/**
    *    Copyright 2009-2015 the original author or authors.
    *
    *    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 org.apache.ibatis.parsing;
  
  /**
   * @author Clinton Begin
   */
  public class GenericTokenParser {
  
    private final String openToken;
    private final String closeToken;
    private final TokenHandler handler;
  
    public GenericTokenParser(String openToken, String closeToken, TokenHandler handler) {
      this.openToken = openToken;
      this.closeToken = closeToken;
      this.handler = handler;
    }
  
    public String parse(String text) {
      StringBuilder builder = new StringBuilder();
      if (text != null && text.length() > 0) {
        char[] src = text.toCharArray();
        int offset = 0;
        int start = text.indexOf(openToken, offset);
        while (start > -1) {
          if (start > 0 && src[start - 1] == '\\') {
            // the variable is escaped. remove the backslash.
            builder.append(src, offset, start - offset - 1).append(openToken);
            offset = start + openToken.length();
          } else {
            int end = text.indexOf(closeToken, start);
            if (end == -1) {
              builder.append(src, offset, src.length - offset);
              offset = src.length;
            } else {
              builder.append(src, offset, start - offset);
              offset = start + openToken.length();
              String content = new String(src, offset, end - offset);
              builder.append(handler.handleToken(content));
              offset = end + closeToken.length();
            }
          }
          start = text.indexOf(openToken, offset);
        }
        if (offset < src.length) {
          builder.append(src, offset, src.length - offset);
        }
      }
      return builder.toString();
    }
  
  }