Examples with TableEmpty org.apache.jena.sparql.algebra.table.TableEmpty used on opensource projects

Example 1 with TableEmpty

use of org.apache.jena.sparql.algebra.table.TableEmpty in project jena by apache.

the class Eval method evalGraph.

static Table evalGraph(OpGraph opGraph, Evaluator evaluator) {
    ExecutionContext execCxt = evaluator.getExecContext();
    if (!Var.isVar(opGraph.getNode())) {
        DatasetGraph dsg = execCxt.getDataset();
        Node graphNode = opGraph.getNode();
        if (!dsg.containsGraph(graphNode))
            return new TableEmpty();
        Graph graph = execCxt.getDataset().getGraph(opGraph.getNode());
        if (// But contains was true?!!
        graph == null)
            throw new InternalErrorException("Graph was present, now it's not");
        ExecutionContext execCxt2 = new ExecutionContext(execCxt, graph);
        Evaluator e2 = EvaluatorFactory.create(execCxt2);
        return eval(e2, opGraph.getSubOp());
    }
    // Graph node is a variable.
    Var gVar = Var.alloc(opGraph.getNode());
    Table current = null;
    for (Iterator<Node> iter = execCxt.getDataset().listGraphNodes(); iter.hasNext(); ) {
        Node gn = iter.next();
        Graph graph = execCxt.getDataset().getGraph(gn);
        ExecutionContext execCxt2 = new ExecutionContext(execCxt, graph);
        Evaluator e2 = EvaluatorFactory.create(execCxt2);
        Table tableVarURI = TableFactory.create(gVar, gn);
        // Evaluate the pattern, join with this graph node possibility.
        // XXX If Var.ANON then no-opt.
        Table patternTable = eval(e2, opGraph.getSubOp());
        Table stepResult = evaluator.join(patternTable, tableVarURI);
        if (current == null)
            current = stepResult;
        else
            current = evaluator.union(current, stepResult);
    }
    if (current == null)
        // Nothing to loop over
        return new TableEmpty();
    return current;
}

Example 2 with TableEmpty

use of org.apache.jena.sparql.algebra.table.TableEmpty in project jena by apache.

the class Eval method evalDS.

static Table evalDS(OpDatasetNames opDSN, Evaluator evaluator) {
    Node graphNode = opDSN.getGraphNode();
    if (graphNode.isURI()) {
        if (evaluator.getExecContext().getDataset().containsGraph(graphNode)) {
            return new TableUnit();
        } else // WRONG
        {
            return new TableEmpty();
        }
    }
    if (!Var.isVar(graphNode))
        throw new ARQInternalErrorException("OpDatasetNames: Not a URI or variable: " + graphNode);
    DatasetGraph dsg = evaluator.getExecContext().getDataset();
    Iterator<Node> iter = dsg.listGraphNodes();
    List<Binding> list = new ArrayList<>((int) dsg.size());
    for (; iter.hasNext(); ) {
        Node gn = iter.next();
        Binding b = BindingFactory.binding(Var.alloc(graphNode), gn);
        list.add(b);
    }
    QueryIterator qIter = new QueryIterPlainWrapper(list.iterator(), evaluator.getExecContext());
    return TableFactory.create(qIter);
}

Example 3 with TableEmpty

use of org.apache.jena.sparql.algebra.table.TableEmpty in project jena by apache.

the class Eval method evalQuadPattern.

static Table evalQuadPattern(OpQuadPattern opQuad, Evaluator evaluator) {
    if (opQuad.isEmpty())
        return TableFactory.createUnit();
    ExecutionContext cxt = evaluator.getExecContext();
    DatasetGraph ds = cxt.getDataset();
    BasicPattern pattern = opQuad.getBasicPattern();
    if (!opQuad.getGraphNode().isVariable()) {
        if (!opQuad.getGraphNode().isURI()) {
            throw new ARQInternalErrorException("Not a URI or variable: " + opQuad.getGraphNode());
        }
        Graph g = null;
        if (opQuad.isDefaultGraph())
            g = ds.getDefaultGraph();
        else
            g = ds.getGraph(opQuad.getGraphNode());
        if (g == null)
            return new TableEmpty();
        ExecutionContext cxt2 = new ExecutionContext(cxt, g);
        QueryIterator qIter = executeBGP(pattern, QueryIterRoot.create(cxt2), cxt2);
        return TableFactory.create(qIter);
    } else {
        // Variable.
        Var gVar = Var.alloc(opQuad.getGraphNode());
        // Or just just devolve to OpGraph and get OpUnion chain of OpJoin
        QueryIterConcat concat = new QueryIterConcat(cxt);
        for (Iterator<Node> graphNodes = cxt.getDataset().listGraphNodes(); graphNodes.hasNext(); ) {
            Node gn = graphNodes.next();
            //Op tableVarURI = TableFactory.create(gn.getName(), Node.createURI(uri)) ;
            Graph g = cxt.getDataset().getGraph(gn);
            Binding b = BindingFactory.binding(BindingRoot.create(), gVar, gn);
            ExecutionContext cxt2 = new ExecutionContext(cxt, g);
            // Eval the pattern, eval the variable, join.
            // Pattern may be non-linear in the variable - do a pure execution.  
            Table t1 = TableFactory.create(gVar, gn);
            QueryIterator qIter = executeBGP(pattern, QueryIterRoot.create(cxt2), cxt2);
            Table t2 = TableFactory.create(qIter);
            Table t3 = evaluator.join(t1, t2);
            concat.add(t3.iterator(cxt2));
        }
        return TableFactory.create(concat);
    }
}