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Copy pathstack.py
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86 lines (59 loc) · 1.63 KB
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from node import Node
class Stack:
def __init__(self):
self._last = None
self._len = 0
self._current = None
def __len__(self):
return self._len
def push(self, item):
node = Node(value=item)
if self._len == 0:
self._last = node
else:
node.reference = self._last
self._last = node
self._len += 1
def pop(self, **kwargs):
if self._last:
item = self._last.value
self._last = self._last.reference
self._len -= 1
else:
if 'default' in kwargs:
item = kwargs['default']
else:
raise KeyError('pop from an empty stack')
return item
@property
def last(self):
return getattr(self._last, 'value', None)
def __iter__(self):
self._index = 0
self._current = self._last
return self
def __next__(self):
if not self._current:
raise StopIteration
item = self._current.value
self._current = self._current.reference
return item
def __str__(self):
return '[{}]'.format(', '.join([str(item) for item in self]))
def __repr__(self):
return self.__str__()
if __name__ == '__main__':
import random
samples = list(range(10))
random.shuffle(samples)
stack = Stack()
for item in samples:
stack.push(item)
print(stack)
print()
for item in stack:
print(item, end=', ')
print('\n')
for item in samples:
stack.pop()
print(stack)