bundles/org.eclipse.ui.workbench/Eclipse UI/org/eclipse/ui/internal/commands/ws/SelectAllHandler.java

/*******************************************************************************
 * Copyright (c) 2004 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Common Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 ******************************************************************************/
package org.eclipse.ui.internal.commands.ws;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Map;

import org.eclipse.core.runtime.IConfigurationElement;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Display;
import org.eclipse.ui.commands.ExecutionException;

/**
 * This handler is an adaptation of the widget method handler allowing select
 * all to work even in some cases where the "selectAll" method does not exist.
 * This handler attempts to use "getTextLimit" and "setSelection" to do select
 * all. If this doesn't work, then it finally fails.
 * 
 * @since 3.0
 */
public class SelectAllHandler extends WidgetMethodHandler {

    /**
     * The parameters for a single point select all.
     */
    private static final Class[] METHOD_PARAMETERS = { Point.class };

    /**
     * @see org.eclipse.ui.commands.IHandler#execute(Map)
     */
    public Object execute(Map parameterValuesByName) throws ExecutionException {
        final Method methodToExecute = getMethodToExecute();
        if (methodToExecute != null) {
            try {
                final Control focusControl = Display.getCurrent()
                        .getFocusControl();
                final int numParams = methodToExecute.getParameterTypes().length;

                if (numParams == 0) {
                    // This is a no-argument selectAll method.
                    methodToExecute.invoke(focusControl, null);

                } else if (numParams == 1) {
                    // This is a single-point selection method.
                    final Method textLimitAccessor = focusControl.getClass()
                            .getMethod("getTextLimit", NO_PARAMETERS); //$NON-NLS-1$
                    final Integer textLimit = (Integer) textLimitAccessor
                            .invoke(focusControl, null);
                    final Object[] parameters = { new Point(0, textLimit
                            .intValue()) };
                    methodToExecute.invoke(focusControl, parameters);

                } else {
                    /*
                     * This means that getMethodToExecute() has been changed,
                     * while this method hasn't.
                     */
                    throw new ExecutionException(
                            "Too many parameters on select all", new Exception()); //$NON-NLS-1$

                }

            } catch (IllegalAccessException e) {
                // The method is protected, so do nothing.

            } catch (InvocationTargetException e) {
                throw new ExecutionException(
                        "An exception occurred while executing " //$NON-NLS-1$
                                + getMethodToExecute(), e.getTargetException());

            } catch (NoSuchMethodException e) {
                // I can't get the text limit. Do nothing.

            }
        }

        return null;
    }

    /**
     * Looks up the select all method on the given focus control.
     * 
     * @return The method on the focus control; <code>null</code> if none.
     */
    protected Method getMethodToExecute() {
        Method method = super.getMethodToExecute();

        // Let's see if we have a control that supports point-based selection.
        if (method == null) {
            final Control focusControl = Display.getCurrent().getFocusControl();
            try {
                method = focusControl.getClass().getMethod("setSelection", //$NON-NLS-1$
                        METHOD_PARAMETERS);
            } catch (NoSuchMethodException e) {
                // Do nothing.
            }
        }

        return method;
    }

    /**
     * @see org.eclipse.core.runtime.IExecutableExtension#setInitializationData(org.eclipse.core.runtime.IConfigurationElement,
     *      java.lang.String, java.lang.Object)
     */
    public void setInitializationData(IConfigurationElement config,
            String propertyName, Object data) {
        // The name is always "selectAll".
        methodName = "selectAll"; //$NON-NLS-1$
    }
}