Examples with Extension org.eclipse.rdf4j.query.algebra.Extension used on opensource projects

Example 11 with Extension

use of org.eclipse.rdf4j.query.algebra.Extension in project rdf4j by eclipse.

the class TupleExprBuilder method processHavingClause.

private TupleExpr processHavingClause(ASTHavingClause havingNode, TupleExpr tupleExpr, Group group) throws VisitorException {
    if (havingNode != null) {
        // create an implicit group
        if (group == null) {
            group = new Group(tupleExpr);
        }
        ValueExpr expr = (ValueExpr) havingNode.jjtGetChild(0).jjtAccept(this, tupleExpr);
        // retrieve any aggregate operators from the expression.
        AggregateCollector collector = new AggregateCollector();
        collector.meetOther(expr);
        // replace operator occurrences with an anonymous var, and alias it
        // to the group
        Extension extension = new Extension();
        for (AggregateOperator operator : collector.getOperators()) {
            Var var = createAnonVar();
            // replace occurrence of the operator in the filter expression
            // with the variable.
            AggregateOperatorReplacer replacer = new AggregateOperatorReplacer(operator, var);
            replacer.meetOther(expr);
            String alias = var.getName();
            // create an extension linking the operator to the variable
            // name.
            ExtensionElem pe = new ExtensionElem(operator, alias);
            extension.addElement(pe);
            // add the aggregate operator to the group.
            GroupElem ge = new GroupElem(alias, operator);
            // FIXME quite often the aggregate in the HAVING clause will be
            // a duplicate of an aggregate in the projection. We could
            // perhaps
            // optimize for that, to avoid having to evaluate twice.
            group.addGroupElement(ge);
        }
        extension.setArg(group);
        tupleExpr = new Filter(extension, expr);
    }
    return tupleExpr;
}

Example 12 with Extension

use of org.eclipse.rdf4j.query.algebra.Extension in project rdf4j by eclipse.

the class AbstractQueryBuilder method projection.

private UnaryTupleOperator projection() {
    if (!mProjectionPatterns.isEmpty()) {
        return multiProjection();
    } else {
        Extension aExt = null;
        ProjectionElemList aList = new ProjectionElemList();
        for (String aVar : mProjectionVars) {
            aList.addElement(new ProjectionElem(aVar));
        }
        Projection aProjection = new Projection();
        aProjection.setProjectionElemList(aList);
        if (aExt != null) {
            aProjection.setArg(aExt);
        }
        return aProjection;
    }
}

Example 13 with Extension

use of org.eclipse.rdf4j.query.algebra.Extension in project rdf4j by eclipse.

the class TupleExprBuilder method visit.

@Override
public Object visit(ASTBind node, Object data) throws VisitorException {
    // bind expression
    ValueExpr ve = (ValueExpr) node.jjtGetChild(0).jjtAccept(this, data);
    // name to bind the expression outcome to
    Node aliasNode = node.jjtGetChild(1);
    String alias = ((ASTVar) aliasNode).getName();
    Extension extension = new Extension();
    extension.addElement(new ExtensionElem(ve, alias));
    TupleExpr result = null;
    TupleExpr arg = graphPattern.buildTupleExpr();
    // check if alias is not previously used.
    if (arg.getBindingNames().contains(alias)) {
        // SES-2314 we need to doublecheck that the reused varname is not
        // just
        // for an anonymous var or a constant.
        VarCollector collector = new VarCollector();
        arg.visit(collector);
        for (Var v : collector.getCollectedVars()) {
            if (alias.equals(v.getName())) {
                if (!v.isConstant() && !v.isAnonymous()) {
                    throw new VisitorException(String.format("BIND clause alias '%s' was previously used", alias));
                }
                break;
            }
        }
    }
    if (arg instanceof Filter) {
        result = arg;
        // the BIND expression.
        while (((Filter) arg).getArg() instanceof Filter) {
            arg = ((Filter) arg).getArg();
        }
        extension.setArg(((Filter) arg).getArg());
        ((Filter) arg).setArg(extension);
    } else {
        extension.setArg(arg);
        result = extension;
    }
    GraphPattern replacementGP = new GraphPattern(graphPattern);
    replacementGP.addRequiredTE(result);
    graphPattern = replacementGP;
    return result;
}