001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.juneau.uon;
018
019import static org.apache.juneau.common.utils.StringUtils.*;
020
021import org.apache.juneau.common.utils.*;
022
023/**
024 * Utility methods for the UON and UrlEncoding serializers and parsers.
025 *
026 * <h5 class='section'>See Also:</h5><ul>
027 *    <li class='link'><a class="doclink" href="https://juneau.apache.org/docs/topics/UonBasics">UON Basics</a>
028 * </ul>
029 */
030public class UonUtils {
031
032   private static final AsciiSet needsQuoteChars = AsciiSet.of("),=\n\t\r\b\f ");
033   private static final AsciiSet maybeNeedsQuotesFirstChar = AsciiSet.of("),=\n\t\r\b\f tfn+-.#0123456789");
034
035   /**
036    * Returns <jk>true</jk> if the specified string needs to be quoted per UON notation.
037    *
038    * <p>
039    * For example, strings that start with '(' or '@' or look like boolean or numeric values need to be quoted.
040    *
041    * @param s The string to test.
042    * @return <jk>true</jk> if the specified string needs to be quoted per UON notation.
043    */
044   public static boolean needsQuotes(String s) {
045      char c0 = s.isEmpty() ? 0 : s.charAt(0);
046      return (
047         s.isEmpty()
048         || c0 == '@'
049         || c0 == '('
050         || needsQuoteChars.contains(s)
051         || (
052            maybeNeedsQuotesFirstChar.contains(c0)
053            && (
054               "true".equals(s)
055               || "false".equals(s)
056               || "null".equals(s)
057               || isNumeric(s)
058            )
059         )
060      );
061   }
062}