mako/compat.py

# mako/compat.py
# Copyright 2006-2019 the Mako authors and contributors <see AUTHORS file>
#
# This module is part of Mako and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php

import collections
import inspect
import sys

py3k = sys.version_info >= (3, 0)
py2k = sys.version_info < (3,)
py27 = sys.version_info >= (2, 7)
jython = sys.platform.startswith("java")
win32 = sys.platform.startswith("win")
pypy = hasattr(sys, "pypy_version_info")

ArgSpec = collections.namedtuple(
    "ArgSpec", ["args", "varargs", "keywords", "defaults"]
)


def inspect_getargspec(func):
    """getargspec based on fully vendored getfullargspec from Python 3.3."""

    if inspect.ismethod(func):
        func = func.__func__
    if not inspect.isfunction(func):
        raise TypeError("{!r} is not a Python function".format(func))

    co = func.__code__
    if not inspect.iscode(co):
        raise TypeError("{!r} is not a code object".format(co))

    nargs = co.co_argcount
    names = co.co_varnames
    nkwargs = co.co_kwonlyargcount if py3k else 0
    args = list(names[:nargs])

    nargs += nkwargs
    varargs = None
    if co.co_flags & inspect.CO_VARARGS:
        varargs = co.co_varnames[nargs]
        nargs = nargs + 1
    varkw = None
    if co.co_flags & inspect.CO_VARKEYWORDS:
        varkw = co.co_varnames[nargs]

    return ArgSpec(args, varargs, varkw, func.__defaults__)


if py3k:
    from io import StringIO
    import builtins as compat_builtins
    from urllib.parse import quote_plus, unquote_plus
    from html.entities import codepoint2name, name2codepoint

    string_types = (str,)
    binary_type = bytes
    text_type = str

    from io import BytesIO as byte_buffer

    def u(s):
        return s

    def b(s):
        return s.encode("latin-1")

    def octal(lit):
        return eval("0o" + lit)


else:
    import __builtin__ as compat_builtins  # noqa

    try:
        from cStringIO import StringIO
    except:
        from StringIO import StringIO

    byte_buffer = StringIO

    from urllib import quote_plus, unquote_plus  # noqa
    from htmlentitydefs import codepoint2name, name2codepoint  # noqa

    string_types = (basestring,)  # noqa
    binary_type = str
    text_type = unicode  # noqa

    def u(s):
        return unicode(s, "utf-8")  # noqa

    def b(s):
        return s

    def octal(lit):
        return eval("0" + lit)


if py3k:
    from importlib import machinery

    def load_module(module_id, path):
        return machinery.SourceFileLoader(module_id, path).load_module()


else:
    import imp

    def load_module(module_id, path):
        fp = open(path, "rb")
        try:
            return imp.load_source(module_id, path, fp)
        finally:
            fp.close()


if py3k:

    def reraise(tp, value, tb=None, cause=None):
        if cause is not None:
            value.__cause__ = cause
        if value.__traceback__ is not tb:
            raise value.with_traceback(tb)
        raise value


else:
    exec(
        "def reraise(tp, value, tb=None, cause=None):\n"
        "    raise tp, value, tb\n"
    )


def exception_as():
    return sys.exc_info()[1]


all = all  # noqa


def exception_name(exc):
    return exc.__class__.__name__


################################################
# cross-compatible metaclass implementation
# Copyright (c) 2010-2012 Benjamin Peterson
def with_metaclass(meta, base=object):
    """Create a base class with a metaclass."""
    return meta("%sBase" % meta.__name__, (base,), {})


################################################


def arg_stringname(func_arg):
    """Gets the string name of a kwarg or vararg
    In Python3.4 a function's args are
    of _ast.arg type not _ast.name
    """
    if hasattr(func_arg, "arg"):
        return func_arg.arg
    else:
        return str(func_arg)