Implement invokeGlobal and eval

src/main/kotlin/ru/dbotthepony/kstarbound/lua/LuaThread.kt

@@ -18,6 +18,7 @@ import org.lwjgl.system.MemoryStack
 import org.lwjgl.system.MemoryUtil
 import ru.dbotthepony.kommons.gson.set
 import ru.dbotthepony.kommons.util.Delegate
+import ru.dbotthepony.kommons.util.KOptional
 import ru.dbotthepony.kstarbound.Starbound
 import ru.dbotthepony.kstarbound.defs.AssetPath
 import ru.dbotthepony.kstarbound.json.InternedJsonElementAdapter
@@ -213,6 +214,73 @@ class LuaThread private constructor(
 		return status
 	}
 
+	/**
+	 * Returns boolean indicating whenever function exists
+	 */
+	inline fun invokeGlobal(name: String, arguments: LuaThread.() -> Int): Boolean {
+		val top = stackTop
+
+		try {
+			val type = loadGlobal(name)
+			if (type != LuaType.FUNCTION)
+				return false
+
+			val numArguments = arguments(this)
+			check(numArguments >= 0) { "Invalid amount of arguments provided to Lua function" }
+			call(numArguments)
+			return true
+		} finally {
+			setTop(top)
+		}
+	}
+
+	/**
+	 * Returns empty [KOptional] if function does not exist
+	 */
+	inline fun <T> invokeGlobal(name: String, numResults: Int, arguments: LuaThread.() -> Int, results: LuaThread.(firstValue: Int) -> T): KOptional<T> {
+		require(numResults > 0) { "Invalid amount of results: $numResults" }
+		val top = stackTop
+
+		try {
+			val type = loadGlobal(name)
+			if (type != LuaType.FUNCTION)
+				return KOptional()
+
+			val numArguments = arguments(this)
+			call(numArguments, numResults)
+			return KOptional(results(this, top + 1))
+		} finally {
+			setTop(top)
+		}
+	}
+
+	inline fun <T> eval(chunk: String, name: String = "eval", numResults: Int, arguments: LuaThread.() -> Int, results: LuaThread.(firstValue: Int) -> T): T {
+		require(numResults > 0) { "Invalid amount of results: $numResults" }
+
+		val top = stackTop
+
+		try {
+			val numArguments = arguments(this)
+			load(chunk, name)
+			call(numArguments, numResults)
+			return results(this, top + 1)
+		} finally {
+			setTop(top)
+		}
+	}
+
+	inline fun <T> eval(chunk: String, name: String = "eval", arguments: LuaThread.() -> Int) {
+		val top = stackTop
+
+		try {
+			val numArguments = arguments(this)
+			load(chunk, name)
+			call(numArguments, 0)
+		} finally {
+			setTop(top)
+		}
+	}
+
 	private val attachedScripts = ArrayList<AssetPath>()
 	private var initCalled = false
 
@@ -1122,7 +1190,7 @@ class LuaThread private constructor(
 	}
 
 	companion object {
-		private val LOGGER = LogManager.getLogger()
+		val LOGGER = LogManager.getLogger()
 
 		fun loadInternalScript(name: String): String {
 			return LuaThread::class.java.getResourceAsStream("/scripts/$name.lua")?.readAllBytes()?.toString(Charsets.UTF_8) ?: throw RuntimeException("/scripts/$name.lua is missing!")