/**
* Returns the supplied string as an expression.
*
* <p>This utility function attempts to identify the supplied string as an expression. It tries in
* turn each of the known sub-classes until finally, if none can be recognized, an exception is
* thrown. This function is not immune to mistakenly mis-classifying an expression. It is the
* responsibility of the concrete Exrpession classes to ensure that syntactic integrity is
* maintained with respect to potential cases of mistaken identity.
*
* @param raw The candidate expression
* @throws IllegalArgumentException If no valid expression can be found
*/
static Expression valueOf(String raw) throws IllegalArgumentException {
Expression exp = null;
/*
* TODO It would be better if subclasses registered,
* but this hard coded list will do until such a time
*/
if ((exp = KVOpExpression.valueOf(raw)) == null)
if ((exp = KVExpression.valueOf(raw)) == null) exp = KExpression.valueOf(raw);
if (exp == null) throw new IllegalArgumentException("unrecognized expression: " + raw);
return (exp);
}
