mercurial/pycompat.py

pycompat: make pycompat demandimport friendly

pycompat.py includes hack to import modules whose names are changed in Python 3.
We use try-except to load module according to the version of python. But this
method forces us to import the modules to raise an ImportError and hence making
it demandimport unfriendly.

This patch changes the try-except blocks to a single if-else block. To avoid
test-check-pyflakes.t complain about unused imports, pycompat.py is excluded
from the test.

# pycompat.py - portability shim for python 3
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

"""Mercurial portability shim for python 3.

This contains aliases to hide python version-specific details from the core.
"""

from __future__ import absolute_import

import sys

if sys.version_info[0] < 3:
    import cPickle as pickle
    import cStringIO as io
    import httplib
    import Queue as _queue
    import SocketServer as socketserver
    import urlparse
    import xmlrpclib
else:
    import http.client as httplib
    import io
    import pickle
    import queue as _queue
    import socketserver
    import urllib.parse as urlparse
    import xmlrpc.client as xmlrpclib

stringio = io.StringIO
empty = _queue.Empty
queue = _queue.Queue

class _pycompatstub(object):
    pass

def _alias(alias, origin, items):
    """ populate a _pycompatstub

    copies items from origin to alias
    """
    def hgcase(item):
        return item.replace('_', '').lower()
    for item in items:
        try:
            setattr(alias, hgcase(item), getattr(origin, item))
        except AttributeError:
            pass

httpserver = _pycompatstub()
urlreq = _pycompatstub()
urlerr = _pycompatstub()
try:
    import BaseHTTPServer
    import CGIHTTPServer
    import SimpleHTTPServer
    import urllib2
    import urllib
    _alias(urlreq, urllib, (
        "addclosehook",
        "addinfourl",
        "ftpwrapper",
        "pathname2url",
        "quote",
        "splitattr",
        "splitpasswd",
        "splitport",
        "splituser",
        "unquote",
        "url2pathname",
        "urlencode",
        "urlencode",
    ))
    _alias(urlreq, urllib2, (
        "AbstractHTTPHandler",
        "BaseHandler",
        "build_opener",
        "FileHandler",
        "FTPHandler",
        "HTTPBasicAuthHandler",
        "HTTPDigestAuthHandler",
        "HTTPHandler",
        "HTTPPasswordMgrWithDefaultRealm",
        "HTTPSHandler",
        "install_opener",
        "ProxyHandler",
        "Request",
        "urlopen",
    ))
    _alias(urlerr, urllib2, (
        "HTTPError",
        "URLError",
    ))
    _alias(httpserver, BaseHTTPServer, (
        "HTTPServer",
        "BaseHTTPRequestHandler",
    ))
    _alias(httpserver, SimpleHTTPServer, (
        "SimpleHTTPRequestHandler",
    ))
    _alias(httpserver, CGIHTTPServer, (
        "CGIHTTPRequestHandler",
    ))

except ImportError:
    import urllib.request
    _alias(urlreq, urllib.request, (
        "AbstractHTTPHandler",
        "addclosehook",
        "addinfourl",
        "BaseHandler",
        "build_opener",
        "FileHandler",
        "FTPHandler",
        "ftpwrapper",
        "HTTPHandler",
        "HTTPSHandler",
        "install_opener",
        "pathname2url",
        "HTTPBasicAuthHandler",
        "HTTPDigestAuthHandler",
        "HTTPPasswordMgrWithDefaultRealm",
        "ProxyHandler",
        "quote",
        "Request",
        "splitattr",
        "splitpasswd",
        "splitport",
        "splituser",
        "unquote",
        "url2pathname",
        "urlopen",
    ))
    import urllib.error
    _alias(urlerr, urllib.error, (
        "HTTPError",
        "URLError",
    ))
    import http.server
    _alias(httpserver, http.server, (
        "HTTPServer",
        "BaseHTTPRequestHandler",
        "SimpleHTTPRequestHandler",
        "CGIHTTPRequestHandler",
    ))

try:
    xrange
except NameError:
    import builtins
    builtins.xrange = range