[E4] Introduce EModelService.findMatchingElements() as Xpath replacement

Author: HannesWell

bundles/org.eclipse.e4.ui.model.workbench/src/org/eclipse/e4/ui/model/XPathHelper.java

@@ -0,0 +1,35 @@
+/*******************************************************************************
+ * Copyright (c) 2025, 2025 Hannes Wellmann and others.
+ *
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *     Hannes Wellmann - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.e4.ui.model;
+
+import java.util.stream.Stream;
+import org.eclipse.core.runtime.ILog;
+import org.eclipse.e4.emf.xpath.XPathContextFactory;
+import org.eclipse.emf.ecore.EObject;
+
+public class XPathHelper {
+
+	public static <T> Stream<T> findMatchingElements(EObject contextBean, String xpath, Class<T> clazz) {
+		try {
+			return XPathContextFactory.newInstance().newContext(contextBean).stream(xpath, clazz);
+		} catch (Exception ex) {
+			// custom xpath functions will throw exceptions
+			ILog.get().error("Failed to evaluate xpath: " + xpath, ex); //$NON-NLS-1$
+			return Stream.empty();
+		}
+	}
+
+	// Inline the then still used part of JavaXPathContextFactoryImpl here once the
+	// e4.emf.xpath bundle is finally removed
+}

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

@@ -18,9 +18,7 @@
 import java.util.ArrayList;
 import java.util.List;
 import java.util.regex.Pattern;
-import org.eclipse.e4.emf.xpath.EcoreXPathContextFactory;
-import org.eclipse.e4.emf.xpath.XPathContext;
-import org.eclipse.e4.emf.xpath.XPathContextFactory;
+import org.eclipse.e4.ui.model.XPathHelper;
 import org.eclipse.e4.ui.model.application.MApplication;
 import org.eclipse.e4.ui.model.application.MApplicationElement;
 import org.eclipse.e4.ui.model.fragment.MStringModelFragment;
@@ -282,10 +280,10 @@ public boolean eIsSet(int featureID) {
 			return FEATURENAME_EDEFAULT == null ? featurename != null : !FEATURENAME_EDEFAULT.equals(featurename);
 		case FragmentPackageImpl.STRING_MODEL_FRAGMENT__PARENT_ELEMENT_ID:
 			return PARENT_ELEMENT_ID_EDEFAULT == null ? parentElementId != null
-					: !PARENT_ELEMENT_ID_EDEFAULT.equals(parentElementId);
+			: !PARENT_ELEMENT_ID_EDEFAULT.equals(parentElementId);
 		case FragmentPackageImpl.STRING_MODEL_FRAGMENT__POSITION_IN_LIST:
 			return POSITION_IN_LIST_EDEFAULT == null ? positionInList != null
-					: !POSITION_IN_LIST_EDEFAULT.equals(positionInList);
+			: !POSITION_IN_LIST_EDEFAULT.equals(positionInList);
 		default:
 			return super.eIsSet(featureID);
 		}
@@ -355,15 +353,8 @@ private void mergeXPath(MApplication application, List<MApplicationElement> ret,
 		if ("/".equals(xPath)) {
 			targetElements = List.of(application);
 		} else {
-			XPathContextFactory<EObject> f = EcoreXPathContextFactory.newInstance();
-			XPathContext xpathContext = f.newContext((EObject) application);
-			try {
-				targetElements = xpathContext.stream(xPath, MApplicationElement.class).toList();
-			} catch (Exception ex) {
-				targetElements = List.of();
-				// custom xpath functions will throw exceptions
-				ex.printStackTrace();
-			}
+			EObject appRoot = (EObject) application;
+			targetElements = XPathHelper.findMatchingElements(appRoot, xPath, MApplicationElement.class).toList();
 		}
 		for (MApplicationElement targetElement : targetElements) {
 			EStructuralFeature feature = ((EObject) targetElement).eClass().getEStructuralFeature(getFeaturename());

bundles/org.eclipse.e4.ui.workbench/META-INF/MANIFEST.MF

@@ -1,7 +1,7 @@
 Manifest-Version: 1.0
 Bundle-ManifestVersion: 2
 Bundle-SymbolicName: org.eclipse.e4.ui.workbench;singleton:=true
-Bundle-Version: 1.16.100.qualifier
+Bundle-Version: 1.17.0.qualifier
 Bundle-Name: %pluginName
 Bundle-Vendor: %providerName
 Bundle-Localization: plugin

bundles/org.eclipse.e4.ui.workbench/src/org/eclipse/e4/ui/internal/workbench/ModelServiceImpl.java

@@ -27,12 +27,14 @@
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Objects;
+import java.util.stream.Stream;
 import org.eclipse.core.runtime.Assert;
 import org.eclipse.core.runtime.IExtensionRegistry;
 import org.eclipse.e4.core.contexts.ContextInjectionFactory;
 import org.eclipse.e4.core.contexts.IEclipseContext;
 import org.eclipse.e4.core.services.events.IEventBroker;
 import org.eclipse.e4.core.services.log.Logger;
+import org.eclipse.e4.ui.model.XPathHelper;
 import org.eclipse.e4.ui.model.application.MAddon;
 import org.eclipse.e4.ui.model.application.MApplication;
 import org.eclipse.e4.ui.model.application.MApplicationElement;
@@ -434,6 +436,11 @@ public <T> List<T> findElements(MApplicationElement searchRoot, Class<T> clazz,
 		return new ArrayList<>(elements);
 	}
 
+	@Override
+	public <T> Stream<T> findMatchingElements(MApplicationElement searchRoot, String xpath, Class<T> clazz) {
+		return XPathHelper.findMatchingElements((EObject) searchRoot, xpath, clazz);
+	}
+
 	private <T> Iterable<T> findPerspectiveElements(MUIElement searchRoot, String id,
 			Class<T> clazz,
 			List<String> tagsToMatch) {

bundles/org.eclipse.e4.ui.workbench/src/org/eclipse/e4/ui/workbench/modeling/EModelService.java

@@ -17,6 +17,7 @@
 package org.eclipse.e4.ui.workbench.modeling;
 
 import java.util.List;
+import java.util.stream.Stream;
 import org.eclipse.e4.core.contexts.IEclipseContext;
 import org.eclipse.e4.ui.model.application.MApplicationElement;
 import org.eclipse.e4.ui.model.application.descriptor.basic.MPartDescriptor;
@@ -279,6 +280,11 @@ <T> List<T> findElements(MUIElement searchRoot, String id, Class<T> clazz,
 	<T> List<T> findElements(MApplicationElement searchRoot, Class<T> clazz,
 			int searchFlags, Selector matcher);
 
+	/**
+	 * @since 1.17
+	 */
+	<T> Stream<T> findMatchingElements(MApplicationElement contextBean, String xpath, Class<T> clazz);
+
 	/**
 	 * Returns the first element, recursively searching under the specified search
 	 * root (inclusive)