[New] Implemented StrolchTransaction.findElement(Locator)

Now using a locator, it is possible to query a StrolchElement. It is
possible to query top level i.e. Resource/Order or ParameterBag, or
Parameter.

src/main/java/li/strolch/agent/impl/TransactionalElementMap.java

@@ -24,6 +24,7 @@ public abstract class TransactionalElementMap<T extends StrolchElement> implemen
 
 	@Override
 	public boolean hasElement(StrolchTransaction tx, String type, String id) {
+		// TODO change to dao.hasElement(type, id)
 		return getDao(tx).queryKeySet(type).contains(id);
 	}
 

src/main/java/li/strolch/persistence/api/AbstractTransaction.java

@@ -15,9 +15,19 @@
  */
 package li.strolch.persistence.api;
 
+import java.text.MessageFormat;
+import java.util.List;
+
 import li.strolch.agent.api.OrderMap;
 import li.strolch.agent.api.ResourceMap;
 import li.strolch.agent.impl.StrolchRealm;
+import li.strolch.exception.StrolchException;
+import li.strolch.model.GroupedParameterizedElement;
+import li.strolch.model.Locator;
+import li.strolch.model.ParameterBag;
+import li.strolch.model.StrolchElement;
+import li.strolch.model.Tags;
+import li.strolch.model.parameter.Parameter;
 import li.strolch.persistence.inmemory.InMemoryTransaction;
 
 import org.slf4j.Logger;
@@ -54,4 +64,58 @@ public abstract class AbstractTransaction implements StrolchTransaction {
 	public OrderMap getOrderMap() {
 		return this.realm.getOrderMap();
 	}
+
+	@SuppressWarnings("unchecked")
+	@Override
+	public <T extends StrolchElement> T findElement(Locator locator) {
+
+		if (locator.getSize() < 3) {
+			String msg = "The locator is invalid as it does not have at least three path elements (e.g. Resource/MyType/@id): {0}";
+			msg = MessageFormat.format(msg, locator.toString());
+			throw new StrolchException(msg);
+		} else if (locator.getSize() > 5) {
+			// TODO handle state variables, which will probably be separated by an additional part so we can differentiate between parameters and state variables on a parameter bag
+			String msg = "The locator is invalid as it has more than 5 parts. The fifth part references a Parameter, which is the deepest fetchable entry: {0}";
+			msg = MessageFormat.format(msg, locator.toString());
+			throw new StrolchException(msg);
+		}
+
+		List<String> elements = locator.getPathElements();
+		GroupedParameterizedElement groupedParameterizedElement;
+		String objectClassType = elements.get(0);
+		String type = elements.get(1);
+		String id = elements.get(2);
+		switch (objectClassType) {
+		case Tags.RESOURCE:
+			groupedParameterizedElement = getResourceMap().getBy(this, type, id);
+			break;
+		case Tags.ORDER:
+			groupedParameterizedElement = getOrderMap().getBy(this, type, id);
+			break;
+		default:
+			throw new StrolchException("Unknown object class " + objectClassType);
+		}
+
+		if (groupedParameterizedElement == null) {
+			String msg = "No top level object could be found with locator {0}";
+			throw new StrolchException(MessageFormat.format(msg, locator));
+		}
+
+		if (elements.size() == 3)
+			return (T) groupedParameterizedElement;
+
+		String parameterBagId = elements.get(3);
+		ParameterBag bag = groupedParameterizedElement.getParameterBag(parameterBagId);
+		if (bag == null) {
+			String msg = "Could not find ParameterBag for locator {0} on element {1}";
+			throw new StrolchException(MessageFormat.format(msg, locator, groupedParameterizedElement.getLocator()));
+		}
+
+		if (elements.size() == 4)
+			return (T) bag;
+
+		String parameterId = elements.get(4);
+		Parameter<?> parameter = bag.getParameter(parameterId);
+		return (T) parameter;
+	}
 }

src/main/java/li/strolch/persistence/api/StrolchDao.java

@@ -28,6 +28,8 @@ public interface StrolchDao<T extends StrolchElement> {
 
 	public Set<String> queryKeySet();
 
+	// TODO add method hasElement(String type, String id)
+
 	public Set<String> queryKeySet(String type);
 
 	public Set<String> queryTypes();
@@ -47,6 +49,6 @@ public interface StrolchDao<T extends StrolchElement> {
 	public void updateAll(List<T> elements);
 
 	public void remove(T element);
-	
+
 	public void removeAll(List<T> elements);
 }

src/main/java/li/strolch/persistence/api/StrolchTransaction.java

@@ -17,6 +17,13 @@ package li.strolch.persistence.api;
 
 import li.strolch.agent.api.OrderMap;
 import li.strolch.agent.api.ResourceMap;
+import li.strolch.exception.StrolchException;
+import li.strolch.model.Locator;
+import li.strolch.model.Order;
+import li.strolch.model.ParameterBag;
+import li.strolch.model.Resource;
+import li.strolch.model.StrolchElement;
+import li.strolch.model.parameter.Parameter;
 
 public interface StrolchTransaction extends AutoCloseable {
 
@@ -34,6 +41,35 @@ public interface StrolchTransaction extends AutoCloseable {
 	public ResourceMap getResourceMap();
 
 	public OrderMap getOrderMap();
-	
+
 	public PersistenceHandler getPersistenceHandler();
+
+	/**
+	 * <p>
+	 * Used to find a {@link StrolchElement} by a {@link Locator}.
+	 * </p>
+	 * 
+	 * <p>
+	 * A Locator has the form <i>&lt;ObjectClassType&gt;/&lt;Type&gt;/&lt;Id&gt;</i> - this is the least amount of path
+	 * elements to find an object. Thus to query a {@link Resource} of type "MyType" and the id "@1" use the following
+	 * path: <i>Resourcee/MyType/@1</i>
+	 * </p>
+	 * 
+	 * <p>
+	 * This method can also be used to find a deeper element, e.g. a specific {@link Parameter} on an
+	 * {@link ParameterBag} on an {@link Order}. This would be done as follows: <i>Order/MyType/@1/myParam</i>
+	 * </p>
+	 * 
+	 * @param locator
+	 *            the locator defining the path to the element which is to be found
+	 * 
+	 * @return the element described by the locator
+	 * 
+	 * @throws StrolchException
+	 *             if the element could not be found
+	 * @throws ClassCastException
+	 *             if the querying code is not asking for the correct instance. Do not query a {@link Parameter} if the
+	 *             variable to which the result is to be is stored is a {@link Resource}, etc.
+	 */
+	public <T extends StrolchElement> T findElement(Locator locator) throws StrolchException, ClassCastException;
 }

src/test/java/li/strolch/runtime/test/query/inmemory/FindByLocatorTest.java

@@ -0,0 +1,63 @@
+/*
+ * Copyright 2013 Robert von Burg <eitch@eitchnet.ch>
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package li.strolch.runtime.test.query.inmemory;
+
+import static org.junit.Assert.assertNotNull;
+import li.strolch.agent.api.ComponentContainer;
+import li.strolch.agent.api.StrolchAgent;
+import li.strolch.model.Locator;
+import li.strolch.model.ParameterBag;
+import li.strolch.model.Resource;
+import li.strolch.model.parameter.FloatParameter;
+import li.strolch.model.parameter.StringParameter;
+import li.strolch.persistence.api.StrolchTransaction;
+import li.strolch.runtime.test.component.ComponentContainerTest;
+
+import org.junit.Test;
+
+/**
+ * @author Robert von Burg <eitch@eitchnet.ch>
+ */
+public class FindByLocatorTest {
+
+	private static final String PATH_FIND_BY_LOCATOR_RUNTIME = "target/FindByLocatorTest/";
+
+	@Test
+	public void shouldFindByLocator() {
+
+		StrolchAgent agent = ComponentContainerTest.startContainer(PATH_FIND_BY_LOCATOR_RUNTIME,
+				ComponentContainerTest.PATH_TRANSIENT_CONTAINER);
+		ComponentContainer container = agent.getContainer();
+
+		try (StrolchTransaction tx = container.getDefaultRealm().openTx()) {
+			Locator locResStringParam = Locator.valueOf("Resource/TestType/MyTestResource/@bag01/@param5");
+			StringParameter resStringParam = tx.findElement(locResStringParam);
+			assertNotNull("Should have found a StringParameter with the locator " + locResStringParam, resStringParam);
+
+			Locator locOrderFloatParam = Locator.valueOf("Order/TestType/MyTestOrder/@bag01/@param2");
+			FloatParameter orderFloatP = tx.findElement(locOrderFloatParam);
+			assertNotNull("Should have found a FloatParameter with the locator " + locOrderFloatParam, orderFloatP);
+
+			Locator locOrderBag = Locator.valueOf("Order/TestType/MyTestOrder/@bag01");
+			ParameterBag orderBag = tx.findElement(locOrderBag);
+			assertNotNull("Should have found a FloatParameter with the locator " + locOrderBag, orderBag);
+
+			Locator locResource = Locator.valueOf("Resource/TestType/MyTestResource");
+			Resource resource = tx.findElement(locResource);
+			assertNotNull("Should have found a FloatParameter with the locator " + locResource, resource);
+		}
+	}
+}