# encoding=utf-8
# Copyright (C) 2011-2012 Patrick Totzke <patricktotzke@gmail.com>
# Copyright © 2017 Dylan Baker
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
"""Custom extensions of the argparse module."""
import argparse
import collections
import functools
import itertools
import os
import stat
_TRUEISH = ['true', 'yes', 'on', '1', 't', 'y']
_FALSISH = ['false', 'no', 'off', '0', 'f', 'n']
class ValidationFailed(Exception):
"""Exception raised when Validation fails in a ValidatedStoreAction."""
pass
def _boolean(string):
string = string.lower()
if string in _FALSISH:
return False
elif string in _TRUEISH:
return True
else:
raise ValueError('Option must be one of: {}'.format(
', '.join(itertools.chain(iter(_TRUEISH), iter(_FALSISH)))))
def _path_factory(check):
"""Create a function that checks paths."""
@functools.wraps(check)
def validator(paths):
if isinstance(paths, str):
check(paths)
elif isinstance(paths, collections.Sequence):
for path in paths:
check(path)
else:
raise Exception('expected either basestr or sequenc of basstr')
return validator
@_path_factory
def require_file(path):
"""Validator that asserts that a file exists.
This fails if there is nothing at the given path.
"""
if not os.path.isfile(path):
raise ValidationFailed('{} is not a valid file.'.format(path))
@_path_factory
def optional_file_like(path):
"""Validator that ensures that if a file exists it regular, a fifo, or a
character device. The file is not required to exist.
This includes character special devices like /dev/null.
"""
if (os.path.exists(path) and not (os.path.isfile(path) or
stat.S_ISFIFO(os.stat(path).st_mode) or
stat.S_ISCHR(os.stat(path).st_mode))):
raise ValidationFailed(
'{} is not a valid file, character device, or fifo.'.format(path))
@_path_factory
def require_dir(path):
"""Validator that asserts that a directory exists.
This fails if there is nothing at the given path.
"""
if not os.path.isdir(path):
raise ValidationFailed('{} is not a valid directory.'.format(path))
def is_int_or_pm(value):
"""Validator to assert that value is '+', '-', or an integer"""
if value not in ['+', '-']:
try:
value = int(value)
except ValueError:
raise ValidationFailed('value must be an integer or "+" or "-".')
return value
class BooleanAction(argparse.Action):
"""Argparse action that can be used to store boolean values."""
def __init__(self, *args, **kwargs):
kwargs['type'] = _boolean
kwargs['metavar'] = 'BOOL'
argparse.Action.__init__(self, *args, **kwargs)
def __call__(self, parser, namespace, values, option_string=None):
setattr(namespace, self.dest, values)
class ValidatedStoreAction(argparse.Action):
"""An action that allows a validation function to be specificied.
The validator keyword must be a function taking exactly one argument, that
argument is a list of strings or the type specified by the type argument.
It must raise ValidationFailed with a message when validation fails.
"""
def __init__(self, option_strings, dest, validator = None, **kwargs):
super().__init__(option_strings, dest, **kwargs)
self.validator = validator
def __call__(self, parser, namespace, values, option_string=None):
if self.validator:
try:
self.validator(values)
except ValidationFailed as e:
raise argparse.ArgumentError(self, str(e))
setattr(namespace, self.dest, values)
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