view mercurial/pycompat.py @ 37046:1cfef5693203

wireproto: support /api/* URL space for exposing APIs I will soon be introducing a new version of the HTTP wire protocol. One of the things I want to change with it is the URL routing. I want to rely on URL paths to define endpoints rather than the "cmd" query string argument. That should be pretty straightforward. I was thinking about what URL space to reserve for the new protocol. We /could/ put everything at a top-level path. e.g. /wireproto/* or /http-v2-wireproto/*. However, these constrain us a bit because they assume there will only be 1 API: version 2 of the HTTP wire protocol. I think there is room to grow multiple APIs. For example, there may someday be a proper JSON API to query or even manipulate the repository. And I don't think we should have to create a new top-level URL space for each API nor should we attempt to shoehorn each future API into the same shared URL space: that would just be too chaotic. This commits reserves the /api/* URL space for all our future API needs. Essentially, all requests to /api/* get routed to a new WSGI handler. By default, it 404's the entire URL space unless the "api server" feature is enabled. When enabled, requests to "/api" list available APIs. URLs of the form /api/<name>/* are reserved for a particular named API. Behavior within each API is left up to that API. So, we can grow new APIs easily without worrying about URL space conflicts. APIs can be registered by adding entries to a global dict. This allows extensions to provide their own APIs should they choose to do so. This is probably a premature feature. But IMO the code is easier to read if we're not dealing with API-specific behavior like config option querying inline. To prove it works, we implement a very basic API for version 2 of the HTTP wire protocol. It does nothing of value except facilitate testing of the /api/* URL space. We currently emit plain text responses for all /api/* endpoints. There's definitely room to look at Accept and other request headers to vary the response format. But we have to start somewhere. Differential Revision: https://phab.mercurial-scm.org/D2834
author Gregory Szorc <gregory.szorc@gmail.com>
date Tue, 13 Mar 2018 16:53:21 -0700
parents 644a02f6b34f
children 434e520adb8c
line wrap: on
line source

# 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 inspect
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
    oscurdir = os.curdir.encode('ascii')
    oslinesep = os.linesep.encode('ascii')
    osname = os.name.encode('ascii')
    ospathsep = os.pathsep.encode('ascii')
    ospardir = os.pardir.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)
    bytesio = io.BytesIO
    # TODO deprecate stringio name, as it is a lie on Python 3.
    stringio = bytesio

    def maplist(*args):
        return list(map(*args))

    def ziplist(*args):
        return list(zip(*args))

    rawinput = input
    getargspec = inspect.getfullargspec

    # 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
    byterepr = b'%r'.__mod__

    class bytestr(bytes):
        """A bytes which mostly acts as a Python 2 str

        >>> bytestr(), bytestr(bytearray(b'foo')), bytestr(u'ascii'), bytestr(1)
        ('', 'foo', 'ascii', '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())
        '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 __repr__(self):
            return bytes.__repr__(self)[1:]  # drop b''

    def iterbytestr(s):
        """Iterate bytes as if it were a str object of Python 2"""
        return map(bytechr, s)

    def maybebytestr(s):
        """Promote bytes to bytestr"""
        if isinstance(s, bytes):
            return bytestr(s)
        return 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"""
        if isinstance(url, bytes):
            return url.decode(u'ascii')
        return url

    def bytesurl(url):
        """Converts a str url to bytes by encoding in ascii"""
        if isinstance(url, str):
            return url.encode(u'ascii')
        return url

    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, encoding=None):
        return builtins.open(name, sysstr(mode), buffering, encoding)

    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, comments=False, posix=True):
        """
        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'), comments, posix)
        return [a.encode('latin-1') for a in ret]

    def emailparser(*args, **kwargs):
        import email.parser
        return email.parser.BytesParser(*args, **kwargs)

else:
    import cStringIO

    bytechr = chr
    byterepr = repr
    bytestr = str
    iterbytestr = iter
    maybebytestr = identity
    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

    oscurdir = os.curdir
    oslinesep = os.linesep
    osname = os.name
    ospathsep = os.pathsep
    ospardir = os.pardir
    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
    bytesio = cStringIO.StringIO
    stringio = bytesio
    maplist = map
    ziplist = zip
    rawinput = raw_input
    getargspec = inspect.getargspec

    def emailparser(*args, **kwargs):
        import email.parser
        return email.parser.Parser(*args, **kwargs)

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)