mirror of https://github.com/morpheus65535/bazarr
314 lines
8.1 KiB
Python
314 lines
8.1 KiB
Python
from collections.abc import Sequence, Hashable
|
|
from numbers import Integral
|
|
from functools import reduce
|
|
|
|
|
|
class _PListBuilder(object):
|
|
"""
|
|
Helper class to allow construction of a list without
|
|
having to reverse it in the end.
|
|
"""
|
|
__slots__ = ('_head', '_tail')
|
|
|
|
def __init__(self):
|
|
self._head = _EMPTY_PLIST
|
|
self._tail = _EMPTY_PLIST
|
|
|
|
def _append(self, elem, constructor):
|
|
if not self._tail:
|
|
self._head = constructor(elem)
|
|
self._tail = self._head
|
|
else:
|
|
self._tail.rest = constructor(elem)
|
|
self._tail = self._tail.rest
|
|
|
|
return self._head
|
|
|
|
def append_elem(self, elem):
|
|
return self._append(elem, lambda e: PList(e, _EMPTY_PLIST))
|
|
|
|
def append_plist(self, pl):
|
|
return self._append(pl, lambda l: l)
|
|
|
|
def build(self):
|
|
return self._head
|
|
|
|
|
|
class _PListBase(object):
|
|
__slots__ = ('__weakref__',)
|
|
|
|
# Selected implementations can be taken straight from the Sequence
|
|
# class, other are less suitable. Especially those that work with
|
|
# index lookups.
|
|
count = Sequence.count
|
|
index = Sequence.index
|
|
|
|
def __reduce__(self):
|
|
# Pickling support
|
|
return plist, (list(self),)
|
|
|
|
def __len__(self):
|
|
"""
|
|
Return the length of the list, computed by traversing it.
|
|
|
|
This is obviously O(n) but with the current implementation
|
|
where a list is also a node the overhead of storing the length
|
|
in every node would be quite significant.
|
|
"""
|
|
return sum(1 for _ in self)
|
|
|
|
def __repr__(self):
|
|
return "plist({0})".format(list(self))
|
|
__str__ = __repr__
|
|
|
|
def cons(self, elem):
|
|
"""
|
|
Return a new list with elem inserted as new head.
|
|
|
|
>>> plist([1, 2]).cons(3)
|
|
plist([3, 1, 2])
|
|
"""
|
|
return PList(elem, self)
|
|
|
|
def mcons(self, iterable):
|
|
"""
|
|
Return a new list with all elements of iterable repeatedly cons:ed to the current list.
|
|
NB! The elements will be inserted in the reverse order of the iterable.
|
|
Runs in O(len(iterable)).
|
|
|
|
>>> plist([1, 2]).mcons([3, 4])
|
|
plist([4, 3, 1, 2])
|
|
"""
|
|
head = self
|
|
for elem in iterable:
|
|
head = head.cons(elem)
|
|
|
|
return head
|
|
|
|
def reverse(self):
|
|
"""
|
|
Return a reversed version of list. Runs in O(n) where n is the length of the list.
|
|
|
|
>>> plist([1, 2, 3]).reverse()
|
|
plist([3, 2, 1])
|
|
|
|
Also supports the standard reversed function.
|
|
|
|
>>> reversed(plist([1, 2, 3]))
|
|
plist([3, 2, 1])
|
|
"""
|
|
result = plist()
|
|
head = self
|
|
while head:
|
|
result = result.cons(head.first)
|
|
head = head.rest
|
|
|
|
return result
|
|
__reversed__ = reverse
|
|
|
|
def split(self, index):
|
|
"""
|
|
Spilt the list at position specified by index. Returns a tuple containing the
|
|
list up until index and the list after the index. Runs in O(index).
|
|
|
|
>>> plist([1, 2, 3, 4]).split(2)
|
|
(plist([1, 2]), plist([3, 4]))
|
|
"""
|
|
lb = _PListBuilder()
|
|
right_list = self
|
|
i = 0
|
|
while right_list and i < index:
|
|
lb.append_elem(right_list.first)
|
|
right_list = right_list.rest
|
|
i += 1
|
|
|
|
if not right_list:
|
|
# Just a small optimization in the cases where no split occurred
|
|
return self, _EMPTY_PLIST
|
|
|
|
return lb.build(), right_list
|
|
|
|
def __iter__(self):
|
|
li = self
|
|
while li:
|
|
yield li.first
|
|
li = li.rest
|
|
|
|
def __lt__(self, other):
|
|
if not isinstance(other, _PListBase):
|
|
return NotImplemented
|
|
|
|
return tuple(self) < tuple(other)
|
|
|
|
def __eq__(self, other):
|
|
"""
|
|
Traverses the lists, checking equality of elements.
|
|
|
|
This is an O(n) operation, but preserves the standard semantics of list equality.
|
|
"""
|
|
if not isinstance(other, _PListBase):
|
|
return NotImplemented
|
|
|
|
self_head = self
|
|
other_head = other
|
|
while self_head and other_head:
|
|
if not self_head.first == other_head.first:
|
|
return False
|
|
self_head = self_head.rest
|
|
other_head = other_head.rest
|
|
|
|
return not self_head and not other_head
|
|
|
|
def __getitem__(self, index):
|
|
# Don't use this this data structure if you plan to do a lot of indexing, it is
|
|
# very inefficient! Use a PVector instead!
|
|
|
|
if isinstance(index, slice):
|
|
if index.start is not None and index.stop is None and (index.step is None or index.step == 1):
|
|
return self._drop(index.start)
|
|
|
|
# Take the easy way out for all other slicing cases, not much structural reuse possible anyway
|
|
return plist(tuple(self)[index])
|
|
|
|
if not isinstance(index, Integral):
|
|
raise TypeError("'%s' object cannot be interpreted as an index" % type(index).__name__)
|
|
|
|
if index < 0:
|
|
# NB: O(n)!
|
|
index += len(self)
|
|
|
|
try:
|
|
return self._drop(index).first
|
|
except AttributeError as e:
|
|
raise IndexError("PList index out of range") from e
|
|
|
|
def _drop(self, count):
|
|
if count < 0:
|
|
raise IndexError("PList index out of range")
|
|
|
|
head = self
|
|
while count > 0:
|
|
head = head.rest
|
|
count -= 1
|
|
|
|
return head
|
|
|
|
def __hash__(self):
|
|
return hash(tuple(self))
|
|
|
|
def remove(self, elem):
|
|
"""
|
|
Return new list with first element equal to elem removed. O(k) where k is the position
|
|
of the element that is removed.
|
|
|
|
Raises ValueError if no matching element is found.
|
|
|
|
>>> plist([1, 2, 1]).remove(1)
|
|
plist([2, 1])
|
|
"""
|
|
|
|
builder = _PListBuilder()
|
|
head = self
|
|
while head:
|
|
if head.first == elem:
|
|
return builder.append_plist(head.rest)
|
|
|
|
builder.append_elem(head.first)
|
|
head = head.rest
|
|
|
|
raise ValueError('{0} not found in PList'.format(elem))
|
|
|
|
|
|
class PList(_PListBase):
|
|
"""
|
|
Classical Lisp style singly linked list. Adding elements to the head using cons is O(1).
|
|
Element access is O(k) where k is the position of the element in the list. Taking the
|
|
length of the list is O(n).
|
|
|
|
Fully supports the Sequence and Hashable protocols including indexing and slicing but
|
|
if you need fast random access go for the PVector instead.
|
|
|
|
Do not instantiate directly, instead use the factory functions :py:func:`l` or :py:func:`plist` to
|
|
create an instance.
|
|
|
|
Some examples:
|
|
|
|
>>> x = plist([1, 2])
|
|
>>> y = x.cons(3)
|
|
>>> x
|
|
plist([1, 2])
|
|
>>> y
|
|
plist([3, 1, 2])
|
|
>>> y.first
|
|
3
|
|
>>> y.rest == x
|
|
True
|
|
>>> y[:2]
|
|
plist([3, 1])
|
|
"""
|
|
__slots__ = ('first', 'rest')
|
|
|
|
def __new__(cls, first, rest):
|
|
instance = super(PList, cls).__new__(cls)
|
|
instance.first = first
|
|
instance.rest = rest
|
|
return instance
|
|
|
|
def __bool__(self):
|
|
return True
|
|
__nonzero__ = __bool__
|
|
|
|
|
|
Sequence.register(PList)
|
|
Hashable.register(PList)
|
|
|
|
|
|
class _EmptyPList(_PListBase):
|
|
__slots__ = ()
|
|
|
|
def __bool__(self):
|
|
return False
|
|
__nonzero__ = __bool__
|
|
|
|
@property
|
|
def first(self):
|
|
raise AttributeError("Empty PList has no first")
|
|
|
|
@property
|
|
def rest(self):
|
|
return self
|
|
|
|
|
|
Sequence.register(_EmptyPList)
|
|
Hashable.register(_EmptyPList)
|
|
|
|
_EMPTY_PLIST = _EmptyPList()
|
|
|
|
|
|
def plist(iterable=(), reverse=False):
|
|
"""
|
|
Creates a new persistent list containing all elements of iterable.
|
|
Optional parameter reverse specifies if the elements should be inserted in
|
|
reverse order or not.
|
|
|
|
>>> plist([1, 2, 3])
|
|
plist([1, 2, 3])
|
|
>>> plist([1, 2, 3], reverse=True)
|
|
plist([3, 2, 1])
|
|
"""
|
|
if not reverse:
|
|
iterable = list(iterable)
|
|
iterable.reverse()
|
|
|
|
return reduce(lambda pl, elem: pl.cons(elem), iterable, _EMPTY_PLIST)
|
|
|
|
|
|
def l(*elements):
|
|
"""
|
|
Creates a new persistent list containing all arguments.
|
|
|
|
>>> l(1, 2, 3)
|
|
plist([1, 2, 3])
|
|
"""
|
|
return plist(elements)
|