introduce new event system bus

src/main/java/de/marhali/easyi18n/DataBus.java

@@ -0,0 +1,55 @@
+package de.marhali.easyi18n;
+
+import de.marhali.easyi18n.model.BusListener;
+import de.marhali.easyi18n.model.TranslationData;
+
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * Data-bus which is used to distribute changes regarding translations or ui tools to the participating components.
+ * @author marhali
+ */
+public class DataBus {
+
+    private final Set<BusListener> listener;
+
+    protected DataBus() {
+        this.listener = new HashSet<>();
+    }
+
+    /**
+     * Adds a participant to the event bus. Every participant needs to be added manually.
+     * @param listener Bus listener
+     */
+    public void addListener(BusListener listener) {
+        this.listener.add(listener);
+    }
+
+    /**
+     * Fires the called events on the returned prototype.
+     * The event will be distributed to all participants which were registered at execution time.
+     * @return Listener prototype
+     */
+    public BusListener propagate() {
+        return new BusListener() {
+            @Override
+            public void onUpdateData(@NotNull TranslationData data) {
+                listener.forEach(li -> li.onUpdateData(data));
+            }
+
+            @Override
+            public void onFocusKey(@Nullable String key) {
+                listener.forEach(li -> li.onFocusKey(key));
+            }
+
+            @Override
+            public void onSearchQuery(@Nullable String query) {
+                listener.forEach(li -> li.onSearchQuery(query));
+            }
+        };
+    }
+}

src/main/java/de/marhali/easyi18n/model/BusListener.java

@@ -0,0 +1,29 @@
+package de.marhali.easyi18n.model;
+
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * Interface for communication of changes for participants of the data bus.
+ * @author marhali
+ */
+public interface BusListener {
+    /**
+     * Update the translations based on the supplied data.
+     * @param data Updated translations
+     */
+    void onUpdateData(@NotNull TranslationData data);
+
+    /**
+     * Move the specified translation key (full-key) into focus.
+     * @param key Absolute translation key
+     */
+    void onFocusKey(@Nullable String key);
+
+    /**
+     * Filter the displayed data according to the search query. Supply 'null' to return to the normal state.
+     * The keys and the content itself should be considered.
+     * @param query Filter key or content
+     */
+    void onSearchQuery(@Nullable String query);
+}