/**
* Applies a mapping to a collation list.
*
* @param mapping Mapping
* @param collationList Collation list
* @return collation list with mapping applied to each field
*/
public static List<RelCollation> apply(
Mappings.TargetMapping mapping, List<RelCollation> collationList) {
final List<RelCollation> newCollationList = new ArrayList<RelCollation>();
for (RelCollation collation : collationList) {
final List<RelFieldCollation> newFieldCollationList = new ArrayList<RelFieldCollation>();
for (RelFieldCollation fieldCollation : collation.getFieldCollations()) {
final RelFieldCollation newFieldCollation = apply(mapping, fieldCollation);
if (newFieldCollation == null) {
// This field is not mapped. Stop here. The leading edge
// of the collation is still valid (although it's useless
// if it's empty).
break;
}
newFieldCollationList.add(newFieldCollation);
}
// Truncation to collations to their leading edge creates empty
// and duplicate collations. Ignore these.
if (!newFieldCollationList.isEmpty()) {
final RelCollationImpl newCollation = new RelCollationImpl(newFieldCollationList);
if (!newCollationList.contains(newCollation)) {
newCollationList.add(newCollation);
}
}
}
// REVIEW: There might be redundant collations in the list. For example,
// in {(x), (x, y)}, (x) is redundant because it is a leading edge of
// another collation in the list. Could remove redundant collations.
return newCollationList;
}
public void setGroupBy(SqlNodeList nodeList) {
assert clauses.contains(Clause.GROUP_BY);
select.setGroupBy(nodeList);
}
public void setOrderBy(SqlNodeList nodeList) {
assert clauses.contains(Clause.ORDER_BY);
select.setOrderBy(nodeList);
}
public void setWhere(SqlNode node) {
assert clauses.contains(Clause.WHERE);
select.setWhere(node);
}
