Kotlin JSON DSL

kotlin_json_dsl.kt

import org.json.JSONArray
import org.json.JSONObject

class Json() : JSONObject() {
	constructor(init: Json.() -> Unit) : this() {
		this.init()
	}

	infix fun Any.to(json: Json.() -> Unit) {
		if (this !is String) throw UnsupportedOperationException("keys must be string: $this")
		put(this, Json().apply(json))
	}

	infix fun <T> Any.to(value: T) {
		if (this !is String) throw UnsupportedOperationException("keys must be string: $this")
		put(this, value)
	}

	infix fun <T> Any.to(values: List<T>) {
		val key = this
		if (key !is String) throw UnsupportedOperationException("keys must be string: $key")
		put(key, JSONArray().apply {
			values.forEach {
				if (it is Function0<*>) {
					throw UnsupportedOperationException("Use 'Json {...}' syntax instead of '{...}' for json objects in array '$key'")
				} else {
					put(it)
				}
			}
		})
	}
}

val example = Json {
	"a" to "aa"
	"b" to 1
	"c" to 3.14
	"d" to false
	"e" to null
	"f" to Json {
		"a" to "b"
	}
	"g" to listOf(
		Json {
			"a" to "b"
		},
		"23",
		3,
		false,
		null
	)
	"h" to {
		"a" to "b"
	}
}