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

Example 6 with Group

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

the class TupleExprBuilder method visit.

@Override
public TupleExpr visit(ASTConstructQuery node, Object data) throws VisitorException {
    // Start with building the graph pattern
    graphPattern = new GraphPattern();
    node.getWhereClause().jjtAccept(this, null);
    TupleExpr tupleExpr = graphPattern.buildTupleExpr();
    // Apply grouping
    ASTGroupClause groupNode = node.getGroupClause();
    if (groupNode != null) {
        tupleExpr = (TupleExpr) groupNode.jjtAccept(this, tupleExpr);
    }
    Group group = null;
    if (tupleExpr instanceof Group) {
        group = (Group) tupleExpr;
    } else {
        // create a new implicit group. Note that this group will only
        // actually
        // be used in the query model if the query has HAVING or ORDER BY
        // clause
        group = new Group(tupleExpr);
    }
    // Apply HAVING group filter condition
    tupleExpr = processHavingClause(node.getHavingClause(), tupleExpr, group);
    // process bindings clause
    ASTBindingsClause bindingsClause = node.getBindingsClause();
    if (bindingsClause != null) {
        tupleExpr = new Join((BindingSetAssignment) bindingsClause.jjtAccept(this, null), tupleExpr);
    }
    // Apply result ordering
    tupleExpr = processOrderClause(node.getOrderClause(), tupleExpr, null);
    // Process construct clause
    ASTConstruct constructNode = node.getConstruct();
    if (!constructNode.isWildcard()) {
        tupleExpr = (TupleExpr) constructNode.jjtAccept(this, tupleExpr);
    } else {
        // create construct clause from graph pattern.
        ConstructorBuilder cb = new ConstructorBuilder();
        // possible future use.
        try {
            tupleExpr = cb.buildConstructor(tupleExpr, false, false);
        } catch (MalformedQueryException e) {
            throw new VisitorException(e.getMessage());
        }
    }
    // process limit and offset clauses
    ASTLimit limitNode = node.getLimit();
    long limit = -1L;
    if (limitNode != null) {
        limit = (Long) limitNode.jjtAccept(this, null);
    }
    ASTOffset offsetNode = node.getOffset();
    long offset = -1;
    if (offsetNode != null) {
        offset = (Long) offsetNode.jjtAccept(this, null);
    }
    if (offset >= 1 || limit >= 0) {
        tupleExpr = new Slice(tupleExpr, offset, limit);
    }
    return tupleExpr;
}

Example 7 with Group

use of org.eclipse.rdf4j.query.algebra.Group 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 8 with Group

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

the class TupleExprBuilder method visit.

@Override
public TupleExpr visit(ASTAskQuery node, Object data) throws VisitorException {
    graphPattern = new GraphPattern();
    super.visit(node, null);
    TupleExpr tupleExpr = graphPattern.buildTupleExpr();
    tupleExpr = new Slice(tupleExpr, 0, 1);
    // Apply grouping
    Group group = null;
    ASTGroupClause groupNode = node.getGroupClause();
    if (groupNode != null) {
        tupleExpr = (TupleExpr) groupNode.jjtAccept(this, tupleExpr);
        group = (Group) tupleExpr;
    }
    final ASTHavingClause havingClause = node.getHavingClause();
    if (havingClause != null) {
        if (group == null) {
            // create implicit group
            group = new Group(tupleExpr);
        }
        // Apply HAVING group filter condition
        tupleExpr = processHavingClause(havingClause, tupleExpr, group);
    }
    // process bindings clause
    final ASTBindingsClause bindingsClause = node.getBindingsClause();
    if (bindingsClause != null) {
        tupleExpr = new Join((BindingSetAssignment) bindingsClause.jjtAccept(this, null), tupleExpr);
    }
    final ASTOrderClause orderClause = node.getOrderClause();
    if (orderClause != null) {
        if (group == null) {
            // create implicit group
            group = new Group(tupleExpr);
        }
        // Apply result ordering
        tupleExpr = processOrderClause(node.getOrderClause(), tupleExpr, group);
    }
    return tupleExpr;
}