mirror of
https://github.com/TheAlgorithms/Python.git
synced 2024-10-07 14:19:31 +00:00
134 lines
3.3 KiB
Python
134 lines
3.3 KiB
Python
from __future__ import annotations
|
|
|
|
from typing import Generic, TypeVar
|
|
|
|
T = TypeVar("T")
|
|
|
|
|
|
class StackOverflowError(BaseException):
|
|
pass
|
|
|
|
|
|
class StackUnderflowError(BaseException):
|
|
pass
|
|
|
|
|
|
class Stack(Generic[T]):
|
|
"""A stack is an abstract data type that serves as a collection of
|
|
elements with two principal operations: push() and pop(). push() adds an
|
|
element to the top of the stack, and pop() removes an element from the top
|
|
of a stack. The order in which elements come off of a stack are
|
|
Last In, First Out (LIFO).
|
|
https://en.wikipedia.org/wiki/Stack_(abstract_data_type)
|
|
"""
|
|
|
|
def __init__(self, limit: int = 10):
|
|
self.stack: list[T] = []
|
|
self.limit = limit
|
|
|
|
def __bool__(self) -> bool:
|
|
return bool(self.stack)
|
|
|
|
def __str__(self) -> str:
|
|
return str(self.stack)
|
|
|
|
def push(self, data: T) -> None:
|
|
"""Push an element to the top of the stack."""
|
|
if len(self.stack) >= self.limit:
|
|
raise StackOverflowError
|
|
self.stack.append(data)
|
|
|
|
def pop(self) -> T:
|
|
"""
|
|
Pop an element off of the top of the stack.
|
|
|
|
>>> Stack().pop()
|
|
Traceback (most recent call last):
|
|
...
|
|
data_structures.stacks.stack.StackUnderflowError
|
|
"""
|
|
if not self.stack:
|
|
raise StackUnderflowError
|
|
return self.stack.pop()
|
|
|
|
def peek(self) -> T:
|
|
"""
|
|
Peek at the top-most element of the stack.
|
|
|
|
>>> Stack().pop()
|
|
Traceback (most recent call last):
|
|
...
|
|
data_structures.stacks.stack.StackUnderflowError
|
|
"""
|
|
if not self.stack:
|
|
raise StackUnderflowError
|
|
return self.stack[-1]
|
|
|
|
def is_empty(self) -> bool:
|
|
"""Check if a stack is empty."""
|
|
return not bool(self.stack)
|
|
|
|
def is_full(self) -> bool:
|
|
return self.size() == self.limit
|
|
|
|
def size(self) -> int:
|
|
"""Return the size of the stack."""
|
|
return len(self.stack)
|
|
|
|
def __contains__(self, item: T) -> bool:
|
|
"""Check if item is in stack"""
|
|
return item in self.stack
|
|
|
|
|
|
def test_stack() -> None:
|
|
"""
|
|
>>> test_stack()
|
|
"""
|
|
stack: Stack[int] = Stack(10)
|
|
assert bool(stack) is False
|
|
assert stack.is_empty() is True
|
|
assert stack.is_full() is False
|
|
assert str(stack) == "[]"
|
|
|
|
try:
|
|
_ = stack.pop()
|
|
assert False # This should not happen
|
|
except StackUnderflowError:
|
|
assert True # This should happen
|
|
|
|
try:
|
|
_ = stack.peek()
|
|
assert False # This should not happen
|
|
except StackUnderflowError:
|
|
assert True # This should happen
|
|
|
|
for i in range(10):
|
|
assert stack.size() == i
|
|
stack.push(i)
|
|
|
|
assert bool(stack)
|
|
assert not stack.is_empty()
|
|
assert stack.is_full()
|
|
assert str(stack) == str(list(range(10)))
|
|
assert stack.pop() == 9
|
|
assert stack.peek() == 8
|
|
|
|
stack.push(100)
|
|
assert str(stack) == str([0, 1, 2, 3, 4, 5, 6, 7, 8, 100])
|
|
|
|
try:
|
|
stack.push(200)
|
|
assert False # This should not happen
|
|
except StackOverflowError:
|
|
assert True # This should happen
|
|
|
|
assert not stack.is_empty()
|
|
assert stack.size() == 10
|
|
|
|
assert 5 in stack
|
|
assert 55 not in stack
|
|
|
|
|
|
if __name__ == "__main__":
|
|
test_stack()
|