Examples with ProjectionElem org.openrdf.query.algebra.ProjectionElem used on opensource projects

Example 1 with ProjectionElem

use of org.openrdf.query.algebra.ProjectionElem in project backstage by zepheira.

the class Expression method computeOutputOnValue.

public ExpressionQueryResult computeOutputOnValue(Value value, Database database, SailRepositoryConnection connection) throws ExpressionException {
    TupleQueryBuilder builder = new TupleQueryBuilder();
    Var valueVar = builder.makeVar("value", value);
    ExpressionResult expressionResult = computeOutputOnItem(database, builder, valueVar);
    if (expressionResult.valueExpr instanceof Var) {
        Var resultVar = (Var) expressionResult.valueExpr;
        ProjectionElemList projectionElements = new ProjectionElemList();
        projectionElements.addElement(new ProjectionElem(resultVar.getName()));
        TupleExpr t = builder.makeFilterTupleExpr();
        if (t == null) {
            // TODO[dfhuynh]: This happens if the expression is just "value". I'm not sure what to do here.
            return null;
        }
        Projection projection = new Projection(t, projectionElements);
        TupleQuery query = new MyTupleQuery(new ParsedTupleQuery(projection), connection);
        return new ExpressionQueryResult(query, expressionResult.valueType, resultVar);
    }
    return null;
}