135 lines
4.5 KiB
Python
135 lines
4.5 KiB
Python
# Copyright 2013-present MongoDB, 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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"""Tools for representing MongoDB regular expressions."""
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import re
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from typing import Any, Generic, Pattern, Type, TypeVar, Union
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from bson._helpers import _getstate_slots, _setstate_slots
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from bson.son import RE_TYPE
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def str_flags_to_int(str_flags: str) -> int:
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flags = 0
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if "i" in str_flags:
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flags |= re.IGNORECASE
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if "l" in str_flags:
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flags |= re.LOCALE
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if "m" in str_flags:
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flags |= re.MULTILINE
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if "s" in str_flags:
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flags |= re.DOTALL
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if "u" in str_flags:
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flags |= re.UNICODE
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if "x" in str_flags:
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flags |= re.VERBOSE
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return flags
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_T = TypeVar("_T", str, bytes)
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class Regex(Generic[_T]):
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"""BSON regular expression data."""
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__slots__ = ("pattern", "flags")
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__getstate__ = _getstate_slots
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__setstate__ = _setstate_slots
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_type_marker = 11
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@classmethod
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def from_native(cls: Type["Regex"], regex: "Pattern[_T]") -> "Regex[_T]":
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"""Convert a Python regular expression into a ``Regex`` instance.
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Note that in Python 3, a regular expression compiled from a
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:class:`str` has the ``re.UNICODE`` flag set. If it is undesirable
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to store this flag in a BSON regular expression, unset it first::
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>>> pattern = re.compile('.*')
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>>> regex = Regex.from_native(pattern)
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>>> regex.flags ^= re.UNICODE
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>>> db.collection.insert_one({'pattern': regex})
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:Parameters:
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- `regex`: A regular expression object from ``re.compile()``.
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.. warning::
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Python regular expressions use a different syntax and different
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set of flags than MongoDB, which uses `PCRE`_. A regular
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expression retrieved from the server may not compile in
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Python, or may match a different set of strings in Python than
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when used in a MongoDB query.
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.. _PCRE: http://www.pcre.org/
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"""
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if not isinstance(regex, RE_TYPE):
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raise TypeError("regex must be a compiled regular expression, not %s" % type(regex))
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return Regex(regex.pattern, regex.flags)
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def __init__(self, pattern: _T, flags: Union[str, int] = 0) -> None:
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"""BSON regular expression data.
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This class is useful to store and retrieve regular expressions that are
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incompatible with Python's regular expression dialect.
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:Parameters:
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- `pattern`: string
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- `flags`: (optional) an integer bitmask, or a string of flag
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characters like "im" for IGNORECASE and MULTILINE
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"""
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if not isinstance(pattern, (str, bytes)):
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raise TypeError("pattern must be a string, not %s" % type(pattern))
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self.pattern: _T = pattern
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if isinstance(flags, str):
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self.flags = str_flags_to_int(flags)
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elif isinstance(flags, int):
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self.flags = flags
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else:
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raise TypeError("flags must be a string or int, not %s" % type(flags))
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def __eq__(self, other: Any) -> bool:
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if isinstance(other, Regex):
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return self.pattern == other.pattern and self.flags == other.flags
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else:
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return NotImplemented
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__hash__ = None # type: ignore
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def __ne__(self, other: Any) -> bool:
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return not self == other
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def __repr__(self):
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return f"Regex({self.pattern!r}, {self.flags!r})"
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def try_compile(self) -> "Pattern[_T]":
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"""Compile this :class:`Regex` as a Python regular expression.
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.. warning::
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Python regular expressions use a different syntax and different
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set of flags than MongoDB, which uses `PCRE`_. A regular
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expression retrieved from the server may not compile in
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Python, or may match a different set of strings in Python than
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when used in a MongoDB query. :meth:`try_compile()` may raise
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:exc:`re.error`.
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.. _PCRE: http://www.pcre.org/
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"""
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return re.compile(self.pattern, self.flags)
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