Source code for transit.read_handlers

## Copyright 2014 Cognitect. All Rights Reserved.
##
## 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.

import transit_types
import uuid
import ctypes
import dateutil.parser
import datetime
import dateutil.tz
from helpers import pairs
from decimal import Decimal

## Read handlers are used by the decoder when parsing/reading in Transit
## data and returning Python objects


class DefaultHandler(object):
    @staticmethod
    def from_rep(t, v):
        return transit_types.TaggedValue(t, v)


class NoneHandler(object):
    @staticmethod
    def from_rep(_):
        return None


class KeywordHandler(object):
    @staticmethod
    def from_rep(v):
        return transit_types.Keyword(v)


class SymbolHandler(object):
    @staticmethod
    def from_rep(v):
        return transit_types.Symbol(v)


class BigDecimalHandler(object):
    @staticmethod
    def from_rep(v):
        return Decimal(v)


class BooleanHandler(object):
    @staticmethod
    def from_rep(x):
        return transit_types.true if x == "t" else transit_types.false


class IntHandler(object):
    @staticmethod
    def from_rep(v):
        return int(v)


class FloatHandler(object):
    @staticmethod
    def from_rep(v):
        return float(v)


class UuidHandler(object):
    @staticmethod
    def from_rep(u):
        """Given a string, return a UUID object."""
        if isinstance(u, basestring):
            return uuid.UUID(u)

        # hack to remove signs
        a = ctypes.c_ulong(u[0])
        b = ctypes.c_ulong(u[1])
        combined = a.value << 64 | b.value
        return uuid.UUID(int=combined)


class UriHandler(object):
    @staticmethod
    def from_rep(u):
        return transit_types.URI(u)


class DateHandler(object):
    @staticmethod
    def from_rep(d):
        if isinstance(d, (long, int)):
            return DateHandler._convert_timestamp(d)
        if "T" in d:
            return dateutil.parser.parse(d)
        return DateHandler._convert_timestamp(long(d))

    @staticmethod
    def _convert_timestamp(ms):
        """Given a timestamp in ms, return a DateTime object."""
        return datetime.datetime.fromtimestamp(ms/1000.0, dateutil.tz.tzutc())


class BigIntegerHandler(object):
    @staticmethod
    def from_rep(d):
        return long(d)


class LinkHandler(object):
    @staticmethod
    def from_rep(l):
        return transit_types.Link(**l)


class ListHandler(object):
    @staticmethod
    def from_rep(l):
        return l


class SetHandler(object):
    @staticmethod
    def from_rep(s):
        return frozenset(s)


class CmapHandler(object):
    @staticmethod
    def from_rep(cmap):
        return transit_types.frozendict(pairs(cmap))


class IdentityHandler(object):
    @staticmethod
    def from_rep(i):
        return i


class SpecialNumbersHandler(object):
    @staticmethod
    def from_rep(z):
        if z == 'NaN':
            return float('Nan')
        if z == 'INF':
            return float('Inf')
        if z == '-INF':
            return float('-Inf')
        raise ValueError("Don't know how to handle: " + str(z) + " as \"z\"")