/**
* Return true if the supplied expression "contradicts" this expression. If the supplied
* expression is not of the same type, then it cannot contradict it. If the names are different
* then there can be no contradiction.
*
* <p>Contradiction occurs if the value is different.
*
* @param o Expression to examine for contradiction.
*/
public boolean contradicts(Expression o) {
if (!(o instanceof KVExpression)) return (false);
KVExpression other = (KVExpression) o;
if (getName().compareTo(other.getName()) != 0) return (false);
if (val.compareTo(other.getValue()) == 0) return (false);
return (true);
}
/**
* Indicates whether some other KVExpression is "equal to this one.
*
* @param o the reference object with which to compare.
* @return <code>true</code> if this object is the same as the o argument; <code>false</code>
* otherwise.
* @see #hashCode()
*/
public boolean equals(Object o) {
if (o == this) return (true);
if (!(o instanceof KVExpression)) return (false);
KVExpression other = (KVExpression) o;
if (getName().compareTo(other.getName()) != 0 || val.compareTo(other.getValue()) != 0)
return (false);
return (true);
}
/**
* 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);
}