130 lines
3.7 KiB
Python
130 lines
3.7 KiB
Python
# Copyright 2017 by Rackspace Hosting, Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import abc
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from datetime import datetime
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import uuid
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import six
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# PERF(kgriffs): Avoid an extra namespace lookup when using this function
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strptime = datetime.strptime
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@six.add_metaclass(abc.ABCMeta)
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class BaseConverter(object):
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"""Abstract base class for URI template field converters."""
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@abc.abstractmethod # pragma: no cover
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def convert(self, value):
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"""Convert a URI template field value to another format or type.
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Args:
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value (str): Original string to convert.
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Returns:
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object: Converted field value, or ``None`` if the field
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can not be converted.
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"""
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class IntConverter(BaseConverter):
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"""Converts a field value to an int.
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Keyword Args:
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num_digits (int): Require the value to have the given
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number of digits.
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min (int): Reject the value if it is less than this number.
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max (int): Reject the value if it is greater than this number.
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"""
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__slots__ = ('_num_digits', '_min', '_max')
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def __init__(self, num_digits=None, min=None, max=None):
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if num_digits is not None and num_digits < 1:
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raise ValueError('num_digits must be at least 1')
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self._num_digits = num_digits
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self._min = min
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self._max = max
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def convert(self, value):
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if self._num_digits is not None and len(value) != self._num_digits:
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return None
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# NOTE(kgriffs): int() will accept numbers with preceding or
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# trailing whitespace, so we need to do our own check. Using
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# strip() is faster than either a regex or a series of or'd
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# membership checks via "in", esp. as the length of contiguous
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# numbers in the value grows.
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if value.strip() != value:
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return None
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try:
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value = int(value)
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except ValueError:
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return None
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if self._min is not None and value < self._min:
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return None
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if self._max is not None and value > self._max:
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return None
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return value
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class DateTimeConverter(BaseConverter):
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"""Converts a field value to a datetime.
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Keyword Args:
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format_string (str): String used to parse the field value
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into a datetime. Any format recognized by strptime() is
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supported (default ``'%Y-%m-%dT%H:%M:%SZ'``).
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"""
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__slots__ = ('_format_string',)
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def __init__(self, format_string='%Y-%m-%dT%H:%M:%SZ'):
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self._format_string = format_string
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def convert(self, value):
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try:
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return strptime(value, self._format_string)
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except ValueError:
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return None
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class UUIDConverter(BaseConverter):
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"""Converts a field value to a uuid.UUID.
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In order to be converted, the field value must consist of a
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string of 32 hexadecimal digits, as defined in RFC 4122, Section 3.
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Note, however, that hyphens and the URN prefix are optional.
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"""
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def convert(self, value):
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try:
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return uuid.UUID(value)
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except ValueError:
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return None
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BUILTIN = (
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('int', IntConverter),
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('dt', DateTimeConverter),
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('uuid', UUIDConverter),
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)
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