Copyright (c) 2003, 2016 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) 2003, 2016 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.osgi.internal.util;

import java.util.ArrayList;
import java.util.List;

Simple tokenizer class. Used to parse data.
/**
 * Simple tokenizer class. Used to parse data.
 */
public class Tokenizer {
	protected char value[];
	protected int max;
	protected int cursor;

	public Tokenizer(String value) {
		this.value = value.toCharArray();
		max = this.value.length;
		cursor = 0;
	}

	private void skipWhiteSpace() {
		char[] val = value;
		int cur = cursor;

		for (; cur < max; cur++) {
			char c = val[cur];
			if ((c == ' ') || (c == '\t') || (c == '\n') || (c == '\r')) {
				continue;
			}
			break;
		}
		cursor = cur;
	}

	public String getToken(String terminals) {
		skipWhiteSpace();
		char[] val = value;
		int cur = cursor;

		int begin = cur;
		for (; cur < max; cur++) {
			char c = val[cur];
			if ((terminals.indexOf(c) != -1)) {
				break;
			}
		}
		cursor = cur;
		int count = cur - begin;
		if (count > 0) {
			skipWhiteSpace();
			while (count > 0 && (val[begin + count - 1] == ' ' || val[begin + count - 1] == '\t'))
				count--;
			return (new String(val, begin, count));
		}
		return (null);
	}

	public String getEscapedToken(String terminals) {
		char[] val = value;
		int cur = cursor;
		if (cur >= max)
			return null;
		StringBuilder sb = new StringBuilder();
		char c;
		for (; cur < max; cur++) {
			c = val[cur];
			// this is an escaped char
			if (c == '\\') {
				cur++; // skip the escape char
				if (cur == max)
					break;
				c = val[cur]; // include the escaped char
			} else if (terminals.indexOf(c) != -1) {
				break;
			}
			sb.append(c);
		}

		cursor = cur;
		return sb.toString();
	}

	public List<String> getEscapedTokens(String terminals) {
		List<String> result = new ArrayList<>();
		for (String token = getEscapedToken(terminals); token != null; token = getEscapedToken(terminals)) {
			result.add(token);
			getChar(); // consume terminal
		}
		return result;
	}

	public String getString(String terminals, String preserveEscapes) {
		skipWhiteSpace();
		char[] val = value;
		int cur = cursor;

		if (cur < max) {
			if (val[cur] == '\"') /* if a quoted string */
			{
				StringBuilder sb = new StringBuilder();
				cur++; /* skip quote */
				char c = '\0';
				for (; cur < max; cur++) {
					c = val[cur];
					// this is an escaped char
					if (c == '\\') {
						cur++; // skip the escape char
						if (cur == max)
							break;
						c = val[cur]; // include the escaped char
						if (preserveEscapes != null && preserveEscapes.indexOf(c) != -1)
							sb.append('\\'); // must preserve escapes for c
					} else if (c == '\"') {
						break;
					}
					sb.append(c);
				}

				if (c == '\"') {
					cur++;
				} // TODO else error; no closing quote?

				cursor = cur;
				skipWhiteSpace();
				return sb.toString();

			}
			/* not a quoted string; same as token */
			return getToken(terminals);
		}
		return (null);
	}

	public String getString(String terminals) {
		return getString(terminals, null);
	}

	public char getChar() {
		int cur = cursor;
		if (cur < max) {
			cursor = cur + 1;
			return (value[cur]);
		}
		return ('\0'); /* end of value */
	}

	public boolean hasMoreTokens() {
		if (cursor < max) {
			return true;
		}
		return false;
	}
}