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Source code for past.types.oldstr

"""
Pure-Python implementation of a Python 2-like str object for Python 3.
"""

from collections import Iterable
from numbers import Integral

from past.utils import PY2, with_metaclass


_builtin_bytes = bytes


class BaseOldStr(type):
    def __instancecheck__(cls, instance):
        return isinstance(instance, _builtin_bytes)


def unescape(s):
    """
    Interprets strings with escape sequences

    Example:
    >>> s = unescape(r'abc\\def')   # i.e. 'abc\\\\def'
    >>> print(s)
    'abc\def'
    >>> s2 = unescape('abc\\ndef')
    >>> len(s2)
    8
    >>> print(s2)
    abc
    def
    """
    return s.encode().decode('unicode_escape')
    

[docs]class oldstr(with_metaclass(BaseOldStr, _builtin_bytes)): """ A forward port of the Python 2 8-bit string object to Py3 """ # Python 2 strings have no __iter__ method: @property def __iter__(self): raise AttributeError def __dir__(self): return [thing for thing in dir(_builtin_bytes) if thing != '__iter__'] # def __new__(cls, *args, **kwargs): # """ # From the Py3 bytes docstring: # bytes(iterable_of_ints) -> bytes # bytes(string, encoding[, errors]) -> bytes # bytes(bytes_or_buffer) -> immutable copy of bytes_or_buffer # bytes(int) -> bytes object of size given by the parameter initialized with null bytes # bytes() -> empty bytes object # # Construct an immutable array of bytes from: # - an iterable yielding integers in range(256) # - a text string encoded using the specified encoding # - any object implementing the buffer API. # - an integer # """ # # if len(args) == 0: # return super(newbytes, cls).__new__(cls) # # Was: elif isinstance(args[0], newbytes): # # We use type() instead of the above because we're redefining # # this to be True for all unicode string subclasses. Warning: # # This may render newstr un-subclassable. # elif type(args[0]) == newbytes: # return args[0] # elif isinstance(args[0], _builtin_bytes): # value = args[0] # elif isinstance(args[0], unicode): # if 'encoding' not in kwargs: # raise TypeError('unicode string argument without an encoding') # ### # # Was: value = args[0].encode(**kwargs) # # Python 2.6 string encode() method doesn't take kwargs: # # Use this instead: # newargs = [kwargs['encoding']] # if 'errors' in kwargs: # newargs.append(kwargs['errors']) # value = args[0].encode(*newargs) # ### # elif isinstance(args[0], Iterable): # if len(args[0]) == 0: # # What is this? # raise ValueError('unknown argument type') # elif len(args[0]) > 0 and isinstance(args[0][0], Integral): # # It's a list of integers # value = b''.join([chr(x) for x in args[0]]) # else: # raise ValueError('item cannot be interpreted as an integer') # elif isinstance(args[0], Integral): # if args[0] < 0: # raise ValueError('negative count') # value = b'\x00' * args[0] # else: # value = args[0] # return super(newbytes, cls).__new__(cls, value) def __repr__(self): s = super(oldstr, self).__repr__() # e.g. b'abc' on Py3, b'abc' on Py3 return s[1:] def __str__(self): s = super(oldstr, self).__str__() # e.g. "b'abc'" or "b'abc\\ndef' # TODO: fix this: assert s[:2] == "b'" and s[-1] == "'" return unescape(s[2:-1]) # e.g. 'abc' or 'abc\ndef' def __getitem__(self, y): if isinstance(y, Integral): return super(oldstr, self).__getitem__(slice(y, y+1)) else: return super(oldstr, self).__getitem__(y) def __getslice__(self, *args): return self.__getitem__(slice(*args)) def __contains__(self, key): if isinstance(key, int): return False def __native__(self): return bytes(self)
__all__ = ['oldstr']