Lua中的双向映射

function createBidirectionalMap()
    local map = {}
    local reverseMap = {}

    function map:set(key, value)
        self[key] = value
        reverseMap[value] = key
    end

    function map:get(keyOrValue)
        if self[keyOrValue] then
            return self[keyOrValue]
        elseif reverseMap[keyOrValue] then
            return reverseMap[keyOrValue]
        end
        return nil
    end

    return map
end

-- 使用示例
local myMap = createBidirectionalMap()
myMap:set("apple", "fruit")
myMap:set("banana", "fruit")
myMap:set("carrot", "vegetable")

print(myMap:get("apple")) -- 输出：fruit
print(myMap:get("fruit")) -- 输出：apple
print(myMap:get("carrot")) -- 输出：vegetable