private Optional<ResolvedField> resolveField(Expression node, QualifiedName name, boolean local) {
List<Field> matches = relation.resolveFields(name);
if (matches.size() > 1) {
throwAmbiguousAttributeException(node, name);
}
if (matches.isEmpty()) {
if (isColumnReference(name, relation)) {
return Optional.empty();
}
Scope boundary = this;
while (!boundary.queryBoundary) {
if (boundary.parent.isPresent()) {
boundary = boundary.parent.get();
} else {
return Optional.empty();
}
}
if (boundary.parent.isPresent()) {
// jump over the query boundary
return boundary.parent.get().resolveField(node, name, false);
}
return Optional.empty();
} else {
return Optional.of(asResolvedField(getOnlyElement(matches), local));
}
}
private static boolean isColumnReference(QualifiedName name, RelationType relation) {
while (name.getPrefix().isPresent()) {
name = name.getPrefix().get();
if (!relation.resolveFields(name).isEmpty()) {
return true;
}
}
return false;
}
