# Copyright 2007 Google, Inc. All Rights Reserved.
# Licensed to PSF under a Contributor Agreement.

"""Abstract Base Classes (ABCs) for collections, according to PEP 3119.

Unit tests are in test_collections.
"""

from abc import ABCMeta, abstractmethod
import sys

__all__ = ["Awaitable", "Coroutine",
 "AsyncIterable", "AsyncIterator", "AsyncGenerator",
 "Hashable", "Iterable", "Iterator", "Generator", "Reversible",
 "Sized", "Container", "Callable", "Collection",
 "Set", "MutableSet",
 "Mapping", "MutableMapping",
 "MappingView", "KeysView", "ItemsView", "ValuesView",
 "Sequence", "MutableSequence",
 "ByteString",
 ]

# This module has been renamed from collections.abc to _collections_abc to
# speed up interpreter startup. Some of the types such as MutableMapping are
# required early but collections module imports a lot of other modules.
# See issue #19218
__name__ = "collections.abc"

# Private list of types that we want to register with the various ABCs
# so that they will pass tests like:
# it = iter(somebytearray)
# assert isinstance(it, Iterable)
# Note: in other implementations, these types might not be distinct
# and they may have their own implementation specific types that
# are not included on this list.
bytes_iterator = type(iter(b''))
bytearray_iterator = type(iter(bytearray()))
#callable_iterator = ???
dict_keyiterator = type(iter({}.keys()))
dict_valueiterator = type(iter({}.values()))
dict_itemiterator = type(iter({}.items()))
list_iterator = type(iter([]))
list_reverseiterator = type(iter(reversed([])))
range_iterator = type(iter(range(0)))
longrange_iterator = type(iter(range(1 << 1000)))
set_iterator = type(iter(set()))
str_iterator = type(iter(""))
tuple_iterator = type(iter(()))
zip_iterator = type(iter(zip()))
## views ##
dict_keys = type({}.keys())
dict_values = type({}.values())
dict_items = type({}.items())
## misc ##
mappingproxy = type(type.__dict__)
generator = type((lambda: (yield))())
## coroutine ##
async def _coro(): pass
_coro = _coro()
coroutine = type(_coro)
_coro.close() # Prevent ResourceWarning
del _coro
## asynchronous generator ##
async def _ag(): yield
_ag = _ag()
async_generator = type(_ag)
del _ag


### ONE-TRICK PONIES ###

def _check_methods(C, *methods):
 mro = C.__mro__
 for method in methods:
 for B in mro:
 if method in B.__dict__:
 if B.__dict__[method] is None:
 return NotImplemented
 break
 else:
 return NotImplemented
 return True

class Hashable(metaclass=ABCMeta):

 __slots__ = ()

 @abstractmethod
 def __hash__(self):
 return 0

 @classmethod
 def __subclasshook__(cls, C):
 if cls is Hashable:
 return _check_methods(C, "__hash__")
 return NotImplemented


class Awaitable(metaclass=ABCMeta):

 __slots__ = ()

 @abstractmethod
 def __await__(self):
 yield

 @classmethod
 def __subclasshook__(cls, C):
 if cls is Awaitable:
 return _check_methods(C, "__await__")
 return NotImplemented


class Coroutine(Awaitable):

 __slots__ = ()

 @abstractmethod
 def send(self, value):
 """Send a value into the coroutine.
 Return next yielded value or raise StopIteration.
 """
 raise StopIteration

 @abstractmethod
 def throw(self, typ, val=None, tb=None):
 """Raise an exception in the coroutine.
 Return next yielded value or raise StopIteration.
 """
 if val is None:
 if tb is None:
 raise typ
 val = typ()
 if tb is not None:
 val = val.with_traceback(tb)
 raise val

 def close(self):
 """Raise GeneratorExit inside coroutine.
 """
 try:
 self.throw(GeneratorExit)
 except (GeneratorExit, StopIteration):
 pass
 else:
 raise RuntimeError("coroutine ignored GeneratorExit")

 @classmethod
 def __subclasshook__(cls, C):
 if cls is Coroutine:
 return _check_methods(C, '__await__', 'send', 'throw', 'close')
 return NotImplemented


Coroutine.register(coroutine)


class AsyncIterable(metaclass=ABCMeta):

 __slots__ = ()

 @abstractmethod
 def __aiter__(self):
 return AsyncIterator()

 @classmethod
 def __subclasshook__(cls, C):
 if cls is AsyncIterable:
 return _check_methods(C, "__aiter__")
 return NotImplemented


class AsyncIterator(AsyncIterable):

 __slots__ = ()

 @abstractmethod
 async def __anext__(self):
 """Return the next item or raise StopAsyncIteration when exhausted."""
 raise StopAsyncIteration

 def __aiter__(self):
 return self

 @classmethod
 def __subclasshook__(cls, C):
 if cls is AsyncIterator:
 return _check_methods(C, "__anext__", "__aiter__")
 return NotImplemented


class AsyncGenerator(AsyncIterator):

 __slots__ = ()

 async def __anext__(self):
 """Return the next item from the asynchronous generator.
 When exhausted, raise StopAsyncIteration.
 """
 return await self.asend(None)

 @abstractmethod
 async def asend(self, value):
 """Send a value into the asynchronous generator.
 Return next yielded value or raise StopAsyncIteration.
 """
 raise StopAsyncIteration

 @abstractmethod
 async def athrow(self, typ, val=None, tb=None):
 """Raise an exception in the asynchronous generator.
 Return next yielded value or raise StopAsyncIteration.
 """
 if val is None:
 if tb is None:
 raise typ
 val = typ()
 if tb is not None:
 val = val.with_traceback(tb)
 raise val

 async def aclose(self):
 """Raise GeneratorExit inside coroutine.
 """
 try:
 await self.athrow(GeneratorExit)
 except (GeneratorExit, StopAsyncIteration):
 pass
 else:
 raise RuntimeError("asynchronous generator ignored GeneratorExit")

 @classmethod
 def __subclasshook__(cls, C):
 if cls is AsyncGenerator:
 return _check_methods(C, '__aiter__', '__anext__',
 'asend', 'athrow', 'aclose')
 return NotImplemented


AsyncGenerator.register(async_generator)


class Iterable(metaclass=ABCMeta):

 __slots__ = ()

 @abstractmethod
 def __iter__(self):
 while False:
 yield None

 @classmethod
 def __subclasshook__(cls, C):
 if cls is Iterable:
 return _check_methods(C, "__iter__")
 return NotImplemented


class Iterator(Iterable):

 __slots__ = ()

 @abstractmethod
 def __next__(self):
 'Return the next item from the iterator. When exhausted, raise StopIteration'
 raise StopIteration

 def __iter__(self):
 return self

 @classmethod
 def __subclasshook__(cls, C):
 if cls is Iterator:
 return _check_methods(C, '__iter__', '__next__')
 return NotImplemented

Iterator.register(bytes_iterator)
Iterator.register(bytearray_iterator)
#Iterator.register(callable_iterator)
Iterator.register(dict_keyiterator)
Iterator.register(dict_valueiterator)
Iterator.register(dict_itemiterator)
Iterator.register(list_iterator)
Iterator.register(list_reverseiterator)
Iterator.register(range_iterator)
Iterator.register(longrange_iterator)
Iterator.register(set_iterator)
Iterator.register(str_iterator)
Iterator.register(tuple_iterator)
Iterator.register(zip_iterator)


class Reversible(Iterable):

 __slots__ = ()

 @abstractmethod
 def __reversed__(self):
 while False:
 yield None

 @classmethod
 def __subclasshook__(cls, C):
 if cls is Reversible:
 return _check_methods(C, "__reversed__", "__iter__")
 return NotImplemented


class Generator(Iterator):

 __slots__ = ()

 def __next__(self):
 """Return the next item from the generator.
 When exhausted, raise StopIteration.
 """
 return self.send(None)

 @abstractmethod
 def send(self, value):
 """Send a value into the generator.
 Return next yielded value or raise StopIteration.
 """
 raise StopIteration

 @abstractmethod
 def throw(self, typ, val=None, tb=None):
 """Raise an exception in the generator.
 Return next yielded value or raise StopIteration.
 """
 if val is None:
 if tb is None:
 raise typ
 val = typ()
 if tb is not None:
 val = val.with_traceback(tb)
 raise val

 def close(self):
 """Raise GeneratorExit inside generator.
 """
 try:
 self.throw(GeneratorExit)
 except (GeneratorExit, StopIteration):
 pass
 else:
 raise RuntimeError("generator ignored GeneratorExit")

 @classmethod
 def __subclasshook__(cls, C):
 if cls is Generator:
 return _check_methods(C, '__iter__', '__next__',
 'send', 'throw', 'close')
 return NotImplemented

Generator.register(generator)


class Sized(metaclass=ABCMeta):

 __slots__ = ()

 @abstractmethod
 def __len__(self):
 return 0

 @classmethod
 def __subclasshook__(cls, C):
 if cls is Sized:
 return _check_methods(C, "__len__")
 return NotImplemented


class Container(metaclass=ABCMeta):

 __slots__ = ()

 @abstractmethod
 def __contains__(self, x):
 return False

 @classmethod
 def __subclasshook__(cls, C):
 if cls is Container:
 return _check_methods(C, "__contains__")
 return NotImplemented

class Collection(Sized, Iterable, Container):

 __slots__ = ()

 @classmethod
 def __subclasshook__(cls, C):
 if cls is Collection:
 return _check_methods(C, "__len__", "__iter__", "__contains__")
 return NotImplemented

class Callable(metaclass=ABCMeta):

 __slots__ = ()

 @abstractmethod
 def __call__(self, *args, **kwds):
 return False

 @classmethod
 def __subclasshook__(cls, C):
 if cls is Callable:
 return _check_methods(C, "__call__")
 return NotImplemented


### SETS ###


class Set(Collection):

 """A set is a finite, iterable container.

 This class provides concrete generic implementations of all
 methods except for __contains__, __iter__ and __len__.

 To override the comparisons (presumably for speed, as the
 semantics are fixed), redefine __le__ and __ge__,
 then the other operations will automatically follow suit.
 """

 __slots__ = ()

 def __le__(self, other):
 if not isinstance(other, Set):
 return NotImplemented
 if len(self) > len(other):
 return False
 for elem in self:
 if elem not in other:
 return False
 return True

 def __lt__(self, other):
 if not isinstance(other, Set):
 return NotImplemented
 return len(self) < len(other) and self.__le__(other)

 def __gt__(self, other):
 if not isinstance(other, Set):
 return NotImplemented
 return len(self) > len(other) and self.__ge__(other)

 def __ge__(self, other):
 if not isinstance(other, Set):
 return NotImplemented
 if len(self) < len(other):
 return False
 for elem in other:
 if elem not in self:
 return False
 return True

 def __eq__(self, other):
 if not isinstance(other, Set):
 return NotImplemented
 return len(self) == len(other) and self.__le__(other)

 @classmethod
 def _from_iterable(cls, it):
 '''Construct an instance of the class from any iterable input.

 Must override this method if the class constructor signature
 does not accept an iterable for an input.
 '''
 return cls(it)

 def __and__(self, other):
 if not isinstance(other, Iterable):
 return NotImplemented
 return self._from_iterable(value for value in other if value in self)

 __rand__ = __and__

 def isdisjoint(self, other):
 'Return True if two sets have a null intersection.'
 for value in other:
 if value in self:
 return False
 return True

 def __or__(self, other):
 if not isinstance(other, Iterable):
 return NotImplemented
 chain = (e for s in (self, other) for e in s)
 return self._from_iterable(chain)

 __ror__ = __or__

 def __sub__(self, other):
 if not isinstance(other, Set):
 if not isinstance(other, Iterable):
 return NotImplemented
 other = self._from_iterable(other)
 return self._from_iterable(value for value in self
 if value not in other)

 def __rsub__(self, other):
 if not isinstance(other, Set):
 if not isinstance(other, Iterable):
 return NotImplemented
 other = self._from_iterable(other)
 return self._from_iterable(value for value in other
 if value not in self)

 def __xor__(self, other):
 if not isinstance(other, Set):
 if not isinstance(other, Iterable):
 return NotImplemented
 other = self._from_iterable(other)
 return (self - other) | (other - self)

 __rxor__ = __xor__

 def _hash(self):
 """Compute the hash value of a set.

 Note that we don't define __hash__: not all sets are hashable.
 But if you define a hashable set type, its __hash__ should
 call this function.

 This must be compatible __eq__.

 All sets ought to compare equal if they contain the same
 elements, regardless of how they are implemented, and
 regardless of the order of the elements; so there's not much
 freedom for __eq__ or __hash__. We match the algorithm used
 by the built-in frozenset type.
 """
 MAX = sys.maxsize
 MASK = 2 * MAX + 1
 n = len(self)
 h = 1927868237 * (n + 1)
 h &= MASK
 for x in self:
 hx = hash(x)
 h ^= (hx ^ (hx << 16) ^ 89869747) * 3644798167
 h &= MASK
 h = h * 69069 + 907133923
 h &= MASK
 if h > MAX:
 h -= MASK + 1
 if h == -1:
 h = 590923713
 return h

Set.register(frozenset)


class MutableSet(Set):
 """A mutable set is a finite, iterable container.

 This class provides concrete generic implementations of all
 methods except for __contains__, __iter__, __len__,
 add(), and discard().

 To override the comparisons (presumably for speed, as the
 semantics are fixed), all you have to do is redefine __le__ and
 then the other operations will automatically follow suit.
 """

 __slots__ = ()

 @abstractmethod
 def add(self, value):
 """Add an element."""
 raise NotImplementedError

 @abstractmethod
 def discard(self, value):
 """Remove an element. Do not raise an exception if absent."""
 raise NotImplementedError

 def remove(self, value):
 """Remove an element. If not a member, raise a KeyError."""
 if value not in self:
 raise KeyError(value)
 self.discard(value)

 def pop(self):
 """Return the popped value. Raise KeyError if empty."""
 it = iter(self)
 try:
 value = next(it)
 except StopIteration:
 raise KeyError from None
 self.discard(value)
 return value

 def clear(self):
 """This is slow (creates N new iterators!) but effective."""
 try:
 while True:
 self.pop()
 except KeyError:
 pass

 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(Collection):

 __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())

 __reversed__ = None

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 is value or v == value

 def __iter__(self):
 for key in self._mapping:
 yield (key, self._mapping[key])

ItemsView.register(dict_items)


class ValuesView(MappingView, Collection):

 __slots__ = ()

 def __contains__(self, value):
 for key in self._mapping:
 v = self._mapping[key]
 if v is value or v == value:
 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 from None
 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(self, other=(), /, **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 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(Reversible, Collection):

 """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 is value or 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.

 Supporting start and stop arguments is optional, but
 recommended.
 '''
 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:
 v = self[i]
 if v is value or v == 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 is value or 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'
 if values is self:
 values = list(values)
 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