source: uri/rfc3986/compat.py@ 1281

# -*- coding: utf-8 -*-
# Copyright (c) 2014 Rackspace
# 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.
"""Compatibility module for Python 2 and 3 support."""
import sys

try:
    from urllib.parse import quote as urlquote
except ImportError:  # Python 2.x
    from urllib import quote as urlquote

try:
    from urllib.parse import parse_qsl
except ImportError:  # Python 2.x
    from urlparse import parse_qsl

try:
    from urllib.parse import urlencode
except ImportError:  # Python 2.x
    from urllib import urlencode

__all__ = (
    "to_bytes",
    "to_str",
    "urlquote",
    "urlencode",
    "parse_qsl",
)

PY3 = (3, 0) <= sys.version_info < (4, 0)
PY2 = (2, 6) <= sys.version_info < (2, 8)


if PY3:
    unicode = str  # Python 3.x


def to_str(b, encoding="utf-8"):
    """Ensure that b is text in the specified encoding."""
    if hasattr(b, "decode") and not isinstance(b, unicode):
        b = b.decode(encoding)
    return b


def to_bytes(s, encoding="utf-8"):
    """Ensure that s is converted to bytes from the encoding."""
    if hasattr(s, "encode") and not isinstance(s, bytes):
        s = s.encode(encoding)
    return s