plugins/org.eclipse.wst.validation/vf2/org/eclipse/wst/validation/internal/ValidatorExtensionReader.java - webtools-common/webtools.common - Git at Google

 /*******************************************************************************
  * Copyright (c) 2007, 2010 IBM Corporation and others.
  * 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:
  *     IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.wst.validation.internal;

 import java.util.Collection;
 import java.util.HashMap;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;

 import org.eclipse.core.resources.IProject;
 import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.IConfigurationElement;
 import org.eclipse.core.runtime.IContributor;
 import org.eclipse.core.runtime.IExtension;
 import org.eclipse.core.runtime.IExtensionPoint;
 import org.eclipse.core.runtime.IExtensionRegistry;
 import org.eclipse.core.runtime.IStatus;
 import org.eclipse.core.runtime.Platform;
 import org.eclipse.core.runtime.Status;
 import org.eclipse.osgi.util.NLS;
 import org.eclipse.wst.validation.MessageSeveritySetting;
 import org.eclipse.wst.validation.Validator;
 import org.eclipse.wst.validation.Validator.V2;
 import org.eclipse.wst.validation.internal.model.FilterGroup;
 import org.eclipse.wst.validation.internal.model.FilterRule;
 import org.eclipse.wst.validation.internal.plugin.ValidationPlugin;

 /**
  * Process the validator (version 2) extension point.
  *
  * @author karasiuk
  *
  */
 public class ValidatorExtensionReader {

 	private static ValidatorExtensionReader _me = new ValidatorExtensionReader();

 	public  static ValidatorExtensionReader getDefault(){
 		return _me;
 	}

 	private ValidatorExtensionReader(){}

 	/**
 	 * Process the v2 extensions, returning all the v2 validators.
 	 */
 	Collection<Validator> process() {
 		Map<String,Validator> map = new HashMap<String, Validator>(100);
 		IExtensionPoint extensionPoint = getExtensionPoint();
 		if (extensionPoint == null)return map.values();

 		for (IExtension ext : extensionPoint.getExtensions()){
 			for (IConfigurationElement validator : ext.getConfigurationElements()){
 				String id = ext.getUniqueIdentifier();
 				if (Tracing.isEnabled(id)){
 					Validator v = processValidator(validator, id, ext.getLabel(), null);
 					if (v != null)map.put(v.getId(),v);
 				}
 			}
 		}

 		extensionPoint = getExtensionPointExclude();
 		if (extensionPoint != null){
 			for (IExtension ext : extensionPoint.getExtensions()){
 				for (IConfigurationElement validator : ext.getConfigurationElements()){
 					String id = validator.getAttribute(ExtensionConstants.Exclude.id);
 					Validator v = map.get(id);
 					V2 v2 = null;
 					if (v != null)v2 = v.asV2Validator();

 					if (v2 == null){
 						String msg = NLS.bind("Plug-in configuration error, extension {0} references validator id {1} but this id does not exist.",  //$NON-NLS-1$
 							extensionPoint.getUniqueIdentifier(), id);
 						CoreException ex = new CoreException(new Status(IStatus.ERROR, ValidationPlugin.PLUGIN_ID, msg));
 						ValidationPlugin.getPlugin().handleException(ex);
 					}
 					else {
 						for (IConfigurationElement exclude : validator.getChildren()){
 							FilterGroup fg = null;
 							try {
 								fg = createFilterGroup(exclude);
 							}
 							catch (Exception e){
 								ValidationPlugin.getPlugin().handleException(e);
 								IContributor contrib = validator.getContributor();
 								String message = NLS.bind(ValMessages.ErrConfig, contrib.getName());
 								ValidationPlugin.getPlugin().logMessage(IStatus.ERROR, message);
 							}
 							if (fg != null && fg.isExclude()){
 								mergeExcludeGroup(v2, fg);
 							}
 						}
 					}
 				}
 			}

 		}

 		for (String removedValidator : getRemovedValidators()){
 			if (removedValidator != null) {
 				map.remove(removedValidator);
 			}
 		}

 		return map.values();

 	}

 	/**
 	 * Merge the rules from the filter group into the current exclude group, creating a current exclude
 	 * group if need be.
 	 * @param v2
 	 * @param fg
 	 */
 	private void mergeExcludeGroup(V2 v2, FilterGroup fg){
 		FilterGroup existing = null;
 		for (FilterGroup group : v2.getGroups()){
 			if (group.isExclude()){
 				existing = group;
 				break;
 			}
 		}
 		if (existing == null)v2.add(fg);
 		else {
 			List<FilterRule> rules = new LinkedList<FilterRule>();
 			for (FilterRule rule : existing.getRules())rules.add(rule);

 			for (FilterRule rule : fg.getRules())rules.add(rule);

 			FilterRule[] filterRules = new FilterRule[rules.size()];
 			rules.toArray(filterRules);
 			FilterGroup merged = FilterGroup.create(existing.isExclude(), filterRules);

 			v2.replaceFilterGroup(existing, merged);
 		}
 	}

 	/**
 	 * Process the validator element in a validator extension.
 	 *
 	 * @param validator
 	 *            The validator element.
 	 *
 	 * @param deep
 	 *            If true load all the configuration elements for each
 	 *            validator, if false do a shallow load, where only the
 	 *            validator class, id and name's are loaded.
 	 *
 	 * @param project
 	 *            The project that you are defined in. This can be null which
 	 *            means that you are a global validator.
 	 *
 	 * @return a configured validator or null if there was an error.
 	 */
 	private Validator processValidator(IConfigurationElement validator, String id, String label, IProject project) {
 		Validator.V2 v = null;
 		try {
 			v = Validator.create(validator, project).asV2Validator();
 			v.setLevel(Validator.Level.Extension);
 			v.setId(id);
 			v.setName(label);
 			v.setBuildValidation(getAttribute(validator, ExtensionConstants.build, true));
 			v.setManualValidation(getAttribute(validator, ExtensionConstants.manual, true));
 			v.setMarkerId(validator.getAttribute(ExtensionConstants.markerId));
 			v.setVersion(getAttribute(validator, ExtensionConstants.version, 1));
 			v.setSourceId(validator.getAttribute(ExtensionConstants.sourceId));
 			IConfigurationElement[] children = validator.getChildren();
 			for (IConfigurationElement child : children)processIncludeAndExcludeElement(v, child);
 		}
 		catch (Exception e){
 			ValidationPlugin.getPlugin().handleException(e);
 			IContributor contrib = validator.getContributor();
 			String message = NLS.bind(ValMessages.ErrConfig, contrib.getName());
 			ValidationPlugin.getPlugin().logMessage(IStatus.ERROR, message);
 		}
 		return v;
 	}

 	/**
 	 * Answer all the messages that this validator has defined.
 	 * @param v
 	 * @return an empty list if the validator did not define any messages.
 	 */
 	public List<MessageSeveritySetting> addMessages(Validator v){
 		List<MessageSeveritySetting> list = new LinkedList<MessageSeveritySetting>();
 		IExtensionPoint extensionPoint = getExtensionPoint();
 		if (extensionPoint == null)return list;
 		IExtension ext = extensionPoint.getExtension(v.getId());
 		if (ext == null)return list;

 		for (IConfigurationElement elem : ext.getConfigurationElements()){
 			for (IConfigurationElement ce : elem.getChildren(ExtensionConstants.MessageCategory.name)){
 				list.add(processMessage(ce));
 			}
 		}

 		return list;
 	}

 	/**
 	 * Answer the extension point for the v2 validators.
 	 *
 	 * @return null if there is a problem or no extensions.
 	 */
 	private IExtensionPoint getExtensionPoint() {
 		IExtensionRegistry registry = Platform.getExtensionRegistry();
 		return registry.getExtensionPoint(ValidationPlugin.PLUGIN_ID, ExtensionConstants.validator);
 	}

 	/**
 	 * Answer the extension point for adding exclusion filters. This is where another validator can
 	 * further restrict an existing validator.
 	 *
 	 * @return null if there is a problem or no extensions.
 	 */
 	private IExtensionPoint getExtensionPointExclude() {
 		IExtensionRegistry registry = Platform.getExtensionRegistry();
 		return registry.getExtensionPoint(ValidationPlugin.PLUGIN_ID, ExtensionConstants.excludeExtension);
 	}

 	/**
 	 * Answer the extension point for removing a validator.
 	 *
 	 * @return list of validator ID or null if no validator will be removed
 	 */
 	private List<String> getRemovedValidators(){
 		IExtensionRegistry registry = Platform.getExtensionRegistry();
 		IExtensionPoint extensionPoint = registry.getExtensionPoint(ValidationPlugin.PLUGIN_ID, ExtensionConstants.removedValidatorExtension);
 		List<String> val = new LinkedList<String>();
 		for (IExtension ext : extensionPoint.getExtensions()){
 			for (IConfigurationElement validator : ext.getConfigurationElements()){
 				val.add(validator.getAttribute(ExtensionConstants.RemovedValidator.validatorIDAttr));
 			}
 		}
 		return val;
 	}
 	/**
 	 * Process a message element for the validator, by creating a MessageCategory for it.
 	 *
 	 * @param ce a MessageCategory element.
 	 */
 	private MessageSeveritySetting processMessage(IConfigurationElement ce) {
 		String s = ce.getAttribute(ExtensionConstants.MessageCategory.severity);
 		MessageSeveritySetting.Severity sev = null;
 		if (ExtensionConstants.MessageCategory.sevError.equals(s))sev = MessageSeveritySetting.Severity.Error;
 		else if (ExtensionConstants.MessageCategory.sevWarning.equals(s))sev = MessageSeveritySetting.Severity.Warning;
 		else if (ExtensionConstants.MessageCategory.sevIgnore.equals(s))sev = MessageSeveritySetting.Severity.Ignore;

 		return new MessageSeveritySetting(ce.getAttribute(ExtensionConstants.MessageCategory.id),
 			ce.getAttribute(ExtensionConstants.MessageCategory.label), sev);
 	}

 	/**
 	 * Process the include and exclude elements.
 	 *
 	 *  @param v The validator that we are building up.
 	 *  @param group The children of the validator tag. This may included include and exclude elements.
 	 *  Other elements are ignored.
 	 */
 	private void processIncludeAndExcludeElement(Validator.V2 v, IConfigurationElement group) {
 		FilterGroup fg = createFilterGroup(group);
 		if (fg != null)v.add(fg);
 	}

 	/**
 	 * Process an include or exclude element, returning a filter group for it.
 	 *
 	 * @param group
 	 *            An include, exclude or some other element. Only include and
 	 *            exclude elements are processed, other types are ignored.
 	 *
 	 * @return a filter group that corresponds to the include or exclude
 	 *         element, or null if the element was not an include or exclude
 	 *         element.
 	 */
 	private FilterGroup createFilterGroup(IConfigurationElement group){
 		String name = group.getName();
 		if (!FilterGroup.isKnownName(name))return null;


 		IConfigurationElement[] rules = group.getChildren(ExtensionConstants.rules);
 		// there should only be one
 		List<FilterRule> list = new LinkedList<FilterRule>();
 		for (int i=0; i<rules.length; i++){
 			IConfigurationElement[] r = rules[i].getChildren();
 			for(int j=0; j<r.length; j++){
 				list.add(processRule(r[j]));
 			}
 		}
 		FilterRule[] filterRules = new FilterRule[list.size()];
 		list.toArray(filterRules);
 		return FilterGroup.create(name, filterRules);
 	}

 	/**
 	 * Process a rule in one of the rule groups.
 	 *
 	 * @param rule a rule in the group, like fileext.
 	 */
 	private FilterRule processRule(IConfigurationElement rule) {
 		FilterRule fr = FilterRule.create(rule);
 		if (fr == null){
 			String contributor = ""; //$NON-NLS-1$
 			String name = ""; //$NON-NLS-1$
 			try {
 				contributor = rule.getDeclaringExtension().getContributor().getName();
 				name = rule.getName();
 			}
 			catch (Exception e){
 				// eat it
 			}
 			throw new IllegalStateException(NLS.bind(ValMessages.ErrFilterRule, contributor, name));
 		}
 		return fr;
 	}

 	/**
 	 * Determine if any of the validators need to be migrated, and if so answer a new
 	 * Validator array.
 	 *
 	 * @param validators the existing validators (from the preferences).
 	 *
 	 * @return null if no validators needed to be migrated.
 	 */
 	Validator[] migrate(Validator[] validators, IProject project) {
 		int count = 0;
 		Map<String, Validator> map = new HashMap<String, Validator>(validators.length);
 		for (Validator v : validators)map.put(v.getId(), v);

 		IExtensionPoint extensionPoint = getExtensionPoint();
 		if (extensionPoint == null)return null;

 		for (IExtension ext : extensionPoint.getExtensions()){
 			for (IConfigurationElement validator : ext.getConfigurationElements()){
 				Validator v = processValidator(validator, ext.getUniqueIdentifier(), ext.getLabel(), project);
 				if (v == null)continue;
 				Validator old = map.get(v.getId());
 				if (old == null || old.getVersion() < v.getVersion()){
 					//TODO we may be replacing user preferences, at some point we may want to do a real migration.
 					map.put(v.getId(), v);
 					count++;
 				}
 			}
 		}

 		if (count > 0){
 			Validator[] vals = new Validator[map.size()];
 			map.values().toArray(vals);
 			return vals;
 		}
 		return null;
 	}

 	private boolean getAttribute(IConfigurationElement element, String name, boolean dft){
 		String v = element.getAttribute(name);
 		if (v == null)return dft;
 		if ("true".equalsIgnoreCase(v))return true; //$NON-NLS-1$
 		if ("false".equalsIgnoreCase(v))return false; //$NON-NLS-1$
 		return dft;
 	}

 	private int getAttribute(IConfigurationElement element, String name, int dft){
 		String v = element.getAttribute(name);
 		if (v == null)return dft;
 		try {
 			return Integer.parseInt(v);
 		}
 		catch (Exception e){
 			// eat it.
 		}
 		return dft;
 	}

 //	/**
 //	 * This method is only used for debugging.
 //	 * @param elem
 //	 */
 //	private static void dump(IConfigurationElement elem){
 //		String name = elem.getName();
 //		String[] attribs = elem.getAttributeNames();
 //		String[] vals = new String[attribs.length];
 //		for (int i=0; i<vals.length; i++)vals[i] = elem.getAttribute(attribs[i]);
 //		String v = elem.getValue();
 //		IConfigurationElement[] children = elem.getChildren();
 //		for (int i=0; i<children.length; i++)dump(children[i]);
 //	}
 }
	/*******************************************************************************
	* Copyright (c) 2007, 2010 IBM Corporation and others.
	* 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:
	* IBM Corporation - initial API and implementation
	*******************************************************************************/
	package org.eclipse.wst.validation.internal;

	import java.util.Collection;
	import java.util.HashMap;
	import java.util.LinkedList;
	import java.util.List;
	import java.util.Map;

	import org.eclipse.core.resources.IProject;
	import org.eclipse.core.runtime.CoreException;
	import org.eclipse.core.runtime.IConfigurationElement;
	import org.eclipse.core.runtime.IContributor;
	import org.eclipse.core.runtime.IExtension;
	import org.eclipse.core.runtime.IExtensionPoint;
	import org.eclipse.core.runtime.IExtensionRegistry;
	import org.eclipse.core.runtime.IStatus;
	import org.eclipse.core.runtime.Platform;
	import org.eclipse.core.runtime.Status;
	import org.eclipse.osgi.util.NLS;
	import org.eclipse.wst.validation.MessageSeveritySetting;
	import org.eclipse.wst.validation.Validator;
	import org.eclipse.wst.validation.Validator.V2;
	import org.eclipse.wst.validation.internal.model.FilterGroup;
	import org.eclipse.wst.validation.internal.model.FilterRule;
	import org.eclipse.wst.validation.internal.plugin.ValidationPlugin;

	/**
	* Process the validator (version 2) extension point.
	*
	* @author karasiuk
	*
	*/
	public class ValidatorExtensionReader {

	private static ValidatorExtensionReader _me = new ValidatorExtensionReader();

	public static ValidatorExtensionReader getDefault(){
	return _me;
	}

	private ValidatorExtensionReader(){}

	/**
	* Process the v2 extensions, returning all the v2 validators.
	*/
	Collection<Validator> process() {
	Map<String,Validator> map = new HashMap<String, Validator>(100);
	IExtensionPoint extensionPoint = getExtensionPoint();
	if (extensionPoint == null)return map.values();

	for (IExtension ext : extensionPoint.getExtensions()){
	for (IConfigurationElement validator : ext.getConfigurationElements()){
	String id = ext.getUniqueIdentifier();
	if (Tracing.isEnabled(id)){
	Validator v = processValidator(validator, id, ext.getLabel(), null);
	if (v != null)map.put(v.getId(),v);
	}
	}
	}

	extensionPoint = getExtensionPointExclude();
	if (extensionPoint != null){
	for (IExtension ext : extensionPoint.getExtensions()){
	for (IConfigurationElement validator : ext.getConfigurationElements()){
	String id = validator.getAttribute(ExtensionConstants.Exclude.id);
	Validator v = map.get(id);
	V2 v2 = null;
	if (v != null)v2 = v.asV2Validator();

	if (v2 == null){
	String msg = NLS.bind("Plug-in configuration error, extension {0} references validator id {1} but this id does not exist.", //$NON-NLS-1$
	extensionPoint.getUniqueIdentifier(), id);
	CoreException ex = new CoreException(new Status(IStatus.ERROR, ValidationPlugin.PLUGIN_ID, msg));
	ValidationPlugin.getPlugin().handleException(ex);
	}
	else {
	for (IConfigurationElement exclude : validator.getChildren()){
	FilterGroup fg = null;
	try {
	fg = createFilterGroup(exclude);
	}
	catch (Exception e){
	ValidationPlugin.getPlugin().handleException(e);
	IContributor contrib = validator.getContributor();
	String message = NLS.bind(ValMessages.ErrConfig, contrib.getName());
	ValidationPlugin.getPlugin().logMessage(IStatus.ERROR, message);
	}
	if (fg != null && fg.isExclude()){
	mergeExcludeGroup(v2, fg);
	}
	}
	}
	}
	}

	}

	for (String removedValidator : getRemovedValidators()){
	if (removedValidator != null) {
	map.remove(removedValidator);
	}
	}

	return map.values();

	}

	/**
	* Merge the rules from the filter group into the current exclude group, creating a current exclude
	* group if need be.
	* @param v2
	* @param fg
	*/
	private void mergeExcludeGroup(V2 v2, FilterGroup fg){
	FilterGroup existing = null;
	for (FilterGroup group : v2.getGroups()){
	if (group.isExclude()){
	existing = group;
	break;
	}
	}
	if (existing == null)v2.add(fg);
	else {
	List<FilterRule> rules = new LinkedList<FilterRule>();
	for (FilterRule rule : existing.getRules())rules.add(rule);

	for (FilterRule rule : fg.getRules())rules.add(rule);

	FilterRule[] filterRules = new FilterRule[rules.size()];
	rules.toArray(filterRules);
	FilterGroup merged = FilterGroup.create(existing.isExclude(), filterRules);

	v2.replaceFilterGroup(existing, merged);
	}
	}

	/**
	* Process the validator element in a validator extension.
	*
	* @param validator
	* The validator element.
	*
	* @param deep
	* If true load all the configuration elements for each
	* validator, if false do a shallow load, where only the
	* validator class, id and name's are loaded.
	*
	* @param project
	* The project that you are defined in. This can be null which
	* means that you are a global validator.
	*
	* @return a configured validator or null if there was an error.
	*/
	private Validator processValidator(IConfigurationElement validator, String id, String label, IProject project) {
	Validator.V2 v = null;
	try {
	v = Validator.create(validator, project).asV2Validator();
	v.setLevel(Validator.Level.Extension);
	v.setId(id);
	v.setName(label);
	v.setBuildValidation(getAttribute(validator, ExtensionConstants.build, true));
	v.setManualValidation(getAttribute(validator, ExtensionConstants.manual, true));
	v.setMarkerId(validator.getAttribute(ExtensionConstants.markerId));
	v.setVersion(getAttribute(validator, ExtensionConstants.version, 1));
	v.setSourceId(validator.getAttribute(ExtensionConstants.sourceId));
	IConfigurationElement[] children = validator.getChildren();
	for (IConfigurationElement child : children)processIncludeAndExcludeElement(v, child);
	}
	catch (Exception e){
	ValidationPlugin.getPlugin().handleException(e);
	IContributor contrib = validator.getContributor();
	String message = NLS.bind(ValMessages.ErrConfig, contrib.getName());
	ValidationPlugin.getPlugin().logMessage(IStatus.ERROR, message);
	}
	return v;
	}

	/**
	* Answer all the messages that this validator has defined.
	* @param v
	* @return an empty list if the validator did not define any messages.
	*/
	public List<MessageSeveritySetting> addMessages(Validator v){
	List<MessageSeveritySetting> list = new LinkedList<MessageSeveritySetting>();
	IExtensionPoint extensionPoint = getExtensionPoint();
	if (extensionPoint == null)return list;
	IExtension ext = extensionPoint.getExtension(v.getId());
	if (ext == null)return list;

	for (IConfigurationElement elem : ext.getConfigurationElements()){
	for (IConfigurationElement ce : elem.getChildren(ExtensionConstants.MessageCategory.name)){
	list.add(processMessage(ce));
	}
	}

	return list;
	}

	/**
	* Answer the extension point for the v2 validators.
	*
	* @return null if there is a problem or no extensions.
	*/
	private IExtensionPoint getExtensionPoint() {
	IExtensionRegistry registry = Platform.getExtensionRegistry();
	return registry.getExtensionPoint(ValidationPlugin.PLUGIN_ID, ExtensionConstants.validator);
	}

	/**
	* Answer the extension point for adding exclusion filters. This is where another validator can
	* further restrict an existing validator.
	*
	* @return null if there is a problem or no extensions.
	*/
	private IExtensionPoint getExtensionPointExclude() {
	IExtensionRegistry registry = Platform.getExtensionRegistry();
	return registry.getExtensionPoint(ValidationPlugin.PLUGIN_ID, ExtensionConstants.excludeExtension);
	}

	/**
	* Answer the extension point for removing a validator.
	*
	* @return list of validator ID or null if no validator will be removed
	*/
	private List<String> getRemovedValidators(){
	IExtensionRegistry registry = Platform.getExtensionRegistry();
	IExtensionPoint extensionPoint = registry.getExtensionPoint(ValidationPlugin.PLUGIN_ID, ExtensionConstants.removedValidatorExtension);
	List<String> val = new LinkedList<String>();
	for (IExtension ext : extensionPoint.getExtensions()){
	for (IConfigurationElement validator : ext.getConfigurationElements()){
	val.add(validator.getAttribute(ExtensionConstants.RemovedValidator.validatorIDAttr));
	}
	}
	return val;
	}
	/**
	* Process a message element for the validator, by creating a MessageCategory for it.
	*
	* @param ce a MessageCategory element.
	*/
	private MessageSeveritySetting processMessage(IConfigurationElement ce) {
	String s = ce.getAttribute(ExtensionConstants.MessageCategory.severity);
	MessageSeveritySetting.Severity sev = null;
	if (ExtensionConstants.MessageCategory.sevError.equals(s))sev = MessageSeveritySetting.Severity.Error;
	else if (ExtensionConstants.MessageCategory.sevWarning.equals(s))sev = MessageSeveritySetting.Severity.Warning;
	else if (ExtensionConstants.MessageCategory.sevIgnore.equals(s))sev = MessageSeveritySetting.Severity.Ignore;

	return new MessageSeveritySetting(ce.getAttribute(ExtensionConstants.MessageCategory.id),
	ce.getAttribute(ExtensionConstants.MessageCategory.label), sev);
	}

	/**
	* Process the include and exclude elements.
	*
	* @param v The validator that we are building up.
	* @param group The children of the validator tag. This may included include and exclude elements.
	* Other elements are ignored.
	*/
	private void processIncludeAndExcludeElement(Validator.V2 v, IConfigurationElement group) {
	FilterGroup fg = createFilterGroup(group);
	if (fg != null)v.add(fg);
	}

	/**
	* Process an include or exclude element, returning a filter group for it.
	*
	* @param group
	* An include, exclude or some other element. Only include and
	* exclude elements are processed, other types are ignored.
	*
	* @return a filter group that corresponds to the include or exclude
	* element, or null if the element was not an include or exclude
	* element.
	*/
	private FilterGroup createFilterGroup(IConfigurationElement group){
	String name = group.getName();
	if (!FilterGroup.isKnownName(name))return null;


	IConfigurationElement[] rules = group.getChildren(ExtensionConstants.rules);
	// there should only be one
	List<FilterRule> list = new LinkedList<FilterRule>();
	for (int i=0; i<rules.length; i++){
	IConfigurationElement[] r = rules[i].getChildren();
	for(int j=0; j<r.length; j++){
	list.add(processRule(r[j]));
	}
	}
	FilterRule[] filterRules = new FilterRule[list.size()];
	list.toArray(filterRules);
	return FilterGroup.create(name, filterRules);
	}

	/**
	* Process a rule in one of the rule groups.
	*
	* @param rule a rule in the group, like fileext.
	*/
	private FilterRule processRule(IConfigurationElement rule) {
	FilterRule fr = FilterRule.create(rule);
	if (fr == null){
	String contributor = ""; //$NON-NLS-1$
	String name = ""; //$NON-NLS-1$
	try {
	contributor = rule.getDeclaringExtension().getContributor().getName();
	name = rule.getName();
	}
	catch (Exception e){
	// eat it
	}
	throw new IllegalStateException(NLS.bind(ValMessages.ErrFilterRule, contributor, name));
	}
	return fr;
	}

	/**
	* Determine if any of the validators need to be migrated, and if so answer a new
	* Validator array.
	*
	* @param validators the existing validators (from the preferences).
	*
	* @return null if no validators needed to be migrated.
	*/
	Validator[] migrate(Validator[] validators, IProject project) {
	int count = 0;
	Map<String, Validator> map = new HashMap<String, Validator>(validators.length);
	for (Validator v : validators)map.put(v.getId(), v);

	IExtensionPoint extensionPoint = getExtensionPoint();
	if (extensionPoint == null)return null;

	for (IExtension ext : extensionPoint.getExtensions()){
	for (IConfigurationElement validator : ext.getConfigurationElements()){
	Validator v = processValidator(validator, ext.getUniqueIdentifier(), ext.getLabel(), project);
	if (v == null)continue;
	Validator old = map.get(v.getId());
	if (old == null \|\| old.getVersion() < v.getVersion()){
	//TODO we may be replacing user preferences, at some point we may want to do a real migration.
	map.put(v.getId(), v);
	count++;
	}
	}
	}

	if (count > 0){
	Validator[] vals = new Validator[map.size()];
	map.values().toArray(vals);
	return vals;
	}
	return null;
	}

	private boolean getAttribute(IConfigurationElement element, String name, boolean dft){
	String v = element.getAttribute(name);
	if (v == null)return dft;
	if ("true".equalsIgnoreCase(v))return true; //$NON-NLS-1$
	if ("false".equalsIgnoreCase(v))return false; //$NON-NLS-1$
	return dft;
	}

	private int getAttribute(IConfigurationElement element, String name, int dft){
	String v = element.getAttribute(name);
	if (v == null)return dft;
	try {
	return Integer.parseInt(v);
	}
	catch (Exception e){
	// eat it.
	}
	return dft;
	}

	// /**
	// * This method is only used for debugging.
	// * @param elem
	// */
	// private static void dump(IConfigurationElement elem){
	// String name = elem.getName();
	// String[] attribs = elem.getAttributeNames();
	// String[] vals = new String[attribs.length];
	// for (int i=0; i<vals.length; i++)vals[i] = elem.getAttribute(attribs[i]);
	// String v = elem.getValue();
	// IConfigurationElement[] children = elem.getChildren();
	// for (int i=0; i<children.length; i++)dump(children[i]);
	// }
	}