// make private?
public Clause maxClause() {
Clause maxClause = null;
for (Clause clause : clauses) {
if (maxClause == null || clause.ordinal() > maxClause.ordinal()) {
maxClause = clause;
}
}
assert maxClause != null;
return maxClause;
}
/**
* Once you have a Result of implementing a child relational expression, call this method to
* create a Builder to implement the current relational expression by adding additional clauses
* to the SQL query.
*
* <p>You need to declare which clauses you intend to add. If the clauses are "later", you can
* add to the same query. For example, "GROUP BY" comes after "WHERE". But if they are the same
* or earlier, this method will start a new SELECT that wraps the previous result.
*
* <p>When you have called {@link Builder#setSelect(org.eigenbase.sql.SqlNodeList)}, {@link
* Builder#setWhere(org.eigenbase.sql.SqlNode)} etc. call {@link
* Builder#result(org.eigenbase.sql.SqlNode, java.util.Collection, org.eigenbase.rel.RelNode)}
* to fix the new query.
*
* @param rel Relational expression being implemented
* @param clauses Clauses that will be generated to implement current relational expression
* @return A builder
*/
public Builder builder(JdbcRel rel, Clause... clauses) {
final Clause maxClause = maxClause();
boolean needNew = false;
for (Clause clause : clauses) {
if (maxClause.ordinal() >= clause.ordinal()) {
needNew = true;
}
}
SqlSelect select;
Expressions.FluentList<Clause> clauseList = Expressions.list();
if (needNew) {
select = subSelect();
} else {
select = asSelect();
clauseList.addAll(this.clauses);
}
clauseList.addAll(Arrays.asList(clauses));
Context newContext;
final SqlNodeList selectList = select.getSelectList();
if (selectList != null) {
newContext =
new Context(selectList.size()) {
@Override
public SqlNode field(int ordinal) {
final SqlNode selectItem = selectList.get(ordinal);
switch (selectItem.getKind()) {
case AS:
return ((SqlCall) selectItem).operand(0);
}
return selectItem;
}
};
} else {
newContext = new AliasContext(aliases, aliases.size() > 1);
}
return new Builder(rel, clauseList, select, newContext);
}