Implement self-handling exceptions

Author: Revxrsal

common/src/main/java/revxrsal/commands/exception/CommandExceptionAdapter.java

@@ -115,7 +115,6 @@ public void sendableException(@NotNull CommandActor actor, @NotNull SendableExce
     private static final List<Method> IGNORED_METHODS = new ArrayList<>();
 
     static {
-        Method onUnhandledException = null, handleException = null;
         for (Method method : CommandExceptionAdapter.class.getDeclaredMethods()) {
             if (method.getParameterCount() != 2) continue;
             if (method.isAnnotationPresent(Ignore.class))
@@ -125,7 +124,10 @@ public void sendableException(@NotNull CommandActor actor, @NotNull SendableExce
 
     @Override @Ignore public void handleException(@NotNull Throwable throwable, @NotNull CommandActor actor) {
         MethodExceptionHandler handler = handlers.getFlexibleOrDefault(throwable.getClass(), unknownHandler);
-        handler.handle(actor, throwable);
+        if (handler == unknownHandler && throwable instanceof SelfHandledException)
+            ((SelfHandledException) throwable).handle(actor);
+        else
+            handler.handle(actor, throwable);
     }
 
     public CommandExceptionAdapter() {

common/src/main/java/revxrsal/commands/exception/SelfHandledException.java

@@ -0,0 +1,44 @@
+/*
+ * This file is part of lamp, licensed under the MIT License.
+ *
+ *  Copyright (c) Revxrsal <reflxction.github@gmail.com>
+ *
+ *  Permission is hereby granted, free of charge, to any person obtaining a copy
+ *  of this software and associated documentation files (the "Software"), to deal
+ *  in the Software without restriction, including without limitation the rights
+ *  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ *  copies of the Software, and to permit persons to whom the Software is
+ *  furnished to do so, subject to the following conditions:
+ *
+ *  The above copyright notice and this permission notice shall be included in all
+ *  copies or substantial portions of the Software.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ *  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ *  SOFTWARE.
+ */
+package revxrsal.commands.exception;
+
+import revxrsal.commands.command.CommandActor;
+
+/**
+ * An interface designed for exceptions that wish to handle themselves, without
+ * having to be explicitly handled by an exception adapter.
+ * <p>
+ * This interface should <em>only</em> be implemented by exceptions,
+ * as it does not expose any information about the exception being handled.
+ */
+public interface SelfHandledException {
+
+    /**
+     * Handles the exception.
+     *
+     * @param actor The command actor
+     */
+    void handle(CommandActor actor);
+
+}