RexNode compose(RexBuilder rexBuilder, Iterable<RexNode> exprs) {
exprs =
Linq4j.asEnumerable(exprs)
.where(
new Predicate1<RexNode>() {
public boolean apply(RexNode expr) {
return expr != null;
}
});
return RexUtil.composeConjunction(rexBuilder, exprs, false);
}
/**
* Computes the cube of bit sets.
*
* <p>For example, <code>rollup({0}, {1})</code> returns <code>({0, 1}, {0}, {})</code>.
*
* <p>Bit sets are not necessarily singletons: <code>rollup({0, 2}, {3, 5})</code> returns <code>
* ({0, 2, 3, 5}, {0, 2}, {})</code>.
*/
@VisibleForTesting
public static ImmutableList<ImmutableBitSet> cube(List<ImmutableBitSet> bitSets) {
// Given the bit sets [{1}, {2, 3}, {5}],
// form the lists [[{1}, {}], [{2, 3}, {}], [{5}, {}]].
final Set<List<ImmutableBitSet>> builder = Sets.newLinkedHashSet();
for (ImmutableBitSet bitSet : bitSets) {
builder.add(Arrays.asList(bitSet, ImmutableBitSet.of()));
}
Set<ImmutableBitSet> flattenedBitSets = Sets.newLinkedHashSet();
for (List<ImmutableBitSet> o : Linq4j.product(builder)) {
flattenedBitSets.add(ImmutableBitSet.union(o));
}
return ImmutableList.copyOf(flattenedBitSets);
}