// 饭店
data class Restaurant(var name: String, var score: Int, var price: Int, var address: String)
// 上下文类
data class Eating(
        var kind: String? = "",
        var area: String? = "",
        var restaurantList: List<Restaurant>? = mutableListOf()
) {
    override fun toString() = StringBuilder().apply {
        append("【${this@Eating.area}】的【${this@Eating.kind}】有下述门店：\n\n")
        this@Eating.restaurantList?.forEach { append("${it.name} - ${it.score}分 - ${it.price}元/人 - ${it.address}\n") }
        append("\n")
    }.toString()
}
class RestaurantBuilder {
    var name: String = ""
    var score: Int = 0
    var price: Int = 0
    var address: String = ""
    fun build(): Restaurant = Restaurant(name, score, price, address)
}
// 中间类，用于实现直接DSL方式添加Restaurant的效果
class EatingBuilder {
    var kind: String? = ""
    var area: String? = ""
    var restaurantList = mutableListOf<Restaurant>()
    fun restaurant(block: RestaurantBuilder.() -> Unit) {
        // 此处演示下invoke实现，可以直接restaurantList.add(RestaurantBuilder().apply(block).build())
        val restaurantBuilder = RestaurantBuilder()
        block.invoke(restaurantBuilder)
        restaurantList.add(restaurantBuilder.build())
    }
    fun build(): Eating = Eating(kind, area, restaurantList)
}
// 创建Eating的DSL写法(顶层函数)
fun eating(block: EatingBuilder.() -> Unit): Eating = EatingBuilder().apply(block).build()
// 此处为了演示使用中缀表达式，实际上可以直接赋值
infix fun Eating.area(area: String) {
    this.area = area
}
fun main() {
    val eating = eating {
        kind = "西式快餐"
        restaurant {
            name = "华莱士·全鸡汉堡"
            score = 5
            price = 19
            address = "观澜牛湖店"
        }
        restaurant {
            name = "汉堡王"
            score = 5
            price = 33
            address = "东海店"
        }
        restaurant {
            name = "麦当劳"
            score = 4
            price = 34
            address = "绒花路店"
        }
    }
    eating.area("平湖区")
    println(eating.toString())
}