code: private String toRegex(String mappings)
      {
          assert mappings != null;
  
          // Get rid of spaces
          mappings = mappings.replaceAll("\\s", "");
  
          // Escape '.'
          mappings = mappings.replaceAll("\\.", "\\\\.");
  
          // Change '*' to '.*' to represent any match
          mappings = mappings.replaceAll("\\*", ".*");
  
          // Split the mappings by changing ';' to '|'
          mappings = mappings.replaceAll(";", "|");
  
          return mappings;
      }
docs: Convert the specified mapping string to an equivalent regular expression.
  
  @param mappings
  le mapping string
  
  @return an uncompiled regular expression representing the mappings