regex.py 文件源码

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)