code: public static ParsedExpression parse(String expression) {
          ParsedExpression pe = (ParsedExpression)PARSED_CACHE.get(expression);
  
          if(pe != null)
              return pe;
  
          try {
              NetUIELParser learn = new NetUIELParser(new StringReader(expression));
  
              ParsedExpression expr = learn.parse();
              expr.seal();
  
              /* infrequent; this should only happen when there is a cache miss */
              synchronized(PARSED_CACHE) {
                  PARSED_CACHE.put(expression, expr);
              }
  
              return expr;
          } catch(ParseException e) {
              String msg = "Error occurred parsing expression \"" + expression + "\".";
              LOGGER.error(msg, e);
              throw new ExpressionParseException(msg, e);
          } catch(TokenMgrError tm) {
              String msg = "Error occurred parsing expression \"" + expression + "\".";
              LOGGER.error(msg, tm);
              throw new ExpressionParseException(msg, tm);
          }
      }
docs: Parse the givne String into a {@link ParsedExpression}.
  @param expression the expression
  @return the parsed expression