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

Example 11 with ExtensionElem

use of org.eclipse.rdf4j.query.algebra.ExtensionElem 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;
}