KTON.kt

package org.jire.kton

import java.util.*

/**
 * Represents an instance of KTON (Kotlin object notation).
 *
 * @author Thomas Nappo
 */
class KTON(private var arrCursor: Int = -1) {

	private var lastCursor = arrCursor

	/**
	 * Maps string keys with their values.
	 */
	private val vars = HashMap<String, Any>()

	/**
	 * Gets the corresponding value of a key, potentially `null`.
	 *
	 * @param key The key of the value.
	 */
	operator fun get(key: String) = vars[formatKey(key)]

	/**
	 * Gets the corresponding KTON body of a key.
	 *
	 * @param key The key of the body.
	 */
	operator fun invoke(key: String) = this[key]!! as KTON

	/**
	 * Gets the corresponding KTON array of an index.
	 *
	 * @param index The index of the array (of declaration order).
	 */
	operator fun get(index: Int): KTON {
		arrCursor = index
		return this
	}

	/**
	 * Establishes (maps) a value to the current string in a KTON.
	 */
	infix fun <V : Any> String.to(value: V) {
		vars[formatKey(this)] = value
	}

	/**
	 * Establishes (maps) a body to the current string in a KTON.
	 *
	 * @param body The body representing the new KTON.
	 */
	operator fun <O> String.invoke(body: KTON.() -> O) = to(kton(body))

	operator fun <O> (() -> O).unaryPlus() {
		if (arrCursor >= 0) throw UnsupportedOperationException("Multi-dimension arrays not supported!")

		arrCursor = lastCursor + 1
		this()
		lastCursor = arrCursor
		arrCursor = -1
	}

	private fun formatKey(key: String) = if (arrCursor < 0) key else "[$arrCursor][$key]"

}

/**
 * Creates a KTON using the supplied body.
 *
 * @param body The body of the KTON used to declare more KTONs or values.
 */
inline fun <O> kton(body: KTON.() -> O): KTON {
	val kton = KTON()
	kton.body()
	return kton
}

fun main(args: Array<String>) {
	val menu = kton {
		"id" to "file"
		"value" to "File"
		"popup" {
			"menuitem" {
				+{ "value" to "New"; "onclick" to "CreateNewDoc()" }
				+{ "value" to "Open"; "onclick" to "OpenDoc()" }
				+{ "value" to "Close"; "onclick" to "CloseDoc()" }
			}
		}
	}

	// Value access through get operator:
	val id = menu["id"] // "file"
	val value = menu["value"] // "File"

	// Body access through invoke operator:
	val popup = menu("popup")
	val menuitems = popup("menuitem")

	// Array access through get operator specifying index:
	val newValue = menuitems[0]["value"] // "New"
	val open = menuitems[1]
	val openValue = open["value"] // "Open"
	val closeOnClick = menuitems[2]["onclick"] // "CloseDoc()"

	assert(id == "File")
	assert(value == "File")
	assert(newValue == "New")
	assert(openValue == "Open")
	assert(closeOnClick == "CloseDoc()")
}