core/org.eclipse.cdt.ui/src/org/eclipse/cdt/ui/newui/AbstractCPropertyTab.java

/*******************************************************************************
 * Copyright (c) 2007, 2016 Intel Corporation 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:
 *     Intel Corporation - initial API and implementation
 *     Markus Schorn (Wind River Systems)
 *     James Blackburn (Broadcom Corp.)
 *     Serge Beauchamp (Freescale Semiconductor) - Bug 406545
 *******************************************************************************/
package org.eclipse.cdt.ui.newui;

import java.lang.reflect.Method;

import org.eclipse.cdt.core.CCorePlugin;
import org.eclipse.cdt.core.cdtvariables.ICdtVariable;
import org.eclipse.cdt.core.cdtvariables.ICdtVariableManager;
import org.eclipse.cdt.core.settings.model.ICConfigurationDescription;
import org.eclipse.cdt.core.settings.model.ICResourceDescription;
import org.eclipse.cdt.internal.core.resources.ResourceLookup;
import org.eclipse.cdt.internal.ui.dialogs.StatusInfo;
import org.eclipse.cdt.internal.ui.newui.Messages;
import org.eclipse.core.resources.IContainer;
import org.eclipse.core.resources.IFile;
import org.eclipse.core.resources.IProject;
import org.eclipse.core.resources.IResource;
import org.eclipse.core.resources.ResourcesPlugin;
import org.eclipse.core.runtime.IPath;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Path;
import org.eclipse.jface.window.Window;
import org.eclipse.swt.SWT;
import org.eclipse.swt.custom.CLabel;
import org.eclipse.swt.events.SelectionAdapter;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.graphics.FontMetrics;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.DirectoryDialog;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.FileDialog;
import org.eclipse.swt.widgets.Group;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Text;
import org.eclipse.ui.PlatformUI;
import org.eclipse.ui.dialogs.ElementTreeSelectionDialog;
import org.eclipse.ui.dialogs.ISelectionStatusValidator;
import org.eclipse.ui.model.WorkbenchContentProvider;
import org.eclipse.ui.model.WorkbenchLabelProvider;
import org.eclipse.ui.part.PageBook;
import org.eclipse.ui.views.navigator.ResourceComparator;

/**
 * It is a parent for all standard property tabs
 * in new CDT model.
 *
 * Although it's enough for new tabs to implement
 * ICPropertyTab interface only, it would be better
 * to extend them from this class.
 *
 * In this case, we'll able to use:
 * - a lot of utility methods via "provider" link.
 *   In particular, it allows to get current project,
 *   configuration etc. See ICPropertyProvider interface.
 * - a standard way to create buttons (ins/edit/del etc)
 *   and to handle their events (see buttonPressed(int))
 * - several utility methods to create widgets in the
 *   uniform manner (setupLabel(), setupText() etc).
 * - means to handle control messages which are the main
 *   communication way for new CDT model pages and tabs.
 */
public abstract class AbstractCPropertyTab implements ICPropertyTab {

	public static final Method GRAY_METHOD = getGrayEnabled();
	public static final int BUTTON_WIDTH = 120; // used as hint for all push buttons

	// commonly used button names
	public static final String EMPTY_STR = ""; //$NON-NLS-1$
	public static final String ADD_STR = Messages.FileListControl_add;
	public static final String DEL_STR = Messages.FileListControl_delete;
	public static final String EDIT_STR = Messages.FileListControl_edit;
	public static final String MOVEUP_STR = Messages.FileListControl_moveup;
	public static final String MOVEDOWN_STR = Messages.FileListControl_movedown;
	/** @since 5.4 */
	public static final String PROJECTBUTTON_NAME = "Project...";
	public static final String WORKSPACEBUTTON_NAME = Messages.FileListControl_button_workspace;
	public static final String FILESYSTEMBUTTON_NAME = Messages.FileListControl_button_fs;
	public static final String VARIABLESBUTTON_NAME = Messages.AbstractCPropertyTab_1;
	public static final String FILESYSTEM_DIR_DIALOG_MSG = Messages.BrowseEntryDialog_fs_dir_dlg_msg;
	public static final String FILESYSTEM_FILE_DIALOG_TITLE = EMPTY_STR;
	public static final String WORKSPACE_DIR_DIALOG_TITLE = Messages.BrowseEntryDialog_wsp_dir_dlg_title;
	public static final String WORKSPACE_FILE_DIALOG_TITLE = Messages.BrowseEntryDialog_wsp_file_dlg_title;
	public static final String WORKSPACE_DIR_DIALOG_MSG = Messages.BrowseEntryDialog_wsp_dir_dlg_msg;
	public static final String WORKSPACE_FILE_DIALOG_MSG = Messages.BrowseEntryDialog_wsp_file_dlg_msg;
	public static final String WORKSPACE_FILE_DIALOG_ERR = Messages.BrowseEntryDialog_wsp_file_dlg_err;
	public static final String WORKSPACE_DIR_DIALOG_ERR = Messages.BrowseEntryDialog_wsp_dir_dlg_err;
	public static final String BACKGROUND_TEXT_DEFAULT = Messages.AbstractCPropertyTab_2;
	public static final Color BACKGROUND_FOR_USER_VAR = new Color(Display.getDefault(), 255, 255, 200); // light yellow

	private static final String PREFIX = "org.eclipse.cdt.ui."; //$NON-NLS-1$

	public static final int TRI_UNKNOWN = 2;
	public static final int TRI_YES = 1;
	public static final int TRI_NO = 0;

	protected static final String ENUM = "enum"; //$NON-NLS-1$
	protected static final String SSET = "set"; //$NON-NLS-1$

	private PageBook pageBook; // to select between background and usercomp.
	private CLabel background;
	private Composite userdata;

	protected Composite usercomp; // space where user can create widgets
	protected Composite buttoncomp; // space for buttons on the right
	private Button[] buttons; // buttons in buttoncomp
	public ICPropertyProvider page;
	protected Image icon = null;
	private String helpId = EMPTY_STR;

	protected boolean visible;

	@Override
	public void createControls(Composite _parent, ICPropertyProvider _provider) {
		page = _provider;
		createControls(_parent);
	}

	/**
	 * Creates basic widgets for property tab.
	 * Descendants should, normally, override
	 * this method but call super.createControls().
	 *
	 * @param parent
	 */
	protected void createControls(Composite parent) {
		parent.setLayout(new FillLayout());
		pageBook = new PageBook(parent, SWT.NULL);

		background = new CLabel(pageBook, SWT.CENTER | SWT.SHADOW_NONE);
		background.setText(EMPTY_STR);

		GridData gd;
		userdata = new Composite(pageBook, SWT.NONE);
		userdata.setLayout(new GridLayout(2, false));

		usercomp = new Composite(userdata, SWT.NONE);
		usercomp.setLayoutData(gd = new GridData(GridData.FILL_BOTH));
		gd.widthHint = 150;

		buttoncomp = new Composite(userdata, SWT.NONE);
		buttoncomp.setLayoutData(gd = new GridData(GridData.END));
		// width hint must be set to one, otherwise subclasses that do not have buttons
		// don't look pretty, bug 242408
		gd.widthHint = 1;

		pageBook.showPage(userdata);

		PlatformUI.getWorkbench().getHelpSystem().setHelp(parent, helpId);
	}

	/**
	 * The common way to create buttons cluster
	 * on the right of tab workspace.
	 * @param names : array of button names
	 * null instead of name means "skip place"
	 */
	protected void initButtons(String[] names) {
		initButtons(buttoncomp, names, 80);
	}

	protected void initButtons(String[] names, int width) {
		initButtons(buttoncomp, names, width);
	}

	/**
	 * Ability to create standard button on any composite.
	 * @param c
	 * @param names
	 */
	protected void initButtons(Composite c, String[] names) {
		initButtons(c, names, 80);
	}

	protected void initButtons(Composite c, String[] names, int width) {
		if (names == null || names.length == 0)
			return;
		c.setLayoutData(new GridData(GridData.FILL_VERTICAL));
		c.setLayout(new GridLayout(1, false));
		buttons = new Button[names.length];
		for (int i = 0; i < names.length; i++) {
			buttons[i] = new Button(c, SWT.PUSH);
			GridData gdb = new GridData(GridData.VERTICAL_ALIGN_CENTER);
			gdb.grabExcessHorizontalSpace = false;
			gdb.horizontalAlignment = SWT.FILL;
			gdb.minimumWidth = width;

			if (names[i] != null)
				buttons[i].setText(names[i]);
			else { // no button, but placeholder !
				buttons[i].setVisible(false);
				buttons[i].setEnabled(false);
				gdb.heightHint = 10;
			}

			buttons[i].setLayoutData(gdb);
			buttons[i].addSelectionListener(new SelectionAdapter() {
				@Override
				public void widgetSelected(SelectionEvent event) {
					buttonPressed(event);
				}
			});
		}
	}

	/**
	 * Called when user changes
	 * @param cfg - selected configuration
	 */
	private void configChanged(ICResourceDescription cfg) {
		if (visible)
			updateData(cfg);
	}

	/**
	 * Disposes the SWT resources allocated by this dialog page.
	 */
	public void dispose() {
	}

	/**
	 * Sets the visibility of this property tab.
	 *
	 * @param _visible <code>true</code> to make this tab visible,
	 *  and <code>false</code> to hide it
	 */
	public void setVisible(boolean _visible) {
		visible = _visible;
		if (visible)
			updateData(page.getResDesc());
	}

	/**
	 * Descendant tabs should implement this method so
	 * that it copies it's data from one description
	 * to another. Only data affected by given tab
	 * should be copied.
	 *
	 * @param src
	 * @param dst
	 */
	protected abstract void performApply(ICResourceDescription src, ICResourceDescription dst);

	protected abstract void performDefaults();

	protected abstract void updateData(ICResourceDescription cfg);

	protected abstract void updateButtons();

	protected void performCancel() {
	}

	protected void performOK() {
	}

	/**
	 * @param e - event to be handled
	 */
	private void buttonPressed(SelectionEvent e) {
		for (int i = 0; i < buttons.length; i++) {
			if (buttons[i].equals(e.widget)) {
				buttonPressed(i);
				return;
			}
		}
	}

	/**
	 * Method should be rewritten to handle button presses
	 * @param i : number of button pressed
	 *
	 * Does nothing by default.
	 * May (but not must) be overridden.
	 */
	protected void buttonPressed(int i) {
	}

	/**
	 * Checks state of existing button.
	 *
	 * @param i - button index
	 * @return - true if button exists and enabled
	 */
	protected boolean buttonIsEnabled(int i) {
		if (buttons == null || buttons.length <= i)
			return false;
		return buttons[i].isEnabled();
	}

	/**
	 * Changes state of existing button.
	 * Does nothing if index is invalid
	 *
	 * @param i - button index
	 * @param state - required state
	 */
	protected void buttonSetEnabled(int i, boolean state) {
		if (buttons == null || buttons.length <= i)
			return;
		buttons[i].setEnabled(state);
	}

	/**
	 * Changes text of existing button
	 * Does nothing if index is invalid
	 *
	 * @param i - button index
	 * @param text - text to display
	 */
	protected void buttonSetText(int i, String text) {
		if (buttons == null || buttons.length <= i)
			return;
		buttons[i].setText(text);
		Composite c = buttons[i].getParent();
		if (c != null) {
			c.pack();
			c = c.getParent();
			if (c != null)
				c.layout(true);
		}
	}

	/**********************************************
	 * Utility methods for unified widget creation
	 **********************************************/
	protected Label setupLabel(Composite c, String name, int span, int mode) {
		Label l = new Label(c, SWT.NONE);
		l.setText(name);
		setupControl(l, span, mode);
		return l;
	}

	protected Button setupButton(Composite c, String name, int span, int mode) {
		Button b = new Button(c, SWT.PUSH);
		b.setText(name);
		setupControl(b, span, mode);
		GridData g = (GridData) b.getLayoutData();
		g.minimumWidth = BUTTON_WIDTH;
		g.horizontalAlignment = SWT.RIGHT;
		b.setLayoutData(g);
		return b;
	}

	protected Text setupText(Composite c, int span, int mode) {
		Text t = new Text(c, SWT.SINGLE | SWT.BORDER);
		setupControl(t, span, mode);
		return t;
	}

	protected Group setupGroup(Composite c, String name, int cols, int mode) {
		Group g = new Group(c, SWT.NONE);
		g.setText(name);
		g.setLayout(new GridLayout(cols, false));
		setupControl(g, 1, mode);
		return g;
	}

	/**
	 * @since 7.2
	 */
	protected Composite setupComposite(Composite c, int cols, int mode) {
		Composite c1 = new Composite(c, SWT.NONE);
		c1.setLayout(new GridLayout(cols, false));
		setupControl(c1, 1, mode);
		return c1;
	}

	protected Button setupCheck(Composite c, String name, int span, int mode) {
		Button b = new Button(c, SWT.CHECK);
		b.setText(name);
		setupControl(b, span, mode);
		b.addSelectionListener(new SelectionAdapter() {
			@Override
			public void widgetSelected(SelectionEvent event) {
				((Button) event.widget).setGrayed(false);
				checkPressed(event);
			}
		});
		return b;
	}

	/**
	 * @since 7.2
	 */
	protected Button setupRadio(Composite c, String name, int span, int mode) {
		Button b = new Button(c, SWT.RADIO);
		b.setText(name);
		setupControl(b, span, mode);
		b.addSelectionListener(new SelectionAdapter() {
			@Override
			public void widgetSelected(SelectionEvent event) {
				((Button) event.widget).setGrayed(false);
				checkPressed(event);
			}
		});
		return b;
	}

	/**
	 * Selection handler for checkbox created
	 * by methods "setupCheck()" or "setupTri()"
	 * Descendants should override this method
	 * if they use "setupCheck".
	 * Usually the method body will look like:
	 * {
	 * 		Control b = (Control)e.widget;
	 *   	if (b.equals(myFirstCheckbox) { ... }
	 *   	else if (b.equals(mySecondCheckbox) { ... }
	 *   ... }
	 */
	protected void checkPressed(SelectionEvent e) {
	}

	protected void setupControl(Control c, int span, int mode) {
		// although we use GridLayout usually,
		// exceptions can occur: do nothing.
		if (c != null) {
			if (span != 0) {
				GridData gd = new GridData(mode);
				gd.horizontalSpan = span;
				c.setLayoutData(gd);
			}
			Composite p = c.getParent();
			c.setFont(p.getFont());
		}
	}

	/*
	 * A set of methods providing selection dialogs for files or dirs.
	 */

	public static String getFileSystemDirDialog(Shell shell, String text) {
		DirectoryDialog dialog = new DirectoryDialog(shell, SWT.OPEN | SWT.APPLICATION_MODAL);
		if (text != null && text.trim().length() != 0)
			dialog.setFilterPath(text);
		dialog.setMessage(FILESYSTEM_DIR_DIALOG_MSG);
		return dialog.open();
	}

	public static String getFileSystemFileDialog(Shell shell, String text) {
		FileDialog dialog = new FileDialog(shell);
		if (text != null && text.trim().length() != 0)
			dialog.setFilterPath(text);
		dialog.setText(FILESYSTEM_FILE_DIALOG_TITLE);
		return dialog.open();
	}

	/**
	 * @since 5.3
	 */
	public static String getFileSystemFileDialog(Shell shell, String text, String[] filter) {
		FileDialog dialog = new FileDialog(shell);
		if (text != null && text.trim().length() != 0)
			dialog.setFilterPath(text);
		dialog.setFilterExtensions(filter);
		dialog.setText(FILESYSTEM_FILE_DIALOG_TITLE);
		return dialog.open();
	}

	public static String getVariableDialog(Shell shell, ICConfigurationDescription cfgd) {

		ICdtVariableManager vm = CCorePlugin.getDefault().getCdtVariableManager();
		BuildVarListDialog dialog = new BuildVarListDialog(shell, vm.getVariables(cfgd));
		dialog.setTitle(Messages.AbstractCPropertyTab_0);
		if (dialog.open() == Window.OK) {
			Object[] selected = dialog.getResult();
			if (selected.length > 0) {
				String s = ((ICdtVariable) selected[0]).getName();
				return "${" + s.trim() + "}"; //$NON-NLS-1$//$NON-NLS-2$
			}
		}
		return null;
	}

	public static String getWorkspaceDirDialog(Shell shell, String text) {
		return getWorkspaceDialog(shell, text, true, null);
	}

	public static String getWorkspaceFileDialog(Shell shell, String text) {
		return getWorkspaceDialog(shell, text, false, null);
	}

	/**
	 * @since 5.4
	 */
	public static String getProjectDirDialog(Shell shell, String text, IProject prj) {
		return getWorkspaceDialog(shell, text, true, prj);
	}

	/**
	 * @since 5.4
	 */
	public static String getProjectFileDialog(Shell shell, String text, IProject prj) {
		return getWorkspaceDialog(shell, text, false, prj);
	}

	private static String getWorkspaceDialog(Shell shell, String text, boolean dir, IProject prj) {
		String currentPathText;
		IPath path;
		currentPathText = text;
		/* Remove double quotes */
		currentPathText = currentPathText.replaceAll("\"", ""); //$NON-NLS-1$ //$NON-NLS-2$
		path = new Path(currentPathText);

		ElementTreeSelectionDialog dialog = new ElementTreeSelectionDialog(shell, new WorkbenchLabelProvider(),
				new WorkbenchContentProvider());

		if (prj == null)
			dialog.setInput(ResourcesPlugin.getWorkspace().getRoot());
		else
			dialog.setInput(prj);
		dialog.setComparator(new ResourceComparator(ResourceComparator.NAME));

		if (dir) {
			IResource container = null;
			if (path.isAbsolute()) {
				IContainer cs[] = ResourcesPlugin.getWorkspace().getRoot().findContainersForLocation(path);
				if (cs != null && cs.length > 0)
					container = cs[0];
			}
			dialog.setInitialSelection(container);
			dialog.setValidator(new ISelectionStatusValidator() {
				@Override
				public IStatus validate(Object[] selection) {
					if (selection != null)
						if (selection.length > 0)
							if ((selection[0] instanceof IFile))
								return new StatusInfo(IStatus.ERROR, WORKSPACE_DIR_DIALOG_ERR);
					return new StatusInfo();
				}
			});
			dialog.setTitle(WORKSPACE_DIR_DIALOG_TITLE);
			dialog.setMessage(WORKSPACE_DIR_DIALOG_MSG);
		} else {
			IResource resource = null;
			if (path.isAbsolute()) {
				resource = ResourceLookup.selectFileForLocation(path, prj);
			}
			dialog.setInitialSelection(resource);
			dialog.setValidator(new ISelectionStatusValidator() {
				@Override
				public IStatus validate(Object[] selection) {
					if (selection != null)
						if (selection.length > 0)
							if (!(selection[0] instanceof IFile))
								return new StatusInfo(IStatus.ERROR, WORKSPACE_FILE_DIALOG_ERR);
					return new StatusInfo();
				}
			});
			dialog.setTitle(WORKSPACE_FILE_DIALOG_TITLE);
			dialog.setMessage(WORKSPACE_FILE_DIALOG_MSG);
		}
		if (dialog.open() == Window.OK) {
			IResource resource = (IResource) dialog.getFirstResult();
			if (resource != null) {
				StringBuilder buf = new StringBuilder();
				return buf.append("${").append("workspace_loc:").append(resource.getFullPath()).append("}").toString(); //$NON-NLS-3$ //$NON-NLS-2$ //$NON-NLS-1$
			}
		}
		return null;
	}

	// shortcut to frequently-used method
	public ICResourceDescription getResDesc() {
		return page.getResDesc();
	}

	/**
	 * Common event handler: called by parent for each tab
	 */
	@Override
	public void handleTabEvent(int kind, Object data) {
		switch (kind) {
		case ICPropertyTab.OK:
			if (canBeVisible())
				performOK();
			break;
		case ICPropertyTab.APPLY:
			if (canBeVisible())
				performApply(getResDesc(), (ICResourceDescription) data);
			break;
		case ICPropertyTab.CANCEL:
			if (canBeVisible())
				performCancel();
			break;
		case ICPropertyTab.DEFAULTS:
			if (canBeVisible() /*&& getResDesc() != null*/) {
				updateData(getResDesc());
				performDefaults();
			}
			break;
		case ICPropertyTab.UPDATE:
			if (canSupportMultiCfg() || !page.isMultiCfg()) {
				if (canBeVisible()) {
					setButtonVisible(true);
					configChanged((ICResourceDescription) data);
				}
			} else
				setAllVisible(false, null);
			break;
		case ICPropertyTab.DISPOSE:
			dispose();
			break;
		case ICPropertyTab.VISIBLE:
			if (canSupportMultiCfg() || !page.isMultiCfg()) {
				if (canBeVisible()) {
					setVisible(data != null);
					setButtonVisible(data != null);
				} else
					setVisible(false);
			} else
				setAllVisible(false, null);
			break;
		case ICPropertyTab.SET_ICON:
			icon = (Image) data;
			break;
		default:
			break;
		}
	}

	// By default, returns true (no visibility restriction)
	// But several pages should rewrite this functionality.
	@Override
	public boolean canBeVisible() {
		return true;
	}

	/**
	 * Method to be implemented by inherited classes to indicate whether or not the tab supports displaying
	 * and editing settings for multiple configuration selection.
	 *
	 * Default implementation returns true.
	 *
	 * @return true if the tab supports multiple configurations, false otherwise
	 * @since 5.7
	 */
	public boolean canSupportMultiCfg() {
		return true;
	}

	/**
	 * Returns true if this tab is the one currently selected in the UI.
	 *
	 * @return true if this tab is the one selected in the UI, false otherwise.
	 * @since 5.7
	 */
	public boolean isTabSelected() {
		if (page instanceof ICPropertyProvider2)
			return ((ICPropertyProvider2) page).getSelectedTab() == this;
		return false;
	}

	/**
	 * Added to avoid usage PixelConverter class.
	 * @param control
	 * @return FontMetrics
	 */
	public static FontMetrics getFontMetrics(Control control) {
		GC gc = new GC(control);
		gc.setFont(control.getFont());
		FontMetrics fFontMetrics = gc.getFontMetrics();
		gc.dispose();
		return fFontMetrics;
	}

	/**
	 * Sets checkbox to appropriate state:
	 * 	  unchecked or checked
	 * @param b - checkbox to set
	 * @param state
	 */
	public static void setTriSelection(Button b, boolean state) {
		setTriSelection(b, state ? TRI_YES : TRI_NO);
	}

	/**
	 * Sets checkbox to appropriate state:
	 * 	  unchecked, checked or unknown (grayed)
	 * @param b - checkbox to set
	 * @param state
	 */
	public static void setTriSelection(Button b, int state) {
		switch (state) {
		case TRI_NO:
			b.setGrayed(false);
			b.setSelection(false);
			break;
		case TRI_YES:
			b.setGrayed(false);
			b.setSelection(true);
			break;
		case TRI_UNKNOWN:
			b.setGrayed(true);
			b.setSelection(true);
			break;
		}
	}

	/**
	 * This method will be simplified after M5 release,
	 * when Button.setGrayed() method will be accessible.
	 * In this case, reflection will not be required.
	 *
	 * @param b
	 * @param value
	 * @deprecated call {@link Button#setGrayed(boolean)} instead
	 */
	@Deprecated
	public static void setGrayed(Button b, boolean value) {
		b.setGrayed(value);
	}

	/**
	 * This method will be removed after M5 release,
	 * when Button.setGrayed() will be officially accessible.
	 *
	 * @return reference to Button.setGrayed() method
	 */
	private static Method getGrayEnabled() {
		try {
			Class<?> cl = Class.forName("org.eclipse.swt.widgets.Button"); //$NON-NLS-1$
			return cl.getMethod("setGrayed", new Class[] { boolean.class }); //$NON-NLS-1$
		} catch (ClassNotFoundException e) {
			return null;
		} catch (NoSuchMethodException e) {
			return null;
		}
	}

	/**
	 * Utility method to show/hide working panes
	 * When panes are hidden, message becomes visible
	 *
	 * @param visible - true or false
	 * @param msg - text to be shown instead of panes
	 */
	protected void setAllVisible(boolean visible, String msg) {
		if (!visible) {
			setBackgroundText(msg);
			pageBook.showPage(background);
		} else {
			pageBook.showPage(userdata);
		}
		setButtonVisible(visible);
	}

	/**
	 * Utility method to show/hide the 'Apply' and 'Restore Defaults' buttons
	 * @param visible - true or false
	 * @since 5.7
	 */
	protected void setButtonVisible(boolean visible) {
		if (page != null && isTabSelected()) {
			Button b = page.getAButton();
			if (b != null)
				b.setVisible(visible);
			b = page.getDButton();
			if (b != null)
				b.setVisible(visible);
		}
	}

	/**
	 * Allows changing message on background pane,
	 * which becomes visible after usercomp hidden
	 *
	 * @param s - text to display or null for default
	 */
	protected void setBackgroundText(String s) {
		background.setText(s == null ? BACKGROUND_TEXT_DEFAULT : s);
	}

	/**
	 * Used to display double-clickable buttons for multiple configurations
	 * string list mode (see Multiple Configurations Edit Preference page).
	 *
	 * @deprecated as of CDT 8.0. This functionality is presented as links
	 *    to the preference page, see {@link AbstractLangsListTab#updateStringListModeControl()}
	 */
	@Deprecated
	protected void updateLbs(Label lb1, Label lb2) {
		if (page.isMultiCfg()) {
			if (lb1 != null) {
				lb1.setText(CDTPrefUtil.getDMode());
				lb1.setVisible(true);
			}
			if (lb2 != null) {
				lb2.setText(CDTPrefUtil.getWMode());
				lb2.setVisible(true);
			}
		} else {
			if (lb1 != null)
				lb1.setVisible(false);
			if (lb2 != null)
				lb2.setVisible(false);
		}
	}

	/**
	 * The writing mode for multiple configurations edits (configuration drop-down list
	 * in project properties). This mode applies to lists of entries.
	 * See preference Multiple Configurations Edit, String List Write Mode.
	 *
	 * @return
	 *    {@code true} if each list should be replaced as a whole with the
	 *       list user is currently working with in UI<br/>
	 *    {@code false} if changes apply only to individual entries and unaffected
	 *       entries are preserved.
	 */
	protected boolean isWModifyMode() {
		int wmode = CDTPrefUtil.getMultiCfgStringListWriteMode();
		return (wmode == CDTPrefUtil.WMODE_MODIFY);
	}

	public String getHelpContextId() {
		return helpId;
	}

	public void setHelpContextId(String id) {
		helpId = PREFIX + id;
	}

	/**
	 * Allows subclasses to inform the container about changes relevant to the indexer.
	 * The tab will be asked before the apply is performed. As a consequence of returning
	 * <code>true</code> the user will be asked whether she wants to rebuild the index.
	 * @since 5.2
	 */
	protected boolean isIndexerAffected() {
		return false;
	}
}