protected boolean usesSelector(Join join, SelectorName selector) {
Source left = join.getLeft();
if (left instanceof Selector && selector.equals(((Selector) left).aliasOrName())) return true;
if (left instanceof Join && usesSelector((Join) left, selector)) return true;
Source right = join.getRight();
if (right instanceof Selector && selector.equals(((Selector) right).aliasOrName())) return true;
if (right instanceof Join && usesSelector((Join) right, selector)) return true;
return false;
}
protected Source rewrite(JoinableSources joinableSources) {
// Find the order of the joins ...
List<Join> joins = new LinkedList<Join>();
for (SameNodeJoinCondition joinCondition : joinableSources.getJoinConditions()) {
SelectorName selector1 = joinCondition.selector1Name();
SelectorName selector2 = joinCondition.selector2Name();
boolean found = false;
ListIterator<Join> iter = joins.listIterator();
while (iter.hasNext()) {
Join next = iter.next();
Join replacement = null;
if (usesSelector(next, selector1)) {
Source right = joinableSources.getSelectors().get(selector2.name());
replacement = new Join(next, JoinType.INNER, right, joinCondition);
} else if (usesSelector(next, selector2)) {
Source left = joinableSources.getSelectors().get(selector1.name());
replacement = new Join(left, JoinType.INNER, next, joinCondition);
}
if (replacement != null) {
iter.previous();
iter.remove();
joins.add(replacement);
found = true;
break;
}
}
if (!found) {
// Nothing matched, so add a new join ...
Source left = joinableSources.getSelectors().get(selector1.name());
Source right = joinableSources.getSelectors().get(selector2.name());
if (left == null) {
Position pos = joinableSources.getJoinCriteriaPosition();
String msg =
JcrI18n.selectorUsedInEquiJoinCriteriaDoesNotExistInQuery.text(
selector1.name(), pos.getLine(), pos.getColumn());
throw new ParsingException(pos, msg);
}
if (right == null) {
Position pos = joinableSources.getJoinCriteriaPosition();
String msg =
JcrI18n.selectorUsedInEquiJoinCriteriaDoesNotExistInQuery.text(
selector2.name(), pos.getLine(), pos.getColumn());
throw new ParsingException(pos, msg);
}
joins.add(new Join(left, JoinType.INNER, right, joinCondition));
}
}
if (joins.size() == 1) {
return joins.get(0);
}
// Otherwise the join conditions were not sufficient
return null;
}