[New] Added a StrolchQuery.hasSelection() and Selection.hasSelection()

This allows for checking if a query really has a selection.

src/main/java/li/strolch/model/query/BooleanSelection.java

@@ -45,6 +45,20 @@ public abstract class BooleanSelection implements Selection {
 		this.selections = Arrays.asList(selections);
 	}
 
+	@Override
+	public boolean hasSelection() {
+		if (this.selections == null || this.selections.isEmpty())
+			return false;
+
+		for (Selection selection : this.selections) {
+			if (selection.hasSelection()) {
+				return true;
+			}
+		}
+
+		return false;
+	}
+
 	public List<Selection> getSelections() {
 		return Collections.unmodifiableList(this.selections);
 	}

src/main/java/li/strolch/model/query/OrderSelection.java

@@ -17,7 +17,7 @@ package li.strolch.model.query;
 
 /**
  * @author Robert von Burg <eitch@eitchnet.ch>
- *
+ * 
  */
 public abstract class OrderSelection implements Selection {
 
@@ -26,5 +26,10 @@ public abstract class OrderSelection implements Selection {
 		accept((OrderSelectionVisitor) visitor);
 	}
 
+	@Override
+	public boolean hasSelection() {
+		return true;
+	}
+
 	public abstract void accept(OrderSelectionVisitor visitor);
 }

src/main/java/li/strolch/model/query/ParameterSelection.java

@@ -45,11 +45,27 @@ public abstract class ParameterSelection implements Selection {
 		return this.paramKey;
 	}
 
+	@Override
+	public boolean hasSelection() {
+		return true;
+	}
+
 	@Override
 	public void accept(QueryVisitor visitor) {
 		accept((ParameterSelectionVisitor) visitor);
 	}
 
+	@Override
+	public String toString() {
+		StringBuilder builder = new StringBuilder();
+		builder.append(getClass().getSimpleName() + " [bagKey=");
+		builder.append(this.bagKey);
+		builder.append(", paramKey=");
+		builder.append(this.paramKey);
+		builder.append("]");
+		return builder.toString();
+	}
+
 	public abstract void accept(ParameterSelectionVisitor visitor);
 
 	public static StringParameterSelection stringSelection(String bagKey, String paramKey, String value) {

src/main/java/li/strolch/model/query/Selection.java

@@ -20,6 +20,7 @@ package li.strolch.model.query;
  */
 public interface Selection {
 
-	// marker interface
 	public void accept(QueryVisitor visitor);
+	
+	public boolean hasSelection();
 }

src/main/java/li/strolch/model/query/StrolchElementSelection.java

@@ -25,5 +25,10 @@ public abstract class StrolchElementSelection implements Selection {
 		accept((StrolchElementSelectionVisitor) visitor);
 	}
 
+	@Override
+	public boolean hasSelection() {
+		return true;
+	}
+
 	public abstract void accept(StrolchElementSelectionVisitor visitor);
 }

src/main/java/li/strolch/model/query/StrolchQuery.java

@@ -28,6 +28,14 @@ public abstract class StrolchQuery<T extends QueryVisitor> {
 	public StrolchQuery(Navigation navigation) {
 		this.navigation = navigation;
 	}
+	
+	public boolean hasNavigation() {
+		return navigation != null;
+	}
+	
+	public boolean hasSelection() {
+		return selection != null && selection.hasSelection();
+	}
 
 	public void select(Selection selection) {
 		DBC.PRE.assertNull("A selection is already set! Use a boolean operator to perform multiple selections",