plugins/org.eclipse.wst.validation/validate/org/eclipse/wst/validation/internal/ValidationRegistryReader.java

/*******************************************************************************
 * Copyright (c) 2001, 2004 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.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
import java.util.StringTokenizer;
import java.util.logging.Level;

import org.eclipse.core.resources.IProject;
import org.eclipse.core.resources.IWorkspaceRoot;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IConfigurationElement;
import org.eclipse.core.runtime.IExtension;
import org.eclipse.core.runtime.IExtensionPoint;
import org.eclipse.core.runtime.IPluginRegistry;
import org.eclipse.core.runtime.Platform;
import org.eclipse.wst.validation.core.IValidator;
import org.eclipse.wst.validation.internal.operations.IRuleGroup;
import org.eclipse.wst.validation.internal.operations.IWorkbenchHelper;
import org.eclipse.wst.validation.internal.plugin.ValidationPlugin;

import com.ibm.wtp.common.logger.LogEntry;
import com.ibm.wtp.common.logger.proxy.Logger;


/**
 * ValidationRegistryReader is a singleton who reads the plugin registry for Validator extensions.
 * The read is done once (in the constructor), and the list of validators can be accessed by calling
 * "getValidatorMetaData(String)" on this class. The read is triggered by a call from
 * ValidatorManager's loadValidatorMetaData(IProject) method. ValidatorManager delegates the load
 * call to this class, and if this class is null, the singleton is new'ed up, and the registry is
 * read.
 * 
 * No Validator should need to know about this class. The only class which should call
 * ValidationRegistryReader is ValidatorManager.
 * 
 * The Validator itself is initialized in the "initializeValidator" method.
 * 
 * <extension point="org.eclipse.wst.validation.core.core.validator" id="EJBValidator" name="EJB
 * Validator"> <validator><projectNature id="com.ibm.etools.j2ee.EJBNature" include="false"/>
 * <filter objectClass="org.eclipse.core.resources.IFile" nameFilter = "ejb-jar.xml"/> <filter
 * objectClass="org.eclipse.core.resources.IFile" nameFilter = "*.java"/> <helper
 * class="org.eclipse.wst.validation.core.core.ejb.workbenchimpl.EJBHelper"/> <run
 * class="org.eclipse.wst.validation.core.core.ejb.EJBValidator" incremental="false" enabled="false"
 * pass="fast,full" async="false"/> <aggregateValidator class="my.aggregate.ValidatorClass"/>
 * <migrate><validator from="old.class.name" to="new.class.name"/> </migrate> </validator>
 * </extension>
 */
public final class ValidationRegistryReader implements RegistryConstants {
	private static ValidationRegistryReader inst = null;
	private HashMap _validators; // list of all validators registered, with their associated
	// ValidatorMetaData, indexed by project nature id
	private HashMap _indexedValidators; // list of all validators, indexed by validator class name,
	// with the validator's ValidatorMetaData as the value.
	// Needed by the WorkbenchReporter, because sometimes the
	// IValidator is not enough to remove all messages from the
	// task list.
	private Set _defaultEnabledValidators;
	// Since IProject's contents are all instances of IResource, every type filter for a validator
	// must be an instance of IResource. This applies to both the rebuildCache pass and to the
	// validation pass.
	private static final String IRESOURCE = "org.eclipse.core.resources.IResource"; //$NON-NLS-1$

	private static final String UNKNOWN_PROJECT = "UNKNOWN"; //$NON-NLS-1$ // This 'project nature id' is used as a key to get the validators which can run on a project type which hasn't been explicitly filtered in or out by any validator.
	private static final String EXCLUDED_PROJECT = "EXCLUDED"; //$NON-NLS-1$ // This 'project nature id' is used as a key to get the validators which are excluded on certain projects.

	private List _tempList = null; // list for temporary values. Retrieve and use via the

	// getTempList() method.

	/**
	 * The registry is read once - when this class is instantiated.
	 */
	private ValidationRegistryReader() {
		super();

		try {
			_validators = new HashMap();
			_indexedValidators = new HashMap();
			_defaultEnabledValidators = new HashSet();

			// Read the registry and build a map of validators. The key into
			// the map is the IValidator instance and the value is the ValidatorMetaData
			// which describes the IValidator.
			readRegistry();

			// Once all of the validators have been read, the caches of the
			// validators need to be updated.
			buildCache();
		} catch (Throwable exc) {
			Logger logger = ValidationPlugin.getPlugin().getMsgLogger();
			if (logger.isLoggingLevel(Level.SEVERE)) {
				LogEntry entry = ValidationPlugin.getLogEntry();
				entry.setSourceID("ValidationRegistryReader()"); //$NON-NLS-1$
				entry.setTargetException(exc);
				logger.write(Level.SEVERE, entry);
			}
		}
	}

	/**
	 * Traverse over the list of VMDs which have been added and create copies of it. The copies are
	 * created to increase runtime performance.
	 */
	private void buildCache() {
		Iterator iterator = _indexedValidators.values().iterator();
		while (iterator.hasNext()) {
			ValidatorMetaData vmd = (ValidatorMetaData) iterator.next();
			buildProjectNatureCache(vmd);
			buildDefaultEnabledCache(vmd);
		}

		// Now add the validators which are configured on all projects,
		// and all projects but X.
		addRemainder();

		// this temporary list isn't needed any more. All of the excluded
		// projects have been added to the project natures which they don't exlcude.
		_validators.remove(EXCLUDED_PROJECT);

		Logger logger = ValidationPlugin.getPlugin().getMsgLogger();
		if (logger.isLoggingLevel(Level.FINEST)) {
			LogEntry entry = ValidationPlugin.getLogEntry();
			entry.setSourceID("ValidationRegistryReader.buildCache()"); //$NON-NLS-1$
			entry.setText(debug());
			logger.write(Level.FINEST, entry);
		}

	}

	/**
	 * Build the cache of VMDs which is indexed by project nature ids. If the validator is
	 * registered on all project types, the vmd's project nature filters will be null.
	 */
	private void buildProjectNatureCache(ValidatorMetaData vmd) {
		// Build the cache with the identified project natures in validators'
		// extensions.
		ValidatorNameFilter[] projNatureIds = vmd.getProjectNatureFilters();
		if (projNatureIds == null) {
			// Can run on any project
			add(UNKNOWN_PROJECT, vmd);
		} else {
			boolean noneIncluded = true; // assume that the validator does not include any project
			// natures
			for (int i = 0; i < projNatureIds.length; i++) {
				ValidatorNameFilter pn = projNatureIds[i];
				if (pn.isInclude()) {
					noneIncluded = false;
					add(pn.getNameFilter(), vmd);
				}
			}

			if (noneIncluded) {
				// add it to the list of EXCLUDED projects
				// (that is, a validator which excludes project natures but doesn't
				// explicitly include any. This type of validator runs on any unrecognized (UNKNOWN)
				// projects, but the rest of the cache needs to be built before this is added
				// to the UNKNOWN list. See addExcludedRemainder().
				add(EXCLUDED_PROJECT, vmd);
			}
		}
	}

	/**
	 * Build the list of validators which are enabled by default.
	 */
	private void buildDefaultEnabledCache(ValidatorMetaData vmd) {
		if (vmd == null) {
			return;
		}

		if (vmd.isEnabledByDefault()) {
			_defaultEnabledValidators.add(vmd);
		}
	}

	/**
	 * Add vmd to the list of validators, indexed by validator class name
	 */
	private void add(ValidatorMetaData vmd) {
		if (vmd == null) {
			return;
		}

		_indexedValidators.put(vmd.getValidatorUniqueName(), vmd);
	}

	/*
	 * Some validators can run on any type of project. In order to have a static list, add the "any
	 * project" validators to each "project nature" validators' list. This avoids adding the "any
	 * project" validators to the "project nature" validators at runtime, which results in
	 * performance savings.
	 * 
	 * Some validators run on any type of project but X, where X is an excluded project nature.
	 * Those validators should also be added via this method.
	 */
	private void addRemainder() {
		// First, add all "can-run-on-any-project-type" to every registered project nature type in
		// the cache.
		addAnyRemainder();

		// Then add the "can-run-on-any-project-type-but-X" to every non-X registered project nature
		// type in the cache.
		addExcludedRemainder();
	}

	private void addExcludedRemainder() {
		Set excludedProjVmds = (Set) _validators.get(EXCLUDED_PROJECT);
		if (excludedProjVmds == null) {
			// no excluded project natures
			return;
		}

		Iterator exIterator = excludedProjVmds.iterator();
		while (exIterator.hasNext()) {
			ValidatorMetaData vmd = (ValidatorMetaData) exIterator.next();

			boolean noneIncluded = true; // assume that, by default, if someone explicitly excludes
			// a project nature then they don't include any project
			// natures
			Set keys = _validators.keySet();
			Iterator iterator = keys.iterator();
			while (iterator.hasNext()) {
				String projId = (String) iterator.next();
				if (projId.equals(UNKNOWN_PROJECT) || projId.equals(EXCLUDED_PROJECT)) {
					// Don't add list to a project nature which is excluded or applicable to all.
					continue;
				}

				ValidatorNameFilter filter = vmd.findProjectNature(projId);
				if (filter != null) {
					// Don't add list to itself (filter.isIncluded() == true) or
					// to a list from which it's excluded (filter.isIncluded() == false)
					if (filter.isInclude()) {
						noneIncluded = false;
					}
					continue;
				}

				add(projId, vmd);
			}

			if (noneIncluded) {
				// At this point, the "can-run-on-any-project" becomes
				// "not-excluded-on-these-projects". That is, if the project
				// nature id isn't in the list of _validators, then it isn't
				// included or excluded by any validators, so all validators
				// which can run on any project AND all validators which can
				// run on any but certain excluded projects can run on the
				// given IProject.
				add(UNKNOWN_PROJECT, vmd);
			}
		}
	}

	private void addAnyRemainder() {
		Set anyProjVmds = (Set) _validators.get(UNKNOWN_PROJECT);
		if (anyProjVmds == null) {
			// no validators run on all projects
			return;
		}

		Set keys = _validators.keySet();
		Iterator iterator = keys.iterator();
		while (iterator.hasNext()) {
			String projId = (String) iterator.next();
			if (projId.equals(UNKNOWN_PROJECT) || projId.equals(EXCLUDED_PROJECT)) {
				// Don't add list to itself or to a project nature which is excluded.
				continue;
			}

			add(projId, anyProjVmds);
		}
	}

	private void add(String projectNatureId, Set vmdList) {
		if ((vmdList == null) || (vmdList.size() == 0)) {
			return;
		}

		Set pnVal = createSet(projectNatureId); // whether the validator includes or excludes this
		// project nature id, make sure that an entry is
		// created for it in the table
		pnVal.addAll(vmdList);
		_validators.put(projectNatureId, pnVal);
	}

	private void add(String projectNatureId, ValidatorMetaData vmd) {
		if (vmd == null) {
			return;
		}

		Set pnVal = createSet(projectNatureId); // whether the validator includes or excludes this
		// project nature id, make sure that an entry is
		// created for it in the table
		pnVal.add(vmd);
		_validators.put(projectNatureId, pnVal);
	}

	/**
	 * When a validator's class or helper class cannot be loaded, the vmd calls this method to
	 * disable the validator. The validator will be removed from the preference page, properties
	 * page, and enabled list of any project thereafter validated.
	 */
	public void disableValidator(ValidatorMetaData vmd) {
		_indexedValidators.remove(vmd.getValidatorUniqueName());
		_defaultEnabledValidators.remove(vmd);

		// The whole "on-any-project" and "exclude-this-project-nature" would take
		// a lot of processing time... Instead, traverse the list of proj nature ids,
		// and search the Set of that proj nature id, and remove the vmd if it's in the
		// Set.
		Object[] keys = _validators.keySet().toArray();
		for (int i = 0; i < keys.length; i++) {
			Object key = keys[i];
			Set value = (Set) _validators.get(key);
			if (value == null) {
				continue;
			}

			if (value.contains(vmd)) {
				value.remove(vmd);
				_validators.put(key, value);
			}
		}
	}

	private Set createSet(String projNature) {
		Set v = (Set) _validators.get(projNature);
		if (v == null) {
			v = new HashSet();
		}
		return v;
	}

	/**
	 * Given an IConfigurationElement, if it has a project nature(s) specified, return the
	 * ValidatorNameFilters which represent those natures. Otherwise return null.
	 * 
	 * A project nature can be specified in plugin.xml to indicate what types of IProjects a
	 * validator can run on.
	 */
	private String[] getAggregateValidatorsNames(IConfigurationElement element) {
		IConfigurationElement[] filters = element.getChildren(TAG_AGGREGATE_VALIDATORS);
		if (filters.length == 0)
			return null;

		String[] names = new String[filters.length];
		for (int i = 0; i < names.length; i++) {
			// In order to speed up our String comparisons, load these
			// names into Java's constants space. This way, we'll be able to
			// use pointer comparison instead of the traditional
			// character-by-character comparison. Since these names should
			// never be set by anyone other than this class, and this class
			// sets them only once, it is safe to declare these Strings
			// constants.
			//
			// To load a String into the constants space, call intern() on the String.
			//
			String nameFilter = filters[i].getAttribute(ATT_CLASS);
			if (nameFilter != null) {
				nameFilter = nameFilter.intern();
			}
			names[i] = nameFilter;
		}
		return names;
	}

	/**
	 * Given an IConfigurationElement from plugin.xml, if it has any filter tags, construct the
	 * appropriate ValidatorFilters to represent those tags; else return null.
	 * 
	 * A filter can be specified in plugin.xml to filter out certain resources.
	 */
	private ValidatorFilter[] getFilters(IConfigurationElement element) {
		IConfigurationElement[] filters = element.getChildren(TAG_FILTER);
		if (filters.length == 0)
			return null;

		ValidatorFilter[] vf = new ValidatorFilter[filters.length];
		for (int i = 0; i < filters.length; i++) {
			vf[i] = new ValidatorFilter(IRESOURCE);

			// In order to speed up our String comparisons, load these
			// names into Java's constants space. This way, we'll be able to
			// use pointer comparison instead of the traditional
			// character-by-character comparison. Since these names should
			// never be set by anyone other than this class, and this class
			// sets them only once, it is safe to declare these Strings
			// constants.
			//
			// To load a String into the constants space, call intern() on the String.
			//
			String nameFilter = filters[i].getAttribute(ATT_NAME_FILTER);
			if (nameFilter != null) {
				nameFilter = nameFilter.intern();
			}
			String isCaseSensitive = filters[i].getAttribute(ATT_CASE_SENSITIVE);
			vf[i].setNameFilter(nameFilter, isCaseSensitive);

			String objectClass = filters[i].getAttribute(ATT_OBJECT_CLASS);
			if (objectClass != null) {
				objectClass = objectClass.intern();
			}
			vf[i].setTypeFilter(objectClass);

			String actionFilter = filters[i].getAttribute(ATT_ACTION_FILTER);
			if (actionFilter != null) {
				actionFilter = actionFilter.intern();
			}
			vf[i].setActionFilter(actionFilter);
		}
		return vf;
	}

	public boolean getDependentValidatorValue(IConfigurationElement element) {
		IConfigurationElement[] depValidatorElement = element.getChildren(DEP_VALIDATOR);
		if (depValidatorElement.length == 0)
			return false;
		String depValue = depValidatorElement[0].getAttribute(DEP_VAL_VALUE);
		boolean depBoolValue = (new Boolean(depValue)).booleanValue();
		return depBoolValue;
	}

	/**
	 * Return the name of the helper class associated with the IValidator.
	 */
	public String getMarkerIdValue(IConfigurationElement element) {
		IConfigurationElement[] markerId = element.getChildren(MARKER_ID);
		if (markerId.length == 0)
			return null;
		return markerId[0].getAttribute(MARKER_ID_VALUE);
	}

	/**
	 * Return the name of the helper class associated with the IValidator.
	 */
	private String getHelperName(IConfigurationElement element) {
		IConfigurationElement[] helpers = element.getChildren(TAG_HELPER_CLASS);
		if (helpers.length == 0)
			return null;

		return helpers[0].getAttribute(ATT_CLASS);
	}

	/* package */static IWorkbenchHelper createHelper(IConfigurationElement element, String helperClassName) {
		IWorkbenchHelper wh = null;
		try {
			wh = (IWorkbenchHelper) element.createExecutableExtension(TAG_HELPER_CLASS);
		} catch (Throwable exc) {
			Logger logger = ValidationPlugin.getPlugin().getMsgLogger();
			if (logger.isLoggingLevel(Level.SEVERE)) {
				LogEntry entry = ValidationPlugin.getLogEntry();
				entry.setSourceID("ValidationRegistryReader.createHelper(IConfigurationElement, String)"); //$NON-NLS-1$
				entry.setMessageTypeIdentifier(ResourceConstants.VBF_EXC_SYNTAX_NO_HELPER_THROWABLE);
				entry.setTargetException(exc);
				entry.setTokens(new String[]{helperClassName});
				logger.write(Level.SEVERE, entry);
			}
			return null;
		}
		return wh;
	}

	/* package */static IValidator createValidator(IConfigurationElement element, String validatorClassName) {
		IValidator validator = null;
		try {
			validator = (IValidator) element.createExecutableExtension(TAG_RUN_CLASS);
		} catch (Throwable exc) {
			Logger logger = ValidationPlugin.getPlugin().getMsgLogger();
			if (logger.isLoggingLevel(Level.SEVERE)) {
				LogEntry entry = ValidationPlugin.getLogEntry();
				entry.setSourceID("ValidationRegistryReader.createValidator(IConfigurationElement, String, String)"); //$NON-NLS-1$
				entry.setMessageTypeID(ResourceConstants.VBF_EXC_SYNTAX_NO_VAL_THROWABLE);
				entry.setTokens(new String[]{validatorClassName});
				entry.setTargetException(exc);
				logger.write(Level.SEVERE, entry);
			}
		}

		if (validator == null) {
			Logger logger = ValidationPlugin.getPlugin().getMsgLogger();
			if (logger.isLoggingLevel(Level.FINE)) {
				LogEntry entry = ValidationPlugin.getLogEntry();
				entry.setSourceID("ValidationRegistryReader.createValidator(IConfigurationElement, String)"); //$NON-NLS-1$
				entry.setMessageTypeID(ResourceConstants.VBF_EXC_SYNTAX_NO_VAL_NULL);
				entry.setTokens(new String[]{validatorClassName});
				logger.write(Level.FINE, entry);
			}
			return null;
		}

		return validator;
	}

	/**
	 * Given an IConfigurationElement from plugin.xml, return whether or not the validator is
	 * enabled by default.
	 * 
	 * If no enabled attribute is specified, the default, true (i.e., enabled) is returned.
	 */
	private boolean getEnabledByDefault(IConfigurationElement element) {
		IConfigurationElement[] runChildren = element.getChildren(TAG_RUN_CLASS);
		// Don't need to check if runChildren is null or empty, because that was checked in the
		// initializeValidator method.

		String inc = runChildren[0].getAttribute(ATT_ENABLED);
		if (inc == null) {
			return RegistryConstants.ATT_ENABLED_DEFAULT;
		}

		return Boolean.valueOf(inc.trim().toLowerCase()).booleanValue(); // this will return true
		// if, and only if, the
		// attribute value is
		// "true". For example,
		// "yes" will be considered
		// "false".
	}

	/**
	 * Given an IConfigurationElement from plugin.xml, return whether or not the validator supports
	 * incremental validation.
	 * 
	 * If no incremental attribute is specified, the default, true (i.e., incremental is supported)
	 * is returned.
	 */
	private boolean getIncremental(IConfigurationElement element) {
		IConfigurationElement[] runChildren = element.getChildren(TAG_RUN_CLASS);
		// Don't need to check if runChildren is null or empty, because that was checked in the
		// initializeValidator method.

		String inc = runChildren[0].getAttribute(ATT_INCREMENTAL);
		if (inc == null) {
			return RegistryConstants.ATT_INCREMENTAL_DEFAULT;
		}

		return Boolean.valueOf(inc.trim().toLowerCase()).booleanValue(); // this will return true
		// if, and only if, the
		// attribute value is
		// "true". For example,
		// "yes" will be considered
		// "false".
	}

	/**
	 * Given an IConfigurationElement from plugin.xml, return whether or not the validator supports
	 * full build validation.
	 * 
	 * If no incremental attribute is specified, the default, true (i.e., incremental is supported)
	 * is returned.
	 */
	private boolean getFullBuild(IConfigurationElement element) {
		IConfigurationElement[] runChildren = element.getChildren(TAG_RUN_CLASS);
		// Don't need to check if runChildren is null or empty, because that was checked in the
		// initializeValidator method.

		String fb = runChildren[0].getAttribute(ATT_FULLBUILD);
		if (fb == null) {
			return RegistryConstants.ATT_FULLBUILD_DEFAULT;
		}

		return Boolean.valueOf(fb.trim().toLowerCase()).booleanValue(); // this will return true if,
		// and only if, the
		// attribute value is
		// "true". For example,
		// "yes" will be considered
		// "false".
	}

	/**
	 * Given an IConfigurationElement from plugin.xml, return whether or not the validator supports
	 * asynchronous validation.
	 * 
	 * If no async attribute is specified, the default, true (i.e., the validator is thread-safe) is
	 * returned.
	 */
	private boolean getAsync(IConfigurationElement element) {
		IConfigurationElement[] runChildren = element.getChildren(TAG_RUN_CLASS);
		// Don't need to check if runChildren is null or empty, because that was checked in the
		// initializeValidator method.

		String async = runChildren[0].getAttribute(ATT_ASYNC);
		if (async == null) {
			return RegistryConstants.ATT_ASYNC_DEFAULT;
		}

		return Boolean.valueOf(async.trim().toLowerCase()).booleanValue(); // this will return true
		// if, and only if, the
		// attribute value is
		// "true". For example,
		// "yes" will be
		// considered "false".
	}

	/**
	 * Given an IConfigurationElement from plugin.xml, return the types of validation passes, as
	 * defined in IRuleGroup, that the validator performs.
	 * 
	 * If no pass attribute is specified, the default, IRuleGroup.PASS_FULL, is returned.
	 */
	private int getRuleGroup(IConfigurationElement element) {
		IConfigurationElement[] runChildren = element.getChildren(TAG_RUN_CLASS);
		// Don't need to check if runChildren is null or empty, because that was checked in the
		// initializeValidator method.

		String pass = runChildren[0].getAttribute(ATT_RULE_GROUP);
		if (pass == null) {
			return RegistryConstants.ATT_RULE_GROUP_DEFAULT;
		}

		final String COMMA = ","; //$NON-NLS-1$
		StringTokenizer tokenizer = new StringTokenizer(pass, COMMA, false); // false means don't
		// return the comma as
		// part of the string
		int result = 0; // no passes identified
		while (tokenizer.hasMoreTokens()) {
			String nextAction = tokenizer.nextToken().trim();
			if (nextAction.equals(IRuleGroup.PASS_FAST_NAME)) {
				result = result | IRuleGroup.PASS_FAST;
			} else if (nextAction.equals(IRuleGroup.PASS_FULL_NAME)) {
				result = result | IRuleGroup.PASS_FULL;
			}
		}

		if (result == 0) {
			// No recognized passes. Return the default.
			return RegistryConstants.ATT_RULE_GROUP_DEFAULT;
		}

		return result;
	}

	private ValidatorMetaData.MigrationMetaData getMigrationMetaData(IConfigurationElement element, ValidatorMetaData vmd) {
		IConfigurationElement[] runChildren = element.getChildren(TAG_MIGRATE);
		if ((runChildren == null) || (runChildren.length == 0)) {
			return null;
		}

		// Only supposed to be one "migrate" section in a validator, so ignore the rest
		IConfigurationElement migrate = runChildren[0];

		// Now look for the "validator" elements. Zero or more can be specified.
		IConfigurationElement[] migrateChildren = migrate.getChildren(TAG_VALIDATOR);
		if ((migrateChildren == null) || (migrateChildren.length == 0)) {
			return null;
		}

		ValidatorMetaData.MigrationMetaData mmd = vmd.new MigrationMetaData();
		for (int i = 0; i < migrateChildren.length; i++) {
			IConfigurationElement migrateChild = migrateChildren[i];
			String from = migrateChild.getAttribute(ATT_FROM);
			if (from == null) {
				continue;
			}

			String to = migrateChild.getAttribute(ATT_TO);
			if (to == null) {
				continue;
			}
			mmd.addId(from, to);
		}
		return mmd;
	}

	/**
	 * Given an IConfigurationElement, if it has a project nature(s) specified, return the
	 * ValidatorNameFilters which represent those natures. Otherwise return null.
	 * 
	 * A project nature can be specified in plugin.xml to indicate what types of IProjects a
	 * validator can run on.
	 */
	private ValidatorNameFilter[] getProjectNatureFilters(IConfigurationElement element) {
		IConfigurationElement[] filters = element.getChildren(TAG_PROJECT_NATURE);
		if (filters.length == 0) {
			return null;
		}

		ValidatorNameFilter[] vf = new ValidatorNameFilter[filters.length];
		for (int i = 0; i < filters.length; i++) {
			vf[i] = new ValidatorNameFilter();
			// In order to speed up our String comparisons, load these
			// names into Java's constants space. This way, we'll be able to
			// use pointer comparison instead of the traditional
			// character-by-character comparison. Since these names should
			// never be set by anyone other than this class, and this class
			// sets them only once, it is safe to declare these Strings
			// constants.
			//
			// To load a String into the constants space, call intern() on the String.
			//
			String nameFilter = filters[i].getAttribute(ATT_ID);
			if (nameFilter != null) {
				nameFilter = nameFilter.intern();
			}
			vf[i].setNameFilter(nameFilter);

			String include = filters[i].getAttribute(ATT_INCLUDE);
			vf[i].setInclude(include);
		}
		return vf;
	}

	/**
	 * Returns the singleton ValidationRegistryReader.
	 */
	public static ValidationRegistryReader getReader() {
		if (inst == null) {
			inst = new ValidationRegistryReader();

			EventManager.getManager().setActive(true);
		}
		return inst;
	}

	public static boolean isActivated() {
		// Whether the registry has been read or not is kept in the EventManager
		// class instead of this class in order to work around a shutdown problem.
		// See the comment in the isActive() method of the EventManager class
		// for details.
		return EventManager.getManager().isActive();
	}

	/**
	 * Returns the Validator extension point
	 */
	private IExtensionPoint getValidatorExtensionPoint() {
		IPluginRegistry registry = Platform.getPluginRegistry();
		IExtensionPoint extensionPoint = registry.getExtensionPoint(PLUGIN_ID, VALIDATOR_EXT_PT_ID);
		if (extensionPoint == null) {
			// If this happens it means that someone removed the "validator" extension point
			// declaration
			// from our plugin.xml file.
			Logger logger = ValidationPlugin.getPlugin().getMsgLogger();
			if (logger.isLoggingLevel(Level.FINE)) {
				LogEntry entry = ValidationPlugin.getLogEntry();
				entry.setSourceID("ValidationRegistryReader.getValidatorExtensionPoint()"); //$NON-NLS-1$
				entry.setMessageTypeID(ResourceConstants.VBF_EXC_MISSING_VALIDATOR_EP);
				entry.setTokens(new String[]{ValidationPlugin.PLUGIN_ID + "." + VALIDATOR_EXT_PT_ID}); //$NON-NLS-1$
				logger.write(Level.FINE, entry);
			}
		}
		return extensionPoint;
	}

	/**
	 * It's okay to return a handle to the ValidatorMetaData because the vmd can't be modified by
	 * any code not in this package.
	 */
	public ValidatorMetaData getValidatorMetaData(IValidator validator) {
		// retrieval will be in log(n) time
		if (validator == null) {
			Logger logger = ValidationPlugin.getPlugin().getMsgLogger();
			if (logger.isLoggingLevel(Level.SEVERE)) {
				LogEntry entry = ValidationPlugin.getLogEntry();
				entry.setSourceID("ValidationRegistryReader.getValidatorMetaData(IValidator)"); //$NON-NLS-1$
				entry.setText(ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_ORPHAN_IVALIDATOR, new String[]{"null"})); //$NON-NLS-1$
				logger.write(Level.SEVERE, entry);
			}
			return null;
		}

		String validatorClassName = validator.getClass().getName();
		ValidatorMetaData vmd = getValidatorMetaData(validatorClassName);
		if (vmd != null) {
			return vmd;
		}

		// If we got here, then vmd is neither a root nor an aggregate validator,
		// yet the IValidator exists. Internal error.
		Logger logger = ValidationPlugin.getPlugin().getMsgLogger();
		if (logger.isLoggingLevel(Level.SEVERE)) {
			LogEntry entry = ValidationPlugin.getLogEntry();
			entry.setSourceID("ValidationRegistryReader.getValidatorMetaData(IValidator)"); //$NON-NLS-1$
			entry.setText(ResourceHandler.getExternalizedMessage(ResourceConstants.VBF_EXC_ORPHAN_IVALIDATOR, new String[]{validatorClassName}));
			logger.write(Level.SEVERE, entry);
		}
		return null;
	}

	public Set getValidatorMetaData(IWorkspaceRoot root) {
		// Every validator on the Preferences page must be returned
		Set copy = new HashSet();
		clone(_indexedValidators.values(), copy);
		return copy;
	}

	/**
	 * Return a collection of Validators configured on a certain type of IProject (e.g. EJB Project
	 * vs. Web Project).
	 * 
	 * This is a long-running process. If you can, cache the result.
	 */
	public Set getValidatorMetaData(IProject project) {
		Set copy = new HashSet();
		getValidatorMetaData(project, copy);
		return copy;
	}

	/**
	 * Copy the set of configured validator metadata into the Set.
	 */
	public void getValidatorMetaData(IProject project, Set vmds) {
		if (vmds == null) {
			return;
		}
		vmds.clear();
		int executionMap = 0x0;
		Logger logger = ValidationPlugin.getPlugin().getMsgLogger();
		try {
			if (logger.isLoggingLevel(Level.FINEST)) {
				LogEntry entry = ValidationPlugin.getLogEntry();
				entry.setSourceID("ValidationRegistryReader.getValidatorMetaData(IProject)"); //$NON-NLS-1$
				entry.setText("IProject is " + String.valueOf(project)); //$NON-NLS-1$
				logger.write(Level.FINEST, entry);
			}

			if (project == null) {
				executionMap |= 0x1;
				// vmds is already clear
				return;
			}

			String[] projectNatures = null;
			try {
				projectNatures = project.getDescription().getNatureIds();
			} catch (CoreException exc) {
				executionMap |= 0x2;
				// vmds is already clear
				if (logger.isLoggingLevel(Level.SEVERE)) {
					LogEntry entry = ValidationPlugin.getLogEntry();
					entry.setSourceID("ValidationRegistryReader.getValidatorMetaData(" + project.getName() + ")"); //$NON-NLS-1$  //$NON-NLS-2$
					entry.setTargetException(exc);
					entry.setExecutionMap(executionMap);
					logger.write(Level.SEVERE, entry);
				}
				return;
			}

			// If there are no project natures on a particular project,
			// or if this project nature has no validators configured
			// on it, return the validators which are configured on all
			// projects.
			Set projVmds = null;
			if ((projectNatures == null) || (projectNatures.length == 0)) {
				executionMap |= 0x4;
				clone(getValidatorMetaDataUnknownProject(), vmds);
			} else {
				executionMap |= 0x8;
				if (logger.isLoggingLevel(Level.FINEST)) {
					LogEntry entry = ValidationPlugin.getLogEntry();
					entry.setSourceID("ValidationRegistryReader.getValidatorMetaData(IProject)"); //$NON-NLS-1$
					entry.setTokens(projectNatures);
					logger.write(Level.FINEST, entry);
				}

				for (int i = 0; i < projectNatures.length; i++) {
					String projectNatureId = projectNatures[i];
					projVmds = (Set) _validators.get(projectNatureId);

					if (projVmds == null) {
						// no validators registered for that type of project id
						executionMap |= 0x10;
						continue;
					}

					Iterator iterator = projVmds.iterator();
					while (iterator.hasNext()) {
						ValidatorMetaData vmd = (ValidatorMetaData) iterator.next();
						if (!vmds.contains(vmd)) {
							vmds.add(vmd);
						}
					}
				}

				// Now filter out the validators which must not run on this project
				removeExcludedProjects(project, vmds);

				if (vmds.size() == 0) {
					executionMap |= 0x20;
					clone(getValidatorMetaDataUnknownProject(), vmds);
				}
			}
		} finally {
			if (logger.isLoggingLevel(Level.FINER)) {
				LogEntry entry = ValidationPlugin.getLogEntry();
				entry.setSourceID("ValidationRegistryReader.getValidatorMetaData(IProject)"); //$NON-NLS-1$
				entry.setExecutionMap(executionMap);

				StringBuffer buffer = new StringBuffer();
				Iterator iterator = vmds.iterator();
				while (iterator.hasNext()) {
					ValidatorMetaData vmd = (ValidatorMetaData) iterator.next();
					buffer.append(vmd.getValidatorUniqueName());
					buffer.append("\n"); //$NON-NLS-1$
				}
				entry.setText(buffer.toString());
				logger.write(Level.FINER, entry);
			}
		}
	}

	/*
	 * If one project nature on the project includes a particular validator, but another project
	 * nature excludes that validator, then the validator needs to be removed from the vmd set.
	 * 
	 * For example, if AValidator can run on any java project but not on a J2EE project, which is an
	 * instance of a java project, then the AValidator is included by the java nature and excluded
	 * by the J2EE nature. The AValidator would have to be removed from the set.
	 */
	private void removeExcludedProjects(IProject project, Set vmds) {
		Logger logger = ValidationPlugin.getPlugin().getMsgLogger();
		if (logger.isLoggingLevel(Level.FINEST)) {
			LogEntry entry = ValidationPlugin.getLogEntry();
			entry.setSourceID("ValidationRegistryReader.removeExcludedProjects"); //$NON-NLS-1$

			StringBuffer buffer = new StringBuffer("\nBefore:\n"); //$NON-NLS-1$
			Iterator viterator = vmds.iterator();
			while (viterator.hasNext()) {
				ValidatorMetaData vmd = (ValidatorMetaData) viterator.next();
				buffer.append(vmd.getValidatorUniqueName());
				buffer.append("\n"); //$NON-NLS-1$
			}
			entry.setText(buffer.toString());
			logger.write(Level.FINEST, entry);
		}

		String[] projectNatures = null;
		try {
			projectNatures = project.getDescription().getNatureIds();
		} catch (CoreException exc) {
			// if there's no natures, there's no list.
			if (logger.isLoggingLevel(Level.SEVERE)) {
				LogEntry entry = ValidationPlugin.getLogEntry();
				entry.setSourceID("ValidationRegistryReader.getValidatorMetaData(" + project.getName() + ")"); //$NON-NLS-1$  //$NON-NLS-2$
				entry.setTargetException(exc);
				logger.write(Level.SEVERE, entry);
			}
			return;
		}
		if ((projectNatures == null) || (projectNatures.length == 0)) {
			// nothing needs to be removed from the list
			return;
		}

		// First of all, clone the Set because we need to remove entries
		// from it, and we can't alter the set while we're iterating over
		// it.
		List tempList = getTempList();
		clone(vmds, tempList);

		for (int i = 0; i < projectNatures.length; i++) {
			String nature = projectNatures[i];
			Iterator iterator = tempList.iterator();
			while (iterator.hasNext()) {
				ValidatorMetaData vmd = (ValidatorMetaData) iterator.next();
				ValidatorNameFilter[] natureFilters = vmd.getProjectNatureFilters();
				if (natureFilters == null) {
					// Can run on any project
					continue;
				}

				for (int j = 0; j < natureFilters.length; j++) {
					ValidatorNameFilter pn = natureFilters[j];
					if (nature.equals(pn.getNameFilter()) && !pn.isInclude()) {
						vmds.remove(vmd);
					}
				}
			}
		}

		if (logger.isLoggingLevel(Level.FINEST)) {
			LogEntry entry = ValidationPlugin.getLogEntry();
			entry.setSourceID("ValidationRegistryReader.removeExcludedProjects"); //$NON-NLS-1$

			StringBuffer buffer = new StringBuffer("\nAfter:\n"); //$NON-NLS-1$
			Iterator viterator = vmds.iterator();
			while (viterator.hasNext()) {
				ValidatorMetaData vmd = (ValidatorMetaData) viterator.next();
				buffer.append(vmd.getValidatorUniqueName());
				buffer.append("\n"); //$NON-NLS-1$
			}
			entry.setText(buffer.toString());
			logger.write(Level.FINEST, entry);
		}
	}

	private Collection clone(Collection input, Collection copy) {
		if (input == null) {
			return null;
		}

		if (copy == null) {
			return null;
		}
		copy.clear();
		copy.addAll(input);
		return copy;
	}

	public String debug() {
		StringBuffer buffer = new StringBuffer();
		buffer.append("Project nature => validators configured"); //$NON-NLS-1$
		buffer.append("\n"); //$NON-NLS-1$
		Iterator viterator = _validators.keySet().iterator();
		while (viterator.hasNext()) {
			String projId = (String) viterator.next();
			buffer.append("projId: "); //$NON-NLS-1$
			buffer.append(projId);
			buffer.append("\n"); //$NON-NLS-1$
			Set validators = (Set) _validators.get(projId);
			Iterator innerIterator = validators.iterator();
			while (innerIterator.hasNext()) {
				ValidatorMetaData vmd = (ValidatorMetaData) innerIterator.next();
				buffer.append("\t"); //$NON-NLS-1$
				buffer.append(vmd.getValidatorUniqueName());
				buffer.append("\n"); //$NON-NLS-1$
			}
		}
		buffer.append("\n"); //$NON-NLS-1$

		buffer.append("Enable/disable validator by default"); //$NON-NLS-1$
		buffer.append("\n"); //$NON-NLS-1$
		viterator = _indexedValidators.values().iterator();
		while (viterator.hasNext()) {
			ValidatorMetaData vmd = (ValidatorMetaData) viterator.next();
			buffer.append(vmd.getValidatorUniqueName());
			buffer.append(" enabled? "); //$NON-NLS-1$
			buffer.append(vmd.isEnabledByDefault());
			buffer.append("\n"); //$NON-NLS-1$
		}

		return buffer.toString();
	}

	public boolean isConfiguredOnProject(ValidatorMetaData vmd, IProject project) {
		Set prjVmds = getValidatorMetaData(project);
		if (prjVmds == null) {
			return false;
		}

		if (prjVmds.size() == 0) {
			return false;
		}

		return prjVmds.contains(vmd);
	}

	/**
	 * Return a set of ValidatorMetaData which are configured on all projects or which run on any
	 * projects except certain project types.
	 * 
	 * Unlike other get methods, because this method is private it doesn't return a clone.
	 * 
	 * @see addExcludedRemainder()
	 */
	private Set getValidatorMetaDataUnknownProject() {
		Set projVmds = (Set) _validators.get(UNKNOWN_PROJECT);
		if (projVmds == null) {
			projVmds = Collections.EMPTY_SET;
		}
		return projVmds;
	}

	/**
	 * Return a set of ValidatorMetaData which are enabled by default.
	 */
	public Set getValidatorMetaDataEnabledByDefault() {
		Set copy = new HashSet();
		clone(_defaultEnabledValidators, copy);
		return copy;
	}

	public ValidatorMetaData[] getValidatorMetaDataArrayEnabledByDefault() {
		ValidatorMetaData[] result = new ValidatorMetaData[_defaultEnabledValidators.size()];
		_defaultEnabledValidators.toArray(result);
		return result;
	}

	/**
	 * This method should be called ONLY by the validation framework, UI, or TVT plugin. In general,
	 * only the validation framework and the validation TVT should handle ValidatorMetaData objects.
	 * 
	 * Given a string which identifies a fully-qualified class name of a validator, return the
	 * ValidatorMetaData that uses a validator of that name, if it exists.
	 * 
	 * It's okay to return a handle to the ValidatorMetaData because the vmd can't be modified by
	 * any code not in this package.
	 */
	public ValidatorMetaData getValidatorMetaData(String validatorClassName) {
		if (validatorClassName == null) {
			return null;
		}

		ValidatorMetaData vmd = (ValidatorMetaData) _indexedValidators.get(validatorClassName);
		if (vmd != null) {
			return vmd;
		}

		// Check for an aggregate validator
		Iterator iterator = _indexedValidators.values().iterator();
		while (iterator.hasNext()) {
			vmd = (ValidatorMetaData) iterator.next();
			if (vmd == null) {
				continue;
			}

			if (vmd.getValidatorUniqueName().equals(validatorClassName)) {
				return vmd;
			}

			String[] aggregateNames = vmd.getAggregatedValidatorNames();
			if (aggregateNames != null) {
				for (int i = 0; i < aggregateNames.length; i++) {
					String aggregateName = aggregateNames[i];
					if (validatorClassName.equals(aggregateName)) {
						return vmd;
					}
				}
			}

			// Current name of validator doesn't match; has this validator been
			// migrated from another package?
			ValidatorMetaData.MigrationMetaData mmd = vmd.getMigrationMetaData();
			if (mmd == null) {
				// Validator class name hasn't been migrated
				continue;
			}

			Set idList = mmd.getIds();
			if (idList == null) {
				// Invalid <migrate> element.
				continue;
			}

			Iterator idIterator = idList.iterator();
			while (idIterator.hasNext()) {
				String[] ids = (String[]) idIterator.next();
				if (ids.length != 2) {
					// log
					continue;
				}

				String from = ids[0];
				if (from == null) {
					// log
					continue;
				}

				if (from.equals(validatorClassName)) {
					return vmd;
				}
			}
		}

		// If we got to this point, no validator using that class name is loaded.
		return null;
	}

	/**
	 * Return true if the named validator is installed, otherwise false.
	 */
	public boolean isExistingValidator(String validatorClassName) {
		return (getValidatorMetaData(validatorClassName) != null);
	}

	/**
	 * Initialize the validator with the static metadata (runtime metadata is initialized in the
	 * ValidationOperation class).
	 */
	private ValidatorMetaData initializeValidator(IConfigurationElement element, String validatorName, String pluginId) {
		IConfigurationElement[] runChildren = element.getChildren(TAG_RUN_CLASS);
		if ((runChildren == null) || (runChildren.length < 1)) {
			// How can an IValidatorImpl be created when there no class name to
			// instantiate?
			Logger logger = ValidationPlugin.getPlugin().getMsgLogger();
			if (logger.isLoggingLevel(Level.FINE)) {
				LogEntry entry = ValidationPlugin.getLogEntry();
				entry.setSourceID("ValidationRegistryReader.initializeValidator(IConfigurationElement, String, String)"); //$NON-NLS-1$
				entry.setMessageTypeID(ResourceConstants.VBF_EXC_SYNTAX_NO_VAL_RUN);
				entry.setTokens(new String[]{validatorName});
				logger.write(Level.FINE, entry);
			}
			return null;
		}

		String validatorImplName = runChildren[0].getAttribute(ATT_CLASS);
		if (validatorImplName == null) {
			// Same as before; how can we instantiate when...
			Logger logger = ValidationPlugin.getPlugin().getMsgLogger();
			if (logger.isLoggingLevel(Level.FINE)) {
				LogEntry entry = ValidationPlugin.getLogEntry();
				entry.setSourceID("ValidationRegistryReader.initializeValidator(IConfigurationElement, String, String)"); //$NON-NLS-1$
				entry.setMessageTypeID(ResourceConstants.VBF_EXC_SYNTAX_NO_VAL_CLASS);
				entry.setTokens(new String[]{validatorName});
				logger.write(Level.FINE, entry);
			}
			return null;
		}

		String helperImplName = getHelperName(element);
		if (helperImplName == null) {
			// Same as before; how can we instantiate when...
			Logger logger = ValidationPlugin.getPlugin().getMsgLogger();
			if (logger.isLoggingLevel(Level.FINE)) {
				LogEntry entry = ValidationPlugin.getLogEntry();
				entry.setSourceID("ValidationRegistryReader.initializeValidator(IConfigurationElement, String, String)"); //$NON-NLS-1$
				entry.setMessageTypeID(ResourceConstants.VBF_EXC_SYNTAX_NO_VAL_RUN);
				entry.setTokens(new String[]{validatorImplName});
				logger.write(Level.FINE, entry);
			}
			return null;
		}

		// In order to speed up our String comparisons, load these
		// names into Java's constants space. This way, we'll be able to
		// use pointer comparison instead of the traditional
		// character-by-character comparison. Since these names should
		// never be set by anyone other than this class, and this class
		// sets them only once, it is safe to declare these Strings
		// constants.
		//
		// To load a String into the constants space, call intern() on the String.
		//
		ValidatorMetaData vmd = new ValidatorMetaData();
		vmd.addFilters(getFilters(element)); // validator may, or may not, have filters
		vmd.addProjectNatureFilters(getProjectNatureFilters(element)); // validator may, or may not,
		// specify a project nature
		vmd.addAggregatedValidatorNames(getAggregateValidatorsNames(element)); // if a validator
		// aggregated another
		// validator, it
		// should identify
		// the
		// sub-validator(s)'
		// class name
		vmd.setValidatorDisplayName(validatorName.intern()); // validator must have a display name.
		vmd.setValidatorUniqueName(validatorImplName.intern());
		vmd.setPluginId(pluginId);
		vmd.setIncremental(getIncremental(element));
		vmd.setFullBuild(getFullBuild(element));
		vmd.setAsync(getAsync(element));
		vmd.setRuleGroup(getRuleGroup(element));
		vmd.setEnabledByDefault(getEnabledByDefault(element));
		vmd.setMigrationMetaData(getMigrationMetaData(element, vmd));
		vmd.setHelperClass(element, helperImplName);
		vmd.setValidatorClass(element); // associate the above attributes with the validator
		vmd.addDependentValidator(getDependentValidatorValue(element));
		vmd.setMarkerId(getMarkerIdValue(element));

		Logger logger = ValidationPlugin.getPlugin().getMsgLogger();
		if (logger.isLoggingLevel(Level.FINEST)) {
			LogEntry entry = ValidationPlugin.getLogEntry();
			entry.setSourceID("ValidationRegistryReader.initializeValidator(IConfigurationElement, String, String)"); //$NON-NLS-1$
			entry.setText("validator loaded: " + validatorImplName); //$NON-NLS-1$
			logger.write(Level.FINEST, entry);
		}

		return vmd;
	}

	private List getTempList() {
		// Return a list for temporary use
		if (_tempList == null) {
			_tempList = new ArrayList();
		} else {
			// Prepare list for use
			_tempList.clear();
		}

		return _tempList;
	}

	/**
	 * This method should be called ONLY BY THE VALIDATION FRAMEWORK! The value from this method is
	 * used to populate the validation preference page.
	 */
	public Collection getAllValidators() {
		Set validators = new HashSet();
		clone(_indexedValidators.values(), validators);
		return validators;
	}

	public int numberOfValidators() {
		return _indexedValidators.size();
	}

	/**
	 * Reads one extension by looping through its configuration elements.
	 */
	private void readExtension(IExtension extension) {
		IConfigurationElement[] elements = extension.getConfigurationElements();

		for (int i = 0; i < elements.length; i++) {
			IConfigurationElement element = elements[i];

			String label = extension.getLabel();
			if (label == null || label.equals("")) { //$NON-NLS-1$
				Logger logger = ValidationPlugin.getPlugin().getMsgLogger();
				if (logger.isLoggingLevel(Level.FINE)) {
					String[] msgParm = {extension.getUniqueIdentifier()};
					LogEntry entry = ValidationPlugin.getLogEntry();
					entry.setSourceID("ValidationRegistryReader.readExtension(IExtension)"); //$NON-NLS-1$
					entry.setMessageTypeID(ResourceConstants.VBF_EXC_VALIDATORNAME_IS_NULL);
					entry.setTokens(msgParm);
					logger.write(Level.FINE, entry);
				}
			} else {
				// If getLabel() returns an empty string, this is an illegal validator.
				// The PropertyPage, and other status messages, need to have a displayable name for
				// the validator.
				String pluginId = extension.getDeclaringPluginDescriptor().getUniqueIdentifier();
				ValidatorMetaData vmd = initializeValidator(element, label, pluginId);

				if (vmd != null) {
					// Add this validator to the list of validators; if vmd is null, the validator
					// couldn't be created.
					add(vmd);
				}
			}
		}
	}

	/**
	 * Reads the registry to find the Validators which have been implemented.
	 */
	private void readRegistry() {
		_validators.clear();

		// Get the extensions that have been registered.
		IExtensionPoint validatorEP = getValidatorExtensionPoint();
		if (validatorEP == null) {
			return;
		}
		IExtension[] extensions = validatorEP.getExtensions();

		// find all runtime implementations
		for (int i = 0; i < extensions.length; i++) {
			readExtension(extensions[i]);
		}
	}

}