/*******************************************************************************
 * Copyright (c) 2000, 2018 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
 *     Stephan Herrmann - contribution for bug 337868 - [compiler][model] incomplete support for package-info.java when using SearchableEnvironment
 *******************************************************************************/
package org.eclipse.jdt.internal.core;

import java.io.File;
import java.util.*;
import java.util.function.Function;

import org.eclipse.core.resources.*;
import org.eclipse.core.runtime.IPath;
import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.jdt.core.IClasspathEntry;
import org.eclipse.jdt.core.ICompilationUnit;
import org.eclipse.jdt.core.IField;
import org.eclipse.jdt.core.IInitializer;
import org.eclipse.jdt.core.IJavaElement;
import org.eclipse.jdt.core.IJavaProject;
import org.eclipse.jdt.core.IMethod;
import org.eclipse.jdt.core.IModuleDescription;
import org.eclipse.jdt.core.IOrdinaryClassFile;
import org.eclipse.jdt.core.IPackageFragment;
import org.eclipse.jdt.core.IPackageFragmentRoot;
import org.eclipse.jdt.core.IType;
import org.eclipse.jdt.core.JavaCore;
import org.eclipse.jdt.core.JavaModelException;
import org.eclipse.jdt.core.compiler.CharOperation;
import org.eclipse.jdt.internal.compiler.ast.ASTNode;
import org.eclipse.jdt.internal.compiler.ast.TypeDeclaration;
import org.eclipse.jdt.internal.compiler.env.AccessRestriction;
import org.eclipse.jdt.internal.compiler.env.AccessRuleSet;
import org.eclipse.jdt.internal.compiler.env.IBinaryType;
import org.eclipse.jdt.internal.compiler.env.IModule;
import org.eclipse.jdt.internal.compiler.lookup.TypeConstants;
import org.eclipse.jdt.internal.compiler.parser.ScannerHelper;
import org.eclipse.jdt.internal.compiler.util.HashtableOfObjectToInt;
import org.eclipse.jdt.internal.compiler.util.SuffixConstants;
import org.eclipse.jdt.internal.core.AbstractModule.AutoModule;
import org.eclipse.jdt.internal.core.util.HashtableOfArrayToObject;
import org.eclipse.jdt.internal.core.util.Messages;
import org.eclipse.jdt.internal.core.util.Util;

/**
 * A <code>NameLookup</code> provides name resolution within a Java project.
 * The name lookup facility uses the project's classpath to prioritize the
 * order in which package fragments are searched when resolving a name.
 *
 * <p>Name lookup only returns a handle when the named element actually
 * exists in the model; otherwise <code>null</code> is returned.
 *
 * <p>There are two logical sets of methods within this interface.  Methods
 * which start with <code>find*</code> are intended to be convenience methods for quickly
 * finding an element within another element; for instance, for finding a class within a
 * package.  The other set of methods all begin with <code>seek*</code>.  These methods
 * do comprehensive searches of the <code>IJavaProject</code> returning hits
 * in real time through an <code>IJavaElementRequestor</code>.
 *
 */
@SuppressWarnings({"rawtypes", "unchecked"})
public class NameLookup implements SuffixConstants {

	private static IModuleDescription NO_MODULE = new SourceModule(null, "Not a module") { /* empty */ }; //$NON-NLS-1$

	public static class Answer {
		public IType type;
		public IModuleDescription module;
		AccessRestriction restriction;
		IClasspathEntry entry;
		Answer(IType type, AccessRestriction restriction, IClasspathEntry entry) {
			this(type, restriction, entry, null);
		}
		Answer(IType type, AccessRestriction restriction, IClasspathEntry entry, IModuleDescription module) {
			this.type = type;
			this.restriction = restriction;
			this.entry = entry;
			this.module = module;
		}
		Answer(IModuleDescription module) {
			this.module = module;
			this.restriction = null;
		}
		public boolean ignoreIfBetter() {
			return this.restriction != null && this.restriction.ignoreIfBetter();
		}
		/*
		 * Returns whether this answer is better than the other awswer.
		 * (accessible is better than discouraged, which is better than
		 * non-accessible)
		 */
		public boolean isBetter(Answer otherAnswer) {
			if (otherAnswer == null) return true;
			if (this.restriction == null) return true;
			return otherAnswer.restriction != null
				&& this.restriction.getProblemId() < otherAnswer.restriction.getProblemId();
		}
		@Override
		public String toString() {
			StringBuilder builder = new StringBuilder(this.type.toString());
			builder.append("from ") //$NON-NLS-1$
			.append(this.module);
			return builder.toString();
		}
	}

	private class Selector implements IJavaElementRequestor {
		public List<IPackageFragment> pkgFragments;

		public Selector(String moduleName) {
			this.pkgFragments = new ArrayList<>();
		}

		@Override
		public void acceptField(IField field) {
			// do nothing
		}

		@Override
		public void acceptInitializer(IInitializer initializer) {
			// do nothing
		}

		@Override
		public void acceptMemberType(IType type) {
			// do nothing
		}

		@Override
		public void acceptMethod(IMethod method) {
			// do nothing
		}

		@Override
		public void acceptPackageFragment(IPackageFragment packageFragment) {
			this.pkgFragments.add(packageFragment);
		}

		@Override
		public void acceptType(IType type) {
			// do nothing
		}

		@Override
		public void acceptModule(IModuleDescription module) {
			// do nothing
		}

		@Override
		public boolean isCanceled() {
			// TODO Auto-generated method stub
			return false;
		}
	}

	// TODO (jerome) suppress the accept flags (qualified name is sufficient to find a type)
	/**
	 * Accept flag for specifying classes.
	 */
	public static final int ACCEPT_CLASSES = ASTNode.Bit2;

	/**
	 * Accept flag for specifying interfaces.
	 */
	public static final int ACCEPT_INTERFACES = ASTNode.Bit3;

	/**
	 * Accept flag for specifying enums.
	 */
	public static final int ACCEPT_ENUMS = ASTNode.Bit4;

	/**
	 * Accept flag for specifying annotations.
	 */
	public static final int ACCEPT_ANNOTATIONS = ASTNode.Bit5;

	/*
	 * Accept flag for all kinds of types
	 */
	public static final int ACCEPT_ALL = ACCEPT_CLASSES | ACCEPT_INTERFACES | ACCEPT_ENUMS | ACCEPT_ANNOTATIONS;

	public static boolean VERBOSE = false;

	private static final IType[] NO_TYPES = {};

	/**
	 * The <code>IPackageFragmentRoot</code>'s associated
	 * with the classpath of this NameLookup facility's
	 * project.
	 */
	protected IPackageFragmentRoot[] packageFragmentRoots;

	/**
	 * Table that maps package names to lists of package fragment roots
	 * that contain such a package known by this name lookup facility.
	 * To allow > 1 package fragment with the same name, values are
	 * arrays of package fragment roots ordered as they appear on the
	 * classpath.
	 * Note if the list is of size 1, then the IPackageFragmentRoot object
	 * replaces the array.
	 */
	protected HashtableOfArrayToObject packageFragments;

	/**
	 * Reverse map from root path to corresponding resolved CP entry
	 * (so as to be able to figure inclusion/exclusion rules)
	 */
	protected Map<IPackageFragmentRoot,IClasspathEntry> rootToResolvedEntries;

	protected Map<IPackageFragmentRoot,IModuleDescription> rootToModule;

	/**
	 * A map from package handles to a map from type name to an IType or an IType[].
	 * Allows working copies to take precedence over compilation units.
	 */
	protected HashMap typesInWorkingCopies;

	public long timeSpentInSeekTypesInSourcePackage = 0;
	public long timeSpentInSeekTypesInBinaryPackage = 0;

	public NameLookup(
			IPackageFragmentRoot[] packageFragmentRoots,
			HashtableOfArrayToObject packageFragments,
			ICompilationUnit[] workingCopies,
			Map rootToResolvedEntries) {
		long start = -1;
		if (VERBOSE) {
			Util.verbose(" BUILDING NameLoopkup");  //$NON-NLS-1$
			Util.verbose(" -> pkg roots size: " + (packageFragmentRoots == null ? 0 : packageFragmentRoots.length));  //$NON-NLS-1$
			Util.verbose(" -> pkgs size: " + (packageFragments == null ? 0 : packageFragments.size()));  //$NON-NLS-1$
			Util.verbose(" -> working copy size: " + (workingCopies == null ? 0 : workingCopies.length));  //$NON-NLS-1$
			start = System.currentTimeMillis();
		}
		this.rootToModule = new HashMap<>();
		this.packageFragmentRoots = packageFragmentRoots;
		if (workingCopies == null) {
			this.packageFragments = packageFragments;
		} else {
			// clone tables as we're adding packages from working copies
			try {
				this.packageFragments = (HashtableOfArrayToObject) packageFragments.clone();
			} catch (CloneNotSupportedException e1) {
				// ignore (implementation of HashtableOfArrayToObject supports cloning)
			}
			this.typesInWorkingCopies = new HashMap();
			HashtableOfObjectToInt rootPositions = new HashtableOfObjectToInt();
			for (int i = 0, length = packageFragmentRoots.length; i < length; i++) {
				rootPositions.put(packageFragmentRoots[i], i);
			}
			for (int i = 0, length = workingCopies.length; i < length; i++) {
				ICompilationUnit workingCopy = workingCopies[i];
				PackageFragment pkg = (PackageFragment) workingCopy.getParent();
				IPackageFragmentRoot root = (IPackageFragmentRoot) pkg.getParent();
				int rootPosition = rootPositions.get(root);
				if (rootPosition == -1)
					continue; // working copy is not visible from this project (see https://bugs.eclipse.org/bugs/show_bug.cgi?id=169970)
				HashMap typeMap = (HashMap) this.typesInWorkingCopies.get(pkg);
				if (typeMap == null) {
					typeMap = new HashMap();
					this.typesInWorkingCopies.put(pkg, typeMap);
				}
				try {
					IType[] types = workingCopy.getTypes();
					int typeLength = types.length;
					if (typeLength == 0) {
						String typeName = Util.getNameWithoutJavaLikeExtension(workingCopy.getElementName());
						typeMap.put(typeName, NO_TYPES);
					} else {
						for (int j = 0; j < typeLength; j++) {
							IType type = types[j];
							String typeName = type.getElementName();
							Object existing = typeMap.get(typeName);
							if (existing == null) {
								typeMap.put(typeName, type);
							} else if (existing instanceof IType) {
								typeMap.put(typeName, new IType[] {(IType) existing, type});
							} else {
								IType[] existingTypes = (IType[]) existing;
								int existingTypeLength = existingTypes.length;
								System.arraycopy(existingTypes, 0, existingTypes = new IType[existingTypeLength+1], 0, existingTypeLength);
								existingTypes[existingTypeLength] = type;
								typeMap.put(typeName, existingTypes);
							}
						}
					}
				} catch (JavaModelException e) {
					// working copy doesn't exist -> ignore
				}

				// add root of package fragment to cache
				String[] pkgName = pkg.names;
				Object existing = this.packageFragments.get(pkgName);
				if (existing == null || existing == JavaProjectElementInfo.NO_ROOTS) {
					this.packageFragments.put(pkgName, root);
					// ensure super packages (see https://bugs.eclipse.org/bugs/show_bug.cgi?id=119161)
					// are also in the map
					JavaProjectElementInfo.addSuperPackageNames(pkgName, this.packageFragments);
				} else {
					if (existing instanceof PackageFragmentRoot) {
						int exisitingPosition = rootPositions.get(existing);
						if (rootPosition != exisitingPosition) { // if not equal
							this.packageFragments.put(
								pkgName,
								exisitingPosition < rootPosition ?
									new IPackageFragmentRoot[] {(PackageFragmentRoot) existing, root} :
									new IPackageFragmentRoot[] {root, (PackageFragmentRoot) existing});
						}
					} else {
						// insert root in the existing list
						IPackageFragmentRoot[] roots = (IPackageFragmentRoot[]) existing;
						int rootLength = roots.length;
						int insertionIndex = 0;
						for (int j = 0; j < rootLength; j++) {
							int existingPosition = rootPositions.get(roots[j]);
							if (rootPosition > existingPosition) {
								// root is after this index
								insertionIndex = j;
							} else if (rootPosition == existingPosition) {
								 // root already in the existing list
								insertionIndex = -1;
								break;
							} else if (rootPosition < existingPosition) {
								// root is before this index (thus it is at the insertion index)
								break;
							}
						}
						if (insertionIndex != -1) {
							IPackageFragmentRoot[] newRoots = new IPackageFragmentRoot[rootLength+1];
							System.arraycopy(roots, 0, newRoots, 0, insertionIndex);
							newRoots[insertionIndex] = root;
							System.arraycopy(roots, insertionIndex, newRoots, insertionIndex+1, rootLength-insertionIndex);
							this.packageFragments.put(pkgName, newRoots);
						}
					}
				}
			}
		}

		this.rootToResolvedEntries = rootToResolvedEntries;
        if (VERBOSE) {
            Util.verbose(" -> spent: " + (System.currentTimeMillis() - start) + "ms");  //$NON-NLS-1$ //$NON-NLS-2$
        }
	}

	/**
	 * Returns true if:<ul>
	 *  <li>the given type is an existing class and the flag's <code>ACCEPT_CLASSES</code>
	 *      bit is on
	 *  <li>the given type is an existing interface and the <code>ACCEPT_INTERFACES</code>
	 *      bit is on
	 *  <li>neither the <code>ACCEPT_CLASSES</code> or <code>ACCEPT_INTERFACES</code>
	 *      bit is on
	 *  </ul>
	 * Otherwise, false is returned.
	 */
	protected boolean acceptType(IType type, int acceptFlags, boolean isSourceType) {
		if (acceptFlags == 0 || acceptFlags == ACCEPT_ALL)
			return true; // no flags or all flags, always accepted
		try {
			int kind = isSourceType
					? TypeDeclaration.kind(((SourceTypeElementInfo) ((SourceType) type).getElementInfo()).getModifiers())
					: TypeDeclaration.kind(((IBinaryType) ((BinaryType) type).getElementInfo()).getModifiers());
			switch (kind) {
				case TypeDeclaration.CLASS_DECL :
					return (acceptFlags & ACCEPT_CLASSES) != 0;
				case TypeDeclaration.INTERFACE_DECL :
					return (acceptFlags & ACCEPT_INTERFACES) != 0;
				case TypeDeclaration.ENUM_DECL :
					return (acceptFlags & ACCEPT_ENUMS) != 0;
				default:
					//case IGenericType.ANNOTATION_TYPE :
					return (acceptFlags & ACCEPT_ANNOTATIONS) != 0;
			}
		} catch (JavaModelException npe) {
			return false; // the class is not present, do not accept.
		}
	}

	/**
	 * Finds every type in the project whose simple name matches
	 * the prefix, informing the requestor of each hit. The requestor
	 * is polled for cancellation at regular intervals.
	 *
	 * <p>The <code>partialMatch</code> argument indicates partial matches
	 * should be considered.
	 */
	private void findAllTypes(String prefix, boolean partialMatch, int acceptFlags, IJavaElementRequestor requestor) {
		int count= this.packageFragmentRoots.length;
		for (int i= 0; i < count; i++) {
			if (requestor.isCanceled())
				return;
			IPackageFragmentRoot root= this.packageFragmentRoots[i];
			IJavaElement[] packages= null;
			try {
				packages= root.getChildren();
			} catch (JavaModelException npe) {
				continue; // the root is not present, continue;
			}
			if (packages != null) {
				for (int j= 0, packageCount= packages.length; j < packageCount; j++) {
					if (requestor.isCanceled())
						return;
					seekTypes(prefix, (IPackageFragment) packages[j], partialMatch, acceptFlags, requestor);
				}
			}
		}
	}

	/**
	 * Returns the <code>ICompilationUnit</code> which defines the type
	 * named <code>qualifiedTypeName</code>, or <code>null</code> if
	 * none exists. The domain of the search is bounded by the classpath
	 * of the <code>IJavaProject</code> this <code>NameLookup</code> was
	 * obtained from.
	 * <p>
	 * The name must be fully qualified (eg "java.lang.Object", "java.util.Hashtable$Entry")
	 */
	public ICompilationUnit findCompilationUnit(String qualifiedTypeName) {
		String[] pkgName = CharOperation.NO_STRINGS;
		String cuName = qualifiedTypeName;

		int index= qualifiedTypeName.lastIndexOf('.');
		if (index != -1) {
			pkgName= Util.splitOn('.', qualifiedTypeName, 0, index);
			cuName= qualifiedTypeName.substring(index + 1);
		}
		index= cuName.indexOf('$');
		if (index != -1) {
			cuName= cuName.substring(0, index);
		}
		int pkgIndex = this.packageFragments.getIndex(pkgName);
		if (pkgIndex != -1) {
			Object value = this.packageFragments.valueTable[pkgIndex];
			// reuse existing String[]
			pkgName = (String[]) this.packageFragments.keyTable[pkgIndex];
			if (value instanceof PackageFragmentRoot) {
				return findCompilationUnit(pkgName, cuName, (PackageFragmentRoot) value);
			} else {
				IPackageFragmentRoot[] roots = (IPackageFragmentRoot[]) value;
				for (int i= 0; i < roots.length; i++) {
					PackageFragmentRoot root= (PackageFragmentRoot) roots[i];
					ICompilationUnit cu = findCompilationUnit(pkgName, cuName, root);
					if (cu != null)
						return cu;
				}
			}
		}
		return null;
	}

	private ICompilationUnit findCompilationUnit(String[] pkgName, String cuName, PackageFragmentRoot root) {
		if (!root.isArchive()) {
			IPackageFragment pkg = root.getPackageFragment(pkgName);
			try {
				ICompilationUnit[] cus = pkg.getCompilationUnits();
				for (int j = 0, length = cus.length; j < length; j++) {
					ICompilationUnit cu = cus[j];
					if (Util.equalsIgnoreJavaLikeExtension(cu.getElementName(), cuName))
						return cu;
				}
			} catch (JavaModelException e) {
				// pkg does not exist
				// -> try next package
			}
		}
		return null;
}

	/**
	 * Returns the package fragment whose path matches the given
	 * (absolute) path, or <code>null</code> if none exist. The domain of
	 * the search is bounded by the classpath of the <code>IJavaProject</code>
	 * this <code>NameLookup</code> was obtained from.
	 * The path can be:
	 * 	- internal to the workbench: "/Project/src"
	 *  - external to the workbench: "c:/jdk/classes.zip/java/lang"
	 */
	public IPackageFragment findPackageFragment(IPath path) {
		if (!path.isAbsolute()) {
			throw new IllegalArgumentException(Messages.path_mustBeAbsolute);
		}
/*
 * TODO (jerome) this code should rather use the package fragment map to find the candidate package, then
 * check if the respective enclosing root maps to the one on this given IPath.
 */
		IResource possibleFragment = ResourcesPlugin.getWorkspace().getRoot().findMember(path);
		if (possibleFragment == null) {
			//external jar
			for (int i = 0; i < this.packageFragmentRoots.length; i++) {
				IPackageFragmentRoot root = this.packageFragmentRoots[i];
				if (!root.isExternal()) {
					continue;
				}
				IPath rootPath = root.getPath();
				if (rootPath.isPrefixOf(path)) {
					String name = path.toOSString();
					// + 1 is for the File.separatorChar
					name = name.substring(rootPath.toOSString().length() + 1, name.length());
					name = name.replace(File.separatorChar, '.');
					IJavaElement[] list = null;
					try {
						list = root.getChildren();
					} catch (JavaModelException npe) {
						continue; // the package fragment root is not present;
					}
					int elementCount = list.length;
					for (int j = 0; j < elementCount; j++) {
						IPackageFragment packageFragment = (IPackageFragment) list[j];
						if (nameMatches(name, packageFragment, false)) {
							return packageFragment;
						}
					}
				}
			}
		} else {
			IJavaElement fromFactory = JavaCore.create(possibleFragment);
			if (fromFactory == null) {
				return null;
			}
			switch (fromFactory.getElementType()) {
				case IJavaElement.PACKAGE_FRAGMENT:
					return (IPackageFragment) fromFactory;
				case IJavaElement.JAVA_PROJECT:
					// default package in a default root
					JavaProject project = (JavaProject) fromFactory;
					try {
						IClasspathEntry entry = project.getClasspathEntryFor(path);
						if (entry != null) {
							IPackageFragmentRoot root =
								project.getPackageFragmentRoot(project.getResource());
							Object defaultPkgRoot = this.packageFragments.get(CharOperation.NO_STRINGS);
							if (defaultPkgRoot == null) {
								return null;
							}
							if (defaultPkgRoot instanceof PackageFragmentRoot && defaultPkgRoot.equals(root))
								return  ((PackageFragmentRoot) root).getPackageFragment(CharOperation.NO_STRINGS);
							else {
								IPackageFragmentRoot[] roots = (IPackageFragmentRoot[]) defaultPkgRoot;
								for (int i = 0; i < roots.length; i++) {
									if (roots[i].equals(root)) {
										return  ((PackageFragmentRoot) root).getPackageFragment(CharOperation.NO_STRINGS);
									}
								}
							}
						}
					} catch (JavaModelException e) {
						return null;
					}
					return null;
				case IJavaElement.PACKAGE_FRAGMENT_ROOT:
					return ((PackageFragmentRoot)fromFactory).getPackageFragment(CharOperation.NO_STRINGS);
			}
		}
		return null;
	}

	/**
	 * Returns the package fragments whose name matches the given
	 * (qualified) name, or <code>null</code> if none exist.
	 *
	 * The name can be:
	 * <ul>
	 *		<li>empty: ""</li>
	 *		<li>qualified: "pack.pack1.pack2"</li>
	 * </ul>
	 * @param partialMatch partial name matches qualify when <code>true</code>,
	 *	only exact name matches qualify when <code>false</code>
	 */
	public IPackageFragment[] findPackageFragments(String name, boolean partialMatch) {
		return findPackageFragments(name, partialMatch, false);
	}

	/**
	 * Returns the package fragments whose name matches the given
	 * (qualified) name or pattern, or <code>null</code> if none exist.
	 *
	 * The name can be:
	 * <ul>
	 *		<li>empty: ""</li>
	 *		<li>qualified: "pack.pack1.pack2"</li>
	 * 	<li>a pattern: "pack.*.util"</li>
	 * </ul>
	 * @param partialMatch partial name matches qualify when <code>true</code>,
	 * @param patternMatch <code>true</code> when the given name might be a pattern,
	 *		<code>false</code> otherwise.
	 */
	public IPackageFragment[] findPackageFragments(String name, boolean partialMatch, boolean patternMatch) {
		boolean isStarPattern = name.equals("*"); //$NON-NLS-1$
		boolean hasPatternChars = isStarPattern || (patternMatch && (name.indexOf('*') >= 0 || name.indexOf('?') >= 0));
		if (partialMatch || hasPatternChars) {
			String[] splittedName = Util.splitOn('.', name, 0, name.length());
			IPackageFragment[] oneFragment = null;
			ArrayList pkgs = null;
			char[] lowercaseName = hasPatternChars && !isStarPattern ? name.toLowerCase().toCharArray() : null;
			Object[][] keys = this.packageFragments.keyTable;
			for (int i = 0, length = keys.length; i < length; i++) {
				String[] pkgName = (String[]) keys[i];
				if (pkgName != null) {
					boolean match = isStarPattern || (hasPatternChars
						? CharOperation.match(lowercaseName, Util.concatCompoundNameToCharArray(pkgName), false)
						: Util.startsWithIgnoreCase(pkgName, splittedName, partialMatch));
					if (match) {
						Object value = this.packageFragments.valueTable[i];
						if (value instanceof PackageFragmentRoot) {
							IPackageFragment pkg = ((PackageFragmentRoot) value).getPackageFragment(pkgName);
							if (oneFragment == null) {
								oneFragment = new IPackageFragment[] {pkg};
							} else {
								if (pkgs == null) {
									pkgs = new ArrayList();
									pkgs.add(oneFragment[0]);
								}
								pkgs.add(pkg);
							}
						} else {
							IPackageFragmentRoot[] roots = (IPackageFragmentRoot[]) value;
							for (int j = 0, length2 = roots.length; j < length2; j++) {
								PackageFragmentRoot root = (PackageFragmentRoot) roots[j];
								IPackageFragment pkg = root.getPackageFragment(pkgName);
								if (oneFragment == null) {
									oneFragment = new IPackageFragment[] {pkg};
								} else {
									if (pkgs == null) {
										pkgs = new ArrayList();
										pkgs.add(oneFragment[0]);
									}
									pkgs.add(pkg);
								}
							}
						}
					}
				}
			}
			if (pkgs == null) return oneFragment;
			int resultLength = pkgs.size();
			IPackageFragment[] result = new IPackageFragment[resultLength];
			pkgs.toArray(result);
			return result;
		} else {
			String[] splittedName = Util.splitOn('.', name, 0, name.length());
			int pkgIndex = this.packageFragments.getIndex(splittedName);
			if (pkgIndex == -1)
				return null;
			Object value = this.packageFragments.valueTable[pkgIndex];
			// reuse existing String[]
			String[] pkgName = (String[]) this.packageFragments.keyTable[pkgIndex];
			if (value instanceof PackageFragmentRoot) {
				return new IPackageFragment[] {((PackageFragmentRoot) value).getPackageFragment(pkgName)};
			} else {
				IPackageFragmentRoot[] roots = (IPackageFragmentRoot[]) value;
				IPackageFragment[] result = new IPackageFragment[roots.length];
				for (int i= 0; i < roots.length; i++) {
					result[i] = ((PackageFragmentRoot) roots[i]).getPackageFragment(pkgName);
				}
				return result;
			}
		}
	}

	/*
	 * Find secondary type for a project.
	 */
	private IType findSecondaryType(String packageName, String typeName, IJavaProject project, boolean waitForIndexes, IProgressMonitor monitor) {
		JavaModelManager manager = JavaModelManager.getJavaModelManager();
		try {
			IJavaProject javaProject = project;
			Map secondaryTypePaths = manager.secondaryTypes(javaProject, waitForIndexes, monitor);
			if (secondaryTypePaths.size() > 0) {
				Map types = (Map) secondaryTypePaths.get(packageName==null?"":packageName); //$NON-NLS-1$
				if (types != null && types.size() > 0) {
					IType type = (IType) types.get(typeName);
					if (type != null) {
						if (JavaModelManager.VERBOSE) {
							Util.verbose("NameLookup FIND SECONDARY TYPES:"); //$NON-NLS-1$
							Util.verbose(" -> pkg name: " + packageName);  //$NON-NLS-1$
							Util.verbose(" -> type name: " + typeName);  //$NON-NLS-1$
							Util.verbose(" -> project: "+project.getElementName()); //$NON-NLS-1$
							Util.verbose(" -> type: " + type.getElementName());  //$NON-NLS-1$
						}
						return type;
					}
				}
			}
		}
		catch (JavaModelException jme) {
			// give up
		}
		return null;
	}

	/**
	 * Find type in the given modules considering secondary types but without waiting for indexes.
	 * It means that secondary types may be not found under certain circumstances...
	 * @see "https://bugs.eclipse.org/bugs/show_bug.cgi?id=118789"
	 */
	public Answer findType(String typeName, String packageName, boolean partialMatch, int acceptFlags, boolean checkRestrictions, IPackageFragmentRoot[] moduleContext) {
		return findType(typeName,
			packageName,
			partialMatch,
			acceptFlags,
			true/* consider secondary types */,
			false/* do NOT wait for indexes */,
			checkRestrictions,
			null,
			moduleContext);
	}

	/**
	 * Find type considering secondary types but without waiting for indexes.
	 * It means that secondary types may be not found under certain circumstances...
	 * @see "https://bugs.eclipse.org/bugs/show_bug.cgi?id=118789"
	 */
	public Answer findType(String typeName, String packageName, boolean partialMatch, int acceptFlags, boolean checkRestrictions) {
		return findType(typeName,
			packageName,
			partialMatch,
			acceptFlags,
			true/* consider secondary types */,
			false/* do NOT wait for indexes */,
			checkRestrictions,
			null);
	}
	/**
	 * Find type. Considering secondary types and waiting for indexes depends on given corresponding parameters.
	 */
	public Answer findType(
			String typeName,
			String packageName,
			boolean partialMatch,
			int acceptFlags,
			boolean considerSecondaryTypes,
			boolean waitForIndexes,
			boolean checkRestrictions,
			IProgressMonitor monitor) {

		return findType(typeName,
				packageName,
				partialMatch,
				acceptFlags,
				considerSecondaryTypes,
				waitForIndexes,
				checkRestrictions,
				monitor,
				null); // no module
	}
	/**
	 * Find type. Considering secondary types and waiting for indexes depends on given corresponding parameters.
	 */
	public Answer findType(
			String typeName,
			String packageName,
			boolean partialMatch,
			int acceptFlags,
			boolean considerSecondaryTypes,
			boolean waitForIndexes,
			boolean checkRestrictions,
			IProgressMonitor monitor,
			IPackageFragmentRoot[] moduleContext) {
		if (packageName == null || packageName.length() == 0) {
			packageName= IPackageFragment.DEFAULT_PACKAGE_NAME;
		} else if (typeName.length() > 0 && ScannerHelper.isLowerCase(typeName.charAt(0))) {
			// see if this is a known package and not a type
			if (findPackageFragments(packageName + "." + typeName, false) != null) return null; //$NON-NLS-1$
		}

		// Look for concerned package fragments
		JavaElementRequestor elementRequestor = new JavaElementRequestor();
		seekPackageFragments(packageName, false, elementRequestor, moduleContext);
		IPackageFragment[] packages= elementRequestor.getPackageFragments();

		// Try to find type in package fragments list
		IType type = null;
		int length= packages.length;
		HashSet projects = null;
		IJavaProject javaProject = null;
		Answer suggestedAnswer = null;
		for (int i= 0; i < length; i++) {
			type = findType(typeName, packages[i], partialMatch, acceptFlags, waitForIndexes, considerSecondaryTypes);
			if (type != null) {
				AccessRestriction accessRestriction = null;
				PackageFragmentRoot root = (PackageFragmentRoot) type.getAncestor(IJavaElement.PACKAGE_FRAGMENT_ROOT);
				ClasspathEntry entry = (ClasspathEntry) this.rootToResolvedEntries.get(root);
				if (entry != null) { // reverse map always contains resolved CP entry
					if (checkRestrictions) {
						accessRestriction = getViolatedRestriction(typeName, packageName, entry, accessRestriction);
					}
				}
				Answer answer = new Answer(type, accessRestriction, entry,
										getModuleDescription(root, this.rootToModule, this.rootToResolvedEntries::get));
				if (!answer.ignoreIfBetter()) {
					if (answer.isBetter(suggestedAnswer))
						return answer;
				} else if (answer.isBetter(suggestedAnswer))
					// remember suggestion and keep looking
					suggestedAnswer = answer;
			}
			else if (suggestedAnswer == null && considerSecondaryTypes) {
				if (javaProject == null) {
					javaProject = packages[i].getJavaProject();
				} else if (projects == null)  {
					if (!javaProject.equals(packages[i].getJavaProject())) {
						projects = new HashSet(3);
						projects.add(javaProject);
						projects.add(packages[i].getJavaProject());
					}
				} else {
					projects.add(packages[i].getJavaProject());
				}
			}
		}
		if (suggestedAnswer != null)
			// no better answer was found
			return suggestedAnswer;

		// If type was not found, try to find it as secondary in source folders
		if (considerSecondaryTypes && javaProject != null) {
			if (projects == null) {
				type = findSecondaryType(packageName, typeName, javaProject, waitForIndexes, monitor);
			} else {
				Iterator allProjects = projects.iterator();
				while (type == null && allProjects.hasNext()) {
					type = findSecondaryType(packageName, typeName, (IJavaProject) allProjects.next(), waitForIndexes, monitor);
				}
			}
		}
		if (type != null) {
			ICompilationUnit unit = type.getCompilationUnit();
			if (unit != null && unit.isWorkingCopy()) { // https://bugs.eclipse.org/bugs/show_bug.cgi?id=421902
				IType[] types = null;
				try {
					types = unit.getTypes();
				} catch (JavaModelException e) {
					return null;
				}
				boolean typeFound = false;
				for (int i = 0, typesLength = types == null ? 0 : types.length; i < typesLength; i++) {
					if (types[i].getElementName().equals(typeName)) {
						typeFound = true;
						break;
					}
				}
				if (!typeFound) type = null;
			}
		}
		return type == null ? null : new Answer(type, null, null);
	}

	public static IModule getModuleDescriptionInfo(IModuleDescription moduleDesc) {
		if (moduleDesc != null) {
			try {
				if (moduleDesc instanceof BinaryModule) {
					IJavaElement parent = moduleDesc.getParent();
					if (parent instanceof ModularClassFile)
						return ((ModularClassFile) parent).getBinaryModuleInfo();
				} else if (moduleDesc instanceof SourceModule) {
					return (IModule)((SourceModule) moduleDesc).getElementInfo();
				} else if (moduleDesc instanceof AutoModule) {
					boolean nameFromManifest = ((AutoModule) moduleDesc).isAutoNameFromManifest();
					return IModule.createAutomatic(moduleDesc.getElementName().toCharArray(), nameFromManifest);
				}
			} catch (JavaModelException e) {
				if (!e.isDoesNotExist())
					Util.log(e);
			}
		}
		return null;
	}

	/** Internal utility, which is able to answer explicit and automatic modules. */
	static IModuleDescription getModuleDescription(IPackageFragmentRoot root, Map<IPackageFragmentRoot,IModuleDescription> cache, Function<IPackageFragmentRoot,IClasspathEntry> rootToEntry) {
		IModuleDescription module = cache.get(root);
		if (module != null)
			return module != NO_MODULE ? module : null;
		try {
			if (root.getKind() == IPackageFragmentRoot.K_SOURCE)
				module = root.getJavaProject().getModuleDescription(); // from any root in this project
			else
				module = root.getModuleDescription();
		} catch (JavaModelException e) {
			cache.put(root, NO_MODULE);
			return null;
		}
		if (module == null) {
			// 2nd attempt: try automatic module:
			IClasspathEntry classpathEntry = rootToEntry.apply(root);
			if (classpathEntry instanceof ClasspathEntry) {
				if (((ClasspathEntry) classpathEntry).isModular()) {
					// modular but no module-info implies this is an automatic module
					module = ((PackageFragmentRoot) root).getAutomaticModuleDescription(classpathEntry);
				}
			}
		}
		cache.put(root, module != null ? module : NO_MODULE);
		return module;
	}

	public IModule getModuleDescriptionInfo(PackageFragmentRoot root) {
		IModuleDescription desc = getModuleDescription(root, this.rootToModule, this.rootToResolvedEntries::get);
		if (desc != null) {
			return getModuleDescriptionInfo(desc);
		}
		return null;
	}
	private AccessRestriction getViolatedRestriction(String typeName, String packageName, ClasspathEntry entry, AccessRestriction accessRestriction) {
		AccessRuleSet accessRuleSet = entry.getAccessRuleSet();
		if (accessRuleSet != null) {
			// TODO (philippe) improve char[] <-> String conversions to avoid performing them on the fly
			char[][] packageChars = CharOperation.splitOn('.', packageName.toCharArray());
			char[] typeChars = typeName.toCharArray();
			accessRestriction = accessRuleSet.getViolatedRestriction(CharOperation.concatWith(packageChars, typeChars, '/'));
		}
		return accessRestriction;
	}

	/**
	 * Returns the first type in the given package whose name
	 * matches the given (unqualified) name, or <code>null</code> if none
	 * exist. Specifying a <code>null</code> package will result in no matches.
	 * The domain of the search is bounded by the Java project from which
	 * this name lookup was obtained.
	 *
	 * @param name the name of the type to find
	 * @param pkg the package to search
	 * @param partialMatch partial name matches qualify when <code>true</code>,
	 *	only exact name matches qualify when <code>false</code>
	 * @param acceptFlags a bit mask describing if classes, interfaces or both classes and interfaces
	 * 	are desired results. If no flags are specified, all types are returned.
	 * @param considerSecondaryTypes flag to know whether secondary types has to be considered
	 * 	during the search
	 *
	 * @see #ACCEPT_CLASSES
	 * @see #ACCEPT_INTERFACES
	 * @see #ACCEPT_ENUMS
	 * @see #ACCEPT_ANNOTATIONS
	 */
	public IType findType(String name, IPackageFragment pkg, boolean partialMatch, int acceptFlags, boolean waitForIndices, boolean considerSecondaryTypes) {
		if (pkg == null)
			return null;

		SingleTypeRequestor typeRequestor = new SingleTypeRequestor();
		seekTypes(name, pkg, partialMatch, acceptFlags, typeRequestor, considerSecondaryTypes);
		IType type = typeRequestor.getType();

		if (type == null && considerSecondaryTypes) {
			type = findSecondaryType(pkg.getElementName(), name, pkg.getJavaProject(), waitForIndices, null);
		}
		return type;
	}

	/**
	 * Returns the first type in the given package whose name
	 * matches the given (unqualified) name, or <code>null</code> if none
	 * exist. Specifying a <code>null</code> package will result in no matches.
	 * The domain of the search is bounded by the Java project from which
	 * this name lookup was obtained.
	 * <br>
	 *	Note that this method does not find secondary types.
	 * <br>
	 * @param name the name of the type to find
	 * @param pkg the package to search
	 * @param partialMatch partial name matches qualify when <code>true</code>,
	 *	only exact name matches qualify when <code>false</code>
	 * @param acceptFlags a bit mask describing if classes, interfaces or both classes and interfaces
	 * 	are desired results. If no flags are specified, all types are returned.
	 *
	 * @see #ACCEPT_CLASSES
	 * @see #ACCEPT_INTERFACES
	 * @see #ACCEPT_ENUMS
	 * @see #ACCEPT_ANNOTATIONS
	 */
	public IType findType(String name, IPackageFragment pkg, boolean partialMatch, int acceptFlags) {
		if (pkg == null) return null;

		// Return first found (ignore duplicates).
		SingleTypeRequestor typeRequestor = new SingleTypeRequestor();
		seekTypes(name, pkg, partialMatch, acceptFlags, typeRequestor, false);
		return typeRequestor.getType();
	}

	/**
	 * Returns the type specified by the qualified name, or <code>null</code>
	 * if none exist. The domain of
	 * the search is bounded by the Java project from which this name lookup was obtained.
	 *
	 * @param name the name of the type to find
	 * @param partialMatch partial name matches qualify when <code>true</code>,
	 *	only exact name matches qualify when <code>false</code>
	 * @param acceptFlags a bit mask describing if classes, interfaces or both classes and interfaces
	 * 	are desired results. If no flags are specified, all types are returned.
	 *
	 * @see #ACCEPT_CLASSES
	 * @see #ACCEPT_INTERFACES
	 * @see #ACCEPT_ENUMS
	 * @see #ACCEPT_ANNOTATIONS
	 */
	public IType findType(String name, boolean partialMatch, int acceptFlags) {
		NameLookup.Answer answer = findType(name, partialMatch, acceptFlags, false/*don't check restrictions*/);
		return answer == null ? null : answer.type;
	}

	public Answer findType(String name, boolean partialMatch, int acceptFlags, boolean checkRestrictions) {
		return findType(name, partialMatch, acceptFlags, true/*consider secondary types*/, true/*wait for indexes*/, checkRestrictions, null);
	}
	public Answer findType(String name, boolean partialMatch, int acceptFlags, boolean considerSecondaryTypes, boolean waitForIndexes, boolean checkRestrictions, IProgressMonitor monitor) {
		int index= name.lastIndexOf('.');
		if (index == 0) {
			return null;  // bug 377710 - e.g. ".Foo" (no package, but not "default" package)
		}
		String className= null, packageName= null;
		if (index == -1) {
			packageName= IPackageFragment.DEFAULT_PACKAGE_NAME;
			className= name;
		} else {
			packageName= name.substring(0, index);
			className= name.substring(index + 1);
		}
		return findType(className, packageName, partialMatch, acceptFlags, considerSecondaryTypes, waitForIndexes, checkRestrictions, monitor);
	}
	public Answer findModule(char[] moduleName) {
		JavaElementRequestor requestor = new JavaElementRequestor();
		seekModule(moduleName, false, requestor);
		IModuleDescription[] modules = requestor.getModules();
		if (modules.length == 0) {
			try {
				// FIXME(SHMOD): only considers source modules?? (MODULEPATH container is only experimental)
				JavaModelManager.getModulePathManager().seekModule(moduleName, false, requestor);
				modules = requestor.getModules();
			} catch (JavaModelException e) {
				// TODO Auto-generated catch block
			}
		}
		if (modules.length > 0) { // TODO what to do??
			return new Answer(modules[0]);
		}
		return null;
	}

	private IType getMemberType(IType type, String name, int dot) {
		while (dot != -1) {
			int start = dot+1;
			dot = name.indexOf('.', start);
			String typeName = name.substring(start, dot == -1 ? name.length() : dot);
			type = type.getType(typeName);
		}
		return type;
	}

	public boolean isPackage(String[] pkgName) {
		return this.packageFragments.get(pkgName) != null;
	}

	public boolean isPackage(String[] pkgName, IPackageFragmentRoot[] moduleContext) {
		if (moduleContext == null) // includes the case where looking for module UNNAMED or ANY
			return isPackage(pkgName);
		
		for (IPackageFragmentRoot moduleRoot : moduleContext) {
			if (moduleRoot.getPackageFragment(String.join(".", pkgName)).exists()) //$NON-NLS-1$
				return true;
		}
		return false;
	}

	private boolean moduleMatches(IPackageFragmentRoot root, IPackageFragmentRoot[] moduleContext) {
		for (IPackageFragmentRoot moduleRoot : moduleContext)
			if (moduleRoot.equals(root))
				return true;
		return false;
	}

	/**
	 * Returns true if the given element's name matches the
	 * specified <code>searchName</code>, otherwise false.
	 *
	 * <p>The <code>partialMatch</code> argument indicates partial matches
	 * should be considered.
	 * NOTE: in partialMatch mode, the case will be ignored, and the searchName must already have
	 *          been lowercased.
	 */
	protected boolean nameMatches(String searchName, IJavaElement element, boolean partialMatch) {
		if (partialMatch) {
			// partial matches are used in completion mode, thus case insensitive mode
			return element.getElementName().toLowerCase().startsWith(searchName);
		} else {
			return element.getElementName().equals(searchName);
		}
	}

	/**
	 * Returns true if the given cu's name matches the
	 * specified <code>searchName</code>, otherwise false.
	 *
	 * <p>The <code>partialMatch</code> argument indicates partial matches
	 * should be considered.
	 * NOTE: in partialMatch mode, the case will be ignored, and the searchName must already have
	 *          been lowercased.
	 */
	protected boolean nameMatches(String searchName, ICompilationUnit cu, boolean partialMatch) {
		if (partialMatch) {
			// partial matches are used in completion mode, thus case insensitive mode
			return cu.getElementName().toLowerCase().startsWith(searchName);
		} else {
			return Util.equalsIgnoreJavaLikeExtension(cu.getElementName(), searchName);
		}
	}

	/**
	 * Notifies the given requestor of all package fragments with the
	 * given name. Checks the requestor at regular intervals to see if the
	 * requestor has canceled. The domain of
	 * the search is bounded by the <code>IJavaProject</code>
	 * this <code>NameLookup</code> was obtained from.
	 *
	 * @param partialMatch partial name matches qualify when <code>true</code>;
	 *	only exact name matches qualify when <code>false</code>
	 */
	public void seekPackageFragments(String name, boolean partialMatch, IJavaElementRequestor requestor, IPackageFragmentRoot[] moduleContext) {
		if (moduleContext == null) {
			seekPackageFragments(name, partialMatch, requestor);
			return;
		}
		if (partialMatch) {
			seekModuleAwarePartialPackageFragments(name, requestor, moduleContext);
			return;
		}
		for (IPackageFragmentRoot moduleRoot : moduleContext) {
			IPackageFragment fragment = moduleRoot.getPackageFragment(name);
			if (fragment.exists())
				requestor.acceptPackageFragment(fragment);
		}
	}

	/**
	 * Notifies the given requestor of all package fragments with the
	 * given name. Checks the requestor at regular intervals to see if the
	 * requestor has canceled. The domain of
	 * the search is bounded by the <code>IJavaProject</code>
	 * this <code>NameLookup</code> was obtained from.
	 *
	 * @param partialMatch partial name matches qualify when <code>true</code>;
	 *	only exact name matches qualify when <code>false</code>
	 */
	public void seekTypes(String pkgName, String name, boolean partialMatch, IJavaElementRequestor requestor, 
			int acceptFlags, IPackageFragmentRoot[] moduleContext, String moduleName) {
		Selector selector = new Selector(moduleName);
		seekPackageFragments(pkgName, true /*partialMatch*/, selector, moduleContext);	
		if (selector.pkgFragments.size() == 0) return;
		for (IPackageFragment pkg : selector.pkgFragments) {
			seekTypes(name, pkg, partialMatch, acceptFlags, requestor);
		}
	}
	
	private void seekModuleAwarePartialPackageFragments(String name, IJavaElementRequestor requestor, IPackageFragmentRoot[] moduleContext) {
		boolean allPrefixMatch = CharOperation.equals(name.toCharArray(), CharOperation.ALL_PREFIX);
		String lName = name.toLowerCase();
		Arrays.stream(this.packageFragments.keyTable)
		.filter(k -> k != null)
		.filter(k -> allPrefixMatch || Util.concatWith((String[])k, '.').toLowerCase().startsWith(lName))
		.forEach(k -> {
			checkModulePackages(requestor, moduleContext, this.packageFragments.getIndex(k));
		});
	}

	private void checkModulePackages(IJavaElementRequestor requestor, IPackageFragmentRoot[] moduleContext, int pkgIndex) {
		Object value = this.packageFragments.valueTable[pkgIndex];
		// reuse existing String[]
		String[] pkgName = (String[]) this.packageFragments.keyTable[pkgIndex];
		if (value instanceof PackageFragmentRoot) {
			PackageFragmentRoot root = (PackageFragmentRoot) value;
			if (moduleMatches(root, moduleContext))
				requestor.acceptPackageFragment(root.getPackageFragment(pkgName));
		} else {
			IPackageFragmentRoot[] roots = (IPackageFragmentRoot[]) value;
			if (roots != null) {
				for (int i = 0, length = roots.length; i < length; i++) {
					if (requestor.isCanceled())
						return;
					PackageFragmentRoot root = (PackageFragmentRoot) roots[i];
					if (moduleMatches(root, moduleContext))
						requestor.acceptPackageFragment(root.getPackageFragment(pkgName));
				}
			}
		}
	}

	@FunctionalInterface
	interface IPrefixMatcherCharArray { // note the reversal in the order of params wrt to the string version.
		boolean matches(char[] prefix, char[] name, boolean isCaseSensitive);
	}
	/**
	 * Notifies the given requestor of all package fragments with the
	 * given name. Checks the requestor at regular intervals to see if the
	 * requestor has canceled. The domain of
	 * the search is bounded by the <code>IJavaProject</code>
	 * this <code>NameLookup</code> was obtained from.
	 *
	 * @param partialMatch partial name matches qualify when <code>true</code>;
	 *	only exact name matches qualify when <code>false</code>
	 */
	public void seekPackageFragments(String name, boolean partialMatch, IJavaElementRequestor requestor) {
/*		if (VERBOSE) {
			Util.verbose(" SEEKING PACKAGE FRAGMENTS");  //$NON-NLS-1$
			Util.verbose(" -> name: " + name);  //$NON-NLS-1$
			Util.verbose(" -> partial match:" + partialMatch);  //$NON-NLS-1$
		}
*/
		if (partialMatch) {
			String[] splittedName = Util.splitOn('.', name, 0, name.length());
			Object[][] keys = this.packageFragments.keyTable;
			for (int i = 0, length = keys.length; i < length; i++) {
				if (requestor.isCanceled())
					return;
				String[] pkgName = (String[]) keys[i];
				if (pkgName != null && Util.startsWithIgnoreCase(pkgName, splittedName, partialMatch)) {
					Object value = this.packageFragments.valueTable[i];
					if (value instanceof PackageFragmentRoot) {
						PackageFragmentRoot root = (PackageFragmentRoot) value;
						requestor.acceptPackageFragment(root.getPackageFragment(pkgName));
					} else {
						IPackageFragmentRoot[] roots = (IPackageFragmentRoot[]) value;
						for (int j = 0, length2 = roots.length; j < length2; j++) {
							if (requestor.isCanceled())
								return;
							PackageFragmentRoot root = (PackageFragmentRoot) roots[j];
							requestor.acceptPackageFragment(root.getPackageFragment(pkgName));
						}
					}
				}
			}
		} else {
			String[] splittedName = Util.splitOn('.', name, 0, name.length());
			int pkgIndex = this.packageFragments.getIndex(splittedName);
			if (pkgIndex != -1) {
				Object value = this.packageFragments.valueTable[pkgIndex];
				// reuse existing String[]
				String[] pkgName = (String[]) this.packageFragments.keyTable[pkgIndex];
				if (value instanceof PackageFragmentRoot) {
					requestor.acceptPackageFragment(((PackageFragmentRoot) value).getPackageFragment(pkgName));
				} else {
					IPackageFragmentRoot[] roots = (IPackageFragmentRoot[]) value;
					if (roots != null) {
						for (int i = 0, length = roots.length; i < length; i++) {
							if (requestor.isCanceled())
								return;
							PackageFragmentRoot root = (PackageFragmentRoot) roots[i];
							requestor.acceptPackageFragment(root.getPackageFragment(pkgName));
						}
					}
				}
			}
		}
	}

	public void seekTypes(String name, IPackageFragment pkg, boolean partialMatch, int acceptFlags, IJavaElementRequestor requestor) {
		seekTypes(name, pkg, partialMatch, acceptFlags, requestor, true);
	}

	public void seekModuleReferences(String name, IJavaElementRequestor requestor, IJavaProject javaProject) {
		seekModule(name.toCharArray(), true /* prefix */, requestor);
	}
	public void seekModule(char[] name, boolean prefixMatch, IJavaElementRequestor requestor) {

		IPrefixMatcherCharArray prefixMatcher = prefixMatch 
				? CharOperation.equals(name, CharOperation.ALL_PREFIX) 
						? (x, y, isCaseSensitive) -> true
						: CharOperation::prefixEquals
				: CharOperation::equals;

		int count= this.packageFragmentRoots.length;
		for (int i= 0; i < count; i++) {
			if (requestor.isCanceled())
				return;
			IPackageFragmentRoot root= this.packageFragmentRoots[i];
			IModuleDescription module = null;
			if (root instanceof JrtPackageFragmentRoot) {
				if (!prefixMatcher.matches(name, root.getElementName().toCharArray(), false)) {
					continue;
				}
			}
			module = getModuleDescription(root, this.rootToModule, this.rootToResolvedEntries::get);
			if (module != null && prefixMatcher.matches(name, module.getElementName().toCharArray(), false)) {
				requestor.acceptModule(module);
			}
		}
	}
/**
	 * Notifies the given requestor of all types (classes and interfaces) in the
	 * given package fragment with the given (unqualified) name.
	 * Checks the requestor at regular intervals to see if the requestor
	 * has canceled. If the given package fragment is <code>null</code>, all types in the
	 * project whose simple name matches the given name are found.
	 *
	 * @param name The name to search
	 * @param pkg The corresponding package fragment
	 * @param partialMatch partial name matches qualify when <code>true</code>;
	 *	only exact name matches qualify when <code>false</code>
	 * @param acceptFlags a bit mask describing if classes, interfaces or both classes and interfaces
	 * 	are desired results. If no flags are specified, all types are returned.
	 * @param requestor The requestor that collects the result
	 *
	 * @see #ACCEPT_CLASSES
	 * @see #ACCEPT_INTERFACES
	 * @see #ACCEPT_ENUMS
	 * @see #ACCEPT_ANNOTATIONS
	 */
	public void seekTypes(String name, IPackageFragment pkg, boolean partialMatch, int acceptFlags, IJavaElementRequestor requestor, boolean considerSecondaryTypes) {
/*		if (VERBOSE) {
			Util.verbose(" SEEKING TYPES");  //$NON-NLS-1$
			Util.verbose(" -> name: " + name);  //$NON-NLS-1$
			Util.verbose(" -> pkg: " + ((JavaElement) pkg).toStringWithAncestors());  //$NON-NLS-1$
			Util.verbose(" -> partial match:" + partialMatch);  //$NON-NLS-1$
		}
*/
		String matchName= partialMatch ? name.toLowerCase() : name;
		if (pkg == null) {
			findAllTypes(matchName, partialMatch, acceptFlags, requestor);
			return;
		}
		PackageFragmentRoot root= (PackageFragmentRoot) pkg.getParent();
		try {

			// look in working copies first
			int firstDot = -1;
			String topLevelTypeName = null;
			int packageFlavor= root.internalKind();
			if (this.typesInWorkingCopies != null || packageFlavor == IPackageFragmentRoot.K_SOURCE) {
				firstDot = matchName.indexOf('.');
				if (!partialMatch)
					topLevelTypeName = firstDot == -1 ? matchName : matchName.substring(0, firstDot);
			}
			if (this.typesInWorkingCopies != null) {
				if (seekTypesInWorkingCopies(matchName, pkg, firstDot, partialMatch, topLevelTypeName, acceptFlags, requestor, considerSecondaryTypes))
					return;
			}

			// look in model
			switch (packageFlavor) {
				case IPackageFragmentRoot.K_BINARY :
					matchName= matchName.replace('.', '$');
					seekTypesInBinaryPackage(matchName, pkg, partialMatch, acceptFlags, requestor);
					break;
				case IPackageFragmentRoot.K_SOURCE :
					seekTypesInSourcePackage(matchName, pkg, firstDot, partialMatch, topLevelTypeName, acceptFlags, requestor);
					if (matchName.indexOf('$') != -1) {
						matchName= matchName.replace('$', '.');
						firstDot = matchName.indexOf('.');
						if (!partialMatch)
							topLevelTypeName = firstDot == -1 ? matchName : matchName.substring(0, firstDot);
						seekTypesInSourcePackage(matchName, pkg, firstDot, partialMatch, topLevelTypeName, acceptFlags, requestor);
					}
					break;
				default :
					return;
			}
		} catch (JavaModelException e) {
			return;
		}
	}

	/**
	 * Performs type search in a binary package.
	 */
	protected void seekTypesInBinaryPackage(String name, IPackageFragment pkg, boolean partialMatch, int acceptFlags, IJavaElementRequestor requestor) {
		long start = -1;
		if (VERBOSE)
			start = System.currentTimeMillis();
		try {
			if (!partialMatch) {
				// exact match
				if (requestor.isCanceled()) return;
				ClassFile classFile =  new ClassFile((PackageFragment) pkg, name);
				if (classFile.existsUsingJarTypeCache()) {
					IType type = classFile.getType();
					if (acceptType(type, acceptFlags, false/*not a source type*/)) {
						requestor.acceptType(type);
					}
				}
			} else {
				IJavaElement[] classFiles= null;
				try {
					classFiles= pkg.getChildren();
				} catch (JavaModelException npe) {
					return; // the package is not present
				}
				int length= classFiles.length;
				String unqualifiedName = name;
				int index = name.lastIndexOf('$');
				if (index != -1) {
					//the type name of the inner type
					unqualifiedName = Util.localTypeName(name, index, name.length());
					// unqualifiedName is empty if the name ends with a '$' sign.
					// See http://dev.eclipse.org/bugs/show_bug.cgi?id=14642
				}
				int matchLength = name.length();
				for (int i = 0; i < length; i++) {
					if (requestor.isCanceled())
						return;
					IJavaElement classFile= classFiles[i];
					// MatchName will never have the extension ".class" and the elementName always will.
					String elementName = classFile.getElementName();
					if (elementName.regionMatches(true /*ignore case*/, 0, name, 0, matchLength)) {
						if (classFile instanceof IOrdinaryClassFile) {
							IType type = ((IOrdinaryClassFile) classFile).getType();
							String typeName = type.getElementName();
							if (typeName.length() > 0 && !Character.isDigit(typeName.charAt(0))) { //not an anonymous type
								if (nameMatches(unqualifiedName, type, true/*partial match*/) && acceptType(type, acceptFlags, false/*not a source type*/))
									requestor.acceptType(type);
							}
						}
					}
				}
			}
		} finally {
			if (VERBOSE)
				this.timeSpentInSeekTypesInBinaryPackage += System.currentTimeMillis()-start;
		}
	}

	/**
	 * Performs type search in a source package.
	 */
	protected void seekTypesInSourcePackage(
			String name,
			IPackageFragment pkg,
			int firstDot,
			boolean partialMatch,
			String topLevelTypeName,
			int acceptFlags,
			IJavaElementRequestor requestor) {

		long start = -1;
		if (VERBOSE)
			start = System.currentTimeMillis();
		try {
			if (!partialMatch) {
				try {
					IJavaElement[] compilationUnits = pkg.getChildren();
					for (int i = 0, length = compilationUnits.length; i < length; i++) {
						if (requestor.isCanceled())
							return;
						IJavaElement cu = compilationUnits[i];
						String cuName = cu.getElementName();
						int lastDot = cuName.lastIndexOf('.');
						if (lastDot != topLevelTypeName.length() || !topLevelTypeName.regionMatches(0, cuName, 0, lastDot))
							continue;

						// https://bugs.eclipse.org/bugs/show_bug.cgi?id=351697
						// If we are looking at source location, just ignore binary types
						if (!(cu instanceof ICompilationUnit))
							continue;
						IType type = ((ICompilationUnit) cu).getType(topLevelTypeName);
						type = getMemberType(type, name, firstDot);
						if (acceptType(type, acceptFlags, true/*a source type*/)) { // accept type checks for existence
							requestor.acceptType(type);
							break;  // since an exact match was requested, no other matching type can exist
						}
					}
				} catch (JavaModelException e) {
					// package doesn't exist -> ignore
				}
			} else {
				try {
					String cuPrefix = firstDot == -1 ? name : name.substring(0, firstDot);
					IJavaElement[] compilationUnits = pkg.getChildren();
					for (int i = 0, length = compilationUnits.length; i < length; i++) {
						if (requestor.isCanceled())
							return;
						IJavaElement cu = compilationUnits[i];
						if (!cu.getElementName().toLowerCase().startsWith(cuPrefix))
							continue;
						try {
							IType[] types = ((ICompilationUnit) cu).getTypes();
							for (int j = 0, typeLength = types.length; j < typeLength; j++)
								seekTypesInTopLevelType(name, firstDot, types[j], requestor, acceptFlags);
						} catch (JavaModelException e) {
							// cu doesn't exist -> ignore
						}
					}
				} catch (JavaModelException e) {
					// package doesn't exist -> ignore
				}
			}
		} finally {
			if (VERBOSE)
				this.timeSpentInSeekTypesInSourcePackage += System.currentTimeMillis()-start;
		}
	}

	private boolean isPrimaryType(String name, IType type, boolean partialMatch) {
		/*
		 * Please have a look at: NameLookup#NameLookup
		 * The HashTable this.typesInWorkingCopies contains values which are HashTables themselves.
		 * The values of these HashTables are either of IType or IType[].
		 * These values are types belonging to a compilation unit. Please check:
		 * CompilationUnit#getTypes().
		 * Therefore the parents of these types would be compilation units.
		 */
		ICompilationUnit cu = (ICompilationUnit) type.getParent();
		String cuName = cu.getElementName().substring(0, cu.getElementName().lastIndexOf('.'));
		/*
		 * Secondary types along with primary types have their parent as the compilation unit.
		 * The names of the primary type would match with their compilation unit.
		 */
		if (!cuName.equals(type.getElementName()))
			return false;
		if (partialMatch) {
			return cuName.regionMatches(0, name, 0, name.length());
		} else {
			return cuName.equals(name);
		}
	}

	/**
	 * Notifies the given requestor of all types (classes and interfaces) in the
	 * given type with the given (possibly qualified) name. Checks
	 * the requestor at regular intervals to see if the requestor
	 * has canceled.
	 */
	protected boolean seekTypesInType(String prefix, int firstDot, IType type, IJavaElementRequestor requestor, int acceptFlags) {
		IType[] types= null;
		try {
			types= type.getTypes();
		} catch (JavaModelException npe) {
			return false; // the enclosing type is not present
		}
		int length= types.length;
		if (length == 0) return false;

		String memberPrefix = prefix;
		boolean isMemberTypePrefix = false;
		if (firstDot != -1) {
			memberPrefix= prefix.substring(0, firstDot);
			isMemberTypePrefix = true;
		}
		for (int i= 0; i < length; i++) {
			if (requestor.isCanceled())
				return false;
			IType memberType= types[i];
			if (memberType.getElementName().toLowerCase().startsWith(memberPrefix))
				if (isMemberTypePrefix) {
					String subPrefix = prefix.substring(firstDot + 1, prefix.length());
					return seekTypesInType(subPrefix, subPrefix.indexOf('.'), memberType, requestor, acceptFlags);
				} else {
					if (acceptType(memberType, acceptFlags, true/*a source type*/)) {
						requestor.acceptMemberType(memberType);
						return true;
					}
				}
		}
		return false;
	}

	protected boolean seekTypesInTopLevelType(String prefix, int firstDot, IType topLevelType, IJavaElementRequestor requestor, int acceptFlags) {
		if (!topLevelType.getElementName().toLowerCase().startsWith(prefix))
			return false;
		if (firstDot == -1) {
			if (acceptType(topLevelType, acceptFlags, true/*a source type*/)) {
				requestor.acceptType(topLevelType);
				return true;
			}
		} else {
			return seekTypesInType(prefix, firstDot, topLevelType, requestor, acceptFlags);
		}
		return false;
	}

	/*
	 * Seeks the type with the given name in the map of types with precedence (coming from working copies)
	 * Return whether a type has been found.
	 */
	protected boolean seekTypesInWorkingCopies(
			String name,
			IPackageFragment pkg,
			int firstDot,
			boolean partialMatch,
			String topLevelTypeName,
			int acceptFlags,
			IJavaElementRequestor requestor,
			boolean considerSecondaryTypes) {

		if (!partialMatch) {
			HashMap typeMap = (HashMap) (this.typesInWorkingCopies == null ? null : this.typesInWorkingCopies.get(pkg));
			if (typeMap != null) {
				Object object = typeMap.get(topLevelTypeName);
				if (object instanceof IType) {
					IType type = getMemberType((IType) object, name, firstDot);
					if (!considerSecondaryTypes && !isPrimaryType(name, (IType) object, false))
						return false;
					if (acceptType(type, acceptFlags, true/*a source type*/)) {
						requestor.acceptType(type);
						return true; // don't continue with compilation unit
					}
				} else if (object instanceof IType[]) {
					if (object == NO_TYPES) {
						// all types where deleted -> type is hidden, OR it is the fake type package-info
						String packageInfoName = String.valueOf(TypeConstants.PACKAGE_INFO_NAME);
						if (packageInfoName.equals(name))
							requestor.acceptType(pkg.getCompilationUnit(packageInfoName.concat(SUFFIX_STRING_java)).getType(name));
						return true;
					}
					IType[] topLevelTypes = (IType[]) object;
					for (int i = 0, length = topLevelTypes.length; i < length; i++) {
						if (requestor.isCanceled())
							return false;
						IType type = getMemberType(topLevelTypes[i], name, firstDot);
						if (acceptType(type, acceptFlags, true/*a source type*/)) {
							requestor.acceptType(type);
							return true; // return the first one
						}
					}
				}
			}
		} else {
			HashMap typeMap = (HashMap) (this.typesInWorkingCopies == null ? null : this.typesInWorkingCopies.get(pkg));
			if (typeMap != null) {
				Iterator iterator = typeMap.values().iterator();
				while (iterator.hasNext()) {
					if (requestor.isCanceled())
						return false;
					Object object = iterator.next();
					if (object instanceof IType) {
						if (!considerSecondaryTypes && !isPrimaryType(name, (IType) object, true))
							continue;
						seekTypesInTopLevelType(name, firstDot, (IType) object, requestor, acceptFlags);
					} else if (object instanceof IType[]) {
						IType[] topLevelTypes = (IType[]) object;
						for (int i = 0, length = topLevelTypes.length; i < length; i++)
							seekTypesInTopLevelType(name, firstDot, topLevelTypes[i], requestor, acceptFlags);
					}
				}
			}
		}
		return false;
	}

	public boolean hasCompilationUnit(char[][] pkgName, IPackageFragmentRoot[] moduleContext) {
		String packageName = CharOperation.toString(pkgName);
		if (packageName == null || packageName.length() == 0) {
			packageName= IPackageFragment.DEFAULT_PACKAGE_NAME;
		}

		// Look for concerned package fragments
		JavaElementRequestor elementRequestor = new JavaElementRequestor();
		seekPackageFragments(packageName, false, elementRequestor, moduleContext);
		IPackageFragment[] packages= elementRequestor.getPackageFragments();
		for (IPackageFragment fragment : packages) {
			try {
				if (fragment.containsJavaResources())
					return true;
			} catch (JavaModelException e) {
				// silent
			}
		}
		return false;
	}
}