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

Example 41 with ValueExpr

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

the class ConstructorBuilder method buildConstructor.

private TupleExpr buildConstructor(TupleExpr bodyExpr, TupleExpr constructExpr, boolean explicitConstructor, boolean distinct, boolean reduced) {
    TupleExpr result = bodyExpr;
    // Retrieve all StatementPattern's from the construct expression
    List<StatementPattern> statementPatterns = StatementPatternCollector.process(constructExpr);
    Set<Var> constructVars = getConstructVars(statementPatterns);
    // Finally, the spo-bindings are again filtered for duplicates.
    if (distinct || reduced) {
        // Create projection that removes all bindings that are not used in the
        // constructor
        ProjectionElemList projElemList = new ProjectionElemList();
        for (Var var : constructVars) {
            // the distinct
            if (!var.isAnonymous() && !var.hasValue()) {
                projElemList.addElement(new ProjectionElem(var.getName()));
            }
        }
        result = new Projection(result, projElemList);
        // Filter the duplicates from these projected bindings
        if (distinct) {
            result = new Distinct(result);
        } else {
            result = new Reduced(result);
        }
    }
    // Create BNodeGenerator's for all anonymous variables
    Map<Var, ExtensionElem> extElemMap = new HashMap<Var, ExtensionElem>();
    for (Var var : constructVars) {
        if (var.isAnonymous() && !extElemMap.containsKey(var)) {
            ValueExpr valueExpr = null;
            if (var.hasValue()) {
                valueExpr = new ValueConstant(var.getValue());
            } else if (explicitConstructor) {
                // only generate bnodes in case of an explicit constructor
                valueExpr = new BNodeGenerator();
            }
            if (valueExpr != null) {
                extElemMap.put(var, new ExtensionElem(valueExpr, var.getName()));
            }
        }
    }
    if (!extElemMap.isEmpty()) {
        result = new Extension(result, extElemMap.values());
    }
    // Create a Projection for each StatementPattern in the constructor
    List<ProjectionElemList> projections = new ArrayList<ProjectionElemList>();
    for (StatementPattern sp : statementPatterns) {
        ProjectionElemList projElemList = new ProjectionElemList();
        projElemList.addElement(new ProjectionElem(sp.getSubjectVar().getName(), "subject"));
        projElemList.addElement(new ProjectionElem(sp.getPredicateVar().getName(), "predicate"));
        projElemList.addElement(new ProjectionElem(sp.getObjectVar().getName(), "object"));
        projections.add(projElemList);
    }
    if (projections.size() == 1) {
        result = new Projection(result, projections.get(0));
    // Note: no need to apply the second duplicate elimination step if
    // there's just one projection
    } else if (projections.size() > 1) {
        result = new MultiProjection(result, projections);
        if (distinct) {
            // Add another distinct to filter duplicate statements
            result = new Distinct(result);
        } else if (reduced) {
            result = new Reduced(result);
        }
    } else {
        // Empty constructor
        result = new EmptySet();
    }
    return result;
}

Example 42 with ValueExpr

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

the class UpdateExprBuilder method visit.

@Override
public TupleExpr visit(ASTQuadsNotTriples node, Object data) throws VisitorException {
    GraphPattern parentGP = graphPattern;
    graphPattern = new GraphPattern();
    ValueExpr contextNode = (ValueExpr) node.jjtGetChild(0).jjtAccept(this, data);
    Var contextVar = mapValueExprToVar(contextNode);
    graphPattern.setContextVar(contextVar);
    graphPattern.setStatementPatternScope(Scope.NAMED_CONTEXTS);
    for (int i = 1; i < node.jjtGetNumChildren(); i++) {
        node.jjtGetChild(i).jjtAccept(this, data);
    }
    TupleExpr result = graphPattern.buildTupleExpr();
    parentGP.addRequiredTE(result);
    graphPattern = parentGP;
    return result;
}

Example 43 with ValueExpr

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

the class TupleExprBuilder method visit.

@Override
public TupleExpr visit(ASTDescribe node, Object data) throws VisitorException {
    TupleExpr tupleExpr = (TupleExpr) data;
    if (tupleExpr == null) {
        tupleExpr = new SingletonSet();
    }
    Extension e = new Extension();
    ProjectionElemList projectionElements = new ProjectionElemList();
    for (int i = 0; i < node.jjtGetNumChildren(); i++) {
        ValueExpr resource = (ValueExpr) node.jjtGetChild(i).jjtAccept(this, null);
        if (resource instanceof Var) {
            projectionElements.addElement(new ProjectionElem(((Var) resource).getName()));
        } else {
            String alias = "_describe_" + UUID.randomUUID().toString().replaceAll("-", "_");
            ExtensionElem elem = new ExtensionElem(resource, alias);
            e.addElement(elem);
            projectionElements.addElement(new ProjectionElem(alias));
        }
    }
    if (!e.getElements().isEmpty()) {
        e.setArg(tupleExpr);
        tupleExpr = e;
    }
    Projection p = new Projection(tupleExpr, projectionElements);
    return new DescribeOperator(p);
}

Example 44 with ValueExpr

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

the class TupleExprBuilder method visit.

@Override
public Var visit(ASTCollection node, Object data) throws VisitorException {
    Var rootListVar = createAnonVar();
    Var listVar = rootListVar;
    int childCount = node.jjtGetNumChildren();
    for (int i = 0; i < childCount; i++) {
        ValueExpr childValue = (ValueExpr) node.jjtGetChild(i).jjtAccept(this, null);
        Var childVar = mapValueExprToVar(childValue);
        graphPattern.addRequiredSP(listVar, TupleExprs.createConstVar(RDF.FIRST), childVar);
        Var nextListVar;
        if (i == childCount - 1) {
            nextListVar = TupleExprs.createConstVar(RDF.NIL);
        } else {
            nextListVar = createAnonVar();
        }
        graphPattern.addRequiredSP(listVar, TupleExprs.createConstVar(RDF.REST), nextListVar);
        listVar = nextListVar;
    }
    return rootListVar;
}

Example 45 with ValueExpr

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

the class TupleExprBuilder method visit.

@Override
public Object visit(ASTBNodeFunc node, Object data) throws VisitorException {
    BNodeGenerator generator = new BNodeGenerator();
    if (node.jjtGetNumChildren() > 0) {
        ValueExpr nodeIdExpr = (ValueExpr) node.jjtGetChild(0).jjtAccept(this, null);
        generator.setNodeIdExpr(nodeIdExpr);
    }
    return generator;
}