/**
* Chooses between two non null items based on the value of one of their argument
*
* @param first The first item on which make the choice
* @param second The second item on which make the choice
* @return The choosen item
*/
@Override
protected T choose(T first, T second) {
A firstArgument = argument.evaluate(first);
if (firstArgument == null) return second;
A secondArgument = argument.evaluate(second);
if (secondArgument == null) return first;
return chooseOnArgument(first, firstArgument, second, secondArgument);
}
public Object execute(Evaluator evaluator, Argument[] arguments) {
final Argument memberListExp = arguments[0];
final List memberList = (List) memberListExp.evaluate(evaluator);
final Argument exp = arguments[1];
int nullCount = 0;
int missCount = 0;
for (int i = memberList.size() - 1; i >= 0; --i) {
Member member = (Member) memberList.get(i);
// Create an evaluator with the member as its context.
Evaluator subEvaluator = evaluator.push(member);
int missCountBefore = subEvaluator.getMissCount();
final Object o = exp.evaluateScalar(subEvaluator);
int missCountAfter = subEvaluator.getMissCount();
if (Util.isNull(o)) {
++nullCount;
continue;
}
if (missCountAfter > missCountBefore) {
// There was a cache miss while evaluating the expression, so
// the result is bogus. It would be a mistake to give up after
// one cache miss, because then it would take us N
// evaluate/fetch passes to move back through N members, which
// is way too many.
//
// Carry on until we have seen as many misses as we have seen
// null cells. The effect of this policy is that each pass
// examines twice as many cells as the previous pass. Thus
// we can move back through N members in log2(N) passes.
++missCount;
if (missCount < 2 * nullCount + 1) {
continue;
}
}
if (o == RolapUtil.valueNotReadyException) {
// Value is not in the cache yet, so we don't know whether
// it will be empty. Carry on...
continue;
}
if (o instanceof RuntimeException) {
RuntimeException runtimeException = (RuntimeException) o;
if (o == RolapUtil.valueNotReadyException) {
// Value is not in the cache yet, so we don't know whether
// it will be empty. Carry on...
continue;
}
return runtimeException;
}
return member;
}
// Not found. Return the hierarchy's 'null member'.
// It is possible that a MemberType has a Dimension but
// no hierarchy, so we have to just get the type's Dimension's
// default hierarchy and return it's null member.
final Hierarchy hierarchy = memberListExp.getType().getHierarchy();
return (hierarchy == null)
? memberListExp.getType().getDimension().getHierarchies()[0].getNullMember()
: hierarchy.getNullMember();
}
/** {@inheritDoc} */
public int compare(GroupItem<?> group1, GroupItem<?> group2) {
return nullSafeCompare(
argument.evaluate(group1.getGroupKey()), argument.evaluate(group2.getGroupKey()));
}
