Stack

local Stack = {}
Stack.__index = Stack

function Stack.new()
    local self = setmetatable({}, Stack)

    self.tbl = {}

    return self
end

function Stack:getSize()
    return #self.tbl
end

function Stack:pop()
    if self:getSize() == 0 then
        error("Attempt to pop empty stack")
    end
    return table.remove(self.tbl, self:getSize())
end

function Stack:push(v)
    table.insert(self.tbl, v)
end

function Stack:peek()
    return self.tbl[self:getSize()]
end

return Stack