# Copyright 2013-2015 MongoDB, Inc.
#
# 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.
"""Tools for representing MongoDB regular expressions.
"""
import re
from bson.son import RE_TYPE
from bson.py3compat import string_type, text_type
def str_flags_to_int(str_flags):
flags = 0
if "i" in str_flags:
flags |= re.IGNORECASE
if "l" in str_flags:
flags |= re.LOCALE
if "m" in str_flags:
flags |= re.MULTILINE
if "s" in str_flags:
flags |= re.DOTALL
if "u" in str_flags:
flags |= re.UNICODE
if "x" in str_flags:
flags |= re.VERBOSE
return flags
class Regex(object):
"""BSON regular expression data."""
_type_marker = 11
@classmethod
def from_native(cls, regex):
"""Convert a Python regular expression into a ``Regex`` instance.
Note that in Python 3, a regular expression compiled from a
:class:`str` has the ``re.UNICODE`` flag set. If it is undesirable
to store this flag in a BSON regular expression, unset it first::
>>> pattern = re.compile('.*')
>>> regex = Regex.from_native(pattern)
>>> regex.flags ^= re.UNICODE
>>> db.collection.insert({'pattern': regex})
:Parameters:
- `regex`: A regular expression object from ``re.compile()``.
.. warning::
Python regular expressions use a different syntax and different
set of flags than MongoDB, which uses `PCRE`_. A regular
expression retrieved from the server may not compile in
Python, or may match a different set of strings in Python than
when used in a MongoDB query.
.. _PCRE: http://www.pcre.org/
"""
if not isinstance(regex, RE_TYPE):
raise TypeError(
"regex must be a compiled regular expression, not %s"
% type(regex))
return Regex(regex.pattern, regex.flags)
def __init__(self, pattern, flags=0):
"""BSON regular expression data.
This class is useful to store and retrieve regular expressions that are
incompatible with Python's regular expression dialect.
:Parameters:
- `pattern`: string
- `flags`: (optional) an integer bitmask, or a string of flag
characters like "im" for IGNORECASE and MULTILINE
"""
if not isinstance(pattern, (text_type, bytes)):
raise TypeError("pattern must be a string, not %s" % type(pattern))
self.pattern = pattern
if isinstance(flags, string_type):
self.flags = str_flags_to_int(flags)
elif isinstance(flags, int):
self.flags = flags
else:
raise TypeError(
"flags must be a string or int, not %s" % type(flags))
def __eq__(self, other):
if isinstance(other, Regex):
return self.pattern == self.pattern and self.flags == other.flags
else:
return NotImplemented
__hash__ = None
def __ne__(self, other):
return not self == other
def __repr__(self):
return "Regex(%r, %r)" % (self.pattern, self.flags)
def try_compile(self):
"""Compile this :class:`Regex` as a Python regular expression.
.. warning::
Python regular expressions use a different syntax and different
set of flags than MongoDB, which uses `PCRE`_. A regular
expression retrieved from the server may not compile in
Python, or may match a different set of strings in Python than
when used in a MongoDB query. :meth:`try_compile()` may raise
:exc:`re.error`.
.. _PCRE: http://www.pcre.org/
"""
return re.compile(self.pattern, self.flags)
