refactor: extracted reflection based function calling to be reusable

Author: AlmasB

fxgl-core/src/main/kotlin/com/almasb/fxgl/core/reflect/ReflectionFunctionCaller.kt

@@ -0,0 +1,113 @@
+/*
+ * FXGL - JavaFX Game Library. The MIT License (MIT).
+ * Copyright (c) AlmasB (almaslvl@gmail.com).
+ * See LICENSE for details.
+ */
+
+package com.almasb.fxgl.core.reflect
+
+import java.lang.RuntimeException
+import java.lang.reflect.Method
+import java.util.function.BiFunction
+
+/**
+ * Allows calling methods of any object using its String name
+ * and String arguments.
+ *
+ * @author Almas Baim (https://github.com/AlmasB)
+ */
+class ReflectionFunctionCaller {
+
+    private val functions = hashMapOf<FunctionSignature, ReflectionFunction>()
+
+    /**
+     * Provides conversions from [String] to other types.
+     */
+    private val stringToObject = hashMapOf<Class<*>, (String) -> Any>()
+
+    var defaultFunctionHandler: BiFunction<String, List<String>, Any> = BiFunction { name, args ->
+        throw RuntimeException("No function handler for $name with $args")
+    }
+
+    val methods: List<Method>
+        get() = functions.values.map { it.method }
+
+    init {
+        // register common types
+        stringToObject[String::class.java] = { it }
+        stringToObject[Int::class.java] = { it.toInt() }
+        stringToObject[Double::class.java] = { it.toDouble() }
+        stringToObject[Boolean::class.java] = {
+            when (it) {
+                "true" -> true
+                "false" -> false
+                else -> throw RuntimeException("Cannot convert $it to Boolean")
+            }
+        }
+        stringToObject[List::class.java] = { it.split(",") }
+    }
+
+    fun <T : Any> addStringToObjectConverter(type: Class<T>, converter: (String) -> T) {
+        stringToObject[type] = converter
+    }
+
+    fun removeStringToObjectConverter(type: Class<*>) {
+        stringToObject.remove(type)
+    }
+
+    /**
+     * Add all methods (incl. private) of [targetObject] to be invokable
+     * by this reflection function caller.
+     */
+    fun addFunctionCallTarget(targetObject: Any) {
+        targetObject.javaClass.declaredMethods.forEach {
+            val signature = FunctionSignature(it.name, it.parameterCount)
+            val method = ReflectionFunction(targetObject, it)
+            it.isAccessible = true
+
+            functions[signature] = method
+        }
+    }
+
+    /**
+     * Remove all methods of a previously added [targetObject].
+     */
+    fun removeFunctionCallTarget(targetObject: Any) {
+        functions.filterValues { it.functionCallTarget === targetObject }
+                .forEach { functions.remove(it.key) }
+    }
+
+    /**
+     * @return true if [functionName] with [paramCount] number of parameters exists
+     */
+    fun exists(functionName: String, paramCount: Int): Boolean {
+        return functions.containsKey(FunctionSignature(functionName, paramCount))
+    }
+
+    fun call(functionName: String, args: List<String>): Any {
+        return call(functionName, args.toTypedArray())
+    }
+
+    fun call(functionName: String, args: Array<String>): Any {
+        val function = functions[FunctionSignature(functionName, args.size)]
+
+        if (function != null) {
+            val argsAsObjects = function.method.parameterTypes.mapIndexed { index, type ->
+                val converter = stringToObject[type] ?: throw java.lang.RuntimeException("No converter found from String to $type")
+                converter.invoke(args[index])
+            }
+
+            // void returns null, but Any is expected, so we return 0 in such cases
+            return function.method.invoke(function.functionCallTarget, *argsAsObjects.toTypedArray()) ?: 0
+        }
+
+        return defaultFunctionHandler.apply(functionName, args.toList())
+    }
+
+    private data class FunctionSignature(val name: String, val paramCount: Int)
+
+    /**
+     * Stores the object [functionCallTarget] and the function [method] that can be invoked on the object.
+     */
+    private data class ReflectionFunction(val functionCallTarget: Any, val method: Method)
+}

fxgl-gameplay/src/main/kotlin/com/almasb/fxgl/cutscene/dialogue/DialogueScriptRunner.kt

@@ -7,8 +7,9 @@
 package com.almasb.fxgl.cutscene.dialogue
 
 import com.almasb.fxgl.core.collection.PropertyMap
+import com.almasb.fxgl.core.reflect.ReflectionFunctionCaller
 import com.almasb.fxgl.logging.Logger
-import java.lang.reflect.Method
+import java.util.function.BiFunction
 
 /**
  *
@@ -275,67 +276,35 @@ abstract class FunctionCallHandler : FunctionCallDelegate {
 
     private val log = Logger.get(javaClass)
 
-    private val methods = hashMapOf<MethodSignature, InvokableMethod>()
-
-    /**
-     * Provides conversions from [String] to other types.
-     */
-    val stringToObject = hashMapOf<Class<*>, (String) -> Any>()
+    val rfc = ReflectionFunctionCaller()
 
     init {
-        // register common types
-        stringToObject[String::class.java] = { it }
-        stringToObject[Int::class.java] = { it.toInt() }
-        stringToObject[Double::class.java] = { it.toDouble() }
-        stringToObject[Boolean::class.java] = {
-            when (it) {
-                "true" -> true
-                "false" -> false
-                else -> throw java.lang.RuntimeException("Cannot convert $it to Boolean")
-            }
-        }
-
         // add self as a delegate so that all methods of the implementing class
         // are automatically added into [methods]
-        addFunctionCallDelegate(this)
+        rfc.addFunctionCallTarget(this)
+        rfc.defaultFunctionHandler = BiFunction { name, args ->
+            handle(name, args.toTypedArray())
+        }
     }
 
     fun addFunctionCallDelegate(obj: FunctionCallDelegate) {
-        obj.javaClass.declaredMethods.forEach {
-            val signature = MethodSignature(it.name, it.parameterCount)
-            val method = InvokableMethod(obj, it)
+        rfc.addFunctionCallTarget(obj)
 
-            methods[signature] = method
-
-            log.debug("Added cmd: $method ($signature)")
+        rfc.methods.forEach {
+            log.debug("Added cmd: $it")
         }
     }
 
     fun removeFunctionCallDelegate(obj: FunctionCallDelegate) {
-        methods.filterValues { it.delegate === obj }
-                .forEach { methods.remove(it.key) }
+        rfc.removeFunctionCallTarget(obj)
     }
 
     fun exists(functionName: String, paramCount: Int): Boolean {
-        return methods.containsKey(MethodSignature(functionName, paramCount))
+        return rfc.exists(functionName, paramCount)
     }
 
     fun call(functionName: String, args: Array<String>): Any {
-        val method = methods[MethodSignature(functionName, args.size)]
-
-        if (method != null) {
-            val argsAsObjects = method.function.parameterTypes.mapIndexed { index, type ->
-                val converter = stringToObject[type] ?: throw java.lang.RuntimeException("No converter found from String to $type")
-                converter.invoke(args[index])
-            }
-
-            // void returns null, but Any is expected, so we return 0 in such cases
-            return method.function.invoke(method.delegate, *argsAsObjects.toTypedArray()) ?: 0
-        }
-
-        log.warning("Unrecognized function: $functionName with ${args.size} arguments. Calling default implementation")
-
-        return handle(functionName, args)
+        return rfc.call(functionName, args)
     }
 
     /**
@@ -346,11 +315,4 @@ abstract class FunctionCallHandler : FunctionCallDelegate {
         log.warning("$functionName ${args.toList()}")
         return 0
     }
-
-    private data class MethodSignature(val name: String, val paramCount: Int)
-
-    /**
-     * Stores the object [delegate] and the function [function] that can be invoked on the object.
-     */
-    private data class InvokableMethod(val delegate: FunctionCallDelegate, val function: Method)
 }