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

Example 26 with Var

use of org.eclipse.rdf4j.query.algebra.Var 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 27 with Var

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

the class QueryModelBuilder method visit.

@Override
public Object visit(ASTFrom node, Object data) throws VisitorException {
    StatementPattern.Scope scope = StatementPattern.Scope.DEFAULT_CONTEXTS;
    Var contextVar = null;
    if (node.hasContextID()) {
        scope = StatementPattern.Scope.NAMED_CONTEXTS;
        ValueExpr contextID = (ValueExpr) node.getContextID().jjtAccept(this, null);
        if (contextID instanceof Var) {
            contextVar = (Var) contextID;
        } else if (contextID instanceof ValueConstant) {
            ValueConstant vc = (ValueConstant) contextID;
            contextVar = createConstantVar(vc.getValue());
        } else {
            throw new IllegalArgumentException("Unexpected contextID result type: " + contextID.getClass());
        }
    }
    graphPattern.setStatementPatternScope(scope);
    graphPattern.setContextVar(contextVar);
    node.getPathExpr().jjtAccept(this, null);
    return null;
}

Example 28 with Var

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

the class QueryModelBuilder method createConstantVar.

/*---------*
	 * Methods *
	 *---------*/
private Var createConstantVar(Value value) {
    Var var = new Var("-const-" + constantVarID++);
    var.setAnonymous(true);
    var.setValue(value);
    return var;
}

Example 29 with Var

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

the class QueryModelBuilder method visit.

@Override
public TupleExpr visit(ASTSelect node, Object data) throws VisitorException {
    TupleExpr result = (TupleExpr) data;
    Extension extension = new Extension();
    ProjectionElemList projElemList = new ProjectionElemList();
    for (ASTProjectionElem projElemNode : node.getProjectionElemList()) {
        ValueExpr valueExpr = (ValueExpr) projElemNode.getValueExpr().jjtAccept(this, null);
        String alias = projElemNode.getAlias();
        if (alias != null) {
            // aliased projection element
            extension.addElement(new ExtensionElem(valueExpr, alias));
            projElemList.addElement(new ProjectionElem(alias));
        } else if (valueExpr instanceof Var) {
            // unaliased variable
            Var projVar = (Var) valueExpr;
            projElemList.addElement(new ProjectionElem(projVar.getName()));
        } else {
            throw new IllegalStateException("required alias for non-Var projection elements not found");
        }
    }
    if (!extension.getElements().isEmpty()) {
        extension.setArg(result);
        result = extension;
    }
    result = new Projection(result, projElemList);
    if (node.isDistinct()) {
        result = new Distinct(result);
    } else if (node.isReduced()) {
        result = new Reduced(result);
    }
    return result;
}

Example 30 with Var

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

the class QueryModelBuilder method visit.

@Override
public List<Var> visit(ASTNode node, Object data) throws VisitorException {
    List<Var> nodeVars = new ArrayList<Var>();
    for (ASTNodeElem nodeElem : node.getNodeElemList()) {
        Var nodeVar = (Var) nodeElem.jjtAccept(this, null);
        nodeVars.add(nodeVar);
    }
    // Create any implicit unequalities
    for (int i = 0; i < nodeVars.size() - 1; i++) {
        Var var1 = nodeVars.get(i);
        for (int j = i + 1; j < nodeVars.size(); j++) {
            Var var2 = nodeVars.get(j);
            // for the unequality to make any sense:
            if (!var1.hasValue() || !var2.hasValue()) {
                graphPattern.addConstraint(new Not(new SameTerm(var1, var2)));
            }
        }
    }
    return nodeVars;
}