Class Stack

data_structures/stacks/stack.py:5–49

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

class Stack(object):
    """ 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=10):
        self.stack = []
        self.limit = limit

    def __bool__(self):
        return bool(self.stack)

    def __str__(self):
        return str(self.stack)

    def push(self, data):
        """ Push an element to the top of the stack."""
        if len(self.stack) >= self.limit:
            raise StackOverflowError
        self.stack.append(data)

    def pop(self):
        """ Pop an element off of the top of the stack."""
        if self.stack:
            return self.stack.pop()
        else:
            raise IndexError('pop from an empty stack')

    def peek(self):
        """ Peek at the top-most element of the stack."""
        if self.stack:
            return self.stack[-1]

    def is_empty(self):
        """ Check if a stack is empty."""
        return not bool(self.stack)

    def size(self):
        """ Return the size of the stack."""
        return len(self.stack)


class StackOverflowError(BaseException):