view mercurial/pycompat.py @ 31439:b70407bd84d5

pycompat: add bytestr wrapper which mostly acts as a Python 2 str

This allows us to handle bytes in mostly the same manner as Python 2 str,
so we can get rid of ugly s[i:i + 1] hacks:

  s = bytestr(s)
  while i < len(s):
      c = s[i]
      ...

This is the simpler version of the previous RFC patch which tried to preserve
the bytestr type if possible. New version simply drops the bytestr wrapping
so we aren't likely to pass a bytestr to a function that expects Python 3
bytes.

# 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)

if not ispy3:
    import cPickle as pickle
    import httplib
    import Queue as _queue
    import SocketServer as socketserver
    import urlparse
    urlunquote = urlparse.unquote
    import xmlrpclib
else:
    import http.client as httplib
    import pickle
    import queue as _queue
    import socketserver
    import urllib.parse as urlparse
    urlunquote = urlparse.unquote_to_bytes
    import xmlrpc.client as xmlrpclib

if ispy3:
    import builtins
    import functools
    import io
    import struct

    fsencode = os.fsencode
    fsdecode = os.fsdecode
    # A bytes version of os.name.
    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

    # 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)

        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)):
                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 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 _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

    def open(name, mode='r', buffering=-1):
        return builtins.open(name, sysstr(mode), buffering)

    # getopt.getopt() on Python 3 deals with unicodes internally so we cannot
    # pass bytes there. Passing unicodes will result in unicodes as return
    # values which we need to convert again to bytes.
    def getoptb(args, shortlist, namelist):
        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 = getopt.getopt(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

    # keys of keyword arguments in Python need to be strings which are unicodes
    # Python 3. This function takes keyword arguments, convert the keys to str.
    def strkwargs(dic):
        dic = dict((k.decode('latin-1'), v) for k, v in dic.iteritems())
        return dic

    # keys of keyword arguments need to be unicode while passing into
    # a function. This function helps us to convert those keys back to bytes
    # again as we need to deal with bytes.
    def byteskwargs(dic):
        dic = dict((k.encode('latin-1'), v) for k, v in dic.iteritems())
        return dic

    # shlex.split() accepts unicodes on Python 3. This function takes bytes
    # argument, convert it into unicodes, pass into shlex.split(), convert the
    # returned value to bytes and return that.
    # TODO: handle shlex.shlex().
    def shlexsplit(s):
        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

    def sysstr(s):
        return s

    # 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.
    def fsencode(filename):
        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.
    def fsdecode(filename):
        return filename

    def getoptb(args, shortlist, namelist):
        return getopt.getopt(args, shortlist, namelist)

    def strkwargs(dic):
        return dic

    def byteskwargs(dic):
        return dic

    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

empty = _queue.Empty
queue = _queue.Queue

class _pycompatstub(object):
    def __init__(self):
        self._aliases = {}

    def _registeraliases(self, origin, items):
        """Add items that will be populated at the first access"""
        items = map(sysstr, items)
        self._aliases.update(
            (item.replace(sysstr('_'), sysstr('')).lower(), (origin, item))
            for item in items)

    def __getattr__(self, name):
        try:
            origin, item = self._aliases[name]
        except KeyError:
            raise AttributeError(name)
        self.__dict__[name] = obj = getattr(origin, item)
        return obj

httpserver = _pycompatstub()
urlreq = _pycompatstub()
urlerr = _pycompatstub()
if not ispy3:
    import BaseHTTPServer
    import CGIHTTPServer
    import SimpleHTTPServer
    import urllib2
    import urllib
    urlreq._registeraliases(urllib, (
        "addclosehook",
        "addinfourl",
        "ftpwrapper",
        "pathname2url",
        "quote",
        "splitattr",
        "splitpasswd",
        "splitport",
        "splituser",
        "unquote",
        "url2pathname",
        "urlencode",
    ))
    urlreq._registeraliases(urllib2, (
        "AbstractHTTPHandler",
        "BaseHandler",
        "build_opener",
        "FileHandler",
        "FTPHandler",
        "HTTPBasicAuthHandler",
        "HTTPDigestAuthHandler",
        "HTTPHandler",
        "HTTPPasswordMgrWithDefaultRealm",
        "HTTPSHandler",
        "install_opener",
        "ProxyHandler",
        "Request",
        "urlopen",
    ))
    urlerr._registeraliases(urllib2, (
        "HTTPError",
        "URLError",
    ))
    httpserver._registeraliases(BaseHTTPServer, (
        "HTTPServer",
        "BaseHTTPRequestHandler",
    ))
    httpserver._registeraliases(SimpleHTTPServer, (
        "SimpleHTTPRequestHandler",
    ))
    httpserver._registeraliases(CGIHTTPServer, (
        "CGIHTTPRequestHandler",
    ))

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

    # urllib.parse.quote() accepts both str and bytes, decodes bytes
    # (if necessary), and returns str. This is wonky. We provide a custom
    # implementation that only accepts bytes and emits bytes.
    def quote(s, safe=r'/'):
        s = urllib.parse.quote_from_bytes(s, safe=safe)
        return s.encode('ascii', 'strict')

    urlreq.quote = quote