/**
* Analyzes an expression in a GROUP BY clause.
*
* <p>It may be an expression, an empty list (), or a call to {@code GROUPING SETS}, {@code CUBE}
* or {@code ROLLUP}.
*
* <p>Each group item produces a list of group sets, which are written to {@code topBuilder}. To
* find the grouping sets of the query, we will take the cartesian product of the group sets.
*/
public static void analyzeGroupItem(
SqlValidatorScope scope,
List<SqlNode> groupExprs,
Map<Integer, Integer> groupExprProjection,
ImmutableList.Builder<ImmutableList<ImmutableBitSet>> topBuilder,
SqlNode groupExpr) {
final ImmutableList.Builder<ImmutableBitSet> builder;
switch (groupExpr.getKind()) {
case CUBE:
case ROLLUP:
// E.g. ROLLUP(a, (b, c)) becomes [{0}, {1, 2}]
// then we roll up to [(0, 1, 2), (0), ()] -- note no (0, 1)
List<ImmutableBitSet> bitSets =
analyzeGroupTuple(
scope, groupExprs, groupExprProjection, ((SqlCall) groupExpr).getOperandList());
switch (groupExpr.getKind()) {
case ROLLUP:
topBuilder.add(rollup(bitSets));
return;
default:
topBuilder.add(cube(bitSets));
return;
}
case OTHER:
if (groupExpr instanceof SqlNodeList) {
SqlNodeList list = (SqlNodeList) groupExpr;
for (SqlNode node : list) {
analyzeGroupItem(scope, groupExprs, groupExprProjection, topBuilder, node);
}
return;
}
// fall through
case GROUPING_SETS:
default:
builder = ImmutableList.builder();
convertGroupSet(scope, groupExprs, groupExprProjection, builder, groupExpr);
topBuilder.add(builder.build());
}
}
/** Analyzes a GROUPING SETS item in a GROUP BY clause. */
private static void convertGroupSet(
SqlValidatorScope scope,
List<SqlNode> groupExprs,
Map<Integer, Integer> groupExprProjection,
ImmutableList.Builder<ImmutableBitSet> builder,
SqlNode groupExpr) {
switch (groupExpr.getKind()) {
case GROUPING_SETS:
final SqlCall call = (SqlCall) groupExpr;
for (SqlNode node : call.getOperandList()) {
convertGroupSet(scope, groupExprs, groupExprProjection, builder, node);
}
return;
case ROW:
final List<ImmutableBitSet> bitSets =
analyzeGroupTuple(
scope, groupExprs, groupExprProjection, ((SqlCall) groupExpr).getOperandList());
builder.add(ImmutableBitSet.union(bitSets));
return;
default:
builder.add(analyzeGroupExpr(scope, groupExprs, groupExprProjection, groupExpr));
return;
}
}
