package collections

import "errors"

type Stack struct {
	valores []interface{}
}

func (stack *Stack) Push (valor interface{}) {
	stack.valores = append(stack.valores, valor)
}

func (stack Stack) Lenght () int {
	return len(stack.valores)
}

func (stack Stack) IsEmpty () bool {
	return stack.Lenght() == 0
}

func (stack *Stack) Pull () (interface{}, error) {
	
	if stack.IsEmpty() {
		return nil, errors.New("Pilha Vazia")
	}

	valor := stack.valores[stack.Lenght() - 1]
	stack.valores = stack.valores[:stack.Lenght() - 1]
	return valor, nil
}