Stack ADT

Stack (ABC)

A stack is a Last-In-First-Out ADT that supports insertion (pushing) and removal (popping) of elements from the same end. The order in which elements are pushed into the stack is reversed when popping out elements from the stack.

__len__(self) special

Get the total number of elements stored in the stack

Returns:

Type	Description
int	count of elements in stack

Source code in stacks/stack.py

@abstractmethod
def __len__(self) -> int:
    """Get the total number of elements stored in the stack

    :returns: count of elements in stack
    """
    pass

is_empty(self)

Check if stack contains no elements

Returns:

Type	Description
bool	True if stack is empty, else False

Source code in stacks/stack.py

@abstractmethod
def is_empty(self) -> bool:
    """Check if stack contains no elements

    :return: True if stack is empty, else False
    """
    pass

peek(self)

Get element at the top of the stack without removing it

Returns:

Type	Description
Any	element at top of stack

Source code in stacks/stack.py

@abstractmethod
def peek(self) -> Any:
    """Get element at the top of the stack without removing it

    :return: element at top of stack
    """
    pass

pop(self)

Get element at the top of the stack, and remove it from the stack

Returns:

Type	Description
Any	element at top of stack

Source code in stacks/stack.py

@abstractmethod
def pop(self) -> Any:
    """Get element at the top of the stack, and remove it from the stack

    :return: element at top of stack
    """
    pass

push(self, x)

Insert element x to the top of the stack

Parameters:

Name	Type	Description	Default
x	Any	element to add to the stack	required

Source code in stacks/stack.py

@abstractmethod
def push(self, x: Any) -> None:
    """Insert element x to the top of the stack

    :param x: element to add to the stack
    """
    pass