Disable Toggle Instruction Step Mode command using activity support.

TISM command is always visible if the CDT Debug UI plug-in is not loaded
yet. This happened due to platform limitation.So handle visibility using
activity support.

see #1220

Author: raghucssit

debug/org.eclipse.cdt.debug.ui/plugin.xml

@@ -2675,5 +2675,31 @@
            name="%GenericTarget.name">
      </wizard2>
   </extension>
+  
+  <!-- Activity definition that controls the visibility of  Toggle Instruction Step Mode command-->
+  <extension point="org.eclipse.ui.activities">
+   <category
+         id="org.eclipse.cdt.debug.ui.category"
+         name="CDT Debug UI"
+         description="Controls visibility of CDT Debug UI contributions">
+   </category>
+
+   <activity
+         id="org.eclipse.cdt.debug.ui.activity.toggleInstructionStepMode"
+         name="Toggle Instruction Step Mode Command"
+         description="Activity to control visibility of Toggle Instruction Step Mode command">
+   </activity>
+
+   <activityPatternBinding
+         activityId="org.eclipse.cdt.debug.ui.activity.toggleInstructionStepMode"
+         pattern="org\.eclipse\.cdt\.debug\.ui/org\.eclipse\.cdt\.debug\.internal\.ui\.actions\.ToggleInstructionStepModeCommand">
+   </activityPatternBinding>
+
+   <categoryActivityBinding
+         activityId="org.eclipse.cdt.debug.ui.activity.toggleInstructionStepMode"
+         categoryId="org.eclipse.cdt.debug.ui.category">
+   </categoryActivityBinding>
+</extension>
+  
 
 </plugin>

debug/org.eclipse.cdt.debug.ui/src/org/eclipse/cdt/debug/ui/CDebugUIPlugin.java

@@ -16,7 +16,9 @@
 package org.eclipse.cdt.debug.ui;
 
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.Map;
+import java.util.Set;
 
 import org.eclipse.cdt.debug.core.CDebugCorePlugin;
 import org.eclipse.cdt.debug.internal.ui.CDebugImageDescriptorRegistry;
@@ -61,9 +63,12 @@
 import org.eclipse.ui.ISharedImages;
 import org.eclipse.ui.IViewPart;
 import org.eclipse.ui.IViewReference;
+import org.eclipse.ui.IWorkbench;
+import org.eclipse.ui.IWorkbenchListener;
 import org.eclipse.ui.IWorkbenchPage;
 import org.eclipse.ui.IWorkbenchWindow;
 import org.eclipse.ui.PlatformUI;
+import org.eclipse.ui.activities.IWorkbenchActivitySupport;
 import org.eclipse.ui.editors.text.EditorsUI;
 import org.eclipse.ui.plugin.AbstractUIPlugin;
 import org.eclipse.ui.progress.WorkbenchJob;
@@ -94,6 +99,10 @@ public class CDebugUIPlugin extends AbstractUIPlugin {
 
 	private static IDebuggerConsoleManager fDebuggerConsoleManager;
 
+	private IWorkbenchListener workbenchListener;
+
+	private static final String TISM_ACTIVITY_ID = "org.eclipse.cdt.debug.ui.activity.toggleInstructionStepMode"; //$NON-NLS-1$
+
 	/**
 	 * At least one listener must be registered on the DebugPlugin in order
 	 * for certain actions, like RunToLine, to work. See bug 573696.
@@ -319,10 +328,29 @@ public void start(BundleContext context) throws Exception {
 			@Override
 			public IStatus runInUIThread(IProgressMonitor monitor) {
 				startupInUIThread();
+				// We need to enable Toggle Instruction Step Mode only if Debug UI plug-in is loaded.
+				setActivityEnabled(TISM_ACTIVITY_ID, true);
 				return Status.OK_STATUS;
 			}
 		};
 		wjob.schedule();
+
+		// Disable the activity when the platform shuts down.
+		IWorkbench workbench = PlatformUI.getWorkbench();
+		workbenchListener = new IWorkbenchListener() {
+
+			@Override
+			public boolean preShutdown(IWorkbench workbench, boolean forced) {
+				// Workbench is still alive here – safe to disable activity
+				setActivityEnabled(TISM_ACTIVITY_ID, false);
+				return true;
+			}
+
+			@Override
+			public void postShutdown(IWorkbench workbench) {
+			}
+		};
+		workbench.addWorkbenchListener(workbenchListener);
 	}
 
 	private void startupInUIThread() {
@@ -361,6 +389,9 @@ public void stop(BundleContext context) throws Exception {
 		if (fImageDescriptorRegistry != null) {
 			fImageDescriptorRegistry.dispose();
 		}
+
+		PlatformUI.getWorkbench().removeWorkbenchListener(workbenchListener);
+
 		super.stop(context);
 	}
 
@@ -436,4 +467,26 @@ public static <T> T getService(Class<T> service) {
 		return ref != null ? context.getService(ref) : null;
 	}
 
+	private void setActivityEnabled(String activityId, boolean enabled) {
+		IWorkbench workbench = PlatformUI.getWorkbench();
+		if (workbench == null) {
+			return;
+		}
+		IWorkbenchActivitySupport activitySupport = workbench.getActivitySupport();
+
+		if (activitySupport == null) {
+			return;
+		}
+
+		Set<String> enabledActivities = new HashSet<>(activitySupport.getActivityManager().getEnabledActivityIds());
+
+		if (enabled) {
+			enabledActivities.add(activityId);
+		} else {
+			enabledActivities.remove(activityId);
+		}
+
+		activitySupport.setEnabledActivityIds(enabledActivities);
+	}
+
 }