/*******************************************************************************
 * Copyright (c) 2000, 2019 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *     Harry Terkelsen (het@google.com) - Bug 449262 - Allow the use of third-party Java formatters
 *******************************************************************************/
package org.eclipse.jdt.core;

import org.eclipse.core.resources.IFile;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IConfigurationElement;
import org.eclipse.core.runtime.IExtension;
import org.eclipse.core.runtime.IExtensionPoint;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Platform;
import org.eclipse.core.runtime.Plugin;
import org.eclipse.jdt.core.compiler.IScanner;
import org.eclipse.jdt.core.compiler.ITerminalSymbols;
import org.eclipse.jdt.core.formatter.CodeFormatter;
import org.eclipse.jdt.core.formatter.DefaultCodeFormatterConstants;
import org.eclipse.jdt.core.util.ClassFileBytesDisassembler;
import org.eclipse.jdt.core.util.ClassFormatException;
import org.eclipse.jdt.core.util.IClassFileReader;
import org.eclipse.jdt.internal.compiler.classfmt.ClassFileConstants;
import org.eclipse.jdt.internal.compiler.impl.CompilerOptions;
import org.eclipse.jdt.internal.compiler.util.SuffixConstants;
import org.eclipse.jdt.internal.compiler.util.Util;
import org.eclipse.jdt.internal.core.JarPackageFragmentRoot;
import org.eclipse.jdt.internal.core.JavaElement;
import org.eclipse.jdt.internal.core.JavaModelManager;
import org.eclipse.jdt.internal.core.PackageFragment;
import org.eclipse.jdt.internal.core.util.ClassFileReader;
import org.eclipse.jdt.internal.core.util.Disassembler;
import org.eclipse.jdt.internal.core.util.PublicScanner;
import org.eclipse.jdt.internal.formatter.DefaultCodeFormatter;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.util.HashMap;
import java.util.Map;
import java.util.zip.ZipEntry;
import java.util.zip.ZipFile;

/**
 * Factory for creating various compiler tools, such as scanners, parsers and compilers.
 * <p>
 *  This class provides static methods only.
 * </p>
 *
 * @since 2.0
 * @noinstantiate This class is not intended to be instantiated by clients.
 * @noextend This class is not intended to be subclassed by clients.
 */
@SuppressWarnings({"rawtypes", "unchecked"})
public class ToolFactory {

	/**
	 * This mode is used for formatting new code when some formatter options should not be used.
	 * In particular, options that preserve the indentation of comments are not used.
	 * In the future,  newly added options may be ignored as well.
	 * <p>Clients that are formatting new code are recommended to use this mode.
	 * </p>
	 *
	 * @see DefaultCodeFormatterConstants#FORMATTER_NEVER_INDENT_BLOCK_COMMENTS_ON_FIRST_COLUMN
	 * @see DefaultCodeFormatterConstants#FORMATTER_NEVER_INDENT_LINE_COMMENTS_ON_FIRST_COLUMN
	 * @see #createCodeFormatter(Map, int)
	 * @since 3.3
	 */
	// Supposed to be a non-compile time constant
	public static final int M_FORMAT_NEW = Integer.valueOf(0).intValue();

	/**
	 * This mode is used for formatting existing code when all formatter options should be used.
	 * In particular, options that preserve the indentation of comments are used.
	 * <p>Clients that are formatting existing code are recommended to use this mode.
	 * </p>
	 *
	 * @see DefaultCodeFormatterConstants#FORMATTER_NEVER_INDENT_BLOCK_COMMENTS_ON_FIRST_COLUMN
	 * @see DefaultCodeFormatterConstants#FORMATTER_NEVER_INDENT_LINE_COMMENTS_ON_FIRST_COLUMN
	 * @see #createCodeFormatter(Map, int)
	 * @since 3.3
	 */
	// Supposed to be a non-compile time constant
	public static final int M_FORMAT_EXISTING = Integer.valueOf(1).intValue();

	/**
	 * Create an instance of a code formatter. A code formatter implementation can be contributed via the
	 * extension point "org.eclipse.jdt.core.codeFormatter". If unable to find a registered extension, the factory
	 * will default to using the default code formatter.
	 *
	 * @return an instance of a code formatter
	 * @see ICodeFormatter
	 * @see ToolFactory#createDefaultCodeFormatter(Map)
	 * @deprecated The extension point has been deprecated, use {@link #createCodeFormatter(Map)} instead.
	 */
	public static ICodeFormatter createCodeFormatter(){

			Plugin jdtCorePlugin = JavaCore.getPlugin();
			if (jdtCorePlugin == null) return null;

			IExtensionPoint extension = Platform.getExtensionRegistry().getExtensionPoint(JavaCore.PLUGIN_ID, JavaModelManager.FORMATTER_EXTPOINT_ID);
			if (extension != null) {
				IExtension[] extensions =  extension.getExtensions();
				for(int i = 0; i < extensions.length; i++){
					IConfigurationElement [] configElements = extensions[i].getConfigurationElements();
					for(int j = 0; j < configElements.length; j++){
						try {
							Object execExt = configElements[j].createExecutableExtension("class"); //$NON-NLS-1$
							if (execExt instanceof ICodeFormatter){
								// use first contribution found
								return (ICodeFormatter)execExt;
							}
						} catch(CoreException e){
							// unable to instantiate extension, will answer default formatter instead
						}
					}
				}
			}
		// no proper contribution found, use default formatter
		return createDefaultCodeFormatter(null);
	}

	/**
	 * Create an instance of the built-in code formatter.
	 * <p>The given options should at least provide the source level ({@link JavaCore#COMPILER_SOURCE}),
	 * the  compiler compliance level ({@link JavaCore#COMPILER_COMPLIANCE}) and the target platform
	 * ({@link JavaCore#COMPILER_CODEGEN_TARGET_PLATFORM}).
	 * Without these options, it is not possible for the code formatter to know what kind of source it needs to format.
	 * </p><p>
	 * Note this is equivalent to <code>createCodeFormatter(options, M_FORMAT_NEW)</code>. Thus some code formatter options
	 * may be ignored. See @{link {@link #M_FORMAT_NEW} for more details.
	 * </p>
	 * @param options - the options map to use for formatting with the default code formatter. Recognized options
	 * 	are documented on <code>JavaCore#getDefaultOptions()</code>. If set to <code>null</code>, then use
	 * 	the current settings from <code>JavaCore#getOptions</code>.
	 * @return an instance of the built-in code formatter
	 * @see CodeFormatter
	 * @see JavaCore#getOptions()
	 * @since 3.0
	 */
	public static CodeFormatter createCodeFormatter(Map options){
		return createCodeFormatter(options, M_FORMAT_NEW);
	}

	/**
	 * Creates an instance of a code formatter. A code formatter implementation can be contributed via the extension
	 * point "org.eclipse.jdt.core.javaFormatter". The formatter id specified in the
	 * "org.eclipse.jdt.core.javaFormatter" is instantiated. If unable to find a registered extension, the factory will
	 * default to using the default code formatter.
	 * <p>The given options should at least provide the source level ({@link JavaCore#COMPILER_SOURCE}),
	 * the  compiler compliance level ({@link JavaCore#COMPILER_COMPLIANCE}) and the target platform
	 * ({@link JavaCore#COMPILER_CODEGEN_TARGET_PLATFORM}).
	 * Without these options, it is not possible for the code formatter to know what kind of source it needs to format.
	 * </p>
	 * <p>The given mode determines what options should be enabled when formatting the code. It can have the following
	 * values: {@link #M_FORMAT_NEW}, {@link #M_FORMAT_EXISTING}, but other values may be added in the future.
	 * </p>
	 *
	 * @param options the options map to use for formatting with the default code formatter. Recognized options
	 * 	are documented on <code>JavaCore#getDefaultOptions()</code>. If set to <code>null</code>, then use
	 * 	the current settings from <code>JavaCore#getOptions</code>.
	 * @param mode the given mode to modify the given options.
	 *
	 * @return an instance of the built-in code formatter
	 * @see CodeFormatter
	 * @see JavaCore#getOptions()
	 * @since 3.3
	 */
	public static CodeFormatter createCodeFormatter(Map options, int mode) {
		if (options == null) options = JavaCore.getOptions();
		Map currentOptions = new HashMap(options);
		if (mode == M_FORMAT_NEW) {
			// disable the option for not formatting comments starting on first column
			currentOptions.put(DefaultCodeFormatterConstants.FORMATTER_COMMENT_FORMAT_LINE_COMMENT_STARTING_ON_FIRST_COLUMN, DefaultCodeFormatterConstants.TRUE);
			// disable the option for not indenting comments starting on first column
			currentOptions.put(DefaultCodeFormatterConstants.FORMATTER_NEVER_INDENT_BLOCK_COMMENTS_ON_FIRST_COLUMN, DefaultCodeFormatterConstants.FALSE);
			currentOptions.put(DefaultCodeFormatterConstants.FORMATTER_NEVER_INDENT_LINE_COMMENTS_ON_FIRST_COLUMN, DefaultCodeFormatterConstants.FALSE);
		}
		String formatterId = (String) options.get(JavaCore.JAVA_FORMATTER);
		if (formatterId != null) {
			IExtensionPoint extension = Platform.getExtensionRegistry().getExtensionPoint(JavaCore.PLUGIN_ID,
					JavaCore.JAVA_FORMATTER_EXTENSION_POINT_ID);
			if (extension != null) {
				IExtension[] extensions = extension.getExtensions();
				for (int i = 0; i < extensions.length; i++) {
					IConfigurationElement[] configElements = extensions[i].getConfigurationElements();
					for (int j = 0; j < configElements.length; j++) {
						String initializerID = configElements[j].getAttribute("id"); //$NON-NLS-1$
						if (initializerID != null && initializerID.equals(formatterId)) {
							try {
								Object execExt = configElements[j].createExecutableExtension("class"); //$NON-NLS-1$
								if (execExt instanceof CodeFormatter) {
									CodeFormatter formatter = (CodeFormatter) execExt;
									formatter.setOptions(currentOptions);
									return formatter;
								}
							} catch (CoreException e) {
								org.eclipse.jdt.internal.core.util.Util.log(e.getStatus());
								break;
							}
						}
					}
				}
			}
			org.eclipse.jdt.internal.core.util.Util.log(IStatus.WARNING,
					"Unable to instantiate formatter extension '" + formatterId + "', returning built-in formatter."); //$NON-NLS-1$ //$NON-NLS-2$
		}
		return new DefaultCodeFormatter(currentOptions);
	}

	/**
	 * Create a classfile bytecode disassembler, able to produce a String representation of a given classfile.
	 *
	 * @return a classfile bytecode disassembler
	 * @see ClassFileBytesDisassembler
	 * @since 2.1
	 */
	public static ClassFileBytesDisassembler createDefaultClassFileBytesDisassembler(){
		return new Disassembler();
	}

	/**
	 * Create a classfile bytecode disassembler, able to produce a String representation of a given classfile.
	 *
	 * @return a classfile bytecode disassembler
	 * @see org.eclipse.jdt.core.util.IClassFileDisassembler
	 * @deprecated Use {@link #createDefaultClassFileBytesDisassembler()} instead
	 */
	public static org.eclipse.jdt.core.util.IClassFileDisassembler createDefaultClassFileDisassembler(){
		class DeprecatedDisassembler extends Disassembler implements org.eclipse.jdt.core.util.IClassFileDisassembler {
			// for backward compatibility, defines a disassembler which implements IClassFileDisassembler
		}
		return new DeprecatedDisassembler();
	}

	/**
	 * Create a classfile reader onto a classfile Java element.
	 * Create a default classfile reader, able to expose the internal representation of a given classfile
	 * according to the decoding flag used to initialize the reader.
	 * Answer null if the file named fileName doesn't represent a valid .class file.
	 *
	 * The decoding flags are described in IClassFileReader.
	 *
	 * @param classfile the classfile element to introspect
	 * @param decodingFlag the flag used to decode the class file reader.
	 * @return a default classfile reader
	 *
	 * @see IClassFileReader
	 */
	public static IClassFileReader createDefaultClassFileReader(IClassFile classfile, int decodingFlag){

		IPackageFragmentRoot root = (IPackageFragmentRoot) classfile.getAncestor(IJavaElement.PACKAGE_FRAGMENT_ROOT);
		if (root != null){
			try {
				if (root instanceof JarPackageFragmentRoot) {
					String archiveName = null;
					ZipFile jar = null;
					try {
						jar = ((JarPackageFragmentRoot)root).getJar();
						archiveName = jar.getName();
					} finally {
						JavaModelManager.getJavaModelManager().closeZipFile(jar);
					}
					PackageFragment packageFragment = (PackageFragment) classfile.getParent();
					String classFileName = classfile.getElementName();
					String entryName = org.eclipse.jdt.internal.core.util.Util.concatWith(packageFragment.names, classFileName, '/');
					return createDefaultClassFileReader(archiveName, entryName, decodingFlag);
				} else {
					InputStream in = null;
					try {
						in = ((IFile) ((JavaElement) classfile).resource()).getContents();
						return createDefaultClassFileReader(in, decodingFlag);
					} finally {
						if (in != null)
							try {
								in.close();
							} catch (IOException e) {
								// ignore
							}
					}
				}
			} catch(CoreException e){
				// unable to read
			}
		}
		return null;
	}

	/**
	 * Create a default classfile reader, able to expose the internal representation of a given classfile
	 * according to the decoding flag used to initialize the reader.
	 * Answer null if the input stream contents cannot be retrieved
	 *
	 * The decoding flags are described in IClassFileReader.
	 *
	 * @param stream the given input stream to read
	 * @param decodingFlag the flag used to decode the class file reader.
	 * @return a default classfile reader
	 *
	 * @see IClassFileReader
	 * @since 3.2
	 */
	public static IClassFileReader createDefaultClassFileReader(InputStream stream, int decodingFlag) {
		try {
			return new ClassFileReader(Util.getInputStreamAsByteArray(stream), decodingFlag);
		} catch(ClassFormatException | IOException e) {
			return null;
		}
	}

	/**
	 * Create a default classfile reader, able to expose the internal representation of a given classfile
	 * according to the decoding flag used to initialize the reader.
	 * Answer null if the file named fileName doesn't represent a valid .class file.
	 * The fileName has to be an absolute OS path to the given .class file.
	 *
	 * The decoding flags are described in IClassFileReader.
	 *
	 * @param fileName the name of the file to be read
	 * @param decodingFlag the flag used to decode the class file reader.
	 * @return a default classfile reader
	 *
	 * @see IClassFileReader
	 */
	public static IClassFileReader createDefaultClassFileReader(String fileName, int decodingFlag){
		try {
			return new ClassFileReader(Util.getFileByteContent(new File(fileName)), decodingFlag);
		} catch(ClassFormatException | IOException e) {
			return null;
		}
	}

	/**
	 * Create a default classfile reader, able to expose the internal representation of a given classfile
	 * according to the decoding flag used to initialize the reader.
	 * Answer null if the file named zipFileName doesn't represent a valid zip file or if the zipEntryName
	 * is not a valid entry name for the specified zip file or if the bytes don't represent a valid
	 * .class file according to the JVM specifications.
	 *
	 * The decoding flags are described in IClassFileReader.
	 *
	 * @param zipFileName the name of the zip file
	 * @param zipEntryName the name of the entry in the zip file to be read
	 * @param decodingFlag the flag used to decode the class file reader.
	 * @return a default classfile reader
	 * @see IClassFileReader
	 */
	public static IClassFileReader createDefaultClassFileReader(String zipFileName, String zipEntryName, int decodingFlag){
		ZipFile zipFile = null;
		try {
			if (JavaModelManager.ZIP_ACCESS_VERBOSE) {
				System.out.println("(" + Thread.currentThread() + ") [ToolFactory.createDefaultClassFileReader()] Creating ZipFile on " + zipFileName); //$NON-NLS-1$	//$NON-NLS-2$
			}
			zipFile = new ZipFile(zipFileName);
			ZipEntry zipEntry = zipFile.getEntry(zipEntryName);
			if (zipEntry == null) {
				return null;
			}
			if (!zipEntryName.toLowerCase().endsWith(SuffixConstants.SUFFIX_STRING_class)) {
				return null;
			}
			byte classFileBytes[] = Util.getZipEntryByteContent(zipEntry, zipFile);
			return new ClassFileReader(classFileBytes, decodingFlag);
		} catch(ClassFormatException | IOException e) {
			return null;
		} finally {
			if (zipFile != null) {
				try {
					zipFile.close();
				} catch(IOException e) {
					// ignore
				}
			}
		}
	}

	/**
	 * Create an instance of the default code formatter.
	 *
	 * @param options - the options map to use for formatting with the default code formatter. Recognized options
	 * 	are documented on <code>JavaCore#getDefaultOptions()</code>. If set to <code>null</code>, then use
	 * 	the current settings from <code>JavaCore#getOptions</code>.
	 * @return an instance of the built-in code formatter
	 * @see ICodeFormatter
	 * @see ToolFactory#createCodeFormatter()
	 * @see JavaCore#getOptions()
	 * @deprecated Use {@link #createCodeFormatter(Map)} instead but note the different options
	 */
	public static ICodeFormatter createDefaultCodeFormatter(Map options){
		if (options == null) options = JavaCore.getOptions();
		return new org.eclipse.jdt.internal.formatter.old.CodeFormatter(options);
	}

	/**
	 * Create a scanner, indicating the level of detail requested for tokenizing. The scanner can then be
	 * used to tokenize some source in a Java aware way.
	 * Here is a typical scanning loop:
	 *
	 * <pre>
	 * <code>
	 *   IScanner scanner = ToolFactory.createScanner(false, false, false, false);
	 *   scanner.setSource("int i = 0;".toCharArray());
	 *   while (true) {
	 *     int token = scanner.getNextToken();
	 *     if (token == ITerminalSymbols.TokenNameEOF) break;
	 *     System.out.println(token + " : " + new String(scanner.getCurrentTokenSource()));
	 *   }
	 * </code>
	 * </pre>
	 *
	 * <p>By default the compliance used to create the scanner is the workspace's compliance when running inside the IDE
	 * or 1.4 if running from outside of a headless eclipse.
	 * </p>
	 *
	 * @param tokenizeComments if set to <code>false</code>, comments will be silently consumed
	 * @param tokenizeWhiteSpace if set to <code>false</code>, white spaces will be silently consumed,
	 * @param assertMode if set to <code>false</code>, occurrences of 'assert' will be reported as identifiers
	 * ({@link ITerminalSymbols#TokenNameIdentifier}), whereas if set to <code>true</code>, it
	 * would report assert keywords ({@link ITerminalSymbols#TokenNameassert}). Java 1.4 has introduced
	 * a new 'assert' keyword.
	 * @param recordLineSeparator if set to <code>true</code>, the scanner will record positions of encountered line
	 * separator ends. In case of multi-character line separators, the last character position is considered. These positions
	 * can then be extracted using {@link IScanner#getLineEnds()}. Only non-unicode escape sequences are
	 * considered as valid line separators.
  	 * @return a scanner
	 * @see org.eclipse.jdt.core.compiler.IScanner
	 * @see #createScanner(boolean, boolean, boolean, String, String)
	 */
	@SuppressWarnings("javadoc") // references deprecated TokenNameIdentifier
	public static IScanner createScanner(boolean tokenizeComments, boolean tokenizeWhiteSpace, boolean assertMode, boolean recordLineSeparator){
		// use default workspace compliance
		long complianceLevelValue = CompilerOptions.versionToJdkLevel(JavaCore.getOption(JavaCore.COMPILER_COMPLIANCE));
		if (complianceLevelValue == 0) complianceLevelValue = ClassFileConstants.JDK1_4; // fault-tolerance
		PublicScanner scanner =
			new PublicScanner(
				tokenizeComments,
				tokenizeWhiteSpace,
				false/*nls*/,
				assertMode ? ClassFileConstants.JDK1_4 : ClassFileConstants.JDK1_3/*sourceLevel*/,
				complianceLevelValue,
				null/*taskTags*/,
				null/*taskPriorities*/,
				true/*taskCaseSensitive*/,
				true/*isPreviewEnabled*/,
				recordLineSeparator);
		return scanner;
	}

	/**
	 * Create a scanner, indicating the level of detail requested for tokenizing. The scanner can then be
	 * used to tokenize some source in a Java aware way.
	 * Here is a typical scanning loop:
	 *
	 * <pre>
	 * <code>
	 *   IScanner scanner = ToolFactory.createScanner(false, false, false, false);
	 *   scanner.setSource("int i = 0;".toCharArray());
	 *   while (true) {
	 *     int token = scanner.getNextToken();
	 *     if (token == ITerminalSymbols.TokenNameEOF) break;
	 *     System.out.println(token + " : " + new String(scanner.getCurrentTokenSource()));
	 *   }
	 * </code>
	 * </pre>
	 *
	 * <p>By default the compliance used to create the scanner is the workspace's compliance when running inside the IDE
	 * or 1.4 if running from outside of a headless eclipse.
	 * </p>
	 *
	 * @param tokenizeComments if set to <code>false</code>, comments will be silently consumed
	 * @param tokenizeWhiteSpace if set to <code>false</code>, white spaces will be silently consumed,
	 * @param recordLineSeparator if set to <code>true</code>, the scanner will record positions of encountered line
	 * separator ends. In case of multi-character line separators, the last character position is considered. These positions
	 * can then be extracted using {@link IScanner#getLineEnds()}. Only non-unicode escape sequences are
	 * considered as valid line separators.
	 * @param sourceLevel if set to <code>&quot;1.3&quot;</code> or <code>null</code>, occurrences of 'assert' will be reported as identifiers
	 * ({@link ITerminalSymbols#TokenNameIdentifier}), whereas if set to <code>&quot;1.4&quot;</code>, it
	 * would report assert keywords ({@link ITerminalSymbols#TokenNameassert}). Java 1.4 has introduced
	 * a new 'assert' keyword.
	 * @return a scanner
	 * @see org.eclipse.jdt.core.compiler.IScanner
	 * @see #createScanner(boolean, boolean, boolean, String, String)
	 * @since 3.0
	 */
	@SuppressWarnings("javadoc") // references deprecated TokenNameIdentifier
	public static IScanner createScanner(boolean tokenizeComments, boolean tokenizeWhiteSpace, boolean recordLineSeparator, String sourceLevel) {
		// use default workspace compliance
		long complianceLevelValue = CompilerOptions.versionToJdkLevel(JavaCore.getOption(JavaCore.COMPILER_COMPLIANCE));
		if (complianceLevelValue == 0) complianceLevelValue = ClassFileConstants.JDK1_4; // fault-tolerance
		long sourceLevelValue = CompilerOptions.versionToJdkLevel(sourceLevel);
		if (sourceLevelValue == 0) sourceLevelValue = ClassFileConstants.JDK1_3; // fault-tolerance
		PublicScanner scanner =
			new PublicScanner(
				tokenizeComments,
				tokenizeWhiteSpace,
				false/*nls*/,
				sourceLevelValue /*sourceLevel*/,
				complianceLevelValue,
				null/*taskTags*/,
				null/*taskPriorities*/,
				true/*taskCaseSensitive*/,
				true/*isPreviewEnabled*/,
				recordLineSeparator);
		return scanner;
	}

	/**
	 * Create a scanner, indicating the level of detail requested for tokenizing. The scanner can then be
	 * used to tokenize some source in a Java aware way.
	 * Here is a typical scanning loop:
	 *
	 * <pre>
	 * <code>
	 *   IScanner scanner = ToolFactory.createScanner(false, false, false, false);
	 *   scanner.setSource("int i = 0;".toCharArray());
	 *   while (true) {
	 *     int token = scanner.getNextToken();
	 *     if (token == ITerminalSymbols.TokenNameEOF) break;
	 *     System.out.println(token + " : " + new String(scanner.getCurrentTokenSource()));
	 *   }
	 * </code>
	 * </pre>
	 *
	 * @param tokenizeComments if set to <code>false</code>, comments will be silently consumed
	 * @param tokenizeWhiteSpace if set to <code>false</code>, white spaces will be silently consumed,
	 * @param recordLineSeparator if set to <code>true</code>, the scanner will record positions of encountered line
	 * separator ends. In case of multi-character line separators, the last character position is considered. These positions
	 * can then be extracted using {@link IScanner#getLineEnds()}. Only non-unicode escape sequences are
	 * considered as valid line separators.
	 * @param sourceLevel if set to <code>&quot;1.3&quot;</code> or <code>null</code>, occurrences of 'assert' will be reported as identifiers
	 * ({@link ITerminalSymbols#TokenNameIdentifier}), whereas if set to <code>&quot;1.4&quot;</code>, it
	 * would report assert keywords ({@link ITerminalSymbols#TokenNameassert}). Java 1.4 has introduced
	 * a new 'assert' keyword.
	 * @param complianceLevel This is used to support the Unicode 4.0 character sets. if set to 1.5 or above,
	 * the Unicode 4.0 is supported, otherwise Unicode 3.0 is supported.
	 * @return a scanner
	 * @see org.eclipse.jdt.core.compiler.IScanner
	 *
	 * @since 3.1
	 */
	@SuppressWarnings("javadoc") // references deprecated TokenNameIdentifier
	public static IScanner createScanner(boolean tokenizeComments, boolean tokenizeWhiteSpace, boolean recordLineSeparator, String sourceLevel, String complianceLevel) {
		return createScanner(tokenizeComments, tokenizeWhiteSpace, recordLineSeparator, sourceLevel, complianceLevel, true);
	}
	/**
	 * Create a scanner, indicating the level of detail requested for tokenizing. The scanner can then be
	 * used to tokenize some source in a Java aware way.
	 * Here is a typical scanning loop:
	 *
	 * <pre>
	 * <code>
	 *   IScanner scanner = ToolFactory.createScanner(false, false, false, false);
	 *   scanner.setSource("int i = 0;".toCharArray());
	 *   while (true) {
	 *     int token = scanner.getNextToken();
	 *     if (token == ITerminalSymbols.TokenNameEOF) break;
	 *     System.out.println(token + " : " + new String(scanner.getCurrentTokenSource()));
	 *   }
	 * </code>
	 * </pre>
	 *
	 * @param tokenizeComments if set to <code>false</code>, comments will be silently consumed
	 * @param tokenizeWhiteSpace if set to <code>false</code>, white spaces will be silently consumed,
	 * @param recordLineSeparator if set to <code>true</code>, the scanner will record positions of encountered line
	 * separator ends. In case of multi-character line separators, the last character position is considered. These positions
	 * can then be extracted using {@link IScanner#getLineEnds()}. Only non-unicode escape sequences are
	 * considered as valid line separators.
	 * @param sourceLevel if set to <code>&quot;1.3&quot;</code> or <code>null</code>, occurrences of 'assert' will be reported as identifiers
	 * ({@link ITerminalSymbols#TokenNameIdentifier}), whereas if set to <code>&quot;1.4&quot;</code>, it
	 * would report assert keywords ({@link ITerminalSymbols#TokenNameassert}). Java 1.4 has introduced
	 * a new 'assert' keyword.
	 * @param complianceLevel This is used to support the Unicode 4.0 character sets. if set to 1.5 or above,
	 * the Unicode 4.0 is supported, otherwise Unicode 3.0 is supported.
	 * @param enablePreview specify whether the scanner should look for preview language features for the specified compliance level
	 * @return a scanner
	 * @see org.eclipse.jdt.core.compiler.IScanner
	 *
	 * @since 3.20
	 */
	@SuppressWarnings("javadoc") // references deprecated TokenNameIdentifier
	public static IScanner createScanner(boolean tokenizeComments, boolean tokenizeWhiteSpace, boolean recordLineSeparator, String sourceLevel, String complianceLevel, boolean enablePreview) {
		PublicScanner scanner = null;
		long sourceLevelValue = CompilerOptions.versionToJdkLevel(sourceLevel);
		if (sourceLevelValue == 0) sourceLevelValue = ClassFileConstants.JDK1_3; // fault-tolerance
		long complianceLevelValue = CompilerOptions.versionToJdkLevel(complianceLevel);
		if (complianceLevelValue == 0) complianceLevelValue = ClassFileConstants.JDK1_4; // fault-tolerance
		scanner = new PublicScanner(tokenizeComments, tokenizeWhiteSpace,
				false/*nls*/,sourceLevelValue /*sourceLevel*/, complianceLevelValue,
				null/*taskTags*/, null/*taskPriorities*/, true/*taskCaseSensitive*/,
				enablePreview, recordLineSeparator);
		return scanner;
	}
}
