[#1668] simplify work with launch attributes

* identify launch attribute
* connect it with preference metadata (to supply
defaults/label/description)
* read attribute from configuration
* write attribute to configuration working copy
* demonstrate usage for ExternalTools

Author: ruspl-afed

ant/org.eclipse.ant.launching/src/org/eclipse/ant/internal/launching/debug/model/AntDebugTarget.java

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2004, 2016 IBM Corporation and others.
+ * Copyright (c) 2004, 2025 IBM Corporation and others.
  *
  * This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License 2.0
@@ -10,6 +10,7 @@
  *
  * Contributors:
  *     IBM Corporation - initial API and implementation
+ *     Alexander Fedorov (ArSysOp) - API to process launch configuration attributes
  *******************************************************************************/
 package org.eclipse.ant.internal.launching.debug.model;
 
@@ -22,7 +23,6 @@
 import org.eclipse.core.externaltools.internal.IExternalToolConstants;
 import org.eclipse.core.resources.IMarkerDelta;
 import org.eclipse.core.runtime.CoreException;
-import org.eclipse.core.variables.VariablesPlugin;
 import org.eclipse.debug.core.DebugEvent;
 import org.eclipse.debug.core.DebugException;
 import org.eclipse.debug.core.DebugPlugin;
@@ -108,13 +108,7 @@ public boolean hasThreads() throws DebugException {
 	@Override
 	public String getName() throws DebugException {
 		if (fName == null) {
-			try {
-				fName = getLaunch().getLaunchConfiguration().getAttribute(IExternalToolConstants.ATTR_LOCATION, DebugModelMessages.AntDebugTarget_0);
-				fName = VariablesPlugin.getDefault().getStringVariableManager().performStringSubstitution(fName);
-			}
-			catch (CoreException e) {
-				fName = DebugModelMessages.AntDebugTarget_0;
-			}
+			fName = IExternalToolConstants.LAUNCH_ATTRIBUTE_LOCATION.probe(getLaunch().getLaunchConfiguration()).orElse(DebugModelMessages.AntDebugTarget_0);
 		}
 		return fName;
 	}

ant/org.eclipse.ant.launching/src/org/eclipse/ant/internal/launching/launchConfigurations/AntMigrationDelegate.java

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2006, 2013 IBM Corporation and others.
+ * Copyright (c) 2006, 2025 IBM Corporation and others.
  *
  * This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License 2.0
@@ -10,6 +10,7 @@
  *
  * Contributors:
  *     IBM Corporation - initial API and implementation
+ *     Alexander Fedorov (ArSysOp) - API to process launch configuration attributes
  *******************************************************************************/
 package org.eclipse.ant.internal.launching.launchConfigurations;
 
@@ -18,8 +19,6 @@
 import org.eclipse.core.resources.IFile;
 import org.eclipse.core.resources.IResource;
 import org.eclipse.core.runtime.CoreException;
-import org.eclipse.core.variables.IStringVariableManager;
-import org.eclipse.core.variables.VariablesPlugin;
 import org.eclipse.debug.core.ILaunchConfiguration;
 import org.eclipse.debug.core.ILaunchConfigurationMigrationDelegate;
 import org.eclipse.debug.core.ILaunchConfigurationWorkingCopy;
@@ -40,23 +39,7 @@ public class AntMigrationDelegate implements ILaunchConfigurationMigrationDelega
 	 * @return the buildfile or <code>null</code> if not in the workspace
 	 */
 	protected IFile getFileForCandidate(ILaunchConfiguration candidate) {
-		IFile file = null;
-		String expandedLocation = null;
-		String location = null;
-		IStringVariableManager manager = VariablesPlugin.getDefault().getStringVariableManager();
-		try {
-			location = candidate.getAttribute(IExternalToolConstants.ATTR_LOCATION, (String) null);
-			if (location != null) {
-				expandedLocation = manager.performStringSubstitution(location);
-				if (expandedLocation != null) {
-					file = AntLaunchingUtil.getFileForLocation(expandedLocation, null);
-				}
-			}
-		}
-		catch (CoreException e) {
-			// do nothing
-		}
-		return file;
+		return IExternalToolConstants.LAUNCH_ATTRIBUTE_LOCATION.probe(candidate).map(l -> AntLaunchingUtil.getFileForLocation(l, null)).orElse(null);
 	}
 
 	@Override

ant/org.eclipse.ant.ui/Ant Tools Support/org/eclipse/ant/internal/ui/AntUtil.java

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2000, 2015 IBM Corporation and others.
+ * Copyright (c) 2000, 2025 IBM Corporation and others.
  *
  * This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License 2.0
@@ -10,6 +10,7 @@
  *
  * Contributors:
  *     IBM Corporation - initial API and implementation
+ *     Alexander Fedorov (ArSysOp) - API to process launch configuration attributes
  *******************************************************************************/
 package org.eclipse.ant.internal.ui;
 
@@ -20,7 +21,6 @@
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.Hashtable;
-import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
 import java.util.regex.Pattern;
@@ -195,7 +195,7 @@ public static AntTargetNode[] getTargets(String path, ILaunchConfiguration confi
 	}
 
 	private static Map<String, String> getAllProperties(ILaunchConfiguration config) throws CoreException {
-		String allArgs = config.getAttribute(IExternalToolConstants.ATTR_TOOL_ARGUMENTS, (String) null);
+		String allArgs = IExternalToolConstants.LAUNCH_ATTRIBUTE_ARGUMENTS.read(config);
 		Map<String, String> properties = new HashMap<>();
 		if (allArgs != null) {
 			// filter arguments to avoid resolving variables that will prompt the user
@@ -213,9 +213,7 @@ private static Map<String, String> getAllProperties(ILaunchConfiguration config)
 		}
 		Map<String, String> configProperties = getProperties(config);
 		if (configProperties != null) {
-			Iterator<String> keys = configProperties.keySet().iterator();
-			while (keys.hasNext()) {
-				String name = keys.next();
+			for (String name : configProperties.keySet()) {
 				if (properties.get(name) == null) {
 					properties.put(name, configProperties.get(name));
 				}

ant/org.eclipse.ant.ui/Ant Tools Support/org/eclipse/ant/internal/ui/launchConfigurations/AntMainTab.java

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2000, 2013 IBM Corporation and others.
+ * Copyright (c) 2000, 2025 IBM Corporation and others.
  *
  * This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License 2.0
@@ -10,9 +10,12 @@
  *
  * Contributors:
  *     IBM Corporation - initial API and implementation
+ *     Alexander Fedorov (ArSysOp) - API to process launch configuration attributes
  *******************************************************************************/
 package org.eclipse.ant.internal.ui.launchConfigurations;
 
+import java.util.Optional;
+
 import org.eclipse.ant.internal.core.IAntCoreConstants;
 import org.eclipse.ant.internal.ui.AntUIPlugin;
 import org.eclipse.ant.internal.ui.AntUtil;
@@ -24,7 +27,6 @@
 import org.eclipse.core.resources.IResource;
 import org.eclipse.core.resources.ResourcesPlugin;
 import org.eclipse.core.runtime.CoreException;
-import org.eclipse.core.variables.IStringVariableManager;
 import org.eclipse.core.variables.VariablesPlugin;
 import org.eclipse.debug.core.ILaunchConfiguration;
 import org.eclipse.debug.core.ILaunchConfigurationWorkingCopy;
@@ -45,44 +47,27 @@
 
 public class AntMainTab extends ExternalToolsMainTab {
 
-	private String fCurrentLocation = null;
+	private Optional<String> fCurrentLocation;
 	private Button fSetInputHandlerButton;
 	private IFile fNewFile;
 
 	@Override
 	public void initializeFrom(ILaunchConfiguration configuration) {
 		super.initializeFrom(configuration);
-		try {
-			fCurrentLocation = configuration.getAttribute(IExternalToolConstants.ATTR_LOCATION, (String) null);
-		}
-		catch (CoreException e) {
-			// do nothing
-		}
+		fCurrentLocation = IExternalToolConstants.LAUNCH_ATTRIBUTE_LOCATION.probe(configuration);
 		updateCheckButtons(configuration);
 	}
 
 	@Override
 	public void performApply(ILaunchConfigurationWorkingCopy configuration) {
 		super.performApply(configuration);
-		try {
-			// has the location changed
-			String newLocation = configuration.getAttribute(IExternalToolConstants.ATTR_LOCATION, (String) null);
-			if (newLocation != null) {
-				if (!newLocation.equals(fCurrentLocation)) {
-					updateTargetsTab();
-					fCurrentLocation = newLocation;
-					updateProjectName(configuration);
-				}
-			} else if (fCurrentLocation != null) {
-				updateTargetsTab();
-				fCurrentLocation = newLocation;
-				updateProjectName(configuration);
-			}
-		}
-		catch (CoreException e) {
-			// do nothing
+		// has the location changed
+		Optional<String> newLocation = IExternalToolConstants.LAUNCH_ATTRIBUTE_LOCATION.probe(configuration);
+		if (!newLocation.equals(fCurrentLocation)) {
+			updateTargetsTab();
+			fCurrentLocation = newLocation;
+			updateProjectName(configuration);
 		}
-
 		setMappedResources(configuration);
 		setAttribute(IAntUIConstants.SET_INPUTHANDLER, configuration, fSetInputHandlerButton.getSelection(), true);
 	}
@@ -110,26 +95,12 @@ private void updateProjectName(ILaunchConfigurationWorkingCopy configuration) {
 	}
 
 	private IFile getIFile(ILaunchConfigurationWorkingCopy configuration) {
-		IFile file = null;
 		if (fNewFile != null) {
-			file = fNewFile;
+			IFile file = fNewFile;
 			fNewFile = null;
-		} else {
-			IStringVariableManager manager = VariablesPlugin.getDefault().getStringVariableManager();
-			try {
-				String location = configuration.getAttribute(IExternalToolConstants.ATTR_LOCATION, (String) null);
-				if (location != null) {
-					String expandedLocation = manager.performStringSubstitution(location);
-					if (expandedLocation != null) {
-						file = AntUtil.getFileForLocation(expandedLocation, null);
-					}
-				}
-			}
-			catch (CoreException e) {
-				// do nothing
-			}
+			return file;
 		}
-		return file;
+		return IExternalToolConstants.LAUNCH_ATTRIBUTE_LOCATION.probe(configuration).map(exp -> AntUtil.getFileForLocation(exp, null)).orElse(null);
 	}
 
 	@Override