deb-python-cassandra-driver/cassandra/encoder.py

# Copyright 2013-2014 DataStax, 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.
"""
These functions are used to convert Python objects into CQL strings.
When non-prepared statements are executed, these encoder functions are
called on each query parameter.
"""

import logging
log = logging.getLogger(__name__)

from binascii import hexlify
import calendar
import datetime
import sys
import types
from uuid import UUID
import six

from cassandra.util import OrderedDict

if six.PY3:
    long = int


def cql_quote(term):
    # The ordering of this method is important for the result of this method to
    # be a native str type (for both Python 2 and 3)

    # Handle quoting of native str and bool types
    if isinstance(term, (str, bool)):
        return "'%s'" % str(term).replace("'", "''")
    # This branch of the if statement will only be used by Python 2 to catch
    # unicode strings, text_type is used to prevent type errors with Python 3.
    elif isinstance(term, six.text_type):
        return "'%s'" % term.encode('utf8').replace("'", "''")
    else:
        return str(term)


class ValueSequence(list):
    pass


class Encoder(object):
    """
    A container for mapping python types to CQL string literals when working
    with non-prepared statements.  The type :attr:`~.Encoder.mapping` can be
    directly customized by users.
    """

    mapping = None
    """
    A map of python types to encoder functions.
    """

    def __init__(self):
        self.mapping = {
            float: self.cql_encode_object,
            bytearray: self.cql_encode_bytes,
            str: self.cql_encode_str,
            int: self.cql_encode_object,
            UUID: self.cql_encode_object,
            datetime.datetime: self.cql_encode_datetime,
            datetime.date: self.cql_encode_date,
            dict: self.cql_encode_map_collection,
            OrderedDict: self.cql_encode_map_collection,
            list: self.cql_encode_list_collection,
            tuple: self.cql_encode_list_collection,
            set: self.cql_encode_set_collection,
            frozenset: self.cql_encode_set_collection,
            types.GeneratorType: self.cql_encode_list_collection,
            ValueSequence: self.cql_encode_sequence
        }

        if six.PY2:
            self.mapping.update({
                unicode: self.cql_encode_unicode,
                buffer: self.cql_encode_bytes,
                long: self.cql_encode_object,
                types.NoneType: self.cql_encode_none,
            })
        else:
            self.mapping.update({
                memoryview: self.cql_encode_bytes,
                bytes: self.cql_encode_bytes,
                type(None): self.cql_encode_none,
            })

        # sortedset is optional
        try:
            from blist import sortedset
            self.mapping.update({
                sortedset: self.cql_encode_set_collection
            })
        except ImportError:
            pass

    def cql_encode_none(self, val):
        """
        Converts :const:`None` to the string 'NULL'.
        """
        return 'NULL'

    def cql_encode_unicode(self, val):
        """
        Converts :class:`unicode` objects to UTF-8 encoded strings with quote escaping.
        """
        return cql_quote(val.encode('utf-8'))

    def cql_encode_str(self, val):
        """
        Escapes quotes in :class:`str` objects.
        """
        return cql_quote(val)

    if six.PY3:
        def cql_encode_bytes(self, val):
            return (b'0x' + hexlify(val)).decode('utf-8')
    elif sys.version_info >= (2, 7):
        def cql_encode_bytes(self, val):  # noqa
            return b'0x' + hexlify(val)
    else:
        # python 2.6 requires string or read-only buffer for hexlify
        def cql_encode_bytes(self, val):  # noqa
            return b'0x' + hexlify(buffer(val))

    def cql_encode_object(self, val):
        """
        Default encoder for all objects that do not have a specific encoder function
        registered. This function simply calls :meth:`str()` on the object.
        """
        return str(val)

    def cql_encode_datetime(self, val):
        """
        Converts a :class:`datetime.datetime` object to a (string) integer timestamp
        with millisecond precision.
        """
        timestamp = calendar.timegm(val.utctimetuple())
        return str(long(timestamp * 1e3 + getattr(val, 'microsecond', 0) / 1e3))

    def cql_encode_date(self, val):
        """
        Converts a :class:`datetime.date` object to a string with format
        ``YYYY-MM-DD-0000``.
        """
        return "'%s'" % val.strftime('%Y-%m-%d-0000')

    def cql_encode_sequence(self, val):
        """
        Converts a sequence to a string of the form ``(item1, item2, ...)``.  This
        is suitable for ``IN`` value lists.
        """
        return '( %s )' % ' , '.join(self.mapping.get(type(v), self.cql_encode_object)(v)
                                     for v in val)

    cql_encode_tuple = cql_encode_sequence
    """
    Converts a sequence to a string of the form ``(item1, item2, ...)``.  This
    is suitable for ``tuple`` type columns.
    """

    def cql_encode_map_collection(self, val):
        """
        Converts a dict into a string of the form ``{key1: val1, key2: val2, ...}``.
        This is suitable for ``map`` type columns.
        """
        return '{ %s }' % ' , '.join('%s : %s' % (
            self.mapping.get(type(k), self.cql_encode_object)(k),
            self.mapping.get(type(v), self.cql_encode_object)(v)
        ) for k, v in six.iteritems(val))

    def cql_encode_list_collection(self, val):
        """
        Converts a sequence to a string of the form ``[item1, item2, ...]``.  This
        is suitable for ``list`` type columns.
        """
        return '[ %s ]' % ' , '.join(self.mapping.get(type(v), self.cql_encode_object)(v) for v in val)

    def cql_encode_set_collection(self, val):
        """
        Converts a sequence to a string of the form ``{item1, item2, ...}``.  This
        is suitable for ``set`` type columns.
        """
        return '{ %s }' % ' , '.join(self.mapping.get(type(v), self.cql_encode_object)(v) for v in val)

    def cql_encode_all_types(self, val):
        """
        Converts any type into a CQL string, defaulting to ``cql_encode_object``
        if :attr:`~Encoder.mapping` does not contain an entry for the type.
        """
        return self.mapping.get(type(val), self.cql_encode_object)(val)