mirror of
https://github.com/python/cpython.git
synced 2025-08-01 15:43:13 +00:00
5376ba9630
Summary of changes:
1. Coroutines now have a distinct, separate from generators
type at the C level: PyGen_Type, and a new typedef PyCoroObject.
PyCoroObject shares the initial segment of struct layout with
PyGenObject, making it possible to reuse existing generators
machinery. The new type is exposed as 'types.CoroutineType'.
As a consequence of having a new type, CO_GENERATOR flag is
no longer applied to coroutines.
2. Having a separate type for coroutines made it possible to add
an __await__ method to the type. Although it is not used by the
interpreter (see details on that below), it makes coroutines
naturally (without using __instancecheck__) conform to
collections.abc.Coroutine and collections.abc.Awaitable ABCs.
[The __instancecheck__ is still used for generator-based
coroutines, as we don't want to add __await__ for generators.]
3. Add new opcode: GET_YIELD_FROM_ITER. The opcode is needed to
allow passing native coroutines to the YIELD_FROM opcode.
Before this change, 'yield from o' expression was compiled to:
(o)
GET_ITER
LOAD_CONST
YIELD_FROM
Now, we use GET_YIELD_FROM_ITER instead of GET_ITER.
The reason for adding a new opcode is that GET_ITER is used
in some contexts (such as 'for .. in' loops) where passing
a coroutine object is invalid.
4. Add two new introspection functions to the inspec module:
getcoroutinestate(c) and getcoroutinelocals(c).
5. inspect.iscoroutine(o) is updated to test if 'o' is a native
coroutine object. Before this commit it used abc.Coroutine,
and it was requested to update inspect.isgenerator(o) to use
abc.Generator; it was decided, however, that inspect functions
should really be tailored for checking for native types.
6. sys.set_coroutine_wrapper(w) API is updated to work with only
native coroutines. Since types.coroutine decorator supports
any type of callables now, it would be confusing that it does
not work for all types of coroutines.
7. Exceptions logic in generators C implementation was updated
to raise clearer messages for coroutines:
Before: TypeError("generator raised StopIteration")
After: TypeError("coroutine raised StopIteration")
954 lines
25 KiB
Python
954 lines
25 KiB
Python
# Copyright 2007 Google, Inc. All Rights Reserved.
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# Licensed to PSF under a Contributor Agreement.
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"""Abstract Base Classes (ABCs) for collections, according to PEP 3119.
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Unit tests are in test_collections.
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"""
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from abc import ABCMeta, abstractmethod
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import sys
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__all__ = ["Awaitable", "Coroutine", "AsyncIterable", "AsyncIterator",
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"Hashable", "Iterable", "Iterator", "Generator",
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"Sized", "Container", "Callable",
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"Set", "MutableSet",
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"Mapping", "MutableMapping",
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"MappingView", "KeysView", "ItemsView", "ValuesView",
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"Sequence", "MutableSequence",
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"ByteString",
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]
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# This module has been renamed from collections.abc to _collections_abc to
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# speed up interpreter startup. Some of the types such as MutableMapping are
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# required early but collections module imports a lot of other modules.
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# See issue #19218
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__name__ = "collections.abc"
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# Private list of types that we want to register with the various ABCs
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# so that they will pass tests like:
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# it = iter(somebytearray)
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# assert isinstance(it, Iterable)
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# Note: in other implementations, these types many not be distinct
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# and they make have their own implementation specific types that
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# are not included on this list.
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bytes_iterator = type(iter(b''))
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bytearray_iterator = type(iter(bytearray()))
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#callable_iterator = ???
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dict_keyiterator = type(iter({}.keys()))
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dict_valueiterator = type(iter({}.values()))
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dict_itemiterator = type(iter({}.items()))
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list_iterator = type(iter([]))
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list_reverseiterator = type(iter(reversed([])))
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range_iterator = type(iter(range(0)))
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set_iterator = type(iter(set()))
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str_iterator = type(iter(""))
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tuple_iterator = type(iter(()))
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zip_iterator = type(iter(zip()))
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## views ##
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dict_keys = type({}.keys())
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dict_values = type({}.values())
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dict_items = type({}.items())
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## misc ##
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mappingproxy = type(type.__dict__)
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generator = type((lambda: (yield))())
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## coroutine ##
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async def _coro(): pass
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_coro = _coro()
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coroutine = type(_coro)
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_coro.close() # Prevent ResourceWarning
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del _coro
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### ONE-TRICK PONIES ###
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class Hashable(metaclass=ABCMeta):
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__slots__ = ()
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@abstractmethod
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def __hash__(self):
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return 0
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@classmethod
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def __subclasshook__(cls, C):
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if cls is Hashable:
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for B in C.__mro__:
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if "__hash__" in B.__dict__:
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if B.__dict__["__hash__"]:
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return True
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break
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return NotImplemented
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class _AwaitableMeta(ABCMeta):
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def __instancecheck__(cls, instance):
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# This hook is needed because we can't add
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# '__await__' method to generator objects, and
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# we can't register GeneratorType on Awaitable.
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# NB: 0x100 = CO_ITERABLE_COROUTINE
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# (We don't want to import 'inspect' module, as
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# a dependency for 'collections.abc')
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if (instance.__class__ is generator and
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instance.gi_code.co_flags & 0x100):
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return True
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return super().__instancecheck__(instance)
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class Awaitable(metaclass=_AwaitableMeta):
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__slots__ = ()
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@abstractmethod
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def __await__(self):
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yield
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@classmethod
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def __subclasshook__(cls, C):
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if cls is Awaitable:
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for B in C.__mro__:
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if "__await__" in B.__dict__:
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if B.__dict__["__await__"]:
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return True
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break
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return NotImplemented
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class Coroutine(Awaitable):
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__slots__ = ()
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@abstractmethod
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def send(self, value):
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"""Send a value into the coroutine.
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Return next yielded value or raise StopIteration.
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"""
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raise StopIteration
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@abstractmethod
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def throw(self, typ, val=None, tb=None):
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"""Raise an exception in the coroutine.
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Return next yielded value or raise StopIteration.
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"""
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if val is None:
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if tb is None:
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raise typ
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val = typ()
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if tb is not None:
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val = val.with_traceback(tb)
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raise val
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def close(self):
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"""Raise GeneratorExit inside coroutine.
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"""
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try:
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self.throw(GeneratorExit)
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except (GeneratorExit, StopIteration):
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pass
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else:
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raise RuntimeError("coroutine ignored GeneratorExit")
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@classmethod
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def __subclasshook__(cls, C):
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if cls is Coroutine:
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mro = C.__mro__
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for method in ('__await__', 'send', 'throw', 'close'):
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for base in mro:
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if method in base.__dict__:
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break
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else:
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return NotImplemented
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return True
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return NotImplemented
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Coroutine.register(coroutine)
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class AsyncIterable(metaclass=ABCMeta):
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__slots__ = ()
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@abstractmethod
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async def __aiter__(self):
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return AsyncIterator()
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@classmethod
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def __subclasshook__(cls, C):
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if cls is AsyncIterable:
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if any("__aiter__" in B.__dict__ for B in C.__mro__):
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return True
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return NotImplemented
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class AsyncIterator(AsyncIterable):
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__slots__ = ()
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@abstractmethod
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async def __anext__(self):
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"""Return the next item or raise StopAsyncIteration when exhausted."""
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raise StopAsyncIteration
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async def __aiter__(self):
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return self
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@classmethod
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def __subclasshook__(cls, C):
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if cls is AsyncIterator:
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if (any("__anext__" in B.__dict__ for B in C.__mro__) and
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any("__aiter__" in B.__dict__ for B in C.__mro__)):
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return True
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return NotImplemented
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class Iterable(metaclass=ABCMeta):
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__slots__ = ()
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@abstractmethod
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def __iter__(self):
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while False:
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yield None
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@classmethod
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def __subclasshook__(cls, C):
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if cls is Iterable:
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if any("__iter__" in B.__dict__ for B in C.__mro__):
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return True
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return NotImplemented
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class Iterator(Iterable):
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__slots__ = ()
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@abstractmethod
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def __next__(self):
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'Return the next item from the iterator. When exhausted, raise StopIteration'
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raise StopIteration
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def __iter__(self):
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return self
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@classmethod
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def __subclasshook__(cls, C):
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if cls is Iterator:
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if (any("__next__" in B.__dict__ for B in C.__mro__) and
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any("__iter__" in B.__dict__ for B in C.__mro__)):
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return True
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return NotImplemented
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Iterator.register(bytes_iterator)
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Iterator.register(bytearray_iterator)
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#Iterator.register(callable_iterator)
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Iterator.register(dict_keyiterator)
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Iterator.register(dict_valueiterator)
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Iterator.register(dict_itemiterator)
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Iterator.register(list_iterator)
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Iterator.register(list_reverseiterator)
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Iterator.register(range_iterator)
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Iterator.register(set_iterator)
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Iterator.register(str_iterator)
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Iterator.register(tuple_iterator)
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Iterator.register(zip_iterator)
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class Generator(Iterator):
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__slots__ = ()
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def __next__(self):
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"""Return the next item from the generator.
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When exhausted, raise StopIteration.
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"""
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return self.send(None)
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@abstractmethod
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def send(self, value):
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"""Send a value into the generator.
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Return next yielded value or raise StopIteration.
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"""
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raise StopIteration
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@abstractmethod
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def throw(self, typ, val=None, tb=None):
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"""Raise an exception in the generator.
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Return next yielded value or raise StopIteration.
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"""
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if val is None:
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if tb is None:
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raise typ
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val = typ()
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if tb is not None:
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val = val.with_traceback(tb)
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raise val
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def close(self):
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"""Raise GeneratorExit inside generator.
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"""
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try:
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self.throw(GeneratorExit)
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except (GeneratorExit, StopIteration):
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pass
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else:
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raise RuntimeError("generator ignored GeneratorExit")
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@classmethod
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def __subclasshook__(cls, C):
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if cls is Generator:
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mro = C.__mro__
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for method in ('__iter__', '__next__', 'send', 'throw', 'close'):
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for base in mro:
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if method in base.__dict__:
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break
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else:
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return NotImplemented
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return True
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return NotImplemented
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Generator.register(generator)
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class Sized(metaclass=ABCMeta):
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__slots__ = ()
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@abstractmethod
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def __len__(self):
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return 0
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@classmethod
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def __subclasshook__(cls, C):
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if cls is Sized:
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if any("__len__" in B.__dict__ for B in C.__mro__):
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return True
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return NotImplemented
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class Container(metaclass=ABCMeta):
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__slots__ = ()
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@abstractmethod
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def __contains__(self, x):
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return False
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@classmethod
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def __subclasshook__(cls, C):
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if cls is Container:
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if any("__contains__" in B.__dict__ for B in C.__mro__):
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return True
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return NotImplemented
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class Callable(metaclass=ABCMeta):
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__slots__ = ()
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@abstractmethod
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def __call__(self, *args, **kwds):
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return False
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@classmethod
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def __subclasshook__(cls, C):
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if cls is Callable:
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if any("__call__" in B.__dict__ for B in C.__mro__):
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return True
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return NotImplemented
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### SETS ###
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class Set(Sized, Iterable, Container):
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"""A set is a finite, iterable container.
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This class provides concrete generic implementations of all
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methods except for __contains__, __iter__ and __len__.
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To override the comparisons (presumably for speed, as the
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semantics are fixed), redefine __le__ and __ge__,
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then the other operations will automatically follow suit.
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"""
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__slots__ = ()
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def __le__(self, other):
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if not isinstance(other, Set):
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return NotImplemented
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if len(self) > len(other):
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return False
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for elem in self:
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if elem not in other:
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return False
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return True
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def __lt__(self, other):
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if not isinstance(other, Set):
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return NotImplemented
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return len(self) < len(other) and self.__le__(other)
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def __gt__(self, other):
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if not isinstance(other, Set):
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return NotImplemented
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return len(self) > len(other) and self.__ge__(other)
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def __ge__(self, other):
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if not isinstance(other, Set):
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return NotImplemented
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if len(self) < len(other):
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return False
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for elem in other:
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if elem not in self:
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return False
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return True
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def __eq__(self, other):
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if not isinstance(other, Set):
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return NotImplemented
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return len(self) == len(other) and self.__le__(other)
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@classmethod
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def _from_iterable(cls, it):
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'''Construct an instance of the class from any iterable input.
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Must override this method if the class constructor signature
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does not accept an iterable for an input.
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'''
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return cls(it)
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def __and__(self, other):
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if not isinstance(other, Iterable):
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return NotImplemented
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return self._from_iterable(value for value in other if value in self)
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__rand__ = __and__
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def isdisjoint(self, other):
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'Return True if two sets have a null intersection.'
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for value in other:
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if value in self:
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return False
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return True
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def __or__(self, other):
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if not isinstance(other, Iterable):
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return NotImplemented
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chain = (e for s in (self, other) for e in s)
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return self._from_iterable(chain)
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__ror__ = __or__
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def __sub__(self, other):
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if not isinstance(other, Set):
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if not isinstance(other, Iterable):
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return NotImplemented
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other = self._from_iterable(other)
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return self._from_iterable(value for value in self
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if value not in other)
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def __rsub__(self, other):
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if not isinstance(other, Set):
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if not isinstance(other, Iterable):
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return NotImplemented
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other = self._from_iterable(other)
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return self._from_iterable(value for value in other
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if value not in self)
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def __xor__(self, other):
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if not isinstance(other, Set):
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if not isinstance(other, Iterable):
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return NotImplemented
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other = self._from_iterable(other)
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return (self - other) | (other - self)
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__rxor__ = __xor__
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def _hash(self):
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"""Compute the hash value of a set.
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Note that we don't define __hash__: not all sets are hashable.
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But if you define a hashable set type, its __hash__ should
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call this function.
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This must be compatible __eq__.
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All sets ought to compare equal if they contain the same
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elements, regardless of how they are implemented, and
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regardless of the order of the elements; so there's not much
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freedom for __eq__ or __hash__. We match the algorithm used
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by the built-in frozenset type.
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"""
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MAX = sys.maxsize
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MASK = 2 * MAX + 1
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n = len(self)
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h = 1927868237 * (n + 1)
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h &= MASK
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for x in self:
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hx = hash(x)
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h ^= (hx ^ (hx << 16) ^ 89869747) * 3644798167
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h &= MASK
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h = h * 69069 + 907133923
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h &= MASK
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if h > MAX:
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h -= MASK + 1
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if h == -1:
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h = 590923713
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return h
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Set.register(frozenset)
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class MutableSet(Set):
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"""A mutable set is a finite, iterable container.
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This class provides concrete generic implementations of all
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methods except for __contains__, __iter__, __len__,
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add(), and discard().
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To override the comparisons (presumably for speed, as the
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semantics are fixed), all you have to do is redefine __le__ and
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then the other operations will automatically follow suit.
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"""
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__slots__ = ()
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@abstractmethod
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def add(self, value):
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"""Add an element."""
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raise NotImplementedError
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@abstractmethod
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def discard(self, value):
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"""Remove an element. Do not raise an exception if absent."""
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raise NotImplementedError
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def remove(self, value):
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"""Remove an element. If not a member, raise a KeyError."""
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if value not in self:
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raise KeyError(value)
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self.discard(value)
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def pop(self):
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"""Return the popped value. Raise KeyError if empty."""
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it = iter(self)
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try:
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value = next(it)
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except StopIteration:
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raise KeyError
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self.discard(value)
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return value
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def clear(self):
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"""This is slow (creates N new iterators!) but effective."""
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try:
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while True:
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self.pop()
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except KeyError:
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pass
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|
|
def __ior__(self, it):
|
|
for value in it:
|
|
self.add(value)
|
|
return self
|
|
|
|
def __iand__(self, it):
|
|
for value in (self - it):
|
|
self.discard(value)
|
|
return self
|
|
|
|
def __ixor__(self, it):
|
|
if it is self:
|
|
self.clear()
|
|
else:
|
|
if not isinstance(it, Set):
|
|
it = self._from_iterable(it)
|
|
for value in it:
|
|
if value in self:
|
|
self.discard(value)
|
|
else:
|
|
self.add(value)
|
|
return self
|
|
|
|
def __isub__(self, it):
|
|
if it is self:
|
|
self.clear()
|
|
else:
|
|
for value in it:
|
|
self.discard(value)
|
|
return self
|
|
|
|
MutableSet.register(set)
|
|
|
|
|
|
### MAPPINGS ###
|
|
|
|
|
|
class Mapping(Sized, Iterable, Container):
|
|
|
|
__slots__ = ()
|
|
|
|
"""A Mapping is a generic container for associating key/value
|
|
pairs.
|
|
|
|
This class provides concrete generic implementations of all
|
|
methods except for __getitem__, __iter__, and __len__.
|
|
|
|
"""
|
|
|
|
@abstractmethod
|
|
def __getitem__(self, key):
|
|
raise KeyError
|
|
|
|
def get(self, key, default=None):
|
|
'D.get(k[,d]) -> D[k] if k in D, else d. d defaults to None.'
|
|
try:
|
|
return self[key]
|
|
except KeyError:
|
|
return default
|
|
|
|
def __contains__(self, key):
|
|
try:
|
|
self[key]
|
|
except KeyError:
|
|
return False
|
|
else:
|
|
return True
|
|
|
|
def keys(self):
|
|
"D.keys() -> a set-like object providing a view on D's keys"
|
|
return KeysView(self)
|
|
|
|
def items(self):
|
|
"D.items() -> a set-like object providing a view on D's items"
|
|
return ItemsView(self)
|
|
|
|
def values(self):
|
|
"D.values() -> an object providing a view on D's values"
|
|
return ValuesView(self)
|
|
|
|
def __eq__(self, other):
|
|
if not isinstance(other, Mapping):
|
|
return NotImplemented
|
|
return dict(self.items()) == dict(other.items())
|
|
|
|
Mapping.register(mappingproxy)
|
|
|
|
|
|
class MappingView(Sized):
|
|
|
|
__slots__ = '_mapping',
|
|
|
|
def __init__(self, mapping):
|
|
self._mapping = mapping
|
|
|
|
def __len__(self):
|
|
return len(self._mapping)
|
|
|
|
def __repr__(self):
|
|
return '{0.__class__.__name__}({0._mapping!r})'.format(self)
|
|
|
|
|
|
class KeysView(MappingView, Set):
|
|
|
|
__slots__ = ()
|
|
|
|
@classmethod
|
|
def _from_iterable(self, it):
|
|
return set(it)
|
|
|
|
def __contains__(self, key):
|
|
return key in self._mapping
|
|
|
|
def __iter__(self):
|
|
yield from self._mapping
|
|
|
|
KeysView.register(dict_keys)
|
|
|
|
|
|
class ItemsView(MappingView, Set):
|
|
|
|
__slots__ = ()
|
|
|
|
@classmethod
|
|
def _from_iterable(self, it):
|
|
return set(it)
|
|
|
|
def __contains__(self, item):
|
|
key, value = item
|
|
try:
|
|
v = self._mapping[key]
|
|
except KeyError:
|
|
return False
|
|
else:
|
|
return v == value
|
|
|
|
def __iter__(self):
|
|
for key in self._mapping:
|
|
yield (key, self._mapping[key])
|
|
|
|
ItemsView.register(dict_items)
|
|
|
|
|
|
class ValuesView(MappingView):
|
|
|
|
__slots__ = ()
|
|
|
|
def __contains__(self, value):
|
|
for key in self._mapping:
|
|
if value == self._mapping[key]:
|
|
return True
|
|
return False
|
|
|
|
def __iter__(self):
|
|
for key in self._mapping:
|
|
yield self._mapping[key]
|
|
|
|
ValuesView.register(dict_values)
|
|
|
|
|
|
class MutableMapping(Mapping):
|
|
|
|
__slots__ = ()
|
|
|
|
"""A MutableMapping is a generic container for associating
|
|
key/value pairs.
|
|
|
|
This class provides concrete generic implementations of all
|
|
methods except for __getitem__, __setitem__, __delitem__,
|
|
__iter__, and __len__.
|
|
|
|
"""
|
|
|
|
@abstractmethod
|
|
def __setitem__(self, key, value):
|
|
raise KeyError
|
|
|
|
@abstractmethod
|
|
def __delitem__(self, key):
|
|
raise KeyError
|
|
|
|
__marker = object()
|
|
|
|
def pop(self, key, default=__marker):
|
|
'''D.pop(k[,d]) -> v, remove specified key and return the corresponding value.
|
|
If key is not found, d is returned if given, otherwise KeyError is raised.
|
|
'''
|
|
try:
|
|
value = self[key]
|
|
except KeyError:
|
|
if default is self.__marker:
|
|
raise
|
|
return default
|
|
else:
|
|
del self[key]
|
|
return value
|
|
|
|
def popitem(self):
|
|
'''D.popitem() -> (k, v), remove and return some (key, value) pair
|
|
as a 2-tuple; but raise KeyError if D is empty.
|
|
'''
|
|
try:
|
|
key = next(iter(self))
|
|
except StopIteration:
|
|
raise KeyError
|
|
value = self[key]
|
|
del self[key]
|
|
return key, value
|
|
|
|
def clear(self):
|
|
'D.clear() -> None. Remove all items from D.'
|
|
try:
|
|
while True:
|
|
self.popitem()
|
|
except KeyError:
|
|
pass
|
|
|
|
def update(*args, **kwds):
|
|
''' D.update([E, ]**F) -> None. Update D from mapping/iterable E and F.
|
|
If E present and has a .keys() method, does: for k in E: D[k] = E[k]
|
|
If E present and lacks .keys() method, does: for (k, v) in E: D[k] = v
|
|
In either case, this is followed by: for k, v in F.items(): D[k] = v
|
|
'''
|
|
if not args:
|
|
raise TypeError("descriptor 'update' of 'MutableMapping' object "
|
|
"needs an argument")
|
|
self, *args = args
|
|
if len(args) > 1:
|
|
raise TypeError('update expected at most 1 arguments, got %d' %
|
|
len(args))
|
|
if args:
|
|
other = args[0]
|
|
if isinstance(other, Mapping):
|
|
for key in other:
|
|
self[key] = other[key]
|
|
elif hasattr(other, "keys"):
|
|
for key in other.keys():
|
|
self[key] = other[key]
|
|
else:
|
|
for key, value in other:
|
|
self[key] = value
|
|
for key, value in kwds.items():
|
|
self[key] = value
|
|
|
|
def setdefault(self, key, default=None):
|
|
'D.setdefault(k[,d]) -> D.get(k,d), also set D[k]=d if k not in D'
|
|
try:
|
|
return self[key]
|
|
except KeyError:
|
|
self[key] = default
|
|
return default
|
|
|
|
MutableMapping.register(dict)
|
|
|
|
|
|
### SEQUENCES ###
|
|
|
|
|
|
class Sequence(Sized, Iterable, Container):
|
|
|
|
"""All the operations on a read-only sequence.
|
|
|
|
Concrete subclasses must override __new__ or __init__,
|
|
__getitem__, and __len__.
|
|
"""
|
|
|
|
__slots__ = ()
|
|
|
|
@abstractmethod
|
|
def __getitem__(self, index):
|
|
raise IndexError
|
|
|
|
def __iter__(self):
|
|
i = 0
|
|
try:
|
|
while True:
|
|
v = self[i]
|
|
yield v
|
|
i += 1
|
|
except IndexError:
|
|
return
|
|
|
|
def __contains__(self, value):
|
|
for v in self:
|
|
if v == value:
|
|
return True
|
|
return False
|
|
|
|
def __reversed__(self):
|
|
for i in reversed(range(len(self))):
|
|
yield self[i]
|
|
|
|
def index(self, value, start=0, stop=None):
|
|
'''S.index(value, [start, [stop]]) -> integer -- return first index of value.
|
|
Raises ValueError if the value is not present.
|
|
'''
|
|
if start is not None and start < 0:
|
|
start = max(len(self) + start, 0)
|
|
if stop is not None and stop < 0:
|
|
stop += len(self)
|
|
|
|
i = start
|
|
while stop is None or i < stop:
|
|
try:
|
|
if self[i] == value:
|
|
return i
|
|
except IndexError:
|
|
break
|
|
i += 1
|
|
raise ValueError
|
|
|
|
def count(self, value):
|
|
'S.count(value) -> integer -- return number of occurrences of value'
|
|
return sum(1 for v in self if v == value)
|
|
|
|
Sequence.register(tuple)
|
|
Sequence.register(str)
|
|
Sequence.register(range)
|
|
Sequence.register(memoryview)
|
|
|
|
|
|
class ByteString(Sequence):
|
|
|
|
"""This unifies bytes and bytearray.
|
|
|
|
XXX Should add all their methods.
|
|
"""
|
|
|
|
__slots__ = ()
|
|
|
|
ByteString.register(bytes)
|
|
ByteString.register(bytearray)
|
|
|
|
|
|
class MutableSequence(Sequence):
|
|
|
|
__slots__ = ()
|
|
|
|
"""All the operations on a read-write sequence.
|
|
|
|
Concrete subclasses must provide __new__ or __init__,
|
|
__getitem__, __setitem__, __delitem__, __len__, and insert().
|
|
|
|
"""
|
|
|
|
@abstractmethod
|
|
def __setitem__(self, index, value):
|
|
raise IndexError
|
|
|
|
@abstractmethod
|
|
def __delitem__(self, index):
|
|
raise IndexError
|
|
|
|
@abstractmethod
|
|
def insert(self, index, value):
|
|
'S.insert(index, value) -- insert value before index'
|
|
raise IndexError
|
|
|
|
def append(self, value):
|
|
'S.append(value) -- append value to the end of the sequence'
|
|
self.insert(len(self), value)
|
|
|
|
def clear(self):
|
|
'S.clear() -> None -- remove all items from S'
|
|
try:
|
|
while True:
|
|
self.pop()
|
|
except IndexError:
|
|
pass
|
|
|
|
def reverse(self):
|
|
'S.reverse() -- reverse *IN PLACE*'
|
|
n = len(self)
|
|
for i in range(n//2):
|
|
self[i], self[n-i-1] = self[n-i-1], self[i]
|
|
|
|
def extend(self, values):
|
|
'S.extend(iterable) -- extend sequence by appending elements from the iterable'
|
|
for v in values:
|
|
self.append(v)
|
|
|
|
def pop(self, index=-1):
|
|
'''S.pop([index]) -> item -- remove and return item at index (default last).
|
|
Raise IndexError if list is empty or index is out of range.
|
|
'''
|
|
v = self[index]
|
|
del self[index]
|
|
return v
|
|
|
|
def remove(self, value):
|
|
'''S.remove(value) -- remove first occurrence of value.
|
|
Raise ValueError if the value is not present.
|
|
'''
|
|
del self[self.index(value)]
|
|
|
|
def __iadd__(self, values):
|
|
self.extend(values)
|
|
return self
|
|
|
|
MutableSequence.register(list)
|
|
MutableSequence.register(bytearray) # Multiply inheriting, see ByteString
|