py3: introduce pycompat.ziplist as zip is a generator on Python 3

Similar to map, the return value of zip was also turned into a generator on
Python 3. We have multiple occurences in our codebase where we retrieve the
values of zip multiple times, so let's introduce pycompat.ziplist similar to
pycompat.maplist.

Differential Revision: https://phab.mercurial-scm.org/D1675

mercurial/pycompat.py

@@ -1,328 +1,330 b''
 # 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 getopt
 import os
 import shlex
 import sys
 
 ispy3 = (sys.version_info[0] >= 3)
 ispypy = (r'__pypy__' in sys.builtin_module_names)
 
 if not ispy3:
     import cookielib
     import cPickle as pickle
     import httplib
     import Queue as _queue
     import SocketServer as socketserver
     import xmlrpclib
 else:
     import http.cookiejar as cookielib
     import http.client as httplib
     import pickle
     import queue as _queue
     import socketserver
     import xmlrpc.client as xmlrpclib
 
 empty = _queue.Empty
 queue = _queue.Queue
 
 def identity(a):
     return a
 
 if ispy3:
     import builtins
     import functools
     import io
     import struct
 
     fsencode = os.fsencode
     fsdecode = os.fsdecode
     oslinesep = os.linesep.encode('ascii')
     osname = os.name.encode('ascii')
     ospathsep = os.pathsep.encode('ascii')
     ossep = os.sep.encode('ascii')
     osaltsep = os.altsep
     if osaltsep:
         osaltsep = osaltsep.encode('ascii')
     # os.getcwd() on Python 3 returns string, but it has os.getcwdb() which
     # returns bytes.
     getcwd = os.getcwdb
     sysplatform = sys.platform.encode('ascii')
     sysexecutable = sys.executable
     if sysexecutable:
         sysexecutable = os.fsencode(sysexecutable)
     stringio = io.BytesIO
     maplist = lambda *args: list(map(*args))
+    ziplist = lambda *args: list(zip(*args))
     rawinput = input
 
     # TODO: .buffer might not exist if std streams were replaced; we'll need
     # a silly wrapper to make a bytes stream backed by a unicode one.
     stdin = sys.stdin.buffer
     stdout = sys.stdout.buffer
     stderr = sys.stderr.buffer
 
     # Since Python 3 converts argv to wchar_t type by Py_DecodeLocale() on Unix,
     # we can use os.fsencode() to get back bytes argv.
     #
     # https://hg.python.org/cpython/file/v3.5.1/Programs/python.c#l55
     #
     # TODO: On Windows, the native argv is wchar_t, so we'll need a different
     # workaround to simulate the Python 2 (i.e. ANSI Win32 API) behavior.
     if getattr(sys, 'argv', None) is not None:
         sysargv = list(map(os.fsencode, sys.argv))
 
     bytechr = struct.Struct('>B').pack
 
     class bytestr(bytes):
         """A bytes which mostly acts as a Python 2 str
 
         >>> bytestr(), bytestr(bytearray(b'foo')), bytestr(u'ascii'), bytestr(1)
         (b'', b'foo', b'ascii', b'1')
         >>> s = bytestr(b'foo')
         >>> assert s is bytestr(s)
 
         __bytes__() should be called if provided:
 
         >>> class bytesable(object):
         ...     def __bytes__(self):
         ...         return b'bytes'
         >>> bytestr(bytesable())
         b'bytes'
 
         There's no implicit conversion from non-ascii str as its encoding is
         unknown:
 
         >>> bytestr(chr(0x80)) # doctest: +ELLIPSIS
         Traceback (most recent call last):
           ...
         UnicodeEncodeError: ...
 
         Comparison between bytestr and bytes should work:
 
         >>> assert bytestr(b'foo') == b'foo'
         >>> assert b'foo' == bytestr(b'foo')
         >>> assert b'f' in bytestr(b'foo')
         >>> assert bytestr(b'f') in b'foo'
 
         Sliced elements should be bytes, not integer:
 
         >>> s[1], s[:2]
         (b'o', b'fo')
         >>> list(s), list(reversed(s))
         ([b'f', b'o', b'o'], [b'o', b'o', b'f'])
 
         As bytestr type isn't propagated across operations, you need to cast
         bytes to bytestr explicitly:
 
         >>> s = bytestr(b'foo').upper()
         >>> t = bytestr(s)
         >>> s[0], t[0]
         (70, b'F')
 
         Be careful to not pass a bytestr object to a function which expects
         bytearray-like behavior.
 
         >>> t = bytes(t)  # cast to bytes
         >>> assert type(t) is bytes
         """
 
         def __new__(cls, s=b''):
             if isinstance(s, bytestr):
                 return s
             if (not isinstance(s, (bytes, bytearray))
                 and not hasattr(s, u'__bytes__')):  # hasattr-py3-only
                 s = str(s).encode(u'ascii')
             return bytes.__new__(cls, s)
 
         def __getitem__(self, key):
             s = bytes.__getitem__(self, key)
             if not isinstance(s, bytes):
                 s = bytechr(s)
             return s
 
         def __iter__(self):
             return iterbytestr(bytes.__iter__(self))
 
     def iterbytestr(s):
         """Iterate bytes as if it were a str object of Python 2"""
         return map(bytechr, s)
 
     def sysbytes(s):
         """Convert an internal str (e.g. keyword, __doc__) back to bytes
 
         This never raises UnicodeEncodeError, but only ASCII characters
         can be round-trip by sysstr(sysbytes(s)).
         """
         return s.encode(u'utf-8')
 
     def sysstr(s):
         """Return a keyword str to be passed to Python functions such as
         getattr() and str.encode()
 
         This never raises UnicodeDecodeError. Non-ascii characters are
         considered invalid and mapped to arbitrary but unique code points
         such that 'sysstr(a) != sysstr(b)' for all 'a != b'.
         """
         if isinstance(s, builtins.str):
             return s
         return s.decode(u'latin-1')
 
     def strurl(url):
         """Converts a bytes url back to str"""
         return url.decode(u'ascii')
 
     def bytesurl(url):
         """Converts a str url to bytes by encoding in ascii"""
         return url.encode(u'ascii')
 
     def raisewithtb(exc, tb):
         """Raise exception with the given traceback"""
         raise exc.with_traceback(tb)
 
     def getdoc(obj):
         """Get docstring as bytes; may be None so gettext() won't confuse it
         with _('')"""
         doc = getattr(obj, u'__doc__', None)
         if doc is None:
             return doc
         return sysbytes(doc)
 
     def _wrapattrfunc(f):
         @functools.wraps(f)
         def w(object, name, *args):
             return f(object, sysstr(name), *args)
         return w
 
     # these wrappers are automagically imported by hgloader
     delattr = _wrapattrfunc(builtins.delattr)
     getattr = _wrapattrfunc(builtins.getattr)
     hasattr = _wrapattrfunc(builtins.hasattr)
     setattr = _wrapattrfunc(builtins.setattr)
     xrange = builtins.range
     unicode = str
 
     def open(name, mode='r', buffering=-1):
         return builtins.open(name, sysstr(mode), buffering)
 
     def _getoptbwrapper(orig, args, shortlist, namelist):
         """
         Takes bytes arguments, converts them to unicode, pass them to
         getopt.getopt(), convert the returned values back to bytes and then
         return them for Python 3 compatibility as getopt.getopt() don't accepts
         bytes on Python 3.
         """
         args = [a.decode('latin-1') for a in args]
         shortlist = shortlist.decode('latin-1')
         namelist = [a.decode('latin-1') for a in namelist]
         opts, args = orig(args, shortlist, namelist)
         opts = [(a[0].encode('latin-1'), a[1].encode('latin-1'))
                 for a in opts]
         args = [a.encode('latin-1') for a in args]
         return opts, args
 
     def strkwargs(dic):
         """
         Converts the keys of a python dictonary to str i.e. unicodes so that
         they can be passed as keyword arguments as dictonaries with bytes keys
         can't be passed as keyword arguments to functions on Python 3.
         """
         dic = dict((k.decode('latin-1'), v) for k, v in dic.iteritems())
         return dic
 
     def byteskwargs(dic):
         """
         Converts keys of python dictonaries to bytes as they were converted to
         str to pass that dictonary as a keyword argument on Python 3.
         """
         dic = dict((k.encode('latin-1'), v) for k, v in dic.iteritems())
         return dic
 
     # TODO: handle shlex.shlex().
     def shlexsplit(s):
         """
         Takes bytes argument, convert it to str i.e. unicodes, pass that into
         shlex.split(), convert the returned value to bytes and return that for
         Python 3 compatibility as shelx.split() don't accept bytes on Python 3.
         """
         ret = shlex.split(s.decode('latin-1'))
         return [a.encode('latin-1') for a in ret]
 
 else:
     import cStringIO
 
     bytechr = chr
     bytestr = str
     iterbytestr = iter
     sysbytes = identity
     sysstr = identity
     strurl = identity
     bytesurl = identity
 
     # this can't be parsed on Python 3
     exec('def raisewithtb(exc, tb):\n'
          '    raise exc, None, tb\n')
 
     def fsencode(filename):
         """
         Partial backport from os.py in Python 3, which only accepts bytes.
         In Python 2, our paths should only ever be bytes, a unicode path
         indicates a bug.
         """
         if isinstance(filename, str):
             return filename
         else:
             raise TypeError(
                 "expect str, not %s" % type(filename).__name__)
 
     # In Python 2, fsdecode() has a very chance to receive bytes. So it's
     # better not to touch Python 2 part as it's already working fine.
     fsdecode = identity
 
     def getdoc(obj):
         return getattr(obj, '__doc__', None)
 
     def _getoptbwrapper(orig, args, shortlist, namelist):
         return orig(args, shortlist, namelist)
 
     strkwargs = identity
     byteskwargs = identity
 
     oslinesep = os.linesep
     osname = os.name
     ospathsep = os.pathsep
     ossep = os.sep
     osaltsep = os.altsep
     stdin = sys.stdin
     stdout = sys.stdout
     stderr = sys.stderr
     if getattr(sys, 'argv', None) is not None:
         sysargv = sys.argv
     sysplatform = sys.platform
     getcwd = os.getcwd
     sysexecutable = sys.executable
     shlexsplit = shlex.split
     stringio = cStringIO.StringIO
     maplist = map
+    ziplist = zip
     rawinput = raw_input
 
 isjython = sysplatform.startswith('java')
 
 isdarwin = sysplatform == 'darwin'
 isposix = osname == 'posix'
 iswindows = osname == 'nt'
 
 def getoptb(args, shortlist, namelist):
     return _getoptbwrapper(getopt.getopt, args, shortlist, namelist)
 
 def gnugetoptb(args, shortlist, namelist):
     return _getoptbwrapper(getopt.gnu_getopt, args, shortlist, namelist)