in jackrabbit-core/src/main/java/org/apache/jackrabbit/core/query/lucene/join/Join.java [121:251]
public static Join create(final MultiColumnQueryHits left,
final MultiColumnQueryHits right,
final JoinType joinType,
final JoinConditionImpl condition,
final IndexReader reader,
final HierarchyResolver resolver,
final NamespaceMappings nsMappings,
final HierarchyManager hmgr)
throws IOException {
try {
return (Join) condition.accept(new DefaultQOMTreeVisitor() {
private boolean isInner = JoinType.INNER == joinType;
private MultiColumnQueryHits outer;
private int outerIdx;
public Object visit(DescendantNodeJoinConditionImpl node, Object data)
throws Exception {
MultiColumnQueryHits ancestor = getSourceWithName(node.getAncestorSelectorQName(), left, right);
MultiColumnQueryHits descendant = getSourceWithName(node.getDescendantSelectorQName(), left, right);
Condition c;
if (isInner
|| descendant == left && JoinType.LEFT == joinType
|| descendant == right && JoinType.RIGHT == joinType) {
// also applies to inner join
// assumption: DescendantNodeJoin is more
// efficient than AncestorNodeJoin, TODO: verify
outer = descendant;
outerIdx = getIndex(outer, node.getDescendantSelectorQName());
c = new DescendantNodeJoin(ancestor, node.getAncestorSelectorQName(), reader, resolver);
} else {
// left == ancestor
outer = ancestor;
outerIdx = getIndex(outer, node.getAncestorSelectorQName());
c = new AncestorNodeJoin(descendant, node.getDescendantSelectorQName(), reader, resolver);
}
return new Join(outer, outerIdx, isInner, c);
}
public Object visit(EquiJoinConditionImpl node, Object data)
throws Exception {
MultiColumnQueryHits src1 = getSourceWithName(node.getSelector1QName(), left, right);
MultiColumnQueryHits src2 = getSourceWithName(node.getSelector2QName(), left, right);
MultiColumnQueryHits inner;
Name innerName;
Name innerPropName;
Name outerPropName;
if (isInner
|| src1 == left && JoinType.LEFT == joinType
|| src1 == right && JoinType.RIGHT == joinType) {
outer = src1;
outerIdx = getIndex(outer, node.getSelector1QName());
inner = src2;
innerName = node.getSelector2QName();
innerPropName = node.getProperty2QName();
outerPropName = node.getProperty1QName();
} else {
outer = src2;
outerIdx = getIndex(outer, node.getSelector2QName());
inner = src1;
innerName = node.getSelector1QName();
innerPropName = node.getProperty1QName();
outerPropName = node.getProperty2QName();
}
Condition c = new EquiJoin(
inner, getIndex(inner, innerName), nsMappings,
reader, innerPropName, outerPropName);
return new Join(outer, outerIdx, isInner, c);
}
public Object visit(ChildNodeJoinConditionImpl node, Object data)
throws Exception {
MultiColumnQueryHits child = getSourceWithName(node.getChildSelectorQName(), left, right);
MultiColumnQueryHits parent = getSourceWithName(node.getParentSelectorQName(), left, right);
Condition c;
if (child == left && JoinType.LEFT == joinType
|| child == right && JoinType.RIGHT == joinType) {
outer = child;
outerIdx = getIndex(outer, node.getChildSelectorQName());
c = new ChildNodeJoin(parent, reader, resolver, node);
} else {
// also applies to inner joins
// assumption: ParentNodeJoin is more efficient than
// ChildNodeJoin, TODO: verify
outer = parent;
outerIdx = getIndex(outer, node.getParentSelectorQName());
c = new ParentNodeJoin(child, reader, resolver, node);
}
return new Join(outer, outerIdx, isInner, c);
}
public Object visit(SameNodeJoinConditionImpl node, Object data)
throws Exception {
MultiColumnQueryHits src1 = getSourceWithName(node.getSelector1QName(), left, right);
MultiColumnQueryHits src2 = getSourceWithName(node.getSelector2QName(), left, right);
Condition c;
if (isInner
|| src1 == left && JoinType.LEFT == joinType
|| src1 == right && JoinType.RIGHT == joinType) {
outer = src1;
outerIdx = getIndex(outer, node.getSelector1QName());
Path selector2Path = node.getSelector2QPath();
if (selector2Path == null || (selector2Path.getLength() == 1 && selector2Path.denotesCurrent())) {
c = new SameNodeJoin(src2, node.getSelector2QName(), reader);
} else {
c = new DescendantPathNodeJoin(src2, node.getSelector2QName(),
node.getSelector2QPath(), hmgr);
}
} else {
outer = src2;
outerIdx = getIndex(outer, node.getSelector2QName());
Path selector2Path = node.getSelector2QPath();
if (selector2Path == null || (selector2Path.getLength() == 1 && selector2Path.denotesCurrent())) {
c = new SameNodeJoin(src1, node.getSelector1QName(), reader);
} else {
c = new AncestorPathNodeJoin(src1, node.getSelector1QName(),
node.getSelector2QPath(), hmgr);
}
}
return new Join(outer, outerIdx, isInner, c);
}
}, null);
} catch (IOException e) {
throw e;
} catch (Exception e) {
IOException ex = new IOException(e.getMessage());
ex.initCause(e);
throw ex;
}
}