/*******************************************************************************
 * Copyright (c) 2005, 2007 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
 *
 
 *******************************************************************************/
package org.eclipse.dltk.internal.core.util;

import java.io.BufferedInputStream;
import java.io.DataInput;
import java.io.EOFException;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintStream;
import java.io.UTFDataFormatException;
import java.net.URI;
import java.util.StringTokenizer;

import org.eclipse.core.filesystem.EFS;
import org.eclipse.core.filesystem.IFileStore;
import org.eclipse.core.resources.IFile;
import org.eclipse.core.resources.IResource;
import org.eclipse.core.resources.ProjectScope;
import org.eclipse.core.resources.ResourceAttributes;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IPath;
import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Platform;
import org.eclipse.core.runtime.Status;
import org.eclipse.core.runtime.preferences.IScopeContext;
import org.eclipse.core.runtime.preferences.InstanceScope;
import org.eclipse.dltk.compiler.CharOperation;
import org.eclipse.dltk.core.DLTKCore;
import org.eclipse.dltk.core.DLTKLanguageManager;
import org.eclipse.dltk.core.IDLTKLanguageToolkit;
import org.eclipse.dltk.core.IScriptProject;
import org.eclipse.dltk.core.IModelElement;
import org.eclipse.dltk.core.IModelStatusConstants;
import org.eclipse.dltk.core.ModelException;
import org.eclipse.dltk.internal.core.ModelElement;
import org.eclipse.dltk.internal.core.ProjectFragment;

public class Util {
	public interface Displayable {
		String displayString(Object o);
	}

	public interface Comparer {
		/**
		 * Returns 0 if a and b are equal, >0 if a is greater than b, or <0 if a
		 * is less than b.
		 */
		int compare(Object a, Object b);
	}

	private static final String ARGUMENTS_DELIMITER = "#"; //$NON-NLS-1$
	private static final String EMPTY_ARGUMENT = "   "; //$NON-NLS-1$
	public final static String UTF_8 = "UTF-8"; //$NON-NLS-1$

	/**
	 * Converts an array of Objects into String.
	 */
	public static String toString(Object[] objects) {
		return toString(objects, new Displayable() {
			public String displayString(Object o) {
				if (o == null)
					return "null"; //$NON-NLS-1$
				return o.toString();
			}
		});
	}

	/**
	 * Converts an array of Objects into String.
	 */
	public static String toString(Object[] objects, Displayable renderer) {
		if (objects == null)
			return ""; //$NON-NLS-1$
		StringBuffer buffer = new StringBuffer(10);
		for (int i = 0; i < objects.length; i++) {
			if (i > 0)
				buffer.append(", "); //$NON-NLS-1$
			buffer.append(renderer.displayString(objects[i]));
		}
		return buffer.toString();
	}

	/*
	 * Add a log entry
	 */
	public static void log(Throwable e, String message) {
		if(e == null || message != null ) {
			return;
		}
		Throwable nestedException;
		if (e instanceof ModelException
				&& (nestedException = ((ModelException) e).getException()) != null) {
			e = nestedException;
		}
		IStatus status = new Status(IStatus.ERROR, DLTKCore.PLUGIN_ID,
				IStatus.ERROR, message, e);
		DLTKCore.getDefault().getLog().log(status);
	}

	/**
	 * Combines two hash codes to make a new one.
	 */
	public static int combineHashCodes(int hashCode1, int hashCode2) {
		return hashCode1 * 17 + hashCode2;
	}

	/**
	 * Sort the strings in the given collection.
	 */
	private static void quickSort(String[] sortedCollection, int left, int right) {
		int original_left = left;
		int original_right = right;
		String mid = sortedCollection[(left + right) / 2];
		do {
			while (sortedCollection[left].compareTo(mid) < 0) {
				left++;
			}
			while (mid.compareTo(sortedCollection[right]) < 0) {
				right--;
			}
			if (left <= right) {
				String tmp = sortedCollection[left];
				sortedCollection[left] = sortedCollection[right];
				sortedCollection[right] = tmp;
				left++;
				right--;
			}
		} while (left <= right);
		if (original_left < right) {
			quickSort(sortedCollection, original_left, right);
		}
		if (left < original_right) {
			quickSort(sortedCollection, left, original_right);
		}
	}

	/**
	 * Compares two arrays using equals() on the elements. Neither can be null.
	 * Only the first len elements are compared. Return false if either array is
	 * shorter than len.
	 */
	public static boolean equalArrays(Object[] a, Object[] b, int len) {
		if (a == b)
			return true;
		if (a.length < len || b.length < len)
			return false;
		for (int i = 0; i < len; ++i) {
			if (a[i] == null) {
				if (b[i] != null)
					return false;
			} else {
				if (!a[i].equals(b[i]))
					return false;
			}
		}
		return true;
	}

	/**
	 * Compares two arrays using equals() on the elements. Either or both arrays
	 * may be null. Returns true if both are null. Returns false if only one is
	 * null. If both are arrays, returns true iff they have the same length and
	 * all elements compare true with equals.
	 */
	public static boolean equalArraysOrNull(Object[] a, Object[] b) {
		if (a == b)
			return true;
		if (a == null || b == null)
			return false;
		int len = a.length;
		if (len != b.length)
			return false;
		for (int i = 0; i < len; ++i) {
			if (a[i] == null) {
				if (b[i] != null)
					return false;
			} else {
				if (!a[i].equals(b[i]))
					return false;
			}
		}
		return true;
	}

	/**
	 * Put all the arguments in one String.
	 */
	public static String getProblemArgumentsForMarker(String[] arguments) {
		StringBuffer args = new StringBuffer(10);
		args.append(arguments.length);
		args.append(':');
		for (int j = 0; j < arguments.length; j++) {
			if (j != 0)
				args.append(ARGUMENTS_DELIMITER);
			if (arguments[j].length() == 0) {
				args.append(EMPTY_ARGUMENT);
			} else {
				args.append(arguments[j]);
			}
		}
		return args.toString();
	}
	
	public static String[] getProblemArgumentsFromMarker(String argumentsString){
		if (argumentsString == null) return null;
		int index = argumentsString.indexOf(':');
		if(index == -1)
			return null;
		
		int length = argumentsString.length();
		int numberOfArg;
		try{
			numberOfArg = Integer.parseInt(argumentsString.substring(0 , index));
		} catch (NumberFormatException e) {
			return null;
		}
		argumentsString = argumentsString.substring(index + 1, length);
		
		String[] args = new String[length];
		int count = 0;
		
		StringTokenizer tokenizer = new StringTokenizer(argumentsString, ARGUMENTS_DELIMITER);
		while(tokenizer.hasMoreTokens()) {
			String argument = tokenizer.nextToken();
			if(argument.equals(EMPTY_ARGUMENT))
				argument = "";  //$NON-NLS-1$
			args[count++] = argument;
		}
		
		if(count != numberOfArg)
			return null;
		
		System.arraycopy(args, 0, args = new String[count], 0, count);
		return args;
	}

	/**
	 * Returns the given file's contents as a byte array.
	 */
	public static byte[] getResourceContentsAsByteArray(IFile file)
			throws ModelException {
		InputStream stream = null;
		try {
			stream = new BufferedInputStream(file.getContents(true));
		} catch (CoreException e) {
			throw new ModelException(e);
		}
		try {
			return org.eclipse.dltk.compiler.util.Util
					.getInputStreamAsByteArray(stream, -1);
		} catch (IOException e) {
			throw new ModelException(e, IModelStatusConstants.IO_EXCEPTION);
		} finally {
			try {
				stream.close();
			} catch (IOException e) {
				// ignore
			}
		}
	}

	public static byte[] getResourceContentsAsByteArray(File file)
			throws ModelException {
		InputStream stream = null;
		try {
			stream = new BufferedInputStream(new FileInputStream(file));
		} catch (FileNotFoundException e) {
			e.printStackTrace();
			return null;
			// throw new ModelException("getResourceContentAsByteArray");
		}
		try {
			return org.eclipse.dltk.compiler.util.Util
					.getInputStreamAsByteArray(stream, -1);
		} catch (IOException e) {
			throw new ModelException(e, IModelStatusConstants.IO_EXCEPTION);
		} finally {
			try {
				stream.close();
			} catch (IOException e) {
				// ignore
			}
		}
	}

	/**
	 * Returns the line separator found in the given text. If it is null, or not
	 * found return the line delimitor for the given project. If the project is
	 * null, returns the line separator for the workspace. If still null, return
	 * the system line separator.
	 */
	public static String getLineSeparator(String text, IScriptProject project) {
		String lineSeparator = null;
		// line delimiter in given text
		if (text != null && text.length() != 0) {
			lineSeparator = findLineSeparator(text.toCharArray());
			if (lineSeparator != null)
				return lineSeparator;
		}
		// line delimiter in project preference
		IScopeContext[] scopeContext;
		if (project != null) {
			scopeContext = new IScopeContext[] { new ProjectScope(project
					.getProject()) };
			lineSeparator = Platform.getPreferencesService().getString(
					Platform.PI_RUNTIME, Platform.PREF_LINE_SEPARATOR, null,
					scopeContext);
			if (lineSeparator != null)
				return lineSeparator;
		}
		// line delimiter in workspace preference
		scopeContext = new IScopeContext[] { new InstanceScope() };
		lineSeparator = Platform.getPreferencesService().getString(
				Platform.PI_RUNTIME, Platform.PREF_LINE_SEPARATOR, null,
				scopeContext);
		if (lineSeparator != null)
			return lineSeparator;
		// system line delimiter
		return org.eclipse.dltk.compiler.util.Util.LINE_SEPARATOR;
	}

	/**
	 * Finds the first line separator used by the given text.
	 * 
	 * @return </code>"\n"</code> or </code>"\r"</code> or </code>"\r\n"</code>,
	 *         or <code>null</code> if none found
	 */
	public static String findLineSeparator(char[] text) {
		// find the first line separator
		int length = text.length;
		if (length > 0) {
			char nextChar = text[0];
			for (int i = 0; i < length; i++) {
				char currentChar = nextChar;
				nextChar = i < length - 1 ? text[i + 1] : ' ';
				switch (currentChar) {
				case '\n':
					return "\n"; //$NON-NLS-1$
				case '\r':
					return nextChar == '\n' ? "\r\n" : "\r"; //$NON-NLS-1$ //$NON-NLS-2$
				}
			}
		}
		// not found
		return null;
	}

	public static void verbose(String log) {
		verbose(log, System.out);
	}

	public static synchronized void verbose(String log, PrintStream printStream) {
		int start = 0;
		do {
			int end = log.indexOf('\n', start);
			printStream.print(Thread.currentThread());
			printStream.print(" "); //$NON-NLS-1$
			printStream.print(log.substring(start, end == -1 ? log.length()
					: end + 1));
			start = end + 1;
		} while (start != 0);
		printStream.println();
	}

	/**
	 * Returns the given file's contents as a character array.
	 */
	public static char[] getResourceContentsAsCharArray(IFile file)
			throws ModelException {
		// Get encoding from file
		String encoding = null;
		try {
			encoding = file.getCharset();
		} catch (CoreException ce) {
			// do not use any encoding
		}
		return getResourceContentsAsCharArray(file, encoding);
	}

	public static char[] getResourceContentsAsCharArray(File file)
			throws ModelException {
		// Get resource contents
		InputStream stream = null;
		try {
			stream = new BufferedInputStream(new FileInputStream(file));
		} catch (Exception e) {
			throw new ModelException(e,
					IModelStatusConstants.ELEMENT_DOES_NOT_EXIST);
		}
		try {
			return org.eclipse.dltk.compiler.util.Util
					.getInputStreamAsCharArray(stream, -1, null);
		} catch (IOException e) {
			throw new ModelException(e, IModelStatusConstants.IO_EXCEPTION);
		} finally {
			try {
				stream.close();
			} catch (IOException e) {
				// ignore
			}
		}
	}

	public static char[] getResourceContentsAsCharArray(IFile file, String encoding) throws ModelException {		
		// Get file length
		// workaround https://bugs.eclipse.org/bugs/show_bug.cgi?id=130736 by using java.io.File if possible
		IPath location = file.getLocation();
		long length;
		if (location == null) {
			// non local file
			try {
				length = EFS.getStore(file.getLocationURI()).fetchInfo().getLength();
			} catch (CoreException e) {
				throw new ModelException(e);
			}
		} else {
			// local file
			length = location.toFile().length();
		}
		
		// Get resource contents
		InputStream stream= null;
		try {
			stream = file.getContents(true);
		} catch (CoreException e) {
			throw new ModelException(e, IModelStatusConstants.ELEMENT_DOES_NOT_EXIST);
		}
		try {
			return org.eclipse.dltk.compiler.util.Util.getInputStreamAsCharArray(stream, (int) length, encoding);
		} catch (IOException e) {
			throw new ModelException(e, IModelStatusConstants.IO_EXCEPTION);
		} finally {
			try {
				stream.close();
			} catch (IOException e) {
				// ignore
			}
		}
	}

	/**
	 * Returns the toString() of the given full path minus the first given
	 * number of segments. The returned string is always a relative path (it has
	 * no leading slash)
	 */
	public static String relativePath(IPath fullPath, int skipSegmentCount) {
		boolean hasTrailingSeparator = fullPath.hasTrailingSeparator();
		String[] segments = fullPath.segments();
		// compute length
		int length = 0;
		int max = segments.length;
		if (max > skipSegmentCount) {
			for (int i1 = skipSegmentCount; i1 < max; i1++) {
				length += segments[i1].length();
			}
			// add the separator lengths
			length += max - skipSegmentCount - 1;
		}
		if (hasTrailingSeparator)
			length++;
		char[] result = new char[length];
		int offset = 0;
		int len = segments.length - 1;
		if (len >= skipSegmentCount) {
			// append all but the last segment, with separators
			for (int i = skipSegmentCount; i < len; i++) {
				int size = segments[i].length();
				segments[i].getChars(0, size, result, offset);
				offset += size;
				result[offset++] = '/';
			}
			// append the last segment
			int size = segments[len].length();
			segments[len].getChars(0, size, result, offset);
			offset += size;
		}
		if (hasTrailingSeparator)
			result[offset++] = '/';
		return new String(result);
	}

	/*
	 * Returns whether the given model element is exluded from its root's
	 * buildpath. It doesn't check whether the root itself is on the buildpath
	 * or not
	 */
	public static final boolean isExcluded(IModelElement element) {
		int elementType = element.getElementType();
		switch (elementType) {
		case IModelElement.SCRIPT_MODEL:
		case IModelElement.SCRIPT_PROJECT:
		case IModelElement.PROJECT_FRAGMENT:
			return false;
		case IModelElement.SCRIPT_FOLDER:
			ProjectFragment root = (ProjectFragment) element
					.getAncestor(IModelElement.PROJECT_FRAGMENT);
			IResource resource = element.getResource();
			return resource != null
					&& isExcluded(resource, root.fullInclusionPatternChars(),
							root.fullExclusionPatternChars());
		case IModelElement.SOURCE_MODULE:
			root = (ProjectFragment) element
					.getAncestor(IModelElement.PROJECT_FRAGMENT);
			resource = element.getResource();
			if (resource != null
					&& isExcluded(resource, root.fullInclusionPatternChars(),
							root.fullExclusionPatternChars()))
				return true;
			return isExcluded(element.getParent());
		default:
			IModelElement cu = element.getAncestor(IModelElement.SOURCE_MODULE);
			return cu != null && isExcluded(cu);
		}
	}

	/*
	 * Returns whether the given resource path matches one of the
	 * inclusion/exclusion patterns. NOTE: should not be asked directly using
	 * pkg root pathes
	 * 
	 */
	public final static boolean isExcluded(IPath resourcePath,
			char[][] inclusionPatterns, char[][] exclusionPatterns,
			boolean isFolderPath) {
		if (inclusionPatterns == null && exclusionPatterns == null)
			return false;
		return org.eclipse.dltk.compiler.util.Util.isExcluded(resourcePath
				.toString().toCharArray(), inclusionPatterns,
				exclusionPatterns, isFolderPath);
	}

	/*
	 * Returns whether the given resource matches one of the exclusion patterns.
	 * NOTE: should not be asked directly using pkg root pathes
	 * 
	 * @see IBuildpathEntry#getExclusionPatterns
	 */
	public final static boolean isExcluded(IResource resource,
			char[][] inclusionPatterns, char[][] exclusionPatterns) {
		IPath path = resource.getFullPath();
		// ensure that folders are only excluded if all of their children are
		// excluded
		int resourceType = resource.getType();
		return isExcluded(path, inclusionPatterns, exclusionPatterns,
				resourceType == IResource.FOLDER
						|| resourceType == IResource.PROJECT);
	}

	public static boolean isValidSourceModule(IModelElement parent,
			IResource resource) {
		try {
			IDLTKLanguageToolkit toolkit = DLTKLanguageManager
					.getLanguageToolkit(parent);
			if (toolkit != null) {
				return toolkit.validateSourceModule(resource).getSeverity() != IStatus.ERROR;
			} else {
				toolkit = DLTKLanguageManager.findToolkit(resource);
				if (toolkit != null) {
					return toolkit.validateSourceModule(resource).getSeverity() != IStatus.ERROR;
				}
				return false;
			}
		} catch (CoreException ex) {
			return false;
		}
	}

	public static boolean isValidSourceModule(IModelElement parent, IPath path) {
		try {
			IDLTKLanguageToolkit toolkit = DLTKLanguageManager
					.getLanguageToolkit(parent);
			if (toolkit != null) {
				return toolkit.validateSourceModule(path).getSeverity() != IStatus.ERROR;
			} else {
				toolkit = DLTKLanguageManager.findToolkit(path);
				if (toolkit != null) {
					return toolkit.validateSourceModule(path).getSeverity() != IStatus.ERROR;
				}
				return false;
			}
		} catch (CoreException ex) {
			return false;
		}
	}

	public static boolean isValidSourcePackageName(IModelElement parent,
			IPath path) {
		try {
			IDLTKLanguageToolkit toolkit = DLTKLanguageManager
					.getLanguageToolkit(parent);
			if (toolkit != null) {
				return toolkit.validateSourcePackage(path);
			}
			return false;
		} catch (CoreException ex) {
			return false;
		}
	}

	public static boolean isValidSourceModuleName(IModelElement parent,
			String name) {
		try {
			IDLTKLanguageToolkit toolkit = DLTKLanguageManager
					.getLanguageToolkit(parent);
			if (toolkit != null) {
				return toolkit.validateSourceModule(parent, name).getSeverity() != IStatus.ERROR;
			} else {
				return false;
			}
		} catch (CoreException ex) {
			return false;
		}
	}

	public static boolean isValidSourceModule(IResource res) {
		IDLTKLanguageToolkit toolkit = DLTKLanguageManager.findToolkit(res);
		if (toolkit != null) {
			return toolkit.validateSourceModule(res).getSeverity() != IStatus.ERROR;
		}
		return false;
	}

	/*
	 * Converts the given URI to a local file. Use the existing file if the uri
	 * is on the local file system. Otherwise fetch it. Returns null if unable
	 * to fetch it.
	 */
	public static File toLocalFile(URI uri, IProgressMonitor monitor)
			throws CoreException {
		IFileStore fileStore = EFS.getStore(uri);
		File localFile = fileStore.toLocalFile(EFS.NONE, monitor);
		if (localFile == null)
			// non local file system
			localFile = fileStore.toLocalFile(EFS.CACHE, monitor);
		return localFile;
	}

	private static void quickSort(char[][] list, int left, int right) {
		int original_left = left;
		int original_right = right;
		char[] mid = list[(left + right) / 2];
		do {
			while (compare(list[left], mid) < 0) {
				left++;
			}
			while (compare(mid, list[right]) < 0) {
				right--;
			}
			if (left <= right) {
				char[] tmp = list[left];
				list[left] = list[right];
				list[right] = tmp;
				left++;
				right--;
			}
		} while (left <= right);
		if (original_left < right) {
			quickSort(list, original_left, right);
		}
		if (left < original_right) {
			quickSort(list, left, original_right);
		}
	}

	/**
	 * Sort the comparable objects in the given collection.
	 */
	private static void quickSort(Comparable[] sortedCollection, int left,
			int right) {
		int original_left = left;
		int original_right = right;
		Comparable mid = sortedCollection[(left + right) / 2];
		do {
			while (sortedCollection[left].compareTo(mid) < 0) {
				left++;
			}
			while (mid.compareTo(sortedCollection[right]) < 0) {
				right--;
			}
			if (left <= right) {
				Comparable tmp = sortedCollection[left];
				sortedCollection[left] = sortedCollection[right];
				sortedCollection[right] = tmp;
				left++;
				right--;
			}
		} while (left <= right);
		if (original_left < right) {
			quickSort(sortedCollection, original_left, right);
		}
		if (left < original_right) {
			quickSort(sortedCollection, left, original_right);
		}
	}

	private static void quickSort(int[] list, int left, int right) {
		int original_left = left;
		int original_right = right;
		int mid = list[(left + right) / 2];
		do {
			while (list[left] < mid) {
				left++;
			}
			while (mid < list[right]) {
				right--;
			}
			if (left <= right) {
				int tmp = list[left];
				list[left] = list[right];
				list[right] = tmp;
				left++;
				right--;
			}
		} while (left <= right);
		if (original_left < right) {
			quickSort(list, original_left, right);
		}
		if (left < original_right) {
			quickSort(list, left, original_right);
		}
	}

	/**
	 * Sort the objects in the given collection using the given comparer.
	 */
	private static void quickSort(Object[] sortedCollection, int left,
			int right, Comparer comparer) {
		int original_left = left;
		int original_right = right;
		Object mid = sortedCollection[(left + right) / 2];
		do {
			while (comparer.compare(sortedCollection[left], mid) < 0) {
				left++;
			}
			while (comparer.compare(mid, sortedCollection[right]) < 0) {
				right--;
			}
			if (left <= right) {
				Object tmp = sortedCollection[left];
				sortedCollection[left] = sortedCollection[right];
				sortedCollection[right] = tmp;
				left++;
				right--;
			}
		} while (left <= right);
		if (original_left < right) {
			quickSort(sortedCollection, original_left, right, comparer);
		}
		if (left < original_right) {
			quickSort(sortedCollection, left, original_right, comparer);
		}
	}

	public static void sort(char[][] list) {
		if (list.length > 1)
			quickSort(list, 0, list.length - 1);
	}

	/**
	 * Sorts an array of Comparable objects in place.
	 */
	public static void sort(Comparable[] objects) {
		if (objects.length > 1)
			quickSort(objects, 0, objects.length - 1);
	}

	public static void sort(int[] list) {
		if (list.length > 1)
			quickSort(list, 0, list.length - 1);
	}

	/**
	 * Sorts an array of objects in place. The given comparer compares pairs of
	 * items.
	 */
	public static void sort(Object[] objects, Comparer comparer) {
		if (objects.length > 1)
			quickSort(objects, 0, objects.length - 1, comparer);
	}

	/**
	 * Sorts an array of strings in place using quicksort.
	 */
	public static void sort(String[] strings) {
		if (strings.length > 1)
			quickSort(strings, 0, strings.length - 1);
	}

	/**
	 * Sorts an array of Comparable objects, returning a new array with the
	 * sorted items. The original array is left untouched.
	 */
	public static Comparable[] sortCopy(Comparable[] objects) {
		int len = objects.length;
		Comparable[] copy = new Comparable[len];
		System.arraycopy(objects, 0, copy, 0, len);
		sort(copy);
		return copy;
	}

	/**
	 * Sorts an array of elements based on their toStringWithAncestors(),
	 * returning a new array with the sorted items. The original array is left
	 * untouched.
	 */
	public static IModelElement[] sortCopy(IModelElement[] elements) {
		int len = elements.length;
		IModelElement[] copy = new IModelElement[len];
		System.arraycopy(elements, 0, copy, 0, len);
		sort(copy, new Comparer() {
			public int compare(Object a, Object b) {
				return ((org.eclipse.dltk.internal.core.ModelElement) a)
						.toStringWithAncestors().compareTo(
								((ModelElement) b).toStringWithAncestors());
			}
		});
		return copy;
	}

	/**
	 * Sorts an array of Strings, returning a new array with the sorted items.
	 * The original array is left untouched.
	 */
	public static Object[] sortCopy(Object[] objects, Comparer comparer) {
		int len = objects.length;
		Object[] copy = new Object[len];
		System.arraycopy(objects, 0, copy, 0, len);
		sort(copy, comparer);
		return copy;
	}

	/**
	 * Sorts an array of Strings, returning a new array with the sorted items.
	 * The original array is left untouched.
	 */
	public static String[] sortCopy(String[] objects) {
		int len = objects.length;
		String[] copy = new String[len];
		System.arraycopy(objects, 0, copy, 0, len);
		sort(copy);
		return copy;
	}

	/**
	 * Compares two byte arrays. Returns <0 if a byte in a is less than the
	 * corresponding byte in b, or if a is shorter, or if a is null. Returns >0
	 * if a byte in a is greater than the corresponding byte in b, or if a is
	 * longer, or if b is null. Returns 0 if they are equal or both null.
	 */
	public static int compare(byte[] a, byte[] b) {
		if (a == b)
			return 0;
		if (a == null)
			return -1;
		if (b == null)
			return 1;
		int len = Math.min(a.length, b.length);
		for (int i = 0; i < len; ++i) {
			int diff = a[i] - b[i];
			if (diff != 0)
				return diff;
		}
		if (a.length > len)
			return 1;
		if (b.length > len)
			return -1;
		return 0;
	}

	/**
	 * Compares two strings lexicographically. The comparison is based on the
	 * Unicode value of each character in the strings.
	 * 
	 * @return the value <code>0</code> if the str1 is equal to str2; a value
	 *         less than <code>0</code> if str1 is lexicographically less than
	 *         str2; and a value greater than <code>0</code> if str1 is
	 *         lexicographically greater than str2.
	 */
	public static int compare(char[] str1, char[] str2) {
		int len1 = str1.length;
		int len2 = str2.length;
		int n = Math.min(len1, len2);
		int i = 0;
		while (n-- != 0) {
			char c1 = str1[i];
			char c2 = str2[i++];
			if (c1 != c2) {
				return c1 - c2;
			}
		}
		return len1 - len2;
	}

	/**
	 * Returns true if the given folder name is valid for a package, false if it
	 * is not.
	 */
	public static boolean isValidFolderNameForPackage(String folderName) {
		return true;
	}

	/**
	 * Return a new array which is the split of the given string using the given
	 * divider. The given end is exclusive and the given start is inclusive.
	 * <br>
	 * <br>
	 * For example:
	 * <ol>
	 * <li>
	 * 
	 * <pre>
	 *       divider = 'b'
	 *       string = &quot;abbaba&quot;
	 *       start = 2
	 *       end = 5
	 *       result =&gt; { &quot;&quot;, &quot;a&quot;, &quot;&quot; }
	 * </pre>
	 * 
	 * </li>
	 * </ol>
	 * 
	 * @param divider
	 *            the given divider
	 * @param string
	 *            the given string
	 * @param start
	 *            the given starting index
	 * @param end
	 *            the given ending index
	 * @return a new array which is the split of the given string using the
	 *         given divider
	 * @throws ArrayIndexOutOfBoundsException
	 *             if start is lower than 0 or end is greater than the array
	 *             length
	 */
	public static final String[] splitOn(char divider, String string,
			int start, int end) {
		int length = string == null ? 0 : string.length();
		if (length == 0 || start > end)
			return CharOperation.NO_STRINGS;
		int wordCount = 1;
		for (int i = start; i < end; i++)
			if (string.charAt(i) == divider)
				wordCount++;
		String[] split = new String[wordCount];
		int last = start, currentWord = 0;
		for (int i = start; i < end; i++) {
			if (string.charAt(i) == divider) {
				split[currentWord++] = string.substring(last, i);
				last = i + 1;
			}
		}
		split[currentWord] = string.substring(last, end);
		return split;
	}

	/**
	 * Returns the concatenation of the given array parts using the given
	 * separator between each part. <br>
	 * <br>
	 * For example:<br>
	 * <ol>
	 * <li>
	 * 
	 * <pre>
	 *       array = {&quot;a&quot;, &quot;b&quot;}
	 *       separator = '.'
	 *       =&gt; result = &quot;a.b&quot;
	 * </pre>
	 * 
	 * </li>
	 * <li>
	 * 
	 * <pre>
	 *       array = {}
	 *       separator = '.'
	 *       =&gt; result = &quot;&quot;
	 * </pre>
	 * 
	 * </li>
	 * </ol>
	 * 
	 * @param array
	 *            the given array
	 * @param separator
	 *            the given separator
	 * @return the concatenation of the given array parts using the given
	 *         separator between each part
	 */
	public static final String concatWith(String[] array, char separator) {
		StringBuffer buffer = new StringBuffer();
		for (int i = 0, length = array.length; i < length; i++) {
			buffer.append(array[i]);
			if (i < length - 1)
				buffer.append(separator);
		}
		return buffer.toString();
	}

	/**
	 * Returns the concatenation of the given array parts using the given
	 * separator between each part and appending the given name at the end. <br>
	 * <br>
	 * For example:<br>
	 * <ol>
	 * <li>
	 * 
	 * <pre>
	 *       name = &quot;c&quot;
	 *       array = { &quot;a&quot;, &quot;b&quot; }
	 *       separator = '.'
	 *       =&gt; result = &quot;a.b.c&quot;
	 * </pre>
	 * 
	 * </li>
	 * <li>
	 * 
	 * <pre>
	 *       name = null
	 *       array = { &quot;a&quot;, &quot;b&quot; }
	 *       separator = '.'
	 *       =&gt; result = &quot;a.b&quot;
	 * </pre>
	 * 
	 * </li>
	 * <li>
	 * 
	 * <pre>
	 *       name = &quot; c&quot;
	 *       array = null
	 *       separator = '.'
	 *       =&gt; result = &quot;c&quot;
	 * </pre>
	 * 
	 * </li>
	 * </ol>
	 * 
	 * @param array
	 *            the given array
	 * @param name
	 *            the given name
	 * @param separator
	 *            the given separator
	 * @return the concatenation of the given array parts using the given
	 *         separator between each part and appending the given name at the
	 *         end
	 */
	public static final String concatWith(String[] array, String name,
			char separator) {
		if (array == null || array.length == 0)
			return name;
		if (name == null || name.length() == 0)
			return concatWith(array, separator);
		StringBuffer buffer = new StringBuffer();
		for (int i = 0, length = array.length; i < length; i++) {
			buffer.append(array[i]);
			buffer.append(separator);
		}
		buffer.append(name);
		return buffer.toString();
	}

	/**
	 * Returns a new array adding the second array at the end of first array. It
	 * answers null if the first and second are null. If the first array is null
	 * or if it is empty, then a new array is created with second. If the second
	 * array is null, then the first array is returned. <br>
	 * <br>
	 * For example:
	 * <ol>
	 * <li>
	 * 
	 * <pre>
	 *       first = null
	 *       second = &quot;a&quot;
	 *       =&gt; result = {&quot;a&quot;}
	 * </pre>
	 * 
	 * <li>
	 * 
	 * <pre>
	 *       first = {&quot;a&quot;}
	 *       second = null
	 *       =&gt; result = {&quot;a&quot;}
	 * </pre>
	 * 
	 * </li>
	 * <li>
	 * 
	 * <pre>
	 *       first = {&quot;a&quot;}
	 *       second = {&quot;b&quot;}
	 *       =&gt; result = {&quot;a&quot;, &quot;b&quot;}
	 * </pre>
	 * 
	 * </li>
	 * </ol>
	 * 
	 * @param first
	 *            the first array to concatenate
	 * @param second
	 *            the array to add at the end of the first array
	 * @return a new array adding the second array at the end of first array, or
	 *         null if the two arrays are null.
	 */
	public static final String[] arrayConcat(String[] first, String second) {
		if (second == null)
			return first;
		if (first == null)
			return new String[] { second };
		int length = first.length;
		if (first.length == 0) {
			return new String[] { second };
		}
		String[] result = new String[length + 1];
		System.arraycopy(first, 0, result, 0, length);
		result[length] = second;
		return result;
	}

	public static boolean isReadOnly(IResource resource) {
		if (resource != null) {
			ResourceAttributes resourceAttributes = resource
					.getResourceAttributes();
			if (resourceAttributes == null)
				return false; // not supported on this platform for this
			// resource
			return resourceAttributes.isReadOnly();
		}
		return true;
	}

	public static void setReadOnly(IResource resource, boolean readOnly) {
		ResourceAttributes resourceAttributes = resource
				.getResourceAttributes();
		if (resourceAttributes == null)
			return; // not supported on this platform for this resource
		resourceAttributes.setReadOnly(readOnly);
		try {
			resource.setResourceAttributes(resourceAttributes);
		} catch (CoreException e) {
			// ignore
		}
	}

	public static boolean equalsIgnoreExtension(String elementName,
			String cuName) {
		// TODO: Add more complex check here.
		if (DLTKCore.DEBUG) {
			System.out.println("//TODO: Add more complex check here.");
		}
		if (elementName.startsWith(cuName)) {
			return true;
		}
		return false;
	}

	/*
	 * Returns whether the given compound name starts with the given prefix.
	 * Returns true if the n first elements of the prefix are equals and the
	 * last element of the prefix is a prefix of the corresponding element in
	 * the compound name.
	 */
	public static boolean startsWithIgnoreCase(String[] compoundName,
			String[] prefix) {
		int prefixLength = prefix.length;
		int nameLength = compoundName.length;
		if (prefixLength > nameLength)
			return false;
		for (int i = 0; i < prefixLength - 1; i++) {
			if (!compoundName[i].equalsIgnoreCase(prefix[i]))
				return false;
		}
		return compoundName[prefixLength - 1].toLowerCase().startsWith(
				prefix[prefixLength - 1].toLowerCase());
	}

	/**
	 * Reads in a string from the specified data input stream. The string has
	 * been encoded using a modified UTF-8 format.
	 * <p>
	 * The first two bytes are read as if by <code>readUnsignedShort</code>.
	 * This value gives the number of following bytes that are in the encoded
	 * string, not the length of the resulting string. The following bytes are
	 * then interpreted as bytes encoding characters in the UTF-8 format and are
	 * converted into characters.
	 * <p>
	 * This method blocks until all the bytes are read, the end of the stream is
	 * detected, or an exception is thrown.
	 * 
	 * @param in
	 *            a data input stream.
	 * @return a Unicode string.
	 * @exception EOFException
	 *                if the input stream reaches the end before all the bytes.
	 * @exception IOException
	 *                if an I/O error occurs.
	 * @exception UTFDataFormatException
	 *                if the bytes do not represent a valid UTF-8 encoding of a
	 *                Unicode string.
	 * @see java.io.DataInputStream#readUnsignedShort()
	 */
	public final static char[] readUTF(DataInput in) throws IOException {
		int utflen = in.readUnsignedShort();
		char str[] = new char[utflen];
		int count = 0;
		int strlen = 0;
		while (count < utflen) {
			int c = in.readUnsignedByte();
			int char2, char3;
			switch (c >> 4) {
			case 0:
			case 1:
			case 2:
			case 3:
			case 4:
			case 5:
			case 6:
			case 7:
				// 0xxxxxxx
				count++;
				str[strlen++] = (char) c;
				break;
			case 12:
			case 13:
				// 110x xxxx 10xx xxxx
				count += 2;
				if (count > utflen)
					throw new UTFDataFormatException();
				char2 = in.readUnsignedByte();
				if ((char2 & 0xC0) != 0x80)
					throw new UTFDataFormatException();
				str[strlen++] = (char) (((c & 0x1F) << 6) | (char2 & 0x3F));
				break;
			case 14:
				// 1110 xxxx 10xx xxxx 10xx xxxx
				count += 3;
				if (count > utflen)
					throw new UTFDataFormatException();
				char2 = in.readUnsignedByte();
				char3 = in.readUnsignedByte();
				if (((char2 & 0xC0) != 0x80) || ((char3 & 0xC0) != 0x80))
					throw new UTFDataFormatException();
				str[strlen++] = (char) (((c & 0x0F) << 12)
						| ((char2 & 0x3F) << 6) | ((char3 & 0x3F) << 0));
				break;
			default:
				// 10xx xxxx, 1111 xxxx
				throw new UTFDataFormatException();
			}
		}
		if (strlen < utflen) {
			System.arraycopy(str, 0, str = new char[strlen], 0, strlen);
		}
		return str;
	}

	/**
	 * Writes a string to the given output stream using UTF-8 encoding in a
	 * machine-independent manner.
	 * <p>
	 * First, two bytes are written to the output stream as if by the
	 * <code>writeShort</code> method giving the number of bytes to follow.
	 * This value is the number of bytes actually written out, not the length of
	 * the string. Following the length, each character of the string is output,
	 * in sequence, using the UTF-8 encoding for the character.
	 * 
	 * @param str
	 *            a string to be written.
	 * @return the number of bytes written to the stream.
	 * @exception IOException
	 *                if an I/O error occurs.
	 * 
	 */
	public static int writeUTF(OutputStream out, char[] str) throws IOException {
		int strlen = str.length;
		int utflen = 0;
		for (int i = 0; i < strlen; i++) {
			int c = str[i];
			if ((c >= 0x0001) && (c <= 0x007F)) {
				utflen++;
			} else if (c > 0x07FF) {
				utflen += 3;
			} else {
				utflen += 2;
			}
		}
		if (utflen > 65535)
			throw new UTFDataFormatException();
		out.write((utflen >>> 8) & 0xFF);
		out.write((utflen >>> 0) & 0xFF);
		if (strlen == utflen) {
			for (int i = 0; i < strlen; i++)
				out.write(str[i]);
		} else {
			for (int i = 0; i < strlen; i++) {
				int c = str[i];
				if ((c >= 0x0001) && (c <= 0x007F)) {
					out.write(c);
				} else if (c > 0x07FF) {
					out.write(0xE0 | ((c >> 12) & 0x0F));
					out.write(0x80 | ((c >> 6) & 0x3F));
					out.write(0x80 | ((c >> 0) & 0x3F));
				} else {
					out.write(0xC0 | ((c >> 6) & 0x1F));
					out.write(0x80 | ((c >> 0) & 0x3F));
				}
			}
		}
		return utflen + 2; // the number of bytes written to the stream
	}


	/**
	 * Scans the given string for an identifier starting at the given index and
	 * returns the index of the last character. Stop characters are: ";", ":",
	 * "&lt;", "&gt;", "/", ".".
	 * 
	 * @param string
	 *            the signature string
	 * @param start
	 *            the 0-based character index of the first character
	 * @return the 0-based character index of the last character
	 * @exception IllegalArgumentException
	 *                if this is not an identifier
	 */
	public static int scanIdentifier(char[] string, int start) {
		// need a minimum 1 char
		if (start >= string.length) {
			throw new IllegalArgumentException();
		}
		int p = start;
		while (true) {
			char c = string[p];
			if (c == '<' || c == '>' || c == ':' || c == ';' || c == '.'
					|| c == '/') {
				return p - 1;
			}
			p++;
			if (p == string.length) {
				return p - 1;
			}
		}
	}
}
