Code Spitz 90 - 코틀린 언어편 (2) 과제

code_spitz_90_2.kt

// 1. Set도 동작하게
// 2. Map도 동작하게
// 3. inline 함수에 대해 조사한 뒤 최대 반영
// 4. 어떤 클래스에 toJSON():String 메소드가 있다면 그 메소드를 통해 stringify를 하게 하시오
@Target(AnnotationTarget.PROPERTY)
annotation class Ex     // 제외할 속성

@Target(AnnotationTarget.PROPERTY)
annotation class Name(val name: String) // json용 별도 이름지정

fun stringify(value: Any): String = StringBuilder().run {
    jsonValue(value)
    toString()
}
fun StringBuilder.comma() { append(",") }
inline fun StringBuilder.wrap(begin: Char, end: Char, block: StringBuilder.() -> Unit) {
    append(begin)
    block()
    append(end)
}
fun StringBuilder.jsonValue(value: Any?) {
    when(value) {
        null -> append("null")
        is String -> jsonString(value)
        is Boolean, is Number -> append("$value")
        is Map<*, *> -> jsonMap(value)
        is Array<*> -> jsonArray(value)
        is Collection<*> -> jsonCollection(value)
        else -> {
            value::class.members.find { it.name == "toJSON" }.let {
                if (it != null) append(it.call(value) as String)
                else jsonObject(value)
            }
        }
    }
}
private fun StringBuilder.jsonArray(target: Array<*>) {
    wrap('[', ']') {
        target.joinTo(this::comma) {
            jsonValue(it)
        }
    }
}
private fun StringBuilder.jsonCollection(target: Collection<*>) {
    wrap('[', ']') {
        target.joinTo(this::comma) {
            jsonValue(it)
        }
    }
}
private fun StringBuilder.jsonMap(target: Map<*, *>) {
    wrap('{', '}') {
        target.joinTo(this::comma) { k, v ->
            jsonValue(k)
            append(":")
            jsonValue(v)
        }
    }
}
private fun StringBuilder.jsonString(v: String) = append(""""${v.replace("\"", "\\\"")}"""")
private fun <T: Any> StringBuilder.jsonObject(target: T) {
    wrap('{', '}') {
        target::class.members
            .filterIsInstance<KProperty<*>>()
            .filter { it.findAnnotation<Ex>() == null }
            .joinTo(this::comma) {
                jsonValue(it.findAnnotation<Name>()?.name ?: it.name)
                append(":")
                jsonValue(it.getter.call(target))
            }
    }
}
inline fun <T> Array<T>.joinTo(sep:() -> Unit, transform: (T) -> Unit) {
    forEachIndexed { idx, el ->
        if (idx != 0) sep()
        transform(el)
    }
}
inline fun <T> Iterable<T>.joinTo(sep:() -> Unit, transform: (T) -> Unit) {
    forEachIndexed { idx, el ->
        if (idx != 0) sep()
        transform(el)
    }
}
inline fun <K, T> Map<K, T>.joinTo(sep:() -> Unit, transform: (K, T) -> Unit) {
    entries.forEachIndexed { idx, el ->
        if (idx != 0) sep()
        val (key, value) = el
        transform(key, value)
    }
}

class Json1(
    val a: Int,
    val b: String,
    val c: List<Int>,
    val d: Set<String>,
    val e: Map<Any, Any>,
    val f: Array<String>) { }
class Json2(@Ex val a: Int, @Name("title") val b: String) {}
class Json3(val e: Map<Any, Any>) {
    fun toJSON(): String = """{"name":"kim"} """
}
class Json4() {
    fun toJSON(): String = """{"a":3}"""
}

fun main(args: Array<String>) {
    println("ready")
    println(
        stringify(Json1(
            a = 3,
            b = "abc",
            c = arrayListOf(1,2,3),
            d = setOf("kkk", "aaa"),
            e = mapOf(
                "age1" to 10,
                "age2" to 20,
                "props" to mapOf(
                    "name" to "kang",
                    "age" to 42,
                    "skills" to listOf("swift", "js", "ts", "kotlin", 1)
                )
            ),
            f = arrayOf("array", "test")
        ))
    )
    println(stringify(Json2(a = 10, b = "abc")))
    println(
        stringify(Json3(
            e = mapOf(
                "skills" to listOf("swift", "js", "ts", "kotlin", 1),
                "props" to mapOf(
                    "name" to "kang",
                    "age" to 42,
                    "skills" to listOf("swift", "js", "ts", "kotlin", 1)
                )
            )
        ))
    )
    println(stringify(Json4()))
}

/* 출력
ready
{"a":3,"b":"abc","c":[1,2,3],"d":["kkk","aaa"],"e":{"age1":10,"age2":20,"props":{"name":"kang","age":42,"skills":["swift","js","ts","kotlin",1]}},"f":["array","test"]}
{"title":"abc"}
{"name":"kim"}
{"a":3}
*/

수정하였습니다.