Copyright (c) 2000, 2015 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
    James Blackburn (Broadcom Corp.) - ongoing development
    Lars Vogel  - Bug 473427
/*******************************************************************************
 * Copyright (c) 2000, 2015 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
 *     James Blackburn (Broadcom Corp.) - ongoing development
 *     Lars Vogel <Lars.Vogel@vogella.com> - Bug 473427
 *******************************************************************************/
package org.eclipse.core.internal.resources;

import java.util.*;
import org.eclipse.core.internal.utils.Policy;
import org.eclipse.core.resources.ResourcesPlugin;
import org.eclipse.core.runtime.*;

public class MarkerTypeDefinitionCache {
	static class MarkerTypeDefinition {
		boolean isPersistent = false;
		Set<String> superTypes;

		MarkerTypeDefinition(IExtension ext) {
			IConfigurationElement[] elements = ext.getConfigurationElements();
			for (IConfigurationElement element : elements) {
				// supertype
				final String elementName = element.getName();
				if (elementName.equalsIgnoreCase("super")) { //$NON-NLS-1$
					String aType = element.getAttribute("type"); //$NON-NLS-1$
					if (aType != null) {
						if (superTypes == null)
							superTypes = new HashSet<>(8);
						//note that all marker type names will be in the intern table
						//already because there is invariably a constant to describe
						//the type name
						superTypes.add(aType.intern());
					}
				}
				// persistent
				if (elementName.equalsIgnoreCase("persistent")) { //$NON-NLS-1$
					String bool = element.getAttribute("value"); //$NON-NLS-1$
					if (bool != null)
						this.isPersistent = Boolean.parseBoolean(bool);
				}
				// XXX: legacy code for support of <transient> tag. remove later.
				if (elementName.equalsIgnoreCase("transient")) { //$NON-NLS-1$
					String bool = element.getAttribute("value"); //$NON-NLS-1$
					if (bool != null)
						this.isPersistent = !Boolean.parseBoolean(bool);
				}
			}
		}
	}

	
The marker type definitions.  Maps String (markerId) -> MarkerTypeDefinition
/**
	 * The marker type definitions.  Maps String (markerId) -&gt; MarkerTypeDefinition
	 */
	protected HashMap<String, MarkerTypeDefinition> definitions;

	
Constructs a new type cache.
/** Constructs a new type cache.
	 */
	public MarkerTypeDefinitionCache() {
		loadDefinitions();
		HashSet<String> toCompute = new HashSet<>(definitions.keySet());
		for (String markerId : definitions.keySet()) {
			if (toCompute.contains(markerId))
				computeSuperTypes(markerId, toCompute);
		}
	}

	
Computes the transitive set of super types of the given marker type.
Params:
markerId – The type to compute super types for
toCompute – The set of types that have not yet had their
supertypes computed.
Returns:
The transitive set of super types for this marker, or null
if this marker is not defined or has no super types./**
	 * Computes the transitive set of super types of the given marker type.
	 * @param markerId The type to compute super types for
	 * @param toCompute The set of types that have not yet had their
	 * supertypes computed.
	 * @return The transitive set of super types for this marker, or null
	 * if this marker is not defined or has no super types.
	 */
	private Set<String> computeSuperTypes(String markerId, Set<String> toCompute) {
		MarkerTypeDefinition def = definitions.get(markerId);
		if (def == null || def.superTypes == null) {
			//nothing to do if there are no supertypes
			toCompute.remove(markerId);
			return null;
		}
		Set<String> transitiveSuperTypes = new HashSet<>(def.superTypes);
		for (String superId : def.superTypes) {
			Set<String> toAdd = null;
			if (toCompute.contains(superId)) {
				//this type's super types have not been compute yet. Do recursive call
				toAdd = computeSuperTypes(superId, toCompute);
			} else {
				// we have already computed this super type's super types (or it doesn't exist)
				MarkerTypeDefinition parentDef = definitions.get(superId);
				if (parentDef != null)
					toAdd = parentDef.superTypes;
			}
			if (toAdd != null)
				transitiveSuperTypes.addAll(toAdd);
		}
		def.superTypes = transitiveSuperTypes;
		toCompute.remove(markerId);
		return transitiveSuperTypes;
	}

	
Returns true if the given marker type is defined to be persistent.
/**
	 * Returns true if the given marker type is defined to be persistent.
	 */
	public boolean isPersistent(String type) {
		MarkerTypeDefinition def = definitions.get(type);
		return def != null && def.isPersistent;
	}

	
Returns true if the given target class has the specified type as a super type.
/**
	 * Returns true if the given target class has the specified type as a super type.
	 */
	public boolean isSubtype(String type, String superType) {
		//types are considered super types of themselves
		if (type.equals(superType))
			return true;
		MarkerTypeDefinition def = definitions.get(type);
		return def != null && def.superTypes != null && def.superTypes.contains(superType);
	}

	private void loadDefinitions() {
		IExtensionPoint point = Platform.getExtensionRegistry().getExtensionPoint(ResourcesPlugin.PI_RESOURCES, ResourcesPlugin.PT_MARKERS);
		IExtension[] types = point.getExtensions();
		definitions = new HashMap<>(types.length);
		for (IExtension type : types) {
			String markerId = type.getUniqueIdentifier();
			if (markerId != null)
				definitions.put(markerId.intern(), new MarkerTypeDefinition(type));
			else
				Policy.log(IStatus.WARNING, "Missing marker id from plugin: " + type.getContributor().getName(), null); //$NON-NLS-1$
		}
	}
}