from sqlalchemy.dialects.postgresql.base import ischema_names

from sqlalchemy.types import UserDefinedType, Float

class BIT(UserDefinedType):

cache_ok = True

def __init__(self, length=None):

super(UserDefinedType, self).__init__()

self.length = length

def get_col_spec(self, **kw):

if self.length is None:

return 'BIT'

return 'BIT(%d)' % self.length

class comparator_factory(UserDefinedType.Comparator):

def hamming_distance(self, other):

return self.op('<~>', return_type=Float)(other)

def jaccard_distance(self, other):

return self.op('<%>', return_type=Float)(other)

# for reflection

ischema_names['bit'] = BIT