Added new module extension

src/main/java/com/pixelgamelibrary/api/Pixel.java

@@ -28,6 +28,7 @@ import com.pixelgamelibrary.api.interfaces.Internal;
 import com.pixelgamelibrary.api.interfaces.Net;
 import com.pixelgamelibrary.api.interfaces.Utils;
 import com.pixelgamelibrary.api.interfaces.App;
+import com.pixelgamelibrary.api.interfaces.Extension;
 
 /**
  *
@@ -47,38 +48,46 @@ public class Pixel {
 
     ////
     public static App app() {
-        return get().app();
+        return extension().getOrDefault(App.class, get().app());
     }
 
     public static Graphics graphics() {
-        return get().graphics();
+        return extension().getOrDefault(Graphics.class, get().graphics());
     }
 
     public static Audio audio() {
-        return get().audio();
+        return extension().getOrDefault(Audio.class, get().audio());
     }
 
     public static Input input() {
-        return get().input();
+        return extension().getOrDefault(Input.class, get().input());
     }
 
     public static Net net() {
-        return get().net();
+        return extension().getOrDefault(Net.class, get().net());
     }
 
     public static Files files() {
-        return get().files();
+        return extension().getOrDefault(Files.class, get().files());
     }
 
     public static Utils utils() {
-        return get().utils();
+        return extension().getOrDefault(Utils.class, get().utils());
     }
 
     public static Internal internal() {
-        return get().internal();
+        return extension().getOrDefault(Internal.class, get().internal());
     }
-    ////
 
+    public static Extension extension() {
+        return get().extension();
+    }
+
+    public static <T> T get(Class<T> clazz) {
+        return get().get(clazz);
+    }
+
+    ////
     public static void initBackend(PixelBackend pixelBackend) {
         if (isBackendSet()) {
             throw new PixelException("Pixel Backend was already set");

src/main/java/com/pixelgamelibrary/api/extension/ExtensionImpl.java

@@ -0,0 +1,77 @@
+///////////////////////////////////////////////////////////////////////////////////////////////
+// Pixel: Game library.
+// Copyright (C) 2024 the original author or authors.
+//
+// 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/> or write to the Free Software
+// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+///////////////////////////////////////////////////////////////////////////////////////////////
+package com.pixelgamelibrary.api.extension;
+
+import com.pixelgamelibrary.api.PixelException;
+import com.pixelgamelibrary.api.interfaces.Extension;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+/**
+ *
+ * @author robertvokac
+ */
+public class ExtensionImpl implements Extension {
+
+    private static final ExtensionImpl INSTANCE = new ExtensionImpl();
+
+    public static Extension getInstance() {
+        return INSTANCE;
+    }
+
+    public ExtensionImpl() {
+
+    }
+    // Map to hold registered implementations
+    private final Map<Class<?>, Object> implementations = new HashMap<>();
+
+// Implement the method for registering implementations    
+    @Override
+    public <T> void register(Class<T> interfaceClass, T implementation) {
+        if(interfaceClass == Extension.class) {
+            throw new PixelException("Custom implementation of interface Extension cannot be registred.");
+        }
+        implementations.put(interfaceClass, implementation);
+        System.out.println("Registered implementation for: " + interfaceClass.getName());
+    }
+
+// Implementation of the generic method getImplementation    \
+    @Override
+    public <T> T get(Class<T> clazz) {
+        T implementation = (T) implementations.get(clazz);
+        if (implementation == null) {
+            throw new IllegalArgumentException("No implementation registered for: " + clazz.getName());
+        }
+        return implementation;
+    }
+
+    @Override
+    public <T> boolean has(Class<T> clazz) {
+        return implementations.containsKey(clazz);
+    }
+
+    @Override
+    public List<Class<?>> list() {
+        return implementations.keySet().stream().collect(Collectors.toList());
+    }
+
+}

src/main/java/com/pixelgamelibrary/api/interfaces/Extension.java

@@ -0,0 +1,90 @@
+////////////////////////////////////////////////////////////////////////////////////////////////
+// Pixel: Game Library - Extension Module
+// Copyright (C) 2024 the original author or authors.
+//
+// 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/> or write to the Free Software Foundation, Inc., 
+// 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+////////////////////////////////////////////////////////////////////////////////////////////////
+package com.pixelgamelibrary.api.interfaces;
+
+import java.util.List;
+
+/**
+ * The Extension interface allows the registration and retrieval of various 
+ * implementations for specific interfaces. It acts as a flexible extension 
+ * module, enabling dynamic modularization and adding extensibility to the 
+ * Pixel Game Library.
+ *
+ * This interface provides generic methods to register, retrieve, and check 
+ * the availability of registered implementations, offering a loosely coupled 
+ * and highly flexible way to extend the game library.
+ *
+ * @author robertvokac
+ */
+public interface Extension {
+    
+    /**
+     * Registers an implementation for a given interface class.
+     * 
+     * This method allows you to register an implementation for a specific 
+     * interface, enabling the extension mechanism to return the appropriate 
+     * implementation when requested.
+     *
+     * @param <T> the type of the interface to be registered
+     * @param interfaceClass the Class object of the interface to be implemented
+     * @param implementation the instance of the implementation that corresponds to the interface
+     */
+    <T> void register(Class<T> interfaceClass, T implementation);
+
+    /**
+     * Retrieves the registered implementation for a given interface.
+     * 
+     * This method returns the implementation instance that was previously 
+     * registered for the provided interface class.
+     *
+     * @param <T> the type of the interface
+     * @param clazz the Class object of the interface for which the implementation is requested
+     * @return the registered implementation of the interface, or null if no implementation is registered
+     */
+    <T> T get(Class<T> clazz);
+    
+    default <T> T getOrDefault(Class<T> clazz, T defaultInstance) {
+        if(has(clazz)) {
+            return get(clazz);
+        } else {
+            return defaultInstance;
+        }
+    }
+    
+    /**
+     * Checks if an implementation is registered for a specific interface class.
+     * 
+     * This method verifies whether there is an implementation registered for 
+     * the given interface class.
+     *
+     * @param <T> the type of the interface
+     * @param clazz the Class object of the interface to be checked
+     * @return true if an implementation is registered, false otherwise
+     */
+    <T> boolean has(Class<T> clazz);
+    
+    /**
+     * Lists all the registered interface classes.
+     * 
+     * This method provides a list of all the interface classes for which 
+     * implementations have been registered. It can be useful for debugging or 
+     * introspection purposes.
+     *
+     * @return a List of Class objects representing the registered interfaces
+     */
+    List<Class<?>> list();
+}

src/main/java/com/pixelgamelibrary/api/interfaces/PixelBackend.java

@@ -19,6 +19,9 @@
 ///////////////////////////////////////////////////////////////////////////////////////////////
 package com.pixelgamelibrary.api.interfaces;
 
+import com.pixelgamelibrary.api.PixelException;
+import com.pixelgamelibrary.api.extension.ExtensionImpl;
+
 /**
  *
  * @author robertvokac
@@ -29,9 +32,29 @@ public interface PixelBackend {
     Graphics graphics();
     Audio audio();
     Input input();
+    //
     Net net();
     Files files();
     Utils utils();
     Internal internal();
+    //
+    default Extension extension() {
+        return ExtensionImpl.getInstance();
+    }
+
+    default <T> T get(Class<T> clazz) {
+        if(clazz.equals(App.class)) {return (T) app();}
+        if(clazz.equals(Graphics.class)) {return (T) graphics();}
+        if(clazz.equals(Audio.class)) {return (T) audio();}
+        if(clazz.equals(Input.class)) {return (T) input();}
+        //
+        if(clazz.equals(Net.class)) {return (T) net();}
+        if(clazz.equals(Files.class)) {return (T) files();}
+        if(clazz.equals(Utils.class)) {return (T) utils();}
+        if(clazz.equals(Internal.class)) {return (T) internal();}
+        //
+        if(clazz.equals(Extension.class)) {return (T) extension();}
+        throw new PixelException("Unsupported interface: " + clazz.getName());
+    }
 
 }