package org.andromda.translation.ocl.parser;
   
   import java.util.StringTokenizer;
   
   import org.apache.commons.lang.StringUtils;
   
   /**
    * Retrieves information from the OCL parser exceptions in a more user friendly format.
    */
  public class OclParserException
          extends RuntimeException
  {
      private static final long serialVersionUID = 3340016550152777823L;
  
      private StringBuffer messageBuffer;
      private int errorLine;
      private int errorColumn;
  
      /**
       * Constructs an instance of OclParserException.
       *
       * @param message
       */
      public OclParserException(String message)
      {
          super();
          if (StringUtils.isNotBlank(message))
          {
              extractErrorPosition(message);
          }
      }
  
      /**
       * @see Throwable#getMessage()
       */
      public String getMessage()
      {
          int position = 0;
          if (this.errorLine != -1)
          {
              String message = "line: " + errorLine + ' ';
              this.messageBuffer.insert(0, message);
              position = message.length();
          }
          if (this.errorColumn != -1)
          {
              String message = "column: " + errorColumn + ' ';
              this.messageBuffer.insert(position, message);
              position = position + message.length();
          }
          this.messageBuffer.insert(position, "--> ");
          return this.messageBuffer.toString();
      }
  
      /**
       * Extracts the error positioning from exception message, if possible. Assumes SableCC detail message format: "["
       * <line>"," <col>"]" <error message>.
       *
       * @param message the message to extract.
       */
      private void extractErrorPosition(String message)
      {
          this.messageBuffer = new StringBuffer();
          if (StringUtils.isNotBlank(message) && message.charAt(0) == '[')
          {
              // Positional data seems to be available
              StringTokenizer tokenizer = new StringTokenizer(message.substring(1), ",]");
  
              try
              {
                  this.errorLine = Integer.parseInt(tokenizer.nextToken());
                  this.errorColumn = Integer.parseInt(tokenizer.nextToken());
  
                  this.messageBuffer.append(tokenizer.nextToken("").substring(2));
              }
              catch (NumberFormatException ex)
              {
                  // No positional information
                  this.messageBuffer.append(message);
                  this.errorLine = -1;
                  this.errorColumn = -1;
              }
          }
          else
          {
              // No positional information
              this.messageBuffer.append(message);
              this.errorLine = -1;
              this.errorColumn = -1;
          }
      }
  }