Added settable event option

src/main/java/com/github/kerbity/kerb/event/SettableEvent.java

@@ -0,0 +1,47 @@
+/*
+ * Kerb
+ * Event and request distributor server software.
+ *
+ * Copyright (C) 2023  Smuddgge
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.github.kerbity.kerb.event;
+
+import com.github.kerbity.kerb.indicator.Settable;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * Used to create a single settable event.
+ * An event used as a request to get a value from the clients.
+ *
+ * @param <T> The type of class to get.
+ */
+public class SettableEvent<T> implements Event, Settable<T, SettableEvent<T>> {
+
+    private @Nullable T instance;
+
+    @Override
+    public @NotNull SettableEvent<T> set(@Nullable T instance) {
+        this.instance = instance;
+        return this;
+    }
+
+    @Override
+    public @Nullable T get() {
+        return this.instance;
+    }
+}

src/main/java/com/github/kerbity/kerb/indicator/Cancellable.java

@@ -27,7 +27,7 @@
  *
  * @param <T> The instance of the class to return.
  */
-public interface Cancellable<T> {
+public interface Cancellable<T extends Cancellable<T>> {
 
     /**
      * Used to set weather the class is

src/main/java/com/github/kerbity/kerb/indicator/Completable.java

@@ -28,7 +28,7 @@
  * @param <T> The instance of the class that
  *            is completable.
  */
-public interface Completable<T> {
+public interface Completable<T extends Completable<T>> {
 
     /**
      * Used to complete the task.

src/main/java/com/github/kerbity/kerb/indicator/Settable.java

@@ -0,0 +1,49 @@
+/*
+ * Kerb
+ * Event and request distributor server software.
+ *
+ * Copyright (C) 2023  Smuddgge
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.github.kerbity.kerb.indicator;
+
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * Indicates if the class is settable
+ * to a specific type.
+ *
+ * @param <T> The specific settable type.
+ * @param <C> The settable class type.
+ */
+public interface Settable<T, C extends Settable<T, C>> {
+
+    /**
+     * Used to set the settable value.
+     *
+     * @param instance The instance of the value.
+     * @return This instance.
+     */
+    @NotNull C set(@Nullable T instance);
+
+    /**
+     * Used to get the settable value.
+     *
+     * @return The instance of the value.
+     */
+    @Nullable T get();
+}

src/main/java/com/github/kerbity/kerb/result/CompletableResultSet.java

@@ -23,6 +23,7 @@
 import com.github.kerbity.kerb.datatype.Ratio;
 import com.github.kerbity.kerb.indicator.Cancellable;
 import com.github.kerbity.kerb.indicator.Completable;
+import com.github.kerbity.kerb.indicator.Settable;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
@@ -46,6 +47,7 @@ public class CompletableResultSet<T> {
     private boolean isComplete;
     private boolean containsCancelled;
     private boolean containsCompleted;
+    private Object defaultSettableValue;
 
     /**
      * Used to create a completable
@@ -361,7 +363,7 @@ public boolean containsCancelled() {
      */
     public boolean containsCompleted() {
 
-        // Check if a result has been canceled.
+        // Check if a result contains a completed class.
         for (T result : this.result) {
             if (!(result instanceof Completable<?> completable)) continue;
             if (completable.isComplete()) return true;
@@ -370,4 +372,40 @@ public boolean containsCompleted() {
         // Return if all results should be rendered as canceled.
         return this.containsCompleted;
     }
+
+    /**
+     * Used to set the default settable value if no
+     * event returns a settable value.
+     * This is specified in the {@link com.github.kerbity.kerb.indicator.Settable}
+     * interface.
+     *
+     * @param defaultSettableValue The default value.
+     * @return This instance.
+     */
+    public @NotNull CompletableResultSet<T> setDefaultSettableValue(@Nullable Object defaultSettableValue) {
+        this.defaultSettableValue = defaultSettableValue;
+        return this;
+    }
+
+    @SuppressWarnings("unchecked")
+    public <C> @NotNull C getFirstSettable(@NotNull Class<C> type) {
+
+        // Check if a result contains a settable value.
+        for (T result : this.result) {
+            if (!(result instanceof Settable<?, ?> settable)) continue;
+            if (settable.get() == null) continue;
+
+            Object value = settable.get();
+
+            if (!type.isInstance(value)) continue;
+            return (C) value;
+        }
+
+        // Return the default value.
+        try {
+            return (C) this.defaultSettableValue;
+        } catch (Exception ignored) {
+            return null;
+        }
+    }
 }