class SLLStack(object):
def __init__(self):
self.size = 0
self._data = SinglyLinkedList()
def __len__(self):
return self.size
def build(self, list_object):
if not isinstance(list_object, list):
return TypeError('build method only accepts object of type list.')
for i in list_object:
self._data.add_value(i)
self.size += 1
def is_empty(self):
return self.size == 0
def push(self, e):
self.size += 1
self._data.add_value(e)
def pop(self):
if self.is_empty():
raise IndexError("Stack is empty")
top = self._data.head.value
self._data.delete_node(self._data.head)
self.size -= 1
return top
def top(self):
if self.is_empty():
raise IndexError("Stack is empty")
return self._data.head.value
