public static Collection<Quad> collectQuads(Op op, Collection<Quad> result) {
if (op instanceof OpLeftJoin) {
OpLeftJoin x = (OpLeftJoin) op;
collectQuads(x.getLeft(), result);
collectQuads(x.getRight(), result);
} else if (op instanceof OpFilter) {
OpFilter x = (OpFilter) op;
collectQuads(x.getSubOp(), result);
} else if (op instanceof OpJoin) {
OpJoin x = (OpJoin) op;
collectQuads(x.getLeft(), result);
collectQuads(x.getRight(), result);
} else if (op instanceof OpUnion) {
System.out.println(
"Warning: Collecting expressions from unions. Since the same vars may appear within different (parts of) unions, it may be ambiguous to which part the expression refers.");
OpUnion x = (OpUnion) op;
collectQuads(x.getLeft(), result);
collectQuads(x.getRight(), result);
} else if (op instanceof OpQuadPattern) {
OpQuadPattern x = (OpQuadPattern) op;
result.addAll(x.getPattern().getList());
} else if (op instanceof OpSequence) {
OpSequence x = (OpSequence) op;
for (Op element : x.getElements()) {
collectQuads(element, result);
}
} else {
throw new NotImplementedException("Encountered class: " + op);
}
return result;
}
@Override
public Op transform(OpLeftJoin opLeftJoin, Op opLeft, Op opRight) {
// Test whether we can do an indexed substitute into the right if possible.
boolean canDoLinear = LeftJoinClassifier.isLinear(opLeftJoin);
if (canDoLinear) {
// Pass left into right for substitution before right side evaluation.
// In an indexed left join, the LHS bindings are visible to the
// RHS execution so the expression is evaluated by moving it to be
// a filter over the RHS pattern.
if (opLeftJoin.getExprs() != null) opRight = OpFilter.filter(opLeftJoin.getExprs(), opRight);
return new OpConditional(opLeft, opRight);
}
// Not index-able.
return super.transform(opLeftJoin, opLeft, opRight);
}
public static ExprList collectExprs(Op op, ExprList result) {
if (op instanceof OpLeftJoin) {
OpLeftJoin x = (OpLeftJoin) op;
if (x.getExprs() != null) {
result.addAll(x.getExprs());
}
collectExprs(x.getLeft(), result);
collectExprs(x.getRight(), result);
} else if (op instanceof OpFilter) {
OpFilter x = (OpFilter) op;
result.addAll(x.getExprs());
collectExprs(x.getSubOp(), result);
} else if (op instanceof OpJoin) {
OpJoin x = (OpJoin) op;
collectExprs(x.getLeft(), result);
collectExprs(x.getRight(), result);
} else if (op instanceof OpUnion) {
System.out.println(
"Warning: Collecting expressions from unions. Since the same vars may appear within different (parts of) unions, it may be ambiguous to which part the expression refers.");
OpUnion x = (OpUnion) op;
collectExprs(x.getLeft(), result);
collectExprs(x.getRight(), result);
} else if (op instanceof OpQuadPattern) {
} else if (op instanceof OpSequence) {
OpSequence x = (OpSequence) op;
for (Op element : x.getElements()) {
collectExprs(element, result);
}
} else {
throw new RuntimeException("Not implemented. Type: " + op.getClass());
}
return result;
}
public void visit(OpLeftJoin opLeftJoin) {
System.out.println(opLeftJoin.toString());
}
public void visit(OpLeftJoin opLeftJoin) {
Table left = eval(opLeftJoin.getLeft());
Table right = eval(opLeftJoin.getRight());
Table table = evaluator.leftJoin(left, right, opLeftJoin.getExprs());
push(table);
}
