content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you under the Apache License, Version 2.0 (the
   * "License"); you may not use this file except in compliance
   * with the License.  You may obtain a copy of the License at
   *
   * http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing,
   * software distributed under the License is distributed on an
   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   * KIND, either express or implied.  See the License for the
   * specific language governing permissions and limitations
   * under the License.
   */
  package org.apache.chemistry.opencmis.server.support.query;
  
  public final class StringUtil {
  
      private StringUtil() {
      }
  
      /**
       * Removes all escape sequences in a string and return unescaped string
       * escape character is backslash \, so \\ --&gt; \, \' --&gt; ' additional
       * escaped characters can be allowed in escapedChars.
       * 
       * @param literal
       *            String to unescape
       * @param escapedChars
       *            set of allowed characters to be escaped with a backslash, if
       *            set to null then ' (quote) and \ (backslash) are allowed to be
       *            escaped
       * @return unescaped literal or null if the literal is illegal
       */
      public static String unescape(String literal, String escapedChars) {
          char c = '?';
          int i = 0;
  
          if (null == escapedChars) {
              escapedChars = "\\'";
          }
  
          if (null == literal) {
              return null;
          }
  
          int len = literal.length();
  
          if (len == 1 && literal.charAt(0) == '\\') {
              return null;
          }
  
          if (len > 1 && literal.charAt(len - 2) != '\\' && literal.charAt(len - 1) == '\\') {
              return null;
          }
  
          StringBuilder sb = new StringBuilder(len + 16);
  
          for (i = 0; i < len; i++) {
              c = literal.charAt(i);
              if (c == '\\') {
                  char escChar = literal.charAt(i + 1);
                  boolean matched = false;
                  for (int j = 0; j < escapedChars.length(); j++) {
                      if (escChar == escapedChars.charAt(j)) {
                          sb.append(escChar);
                          ++i;
                          matched = true;
                          break;
                      }
                  }
  
                  if (!matched) {
                      return null;
                  }
  
              } else {
                  sb.append(literal.charAt(i));
              }
          }
  
          return sb.toString();
      }
  
  }
  