X-Git-Url: https://gerrit.simantics.org/r/gitweb?a=blobdiff_plain;f=bundles%2Forg.simantics.views.text%2Fsrc%2Forg%2Fsimantics%2Fviews%2Ftext%2Finternal%2FTextViewerUndoHandler.java;fp=bundles%2Forg.simantics.views.text%2Fsrc%2Forg%2Fsimantics%2Fviews%2Ftext%2Finternal%2FTextViewerUndoHandler.java;h=f1c8adeabf1c20e9ba602725a012fcdd6137636e;hb=5b3a1f2d3bffe5a79e344b55087fb161541a4301;hp=0000000000000000000000000000000000000000;hpb=894991ee53490cb8e28dd48b0da686203411324a;p=simantics%2Fplatform.git

diff --git a/bundles/org.simantics.views.text/src/org/simantics/views/text/internal/TextViewerUndoHandler.java b/bundles/org.simantics.views.text/src/org/simantics/views/text/internal/TextViewerUndoHandler.java
new file mode 100644
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+++ b/bundles/org.simantics.views.text/src/org/simantics/views/text/internal/TextViewerUndoHandler.java
@@ -0,0 +1,169 @@
+/*******************************************************************************
+ * Copyright (c) 2017 Association for Decentralized Information Management
+ * in Industry THTH ry.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *     Semantum Oy - (#7066) initial API and implementation
+ *******************************************************************************/
+package org.simantics.views.text.internal;
+
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.util.concurrent.Callable;
+
+import org.eclipse.core.commands.AbstractHandler;
+import org.eclipse.core.commands.ExecutionEvent;
+import org.eclipse.core.commands.ExecutionException;
+import org.eclipse.core.runtime.IConfigurationElement;
+import org.eclipse.core.runtime.IExecutableExtension;
+import org.eclipse.jface.text.IUndoManager;
+import org.eclipse.jface.text.TextViewer;
+import org.eclipse.swt.SWT;
+import org.eclipse.swt.widgets.Control;
+import org.eclipse.swt.widgets.Display;
+import org.eclipse.swt.widgets.Event;
+import org.eclipse.swt.widgets.Listener;
+
+/**
+ * Handles the undo/redo command for {@link TextViewer}s through
+ * {@link IUndoManager}.
+ * 
+ * <p>
+ * The implementation looks for an IUndoManager from the current focus control
+ * using the {@link TextViewerConstants#KEY_UNDO_MANAGER} data key. Its
+ * existence determines whether this handler {@link #isHandled()} returns
+ * <code>true</code> or <code>false</code>.
+ *
+ * <p>
+ * The handler expects to receive a single string as an argument through the
+ * extension definitions ({@link IExecutableExtension}) that determines which
+ * method is invoked from IUndoManager (<code>undo</code> or <code>redo</code>).
+ * 
+ * <p>
+ * Implementation is partially copied from
+ * <code>org.eclipse.ui.internal.handlers.WidgetMethodHandler</code>.
+ * 
+ * @since 1.28.0
+ */
+public class TextViewerUndoHandler extends AbstractHandler implements IExecutableExtension {
+
+	/**
+	 * The parameters to pass to the method this handler invokes. This handler
+	 * always passes no parameters.
+	 */
+	protected static final Class<?>[] NO_PARAMETERS = new Class[0];
+
+	public TextViewerUndoHandler() {
+		display = Display.getCurrent();
+		if (display != null) {
+			focusListener = new Listener() {
+				@Override
+				public void handleEvent(Event event) {
+					updateEnablement();
+				}
+			};
+			display.addFilter(SWT.FocusIn, focusListener);
+		}
+	}
+
+	void updateEnablement() {
+		boolean rc = isHandled();
+		if (rc != isEnabled()) {
+			setBaseEnabled(rc);
+		}
+	}
+
+	/**
+	 * The name of the method to be invoked by this handler. This value should
+	 * never be <code>null</code>.
+	 */
+	protected String methodName;
+	private Listener focusListener;
+	private Display display;
+
+	@Override
+	public Object execute(final ExecutionEvent event) throws ExecutionException {
+		Callable<?> runnable = getMethodToExecute();
+		if (runnable != null) {
+			try {
+				runnable.call();
+			} catch (ExecutionException e) {
+				throw e;
+			} catch (Exception e) {
+				throw new ExecutionException("Unexpected failure executing method " + methodName + " through " + runnable);
+			}
+		}
+		return null;
+	}
+
+	@Override
+	public final boolean isHandled() {
+		return getMethodToExecute() != null;
+	}
+
+	/**
+	 * Looks up the method on the focus control.
+	 *
+	 * @return The method on the focus control; <code>null</code> if none.
+	 */
+	protected Callable<Boolean> getMethodToExecute() {
+		Display display = Display.getCurrent();
+		if (display == null)
+			return null;
+
+		Control focusControl = display.getFocusControl();
+		if (focusControl == null)
+			return null;
+
+		IUndoManager undoManager = (IUndoManager) focusControl.getData(TextViewerConstants.KEY_UNDO_MANAGER);
+		if (undoManager == null)
+			return null;
+
+		try {
+			Method method = undoManager.getClass().getMethod(methodName, NO_PARAMETERS);
+			if (method != null)
+				return runner(undoManager, method);
+		} catch (NoSuchMethodException e) {
+			// 	Fall through...
+		}
+
+		return null;
+	}
+
+	protected Callable<Boolean> runner(IUndoManager undoManager, Method method) {
+		return () -> {
+			try {
+				method.invoke(undoManager);
+				return true;
+			} catch (IllegalAccessException e) {
+				// The method is protected, so do nothing.
+				return false;
+			} catch (InvocationTargetException e) {
+				throw new ExecutionException(
+						"An exception occurred while executing " //$NON-NLS-1$
+								+ method.getName(), e
+								.getTargetException());
+
+			}
+		};
+	}
+
+	@Override
+	public void setInitializationData(IConfigurationElement config, String propertyName, Object data) {
+		methodName = data.toString();
+	}
+
+	@Override
+	public void dispose() {
+		if (display != null && !display.isDisposed()) {
+			display.removeFilter(SWT.FocusIn, focusListener);
+		}
+		display = null;
+		focusListener = null;
+	}
+
+}
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