Array-based List in Pure Lua (Apache 2.0)

array_list.lua

local List = {}
package.loaded["List"] = List

List.__index = List

function List:new()
    self = {}
    self._arr = {}
    setmetatable(self, List)
    return self
end

function List:len()
    return #(self._arr)
end

function List:at(i)
    return self._arr[i]
end

function List:push(data)
    table.insert(self._arr, data)
end

function List:pop()
    if self:len() <= 0 then
        return nil
    end
    
    return table.remove(self._arr)
end

function List:shift(data)
    table.insert(self._arr, 1, data)
end

function List:unshift()
    if self:len() <= 0 then
        return nil
    end
    
    return table.remove(self._arr, 1)
end

function List:insert(index, data)
    table.insert(self._arr, index, data)
end

function List:remove(index)
    if self:len() <= 0 then
        return nil
    end
    
    return table.remove(self._arr, index)
end

return List