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# vim: tabstop=4 shiftwidth=4 softtabstop=4
# Copyright 2011 OpenStack Foundation.
# All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
"""
System-level utilities and helper functions.
"""
import sys
from openstack.common.gettextutils import _
TRUE_STRINGS = ('1', 't', 'true', 'on', 'y', 'yes')
FALSE_STRINGS = ('0', 'f', 'false', 'off', 'n', 'no')
def int_from_bool_as_string(subject):
"""
Interpret a string as a boolean and return either 1 or 0.
Any string value in:
('True', 'true', 'On', 'on', '1')
is interpreted as a boolean True.
Useful for JSON-decoded stuff and config file parsing
"""
return bool_from_string(subject) and 1 or 0
def bool_from_string(subject, strict=False):
"""
Interpret a string as a boolean.
A case-insensitive match is performed such that strings matching 't',
'true', 'on', 'y', 'yes', or '1' are considered True and, when
`strict=False`, anything else is considered False.
Useful for JSON-decoded stuff and config file parsing.
If `strict=True`, unrecognized values, including None, will raise a
ValueError which is useful when parsing values passed in from an API call.
Strings yielding False are 'f', 'false', 'off', 'n', 'no', or '0'.
"""
if not isinstance(subject, basestring):
subject = str(subject)
lowered = subject.strip().lower()
if lowered in TRUE_STRINGS:
return True
elif lowered in FALSE_STRINGS:
return False
elif strict:
acceptable = ', '.join(
"'%s'" % s for s in sorted(TRUE_STRINGS + FALSE_STRINGS))
msg = _("Unrecognized value '%(val)s', acceptable values are:"
" %(acceptable)s") % {'val': subject,
'acceptable': acceptable}
raise ValueError(msg)
else:
return False
def safe_decode(text, incoming=None, errors='strict'):
"""
Decodes incoming str using `incoming` if they're
not already unicode.
:param incoming: Text's current encoding
:param errors: Errors handling policy. See here for valid
values http://docs.python.org/2/library/codecs.html
:returns: text or a unicode `incoming` encoded
representation of it.
:raises TypeError: If text is not an isntance of basestring
"""
if not isinstance(text, basestring):
raise TypeError("%s can't be decoded" % type(text))
if isinstance(text, unicode):
return text
if not incoming:
incoming = (sys.stdin.encoding or
sys.getdefaultencoding())
try:
return text.decode(incoming, errors)
except UnicodeDecodeError:
# Note(flaper87) If we get here, it means that
# sys.stdin.encoding / sys.getdefaultencoding
# didn't return a suitable encoding to decode
# text. This happens mostly when global LANG
# var is not set correctly and there's no
# default encoding. In this case, most likely
# python will use ASCII or ANSI encoders as
# default encodings but they won't be capable
# of decoding non-ASCII characters.
#
# Also, UTF-8 is being used since it's an ASCII
# extension.
return text.decode('utf-8', errors)
def safe_encode(text, incoming=None,
encoding='utf-8', errors='strict'):
"""
Encodes incoming str/unicode using `encoding`. If
incoming is not specified, text is expected to
be encoded with current python's default encoding.
(`sys.getdefaultencoding`)
:param incoming: Text's current encoding
:param encoding: Expected encoding for text (Default UTF-8)
:param errors: Errors handling policy. See here for valid
values http://docs.python.org/2/library/codecs.html
:returns: text or a bytestring `encoding` encoded
representation of it.
:raises TypeError: If text is not an isntance of basestring
"""
if not isinstance(text, basestring):
raise TypeError("%s can't be encoded" % type(text))
if not incoming:
incoming = (sys.stdin.encoding or
sys.getdefaultencoding())
if isinstance(text, unicode):
return text.encode(encoding, errors)
elif text and encoding != incoming:
# Decode text before encoding it with `encoding`
text = safe_decode(text, incoming, errors)
return text.encode(encoding, errors)
return text
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