Copyright (c) 2000, 2009 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
/*******************************************************************************
 * Copyright (c) 2000, 2009 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
 *******************************************************************************/
package org.eclipse.jdt.internal.core.dom.rewrite;

import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Status;
import org.eclipse.jdt.core.JavaCore;
import org.eclipse.jdt.core.compiler.InvalidInputException;
import org.eclipse.jdt.internal.compiler.parser.Scanner;
import org.eclipse.jdt.internal.compiler.parser.TerminalTokens;

Wraps a scanner and offers convenient methods for finding tokens
/**
 * Wraps a scanner and offers convenient methods for finding tokens
 */
public class TokenScanner {

	public static final int END_OF_FILE= 20001;
	public static final int LEXICAL_ERROR= 20002;
	public static final int DOCUMENT_ERROR= 20003;

	private final Scanner scanner;
	private final int endPosition;

	
Creates a TokenScanner
Params:
scanner – The scanner to be wrapped/**
	 * Creates a TokenScanner
	 * @param scanner The scanner to be wrapped
	 */
	public TokenScanner(Scanner scanner) {
		this.scanner= scanner;
		this.endPosition= this.scanner.getSource().length - 1;
	}

	
Returns the wrapped scanner
Returns:
IScanner/**
	 * Returns the wrapped scanner
	 * @return IScanner
	 */
	public Scanner getScanner() {
		return this.scanner;
	}

	
Sets the scanner offset to the given offset.
Params:
offset – The offset to set/**
	 * Sets the scanner offset to the given offset.
	 * @param offset The offset to set
	 */
	public void setOffset(int offset) {
		this.scanner.resetTo(offset, this.endPosition);
	}

	
Returns:
Returns the offset after the current token/**
	 * @return Returns the offset after the current token
	 */
	public int getCurrentEndOffset() {
		return this.scanner.getCurrentTokenEndPosition() + 1;
	}

	
Returns:
Returns the start offset of the current token/**
	 * @return Returns the start offset of the current token
	 */
	public int getCurrentStartOffset() {
		return this.scanner.getCurrentTokenStartPosition();
	}

	
Returns:
Returns the length of the current token/**
	 * @return Returns the length of the current token
	 */
	public int getCurrentLength() {
		return getCurrentEndOffset() - getCurrentStartOffset();
	}

	
Reads the next token.
Params:
ignoreComments – If set, comments will be overread
Throws:
CoreException – Thrown when the end of the file has been reached (code END_OF_FILE)
or a lexical error was detected while scanning (code LEXICAL_ERROR)
Returns:
Return the token id./**
	 * Reads the next token.
	 * @param ignoreComments If set, comments will be overread
	 * @return Return the token id.
	 * @exception CoreException Thrown when the end of the file has been reached (code END_OF_FILE)
	 * or a lexical error was detected while scanning (code LEXICAL_ERROR)
	 */
	public int readNext(boolean ignoreComments) throws CoreException {
		int curr= 0;
		do {
			try {
				curr= this.scanner.getNextToken();
				if (curr == TerminalTokens.TokenNameEOF) {
					throw new CoreException(createError(END_OF_FILE, "End Of File", null)); //$NON-NLS-1$
				}
			} catch (InvalidInputException e) {
				throw new CoreException(createError(LEXICAL_ERROR, e.getMessage(), e));
			}
		} while (ignoreComments && isComment(curr));
		return curr;
	}

	
Reads the next token from the given offset.
Params:
offset – The offset to start reading from.
ignoreComments – If set, comments will be overread.
Throws:
CoreException – Thrown when the end of the file has been reached (code END_OF_FILE)
or a lexical error was detected while scanning (code LEXICAL_ERROR)
Returns:
Returns the token id./**
	 * Reads the next token from the given offset.
	 * @param offset The offset to start reading from.
	 * @param ignoreComments If set, comments will be overread.
	 * @return Returns the token id.
	 * @exception CoreException Thrown when the end of the file has been reached (code END_OF_FILE)
	 * or a lexical error was detected while scanning (code LEXICAL_ERROR)
	 */
	public int readNext(int offset, boolean ignoreComments) throws CoreException {
		setOffset(offset);
		return readNext(ignoreComments);
	}

	
Reads the next token from the given offset and returns the start offset of the token.
Params:
offset – The offset to start reading from.
ignoreComments – If set, comments will be overread
Throws:
CoreException – Thrown when the end of the file has been reached (code END_OF_FILE)
or a lexical error was detected while scanning (code LEXICAL_ERROR)
Returns:
Returns the start position of the next token./**
	 * Reads the next token from the given offset and returns the start offset of the token.
	 * @param offset The offset to start reading from.
	 * @param ignoreComments If set, comments will be overread
	 * @return Returns the start position of the next token.
	 * @exception CoreException Thrown when the end of the file has been reached (code END_OF_FILE)
	 * or a lexical error was detected while scanning (code LEXICAL_ERROR)
	 */
	public int getNextStartOffset(int offset, boolean ignoreComments) throws CoreException {
		readNext(offset, ignoreComments);
		return getCurrentStartOffset();
	}

	
Reads the next token from the given offset and returns the offset after the token.
Params:
offset – The offset to start reading from.
ignoreComments – If set, comments will be overread
Throws:
CoreException – Thrown when the end of the file has been reached (code END_OF_FILE)
or a lexical error was detected while scanning (code LEXICAL_ERROR)
Returns:
Returns the start position of the next token./**
	 * Reads the next token from the given offset and returns the offset after the token.
	 * @param offset The offset to start reading from.
	 * @param ignoreComments If set, comments will be overread
	 * @return Returns the start position of the next token.
	 * @exception CoreException Thrown when the end of the file has been reached (code END_OF_FILE)
	 * or a lexical error was detected while scanning (code LEXICAL_ERROR)
	 */
	public int getNextEndOffset(int offset, boolean ignoreComments) throws CoreException {
		readNext(offset, ignoreComments);
		return getCurrentEndOffset();
	}

	
Reads until a token is reached.
Params:
tok – The token to read to.
Throws:
CoreException – Thrown when the end of the file has been reached (code END_OF_FILE)
or a lexical error was detected while scanning (code LEXICAL_ERROR)/**
	 * Reads until a token is reached.
	 * @param tok The token to read to.
	 * @exception CoreException Thrown when the end of the file has been reached (code END_OF_FILE)
	 * or a lexical error was detected while scanning (code LEXICAL_ERROR)
	 */
	public void readToToken(int tok) throws CoreException {
		int curr= 0;
		do {
			curr= readNext(false);
		} while (curr != tok);
	}

	
Reads until a token is reached, starting from the given offset.
Params:
tok – The token to read to.
offset – The offset to start reading from.
Throws:
CoreException – Thrown when the end of the file has been reached (code END_OF_FILE)
or a lexical error was detected while scanning (code LEXICAL_ERROR)/**
	 * Reads until a token is reached, starting from the given offset.
	 * @param tok The token to read to.
	 * @param offset The offset to start reading from.
	 * @exception CoreException Thrown when the end of the file has been reached (code END_OF_FILE)
	 * or a lexical error was detected while scanning (code LEXICAL_ERROR)
	 */
	public void readToToken(int tok, int offset) throws CoreException {
		setOffset(offset);
		readToToken(tok);
	}

	
Reads from the given offset until a token is reached and returns the start offset of the token.
Params:
token – The token to be found.
startOffset – The offset to start reading from.
Throws:
CoreException – Thrown when the end of the file has been reached (code END_OF_FILE)
or a lexical error was detected while scanning (code LEXICAL_ERROR)
Returns:
Returns the start position of the found token./**
	 * Reads from the given offset until a token is reached and returns the start offset of the token.
	 * @param token The token to be found.
	 * @param startOffset The offset to start reading from.
	 * @return Returns the start position of the found token.
	 * @exception CoreException Thrown when the end of the file has been reached (code END_OF_FILE)
	 * or a lexical error was detected while scanning (code LEXICAL_ERROR)
	 */
	public int getTokenStartOffset(int token, int startOffset) throws CoreException {
		readToToken(token, startOffset);
		return getCurrentStartOffset();
	}

	
Reads from the given offset until a token is reached and returns the offset after the token.
Params:
token – The token to be found.
startOffset – Offset to start reading from
Throws:
CoreException – Thrown when the end of the file has been reached (code END_OF_FILE)
or a lexical error was detected while scanning (code LEXICAL_ERROR)
Returns:
Returns the end position of the found token./**
	 * Reads from the given offset until a token is reached and returns the offset after the token.
	 * @param token The token to be found.
	 * @param startOffset Offset to start reading from
	 * @return Returns the end position of the found token.
	 * @exception CoreException Thrown when the end of the file has been reached (code END_OF_FILE)
	 * or a lexical error was detected while scanning (code LEXICAL_ERROR)
	 */
	public int getTokenEndOffset(int token, int startOffset) throws CoreException {
		readToToken(token, startOffset);
		return getCurrentEndOffset();
	}

	
Reads from the given offset until a token is reached and returns the offset after the previous token.
Params:
token – The token to be found.
startOffset – The offset to start scanning from.
Throws:
CoreException – Thrown when the end of the file has been reached (code END_OF_FILE)
or a lexical error was detected while scanning (code LEXICAL_ERROR)
Returns:
Returns the end offset of the token previous to the given token./**
	 * Reads from the given offset until a token is reached and returns the offset after the previous token.
	 * @param token The token to be found.
	 * @param startOffset The offset to start scanning from.
	 * @return Returns the end offset of the token previous to the given token.
	 * @exception CoreException Thrown when the end of the file has been reached (code END_OF_FILE)
	 * or a lexical error was detected while scanning (code LEXICAL_ERROR)
	 */
	public int getPreviousTokenEndOffset(int token, int startOffset) throws CoreException {
		setOffset(startOffset);
		int res= startOffset;
		int curr= readNext(false);
		while (curr != token) {
			res= getCurrentEndOffset();
			curr= readNext(false);
		}
		return res;
	}

	public static boolean isComment(int token) {
		return token == TerminalTokens.TokenNameCOMMENT_BLOCK || token == TerminalTokens.TokenNameCOMMENT_JAVADOC
			|| token == TerminalTokens.TokenNameCOMMENT_LINE;
	}

	public static boolean isModifier(int token) {
		switch (token) {
			case TerminalTokens.TokenNamepublic:
			case TerminalTokens.TokenNameprotected:
			case TerminalTokens.TokenNameprivate:
			case TerminalTokens.TokenNamestatic:
			case TerminalTokens.TokenNamefinal:
			case TerminalTokens.TokenNameabstract:
			case TerminalTokens.TokenNamenative:
			case TerminalTokens.TokenNamevolatile:
			case TerminalTokens.TokenNamestrictfp:
			case TerminalTokens.TokenNametransient:
			case TerminalTokens.TokenNamesynchronized:
				return true;
			default:
				return false;
		}
	}

	public static IStatus createError(int code, String message, Throwable throwable) {
		return new Status(IStatus.ERROR, JavaCore.PLUGIN_ID, code, message, throwable);
	}

}