content: /*
   * Copyright 1999-2018 Alibaba Group Holding Ltd.
   *
   * Licensed 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 com.alibaba.nacos.config.server.utils;
  
  /**
   * Generic classes for wildcard characters, decisions, and standard canonical transformations that can be supported by
   * ConfigCenter.
   *
   * @author tianhu E-mail:
   */
  public class RegexParser {
      
      private static final char QUESTION_MARK = '?';
      
      /**
       * Replace input string non-regular special characters with standard regular expression strings; Replace '*' with
       * '.* '? 'is replaced by '{n}', n is the number of consecutive ?; Other special characters that are not alphabetic
       * or numeric are preceded by '\'.
       *
       * @param regex  The expression to be formatted
       * @return format content.
       */
      public static String regexFormat(String regex) {
          if (regex == null) {
              throw new NullPointerException("regex string can't be null");
          }
          StringBuilder result = new StringBuilder();
          result.append('^');
          for (int i = 0; i < regex.length(); i++) {
              char ch = regex.charAt(i);
              if (isAsciiAlphanumeric(ch)) {
                  result.append(ch);
              } else if (ch == '*') {
                  result.append(".*");
              } else if (ch == QUESTION_MARK) {
                  int j = 0;
                  for (; j < regex.length() - i && ch == QUESTION_MARK; j++) {
                      ch = regex.charAt(i + j);
                  }
                  if (j == regex.length() - i) {
                      result.append(".{" + j + "}");
                      break;
                  } else {
                      j -= 1;
                      result.append(".{" + (j) + "}");
                      i += j - 1;
                  }
              } else {
                  result.append("\\" + ch);
              }
          }
          result.append('$');
          return result.toString();
      }
      
      public static boolean containsWildcard(String regex) {
          return (regex.contains("?") || regex.contains("*"));
      }
      
      private static Boolean isAsciiAlphanumeric(final char ch) {
          return  isAsciiAlphaUpper(ch) || isAsciiAlphaLower(ch) || isAsciiNumeric(ch);
      }
      
      private static Boolean isAsciiNumeric(final char ch) {
          return ch >= '0' && ch <= '9';
      }
      
      private static Boolean isAsciiAlphaUpper(final char ch) {
          return ch >= 'A' && ch <= 'Z';
      }
      
      private static Boolean isAsciiAlphaLower(final char ch) {
          return ch >= 'a' && ch <= 'z';
      }
      
  }
  