bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/ide/dialogs/FileStatesPage.java - platform/eclipse.platform.ui - Git at Google

 /*******************************************************************************
  * Copyright (c) 2000, 2017 IBM 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:
  *     IBM Corporation - initial API and implementation
  *     Patrik Suzzi <psuzzi@gmail.com> - Bug 489250
  *******************************************************************************/
 package org.eclipse.ui.internal.ide.dialogs;

 import java.text.MessageFormat;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Iterator;

 import org.eclipse.core.resources.IWorkspaceDescription;
 import org.eclipse.core.resources.ResourcesPlugin;
 import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.Preferences;
 import org.eclipse.jface.dialogs.ErrorDialog;
 import org.eclipse.jface.preference.PreferencePage;
 import org.eclipse.osgi.util.NLS;
 import org.eclipse.swt.SWT;
 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.Event;
 import org.eclipse.swt.widgets.Label;
 import org.eclipse.swt.widgets.Listener;
 import org.eclipse.swt.widgets.Text;
 import org.eclipse.ui.IWorkbenchPreferencePage;
 import org.eclipse.ui.PlatformUI;
 import org.eclipse.ui.internal.ide.IDEWorkbenchMessages;
 import org.eclipse.ui.internal.ide.IIDEHelpContextIds;

 /**
  * The FileStatesPage is the page used to set the file states sizes for the workbench.
  */
 public class FileStatesPage extends PreferencePage implements
 		IWorkbenchPreferencePage, Listener {

 	private static final int FAILED_VALUE = -1;

 	//Set the length of the day as we have to convert back and forth
 	private static final long DAY_LENGTH = 86400000;

 	private static final long MEGABYTES = 1024 * 1024;

 	private Text longevityText;

 	private Text maxStatesText;

 	private Text maxStateSizeText;

 	private Button applyPolicyButton;

 	private Button keepDerivedStateButton;

 	private ArrayList<Control> dependentControls = new ArrayList<>();

 	//Choose a maximum to prevent OutOfMemoryErrors
 	private int FILE_STATES_MAXIMUM = 10000;

 	private long STATE_SIZE_MAXIMUM = 100;

 	private static final int INDENT = 20;

 	/**
 	 * This method takes the string for the title of a text field and the value for the
 	 * text of the field.
 	 * @return org.eclipse.swt.widgets.Text
 	 * @param labelString java.lang.String
 	 * @param textValue java.lang.String
 	 * @param parent Composite
 	 */
 	private Text addDependentLabelAndText(String labelString, String textValue,
 			Composite parent) {
 		Label label = new Label(parent, SWT.LEFT);
 		label.setText(labelString);
 		dependentControls.add(label);

 		Text text = new Text(parent, SWT.LEFT | SWT.BORDER);
 		GridData data = new GridData();
 		text.addListener(SWT.Modify, this);
 		data.horizontalAlignment = GridData.FILL;
 		data.grabExcessHorizontalSpace = true;
 		data.verticalAlignment = GridData.CENTER;
 		data.grabExcessVerticalSpace = false;
 		text.setLayoutData(data);
 		text.setText(textValue);
 		dependentControls.add(text);

 		return text;
 	}

 	private Button addCheckBox(String label, boolean selected, Composite parent) {
 		Button button = new Button(parent, SWT.CHECK | SWT.LEFT);
 		button.addListener(SWT.Selection, this);
 		GridData data = new GridData();
 		data.horizontalSpan = 2;
 		data.horizontalIndent= -INDENT;
 		button.setLayoutData(data);
 		button.setText(label);
 		button.setSelection(selected);
 		return button;
 	}

 	/**
 	 * Recomputes the page's error state by validating all
 	 * the fields.
 	 */
 	private void checkState() {
 		// Assume invalid if the controls not created yet
 		if (longevityText == null || maxStatesText == null || maxStateSizeText == null || applyPolicyButton == null
 				|| keepDerivedStateButton == null) {
 			setValid(false);
 			return;
 		}

 		boolean newState= applyPolicyButton.getSelection();
 		Iterator<Control> iter = dependentControls.iterator();
 		while (iter.hasNext())
 			iter.next().setEnabled(newState);

 		if (validateLongTextEntry(longevityText, DAY_LENGTH) == FAILED_VALUE) {
 			setValid(false);
 			return;
 		}

 		if (validateMaxFileStates() == FAILED_VALUE) {
 			setValid(false);
 			return;
 		}

 		if (validateMaxFileStateSize() == FAILED_VALUE) {
 			setValid(false);
 			return;
 		}

 		setValid(true);
 		setErrorMessage(null);
 	}

 	/*
 	 * Create the contents control for the workspace file states.
 	 * @returns Control
 	 * @param parent Composite
 	 */
 	@Override
 	protected Control createContents(Composite parent) {

 		PlatformUI.getWorkbench().getHelpSystem().setHelp(parent,
 				IIDEHelpContextIds.FILE_STATES_PREFERENCE_PAGE);

 		IWorkspaceDescription description = getWorkspaceDescription();

 		//Get the current value and make sure we get at least one day out of it.
 		long days = description.getFileStateLongevity() / DAY_LENGTH;
 		if (days < 1) {
 			days = 1;
 		}

 		long megabytes = description.getMaxFileStateSize() / MEGABYTES;
 		if (megabytes < 1) {
 			megabytes = 1;
 		}

 		// button group
 		Composite composite= new Composite(parent, SWT.NONE);
 		GridLayout layout= new GridLayout();
 		layout.numColumns= 2;
 		layout.marginLeft= INDENT;
 		layout.marginWidth= 0;
 		composite.setLayout(layout);

 		this.keepDerivedStateButton = addCheckBox(IDEWorkbenchMessages.FileHistory_keepDerivedState,
 				description.isKeepDerivedState(), composite);

 		this.applyPolicyButton = addCheckBox(IDEWorkbenchMessages.FileHistory_applyPolicy, description
 				.isApplyFileStatePolicy(), composite);

 		this.longevityText= addDependentLabelAndText(IDEWorkbenchMessages.FileHistory_longevity, String
 				.valueOf(days), composite);
 		this.maxStatesText= addDependentLabelAndText(IDEWorkbenchMessages.FileHistory_entries, String
 				.valueOf(description.getMaxFileStates()), composite);
 		this.maxStateSizeText= addDependentLabelAndText(IDEWorkbenchMessages.FileHistory_diskSpace,
 				String.valueOf(megabytes), composite);

 		checkState();

 		//Create a spacing label to breakup the note from the fields
 		Label spacer = new Label(composite, SWT.NONE);
 		GridData spacerData = new GridData();
 		spacerData.horizontalSpan = 2;
 		spacer.setLayoutData(spacerData);

 		Composite noteComposite = createNoteComposite(parent.getFont(),
 				composite, IDEWorkbenchMessages.Preference_note, IDEWorkbenchMessages.FileHistory_restartNote);
 		GridData noteData = new GridData();
 		noteData.horizontalSpan = 2;
 		noteComposite.setLayoutData(noteData);
 		dependentControls.addAll(Arrays.asList(noteComposite.getChildren()));

 		applyDialogFont(composite);

 		return composite;
 	}

 	/**
 	 * Get the Workspace Description this page is operating on.
 	 * @return org.eclipse.core.resources.IWorkspaceDescription
 	 */
 	private IWorkspaceDescription getWorkspaceDescription() {
 		return ResourcesPlugin.getWorkspace().getDescription();
 	}

 	/**
 	 * Sent when an event that the receiver has registered for occurs.
 	 *
 	 * @param event the event which occurred
 	 */
 	@Override
 	public void handleEvent(Event event) {
 		checkState();
 	}

 	/**
 	 * Initializes this preference page for the given workbench.
 	 * <p>
 	 * This method is called automatically as the preference page is being created
 	 * and initialized. Clients must not call this method.
 	 * </p>
 	 *
 	 * @param workbench the workbench
 	 */
 	@Override
 	public void init(org.eclipse.ui.IWorkbench workbench) {
 	}

 	/**
 	 * Performs special processing when this page's Defaults button has been pressed.
 	 * Reset the entries to their default values.
 	 */
 	@Override
 	protected void performDefaults() {
 		super.performDefaults();

 		Preferences prefs = ResourcesPlugin.getPlugin().getPluginPreferences();

 		long days = prefs
 				.getDefaultLong(ResourcesPlugin.PREF_FILE_STATE_LONGEVITY)
 				/ DAY_LENGTH;
 		long megabytes = prefs
 				.getDefaultLong(ResourcesPlugin.PREF_MAX_FILE_STATE_SIZE)
 				/ MEGABYTES;
 		this.longevityText.setText(String.valueOf(days));
 		this.maxStatesText.setText(prefs
 				.getDefaultString(ResourcesPlugin.PREF_MAX_FILE_STATES));
 		this.maxStateSizeText.setText(String.valueOf(megabytes));
 		this.keepDerivedStateButton.setSelection(prefs.getDefaultBoolean(ResourcesPlugin.PREF_KEEP_DERIVED_STATE));
 		this.applyPolicyButton.setSelection(prefs
 				.getDefaultBoolean(ResourcesPlugin.PREF_APPLY_FILE_STATE_POLICY));
 		checkState();
 	}

 	/**
 	 * Perform the result of the OK from the receiver.
 	 */
 	@Override
 	public boolean performOk() {

 		long longevityValue = validateLongTextEntry(longevityText, DAY_LENGTH);
 		int maxFileStates = validateMaxFileStates();
 		long maxStateSize = validateMaxFileStateSize();
 		boolean keepDerivedState = keepDerivedStateButton.getSelection();
 		boolean applyPolicy = applyPolicyButton.getSelection();
 		if (longevityValue == FAILED_VALUE || maxFileStates == FAILED_VALUE
 				|| maxStateSize == FAILED_VALUE) {
 			return false;
 		}

 		IWorkspaceDescription description = getWorkspaceDescription();
 		description.setFileStateLongevity(longevityValue * DAY_LENGTH);
 		description.setMaxFileStates(maxFileStates);
 		description.setMaxFileStateSize(maxStateSize * MEGABYTES);
 		description.setKeepDerivedState(keepDerivedState);
 		description.setApplyFileStatePolicy(applyPolicy);

 		try {
 			//As it is only a copy save it back in
 			ResourcesPlugin.getWorkspace().setDescription(description);
 		} catch (CoreException exception) {
 			ErrorDialog.openError(getShell(), IDEWorkbenchMessages.FileHistory_exceptionSaving, exception
 					.getMessage(), exception.getStatus());
 			return false;
 		}

 		return true;

 	}

 	/**
 	 * Validate a text entry for an integer field. Return the result if there are
 	 * no errors, otherwise return -1 and set the entry field error.
 	 * @return int
 	 */
 	private int validateIntegerTextEntry(Text text) {

 		int value;

 		try {
 			value = Integer.parseInt(text.getText());

 		} catch (NumberFormatException exception) {
 			setErrorMessage(MessageFormat.format(IDEWorkbenchMessages.FileHistory_invalid,
 					exception.getLocalizedMessage()));
 			return FAILED_VALUE;
 		}

 		//Be sure all values are non zero and positive
 		if (value <= 0) {
 			setErrorMessage(IDEWorkbenchMessages.FileHistory_mustBePositive);
 			return FAILED_VALUE;
 		}

 		return value;
 	}

 	/**
 	 * Validate a text entry for a long field. Return the result if there are
 	 * no errors, otherwise return -1 and set the entry field error.
 	 * @param scale the scale (factor by which the value is multiplied when it is persisted)
 	 * @return long
 	 */
 	private long validateLongTextEntry(Text text, long scale) {

 		long value;

 		try {
 			String string = text.getText();
 			value = Long.parseLong(string);
 			if (value * scale / scale != value)
 				throw new NumberFormatException(string);

 		} catch (NumberFormatException exception) {
 			setErrorMessage(MessageFormat.format(IDEWorkbenchMessages.FileHistory_invalid,
 					exception.getLocalizedMessage()));
 			return FAILED_VALUE;
 		}

 		//Be sure all values are non zero and positive
 		if (value <= 0) {
 			setErrorMessage(IDEWorkbenchMessages.FileHistory_mustBePositive);
 			return FAILED_VALUE;
 		}

 		return value;
 	}

 	/**
 	 * Validate the maximum file states.
 	 * Return the value if successful, otherwise
 	 * return FAILED_VALUE.
 	 * Set the error message if it fails.
 	 * @return int
 	 */
 	private int validateMaxFileStates() {
 		int maxFileStates = validateIntegerTextEntry(this.maxStatesText);
 		if (maxFileStates == FAILED_VALUE) {
 			return maxFileStates;
 		}

 		if (maxFileStates > FILE_STATES_MAXIMUM) {
 			setErrorMessage(NLS.bind(IDEWorkbenchMessages.FileHistory_aboveMaxEntries, String.valueOf(FILE_STATES_MAXIMUM)));
 			return FAILED_VALUE;
 		}

 		return maxFileStates;
 	}

 	/**
 	 * Validate the maximum file state size.
 	 * Return the value if successful, otherwise
 	 * return FAILED_VALUE.
 	 * Set the error message if it fails.
 	 * @return long
 	 */
 	private long validateMaxFileStateSize() {
 		long maxFileStateSize = validateLongTextEntry(this.maxStateSizeText, MEGABYTES);
 		if (maxFileStateSize == FAILED_VALUE) {
 			return maxFileStateSize;
 		}

 		if (maxFileStateSize > STATE_SIZE_MAXIMUM) {
 			setErrorMessage(NLS.bind(IDEWorkbenchMessages.FileHistory_aboveMaxFileSize, String.valueOf(STATE_SIZE_MAXIMUM)));
 			return FAILED_VALUE;
 		}

 		return maxFileStateSize;
 	}

 }
	/*******************************************************************************
	* Copyright (c) 2000, 2017 IBM 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:
	* IBM Corporation - initial API and implementation
	* Patrik Suzzi <psuzzi@gmail.com> - Bug 489250
	*******************************************************************************/
	package org.eclipse.ui.internal.ide.dialogs;

	import java.text.MessageFormat;
	import java.util.ArrayList;
	import java.util.Arrays;
	import java.util.Iterator;

	import org.eclipse.core.resources.IWorkspaceDescription;
	import org.eclipse.core.resources.ResourcesPlugin;
	import org.eclipse.core.runtime.CoreException;
	import org.eclipse.core.runtime.Preferences;
	import org.eclipse.jface.dialogs.ErrorDialog;
	import org.eclipse.jface.preference.PreferencePage;
	import org.eclipse.osgi.util.NLS;
	import org.eclipse.swt.SWT;
	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.Event;
	import org.eclipse.swt.widgets.Label;
	import org.eclipse.swt.widgets.Listener;
	import org.eclipse.swt.widgets.Text;
	import org.eclipse.ui.IWorkbenchPreferencePage;
	import org.eclipse.ui.PlatformUI;
	import org.eclipse.ui.internal.ide.IDEWorkbenchMessages;
	import org.eclipse.ui.internal.ide.IIDEHelpContextIds;

	/**
	* The FileStatesPage is the page used to set the file states sizes for the workbench.
	*/
	public class FileStatesPage extends PreferencePage implements
	IWorkbenchPreferencePage, Listener {

	private static final int FAILED_VALUE = -1;

	//Set the length of the day as we have to convert back and forth
	private static final long DAY_LENGTH = 86400000;

	private static final long MEGABYTES = 1024 * 1024;

	private Text longevityText;

	private Text maxStatesText;

	private Text maxStateSizeText;

	private Button applyPolicyButton;

	private Button keepDerivedStateButton;

	private ArrayList<Control> dependentControls = new ArrayList<>();

	//Choose a maximum to prevent OutOfMemoryErrors
	private int FILE_STATES_MAXIMUM = 10000;

	private long STATE_SIZE_MAXIMUM = 100;

	private static final int INDENT = 20;

	/**
	* This method takes the string for the title of a text field and the value for the
	* text of the field.
	* @return org.eclipse.swt.widgets.Text
	* @param labelString java.lang.String
	* @param textValue java.lang.String
	* @param parent Composite
	*/
	private Text addDependentLabelAndText(String labelString, String textValue,
	Composite parent) {
	Label label = new Label(parent, SWT.LEFT);
	label.setText(labelString);
	dependentControls.add(label);

	Text text = new Text(parent, SWT.LEFT \| SWT.BORDER);
	GridData data = new GridData();
	text.addListener(SWT.Modify, this);
	data.horizontalAlignment = GridData.FILL;
	data.grabExcessHorizontalSpace = true;
	data.verticalAlignment = GridData.CENTER;
	data.grabExcessVerticalSpace = false;
	text.setLayoutData(data);
	text.setText(textValue);
	dependentControls.add(text);

	return text;
	}

	private Button addCheckBox(String label, boolean selected, Composite parent) {
	Button button = new Button(parent, SWT.CHECK \| SWT.LEFT);
	button.addListener(SWT.Selection, this);
	GridData data = new GridData();
	data.horizontalSpan = 2;
	data.horizontalIndent= -INDENT;
	button.setLayoutData(data);
	button.setText(label);
	button.setSelection(selected);
	return button;
	}

	/**
	* Recomputes the page's error state by validating all
	* the fields.
	*/
	private void checkState() {
	// Assume invalid if the controls not created yet
	if (longevityText == null \|\| maxStatesText == null \|\| maxStateSizeText == null \|\| applyPolicyButton == null
	\|\| keepDerivedStateButton == null) {
	setValid(false);
	return;
	}

	boolean newState= applyPolicyButton.getSelection();
	Iterator<Control> iter = dependentControls.iterator();
	while (iter.hasNext())
	iter.next().setEnabled(newState);

	if (validateLongTextEntry(longevityText, DAY_LENGTH) == FAILED_VALUE) {
	setValid(false);
	return;
	}

	if (validateMaxFileStates() == FAILED_VALUE) {
	setValid(false);
	return;
	}

	if (validateMaxFileStateSize() == FAILED_VALUE) {
	setValid(false);
	return;
	}

	setValid(true);
	setErrorMessage(null);
	}

	/*
	* Create the contents control for the workspace file states.
	* @returns Control
	* @param parent Composite
	*/
	@Override
	protected Control createContents(Composite parent) {

	PlatformUI.getWorkbench().getHelpSystem().setHelp(parent,
	IIDEHelpContextIds.FILE_STATES_PREFERENCE_PAGE);

	IWorkspaceDescription description = getWorkspaceDescription();

	//Get the current value and make sure we get at least one day out of it.
	long days = description.getFileStateLongevity() / DAY_LENGTH;
	if (days < 1) {
	days = 1;
	}

	long megabytes = description.getMaxFileStateSize() / MEGABYTES;
	if (megabytes < 1) {
	megabytes = 1;
	}

	// button group
	Composite composite= new Composite(parent, SWT.NONE);
	GridLayout layout= new GridLayout();
	layout.numColumns= 2;
	layout.marginLeft= INDENT;
	layout.marginWidth= 0;
	composite.setLayout(layout);

	this.keepDerivedStateButton = addCheckBox(IDEWorkbenchMessages.FileHistory_keepDerivedState,
	description.isKeepDerivedState(), composite);

	this.applyPolicyButton = addCheckBox(IDEWorkbenchMessages.FileHistory_applyPolicy, description
	.isApplyFileStatePolicy(), composite);

	this.longevityText= addDependentLabelAndText(IDEWorkbenchMessages.FileHistory_longevity, String
	.valueOf(days), composite);
	this.maxStatesText= addDependentLabelAndText(IDEWorkbenchMessages.FileHistory_entries, String
	.valueOf(description.getMaxFileStates()), composite);
	this.maxStateSizeText= addDependentLabelAndText(IDEWorkbenchMessages.FileHistory_diskSpace,
	String.valueOf(megabytes), composite);

	checkState();

	//Create a spacing label to breakup the note from the fields
	Label spacer = new Label(composite, SWT.NONE);
	GridData spacerData = new GridData();
	spacerData.horizontalSpan = 2;
	spacer.setLayoutData(spacerData);

	Composite noteComposite = createNoteComposite(parent.getFont(),
	composite, IDEWorkbenchMessages.Preference_note, IDEWorkbenchMessages.FileHistory_restartNote);
	GridData noteData = new GridData();
	noteData.horizontalSpan = 2;
	noteComposite.setLayoutData(noteData);
	dependentControls.addAll(Arrays.asList(noteComposite.getChildren()));

	applyDialogFont(composite);

	return composite;
	}

	/**
	* Get the Workspace Description this page is operating on.
	* @return org.eclipse.core.resources.IWorkspaceDescription
	*/
	private IWorkspaceDescription getWorkspaceDescription() {
	return ResourcesPlugin.getWorkspace().getDescription();
	}

	/**
	* Sent when an event that the receiver has registered for occurs.
	*
	* @param event the event which occurred
	*/
	@Override
	public void handleEvent(Event event) {
	checkState();
	}

	/**
	* Initializes this preference page for the given workbench.
	* <p>
	* This method is called automatically as the preference page is being created
	* and initialized. Clients must not call this method.
	* </p>
	*
	* @param workbench the workbench
	*/
	@Override
	public void init(org.eclipse.ui.IWorkbench workbench) {
	}

	/**
	* Performs special processing when this page's Defaults button has been pressed.
	* Reset the entries to their default values.
	*/
	@Override
	protected void performDefaults() {
	super.performDefaults();

	Preferences prefs = ResourcesPlugin.getPlugin().getPluginPreferences();

	long days = prefs
	.getDefaultLong(ResourcesPlugin.PREF_FILE_STATE_LONGEVITY)
	/ DAY_LENGTH;
	long megabytes = prefs
	.getDefaultLong(ResourcesPlugin.PREF_MAX_FILE_STATE_SIZE)
	/ MEGABYTES;
	this.longevityText.setText(String.valueOf(days));
	this.maxStatesText.setText(prefs
	.getDefaultString(ResourcesPlugin.PREF_MAX_FILE_STATES));
	this.maxStateSizeText.setText(String.valueOf(megabytes));
	this.keepDerivedStateButton.setSelection(prefs.getDefaultBoolean(ResourcesPlugin.PREF_KEEP_DERIVED_STATE));
	this.applyPolicyButton.setSelection(prefs
	.getDefaultBoolean(ResourcesPlugin.PREF_APPLY_FILE_STATE_POLICY));
	checkState();
	}

	/**
	* Perform the result of the OK from the receiver.
	*/
	@Override
	public boolean performOk() {

	long longevityValue = validateLongTextEntry(longevityText, DAY_LENGTH);
	int maxFileStates = validateMaxFileStates();
	long maxStateSize = validateMaxFileStateSize();
	boolean keepDerivedState = keepDerivedStateButton.getSelection();
	boolean applyPolicy = applyPolicyButton.getSelection();
	if (longevityValue == FAILED_VALUE \|\| maxFileStates == FAILED_VALUE
	\|\| maxStateSize == FAILED_VALUE) {
	return false;
	}

	IWorkspaceDescription description = getWorkspaceDescription();
	description.setFileStateLongevity(longevityValue * DAY_LENGTH);
	description.setMaxFileStates(maxFileStates);
	description.setMaxFileStateSize(maxStateSize * MEGABYTES);
	description.setKeepDerivedState(keepDerivedState);
	description.setApplyFileStatePolicy(applyPolicy);

	try {
	//As it is only a copy save it back in
	ResourcesPlugin.getWorkspace().setDescription(description);
	} catch (CoreException exception) {
	ErrorDialog.openError(getShell(), IDEWorkbenchMessages.FileHistory_exceptionSaving, exception
	.getMessage(), exception.getStatus());
	return false;
	}

	return true;

	}

	/**
	* Validate a text entry for an integer field. Return the result if there are
	* no errors, otherwise return -1 and set the entry field error.
	* @return int
	*/
	private int validateIntegerTextEntry(Text text) {

	int value;

	try {
	value = Integer.parseInt(text.getText());

	} catch (NumberFormatException exception) {
	setErrorMessage(MessageFormat.format(IDEWorkbenchMessages.FileHistory_invalid,
	exception.getLocalizedMessage()));
	return FAILED_VALUE;
	}

	//Be sure all values are non zero and positive
	if (value <= 0) {
	setErrorMessage(IDEWorkbenchMessages.FileHistory_mustBePositive);
	return FAILED_VALUE;
	}

	return value;
	}

	/**
	* Validate a text entry for a long field. Return the result if there are
	* no errors, otherwise return -1 and set the entry field error.
	* @param scale the scale (factor by which the value is multiplied when it is persisted)
	* @return long
	*/
	private long validateLongTextEntry(Text text, long scale) {

	long value;

	try {
	String string = text.getText();
	value = Long.parseLong(string);
	if (value * scale / scale != value)
	throw new NumberFormatException(string);

	} catch (NumberFormatException exception) {
	setErrorMessage(MessageFormat.format(IDEWorkbenchMessages.FileHistory_invalid,
	exception.getLocalizedMessage()));
	return FAILED_VALUE;
	}

	//Be sure all values are non zero and positive
	if (value <= 0) {
	setErrorMessage(IDEWorkbenchMessages.FileHistory_mustBePositive);
	return FAILED_VALUE;
	}

	return value;
	}

	/**
	* Validate the maximum file states.
	* Return the value if successful, otherwise
	* return FAILED_VALUE.
	* Set the error message if it fails.
	* @return int
	*/
	private int validateMaxFileStates() {
	int maxFileStates = validateIntegerTextEntry(this.maxStatesText);
	if (maxFileStates == FAILED_VALUE) {
	return maxFileStates;
	}

	if (maxFileStates > FILE_STATES_MAXIMUM) {
	setErrorMessage(NLS.bind(IDEWorkbenchMessages.FileHistory_aboveMaxEntries, String.valueOf(FILE_STATES_MAXIMUM)));
	return FAILED_VALUE;
	}

	return maxFileStates;
	}

	/**
	* Validate the maximum file state size.
	* Return the value if successful, otherwise
	* return FAILED_VALUE.
	* Set the error message if it fails.
	* @return long
	*/
	private long validateMaxFileStateSize() {
	long maxFileStateSize = validateLongTextEntry(this.maxStateSizeText, MEGABYTES);
	if (maxFileStateSize == FAILED_VALUE) {
	return maxFileStateSize;
	}

	if (maxFileStateSize > STATE_SIZE_MAXIMUM) {
	setErrorMessage(NLS.bind(IDEWorkbenchMessages.FileHistory_aboveMaxFileSize, String.valueOf(STATE_SIZE_MAXIMUM)));
	return FAILED_VALUE;
	}

	return maxFileStateSize;
	}

	}