Support for @EnumSelector annotated methods.

Author: UnquietCode

Documentation.java

@@ -597,6 +597,12 @@ public interface MyHelper {
 // Provide documentation for the method.
 @Documented(String[] value)
 
+// Marks a method has being the target of an enum
+// selector. The method must accept zero arguments,
+// and return a Consumer instance which accepts the
+// enum value.
+@EnumSelector
+
 // Provide an alternate name to use for the interface
 // or class's corresponding generated name, instead of
 // the default (`XyzBuilder`).

flapi-runtime/src/main/java/unquietcode/tools/flapi/runtime/BlockInvocationHandler.java

@@ -101,7 +101,37 @@ private Object invokeAndReturn(Method method, Object[] originalArgs, Object prox
 			chain = info.chainInfo();
 		}
 
-		return invokeAndReturn(method, originalArgs, proxy, info, chain);
+		if (method.getAnnotation(EnumSelectorHint.class) != null) {
+			return invokeEnumSelector(method, originalArgs, proxy, info, chain);
+		} else {
+			return invokeAndReturn(method, originalArgs, proxy, info, chain);
+		}
+	}
+
+	private Object invokeEnumSelector(Method method, Object[] originalArgs, final Object originalProxy, final MethodInfo info, final ChainInfo[] chain) {
+		final Method helperMethod = SpringMethodUtils.findMethod(helper.getClass(), method.getName(), method.getParameterTypes());
+		final Class<? extends Enum> enumType = method.getAnnotation(EnumSelectorHint.class).value();
+
+		@SuppressWarnings("unchecked")
+		final Consumer<Enum<?>> consumer = (Consumer<Enum<?>>) invokeMethod(helperMethod, Arrays.asList(originalArgs));
+
+		if (consumer == null) {
+			throw new IllegalStateException("consumer instance cannot be null");
+		}
+
+		return Proxy.newProxyInstance(Thread.currentThread().getContextClassLoader(), new Class[]{method.getReturnType()}, new InvocationHandler() {
+			public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
+
+				// lookup enum by method name
+				Enum<?> enumValue = Enum.valueOf(enumType, method.getName());
+
+				// accept
+				consumer.accept(enumValue);
+
+				// proceed
+				return computeReturnValue(method, originalProxy, info, chain.length, helperMethod, consumer);
+			}
+		});
 	}
 
 	private Object invokeAndReturn(Method method, Object[] originalArgs, Object proxy, MethodInfo info, ChainInfo[] chain) {
@@ -130,27 +160,8 @@ private Object invokeAndReturn(Method method, Object[] originalArgs, Object prox
 			throw new IllegalStateException("unable to locate method '"+method.getName()+"' on helper");
 		}
 
-		// make accessible if not (debatable as to whether this is a good idea)
-		if (!helperMethod.isAccessible()) {
-			helperMethod.setAccessible(true);
-		}
-
-		final Object[] newArgsArray = newArgs.toArray(new Object[newArgs.size()]);
-
-		// invoke method
-		Object result;
-		try {
-			result = helperMethod.invoke(helper, newArgsArray);
-		} catch (IllegalAccessException ex) {
-			throw new IllegalStateException(ex);
-		} catch (InvocationTargetException ex) {
-			if (ex.getTargetException() instanceof RuntimeException) {
-				throw (RuntimeException) ex.getTargetException();
-			} else {
-				throw new RuntimeException(ex.getTargetException());
-			}
-		}
-
+		// invoke the method
+		Object result = invokeMethod(helperMethod, newArgs);
 		Object _returnValue = computeReturnValue(method, proxy, info, depth, helperMethod, result);
 
 		// unwrap helper results
@@ -171,6 +182,31 @@ private Object invokeAndReturn(Method method, Object[] originalArgs, Object prox
 		return _returnValue;
 	}
 
+	private Object invokeMethod(Method helperMethod, List<Object> args) {
+
+		// make accessible if not (debatable as to whether this is a good idea)
+		if (!helperMethod.isAccessible()) {
+			helperMethod.setAccessible(true);
+		}
+
+		final Object[] argsArray = args.toArray(new Object[args.size()]);
+
+		// invoke method
+		Object result;
+		try {
+			result = helperMethod.invoke(helper, argsArray);
+		} catch (IllegalAccessException ex) {
+			throw new IllegalStateException(ex);
+		} catch (InvocationTargetException ex) {
+			if (ex.getTargetException() instanceof RuntimeException) {
+				throw (RuntimeException) ex.getTargetException();
+			} else {
+				throw new RuntimeException(ex.getTargetException());
+			}
+		}
+		return result;
+	}
+
 	private Object computeReturnValue(Method method, Object proxy, MethodInfo info, int depth, Method helperMethod, Object result) {
 		switch (info.type()) {
 			case Ascending: {

flapi-runtime/src/main/java/unquietcode/tools/flapi/runtime/Consumer.java

@@ -0,0 +1,31 @@
+/*********************************************************************
+ Copyright 2015 the Flapi authors
+
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+
+     http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+ ********************************************************************/
+
+package unquietcode.tools.flapi.runtime;
+
+/**
+ * Simple little ditty to consume things.
+ *
+ * This is meant to be replaced by the real type
+ * contained within Java 8, whenever JDK 7 support
+ * is discontinued.
+ *
+ * @author Ben Fagin
+ * @version 2015-02-18
+ */
+public interface Consumer<T> {
+	void accept(T element);
+}

flapi-runtime/src/main/java/unquietcode/tools/flapi/runtime/EnumSelectorHint.java

@@ -0,0 +1,32 @@
+/*********************************************************************
+ Copyright 2015 the Flapi authors
+
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+
+     http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+ ********************************************************************/
+
+package unquietcode.tools.flapi.runtime;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * @author Ben Fagin
+ * @version 2015-02-18
+ */
+@Target(ElementType.METHOD)
+@Retention(RetentionPolicy.RUNTIME)
+public @interface EnumSelectorHint {
+	Class<? extends Enum> value();
+}

flapi-runtime/src/main/java/unquietcode/tools/flapi/runtime/Helpers.java

@@ -21,6 +21,7 @@
 import java.lang.reflect.Proxy;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.concurrent.atomic.AtomicReference;
 
 public final class Helpers {
 
@@ -81,4 +82,20 @@ private Method getMethod(String methodName, Class[] parameterTypes) {
 			}
 		});
 	}
+
+	public interface Invoker<In> {
+		void call(AtomicReference<In> in);
+	}
+
+	public static <T> T invoke(Invoker<T> invoker) {
+		AtomicReference<T> reference = new AtomicReference<>();
+
+		try {
+			invoker.call(reference);
+		} catch (Exception ex) {
+			throw new RuntimeException(ex);
+		}
+
+		return reference.get();
+	}
 }

src/main/java/unquietcode/tools/flapi/IntrospectorSupport.java

@@ -96,6 +96,7 @@ else if (parameterType.isArray()) {
 			signature.append(makeTypeWithGenerics(typeName, generics));
 
 			// parameter name
+			// TODO improve in JDK8
 			signature.append(" p").append(i);
 		}
 
@@ -115,9 +116,13 @@ protected static String makeTypeWithGenerics(String base, Class<?>[] generics) {
 
 			for (int p = 0; p < generics.length; ++p) {
 				if (p != 0) { sb.append(", "); }
-
 				Class<?> generic = generics[p];
-				sb.append(generic.getName());
+
+				if (generic == null) {
+					sb.append("?");
+				} else {
+					sb.append(generic.getName());
+				}
 			}
 
 			sb.append("> ");