Python-2/data_structures/stacks/stack.py at master · https-github-com-nzysoft/Python-2 · GitHub

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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()

raise AssertionError() # This should not happen

except StackUnderflowError:

assert True # This should happen

try:

_ = stack.peek()

raise AssertionError() # 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)

raise AssertionError() # 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()

Python-2/data_structures/stacks/stack.py at master · https-github-com-nzysoft/Python-2 · GitHub

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