Add XPathContext.stream() and strengthen type of getValue(String, Class)

Author: HannesWell

bundles/org.eclipse.e4.emf.xpath/.settings/.api_filters

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<component id="org.eclipse.e4.emf.xpath" version="2">
+    <resource path="src/org/eclipse/e4/emf/xpath/XPathContext.java" type="org.eclipse.e4.emf.xpath.XPathContext">
+        <filter id="404000815">
+            <message_arguments>
+                <message_argument value="org.eclipse.e4.emf.xpath.XPathContext"/>
+                <message_argument value="stream(String, Class&lt;T&gt;)"/>
+            </message_arguments>
+        </filter>
+    </resource>
+</component>

bundles/org.eclipse.e4.emf.xpath/META-INF/MANIFEST.MF

@@ -2,7 +2,7 @@ Manifest-Version: 1.0
 Bundle-ManifestVersion: 2
 Bundle-Name: %Bundle-Name
 Bundle-SymbolicName: org.eclipse.e4.emf.xpath
-Bundle-Version: 0.4.300.qualifier
+Bundle-Version: 0.5.0.qualifier
 Bundle-RequiredExecutionEnvironment: JavaSE-17
 Require-Bundle: org.eclipse.emf.ecore;bundle-version="2.35.0",
  org.eclipse.core.runtime;bundle-version="3.29.0"

bundles/org.eclipse.e4.emf.xpath/src/org/eclipse/e4/emf/internal/xpath/JXPathContextImpl.java

@@ -21,6 +21,7 @@
 import org.apache.commons.jxpath.JXPathContext;
 import org.apache.commons.jxpath.NodeSet;
 import org.apache.commons.jxpath.Pointer;
+import org.apache.commons.jxpath.util.TypeUtils;
 import org.eclipse.e4.emf.xpath.XPathContext;
 import org.eclipse.emf.ecore.EObject;
 
@@ -84,8 +85,11 @@ public Object getValue(String xpath) {
 	}
 
 	@Override
-	public Object getValue(String xpath, Class<?> requiredType) {
-		return context.getValue(xpath, requiredType);
+	public <T> T getValue(String xpath, Class<T> requiredType) {
+		Object value = context.getValue(xpath, requiredType);
+		@SuppressWarnings("unchecked")
+		T typedValue = (T) TypeUtils.convert(value, requiredType);
+		return typedValue;
 	}
 
 	@Override

bundles/org.eclipse.e4.emf.xpath/src/org/eclipse/e4/emf/xpath/XPathContext.java

@@ -14,6 +14,12 @@
 package org.eclipse.e4.emf.xpath;
 
 import java.util.Iterator;
+import java.util.Spliterator;
+import java.util.Spliterators;
+import java.util.stream.Stream;
+import java.util.stream.StreamSupport;
+
+import org.apache.commons.jxpath.util.TypeUtils;
 
 /**
  * Context in which the xpath is executed
@@ -42,7 +48,7 @@ public interface XPathContext {
 	 *            required type
 	 * @return Object found
 	 */
-	Object getValue(String xpath, Class<?> requiredType);
+	<T> T getValue(String xpath, Class<T> requiredType);
 
 	/**
 	 * Traverses the xpath and returns an Iterator of all results found for the
@@ -55,4 +61,22 @@ public interface XPathContext {
 	 * @return Iterator&lt;Object&gt;
 	 */
 	<T> Iterator<T> iterate(String xpath);
+
+	/**
+	 * Traverses the xpath and returns an {@link Stream} of all results found for
+	 * the path. If the xpath matches no properties in the graph, the stream will be
+	 * empty.
+	 *
+	 * @param <T>   the expected object type
+	 * @param xpath the xpath expression to iterate
+	 * @param type  the type of elements in the returned stream
+	 * @return a stream of elements matching the specified xpath and of the given
+	 *         type
+	 * @since 0.5
+	 */
+	default <T> Stream<T> stream(String xpath, Class<T> type) {
+		Iterator<?> iterator = iterate(xpath);
+		return StreamSupport.stream(Spliterators.spliteratorUnknownSize(iterator, Spliterator.ORDERED), false)
+				.filter(e -> TypeUtils.canConvert(e, type)).map(e -> TypeUtils.convert(e, type)).map(type::cast);
+	}
 }

bundles/org.eclipse.e4.ui.model.workbench/src/org/eclipse/e4/ui/model/fragment/impl/StringModelFragmentImpl.java

@@ -16,8 +16,6 @@
 package org.eclipse.e4.ui.model.fragment.impl;
 
 import java.util.ArrayList;
-import java.util.Collections;
-import java.util.Iterator;
 import java.util.List;
 import java.util.regex.Pattern;
 import org.eclipse.e4.emf.xpath.EcoreXPathContextFactory;
@@ -355,31 +353,22 @@ private void mergeIdList(MApplication application, List<MApplicationElement> ret
 	private void mergeXPath(MApplication application, List<MApplicationElement> ret, String xPath) {
 		List<MApplicationElement> targetElements;
 		if ("/".equals(xPath)) {
-			targetElements = Collections.singletonList(application);
+			targetElements = List.of(application);
 		} else {
 			XPathContextFactory<EObject> f = EcoreXPathContextFactory.newInstance();
 			XPathContext xpathContext = f.newContext((EObject) application);
-			Iterator<Object> i = xpathContext.iterate(xPath);
-
-			targetElements = new ArrayList<>();
 			try {
-				while (i.hasNext()) {
-					Object obj = i.next();
-					if (obj instanceof MApplicationElement) {
-						MApplicationElement o = (MApplicationElement) obj;
-						targetElements.add(o);
-					}
-				}
+				targetElements = xpathContext.stream(xPath, MApplicationElement.class).toList();
 			} catch (Exception ex) {
+				targetElements = List.of();
 				// custom xpath functions will throw exceptions
 				ex.printStackTrace();
 			}
 		}
 		for (MApplicationElement targetElement : targetElements) {
 			EStructuralFeature feature = ((EObject) targetElement).eClass().getEStructuralFeature(getFeaturename());
 			if (feature != null) {
-				List<MApplicationElement> elements;
-				elements = new ArrayList<>();
+				List<MApplicationElement> elements = new ArrayList<>();
 				for (MApplicationElement element : getElements()) {
 					elements.add((MApplicationElement) EcoreUtil.copy((EObject) element));
 				}

tests/org.eclipse.e4.emf.xpath.test/src/org/eclipse/e4/emf/xpath/test/ExampleQueriesApplicationTest.java

@@ -85,6 +85,9 @@ public void testAccessingTheMainMenu() {
 		Object menu = xpathContext.getValue("//mainMenu");
 		assertNotNull(menu);
 		assertTrue(menu instanceof MMenu);
+
+		MMenu mMenu = xpathContext.getValue("//mainMenu", MMenu.class);
+		assertNotNull(mMenu);
 	}
 
 	@Test

tests/org.eclipse.e4.emf.xpath.test/src/org/eclipse/e4/emf/xpath/test/ExampleQueriesTestCase.java

@@ -21,6 +21,7 @@
 import static org.junit.Assert.assertTrue;
 
 import java.util.Iterator;
+import java.util.List;
 
 import org.apache.commons.jxpath.JXPathNotFoundException;
 import org.eclipse.e4.emf.xpath.EcoreXPathContextFactory;
@@ -75,6 +76,9 @@ public void testSimpleQuery() {
 		assertNotNull(application);
 		assertSame(RootImpl.class, application.getClass());
 
+		RootImpl rootApplication = xpathContext.getValue("/", RootImpl.class);
+		assertNotNull(rootApplication);
+
 		application = xpathContext.getValue(".");
 		assertNotNull(application);
 		assertSame(RootImpl.class, application.getClass());
@@ -85,14 +89,19 @@ public void testSimpleQuery() {
 		assertNotNull(application);
 		assertSame(RootImpl.class, application.getClass());
 
+		rootApplication = xpathContext.getValue(".[@id='root']", RootImpl.class);
+		assertNotNull(rootApplication);
+
 		assertEquals("element1",xpathContext.getValue("nodes[1]/@id"));
 
 		assertEquals(NodeImpl.class, xpathContext.getValue("//.[@id='element2.2']").getClass());
 		assertEquals(ExtendedNodeImpl.class,xpathContext.getValue("//.[ecore:eClassName(.)='ExtendedNode']").getClass());
 
+		ExtendedNodeImpl extendedNode = xpathContext.getValue("//.[ecore:eClassName(.)='ExtendedNode']",
+				ExtendedNodeImpl.class);
+		assertNotNull(extendedNode);
 	}
 
-
 	@Test
 	public void testMenuQuery() {
 		Object application = xpathContext.getValue("/");
@@ -109,8 +118,10 @@ public void testMenuQuery() {
 		assertSame(MenuImpl.class, i.next().getClass());
 		// EMF model has a loop in it, it just goes back to the top
 		//assertFalse(i.hasNext());
-	}
-
 
+		List<MenuImpl> list = xpathContext.stream("//.[@id='menu.1']", MenuImpl.class).toList();
+		// EMF model has a loop in it, it just goes back to the top
+		assertEquals(26, list.size());
+	}
 
 }