/*
* See http://www.w3.org/TR/rdf-sparql-query paragraph 11.4.4
*
* "(STR) Returns the lexical form of a literal; returns the codepoint representation of an IRI."
*
* @see http://www.w3.org/TR/rdf-sparql-query
*/
private void convertStr(E_Str expr) {
logger.debug("convertStr " + expr.toString());
expr.getArg().visit(this);
Expression arg = expression.pop();
if (arg instanceof AttributeExprEx) {
// make a new AttributeExprEx with changed NodeMaker, which returns plain literal
// TODO this seems to work, but needs more testing.
AttributeExprEx attribute = (AttributeExprEx) arg;
TypedNodeMaker nodeMaker = (TypedNodeMaker) attribute.getNodeMaker();
TypedNodeMaker newNodeMaker =
new TypedNodeMaker(
TypedNodeMaker.PLAIN_LITERAL, nodeMaker.valueMaker(), nodeMaker.isUnique());
logger.debug("changing nodemaker " + nodeMaker + " to " + newNodeMaker);
expression.push(
new AttributeExprEx((Attribute) attribute.attributes().iterator().next(), newNodeMaker));
} else if (arg instanceof ConstantEx) {
ConstantEx constant = (ConstantEx) arg;
Node node = constant.getNode();
String lexicalForm = node.getLiteral().getLexicalForm();
node = Node.createLiteral(lexicalForm);
ConstantEx constantEx = new ConstantEx(NodeValue.makeNode(node).asString(), node);
logger.debug("pushing " + constantEx);
expression.push(constantEx);
} else {
conversionFailed(expr);
}
}
/**
* Delivers the corresponding sql-expression for a sparql-var
*
* @param exprVar - a sparql-expr-var
* @return List<Expression> - the equivalent sql-expressions
*/
private List<Expression> toExpression(ExprVar exprVar) {
ArrayList<Expression> result = new ArrayList<Expression>();
if (this.nodeRelation != null && exprVar != null) {
// get the nodemaker for the expr-var
NodeMaker nodeMaker = nodeRelation.nodeMaker(exprVar.asVar());
if (nodeMaker instanceof TypedNodeMaker) {
TypedNodeMaker typedNodeMaker = (TypedNodeMaker) nodeMaker;
Iterator<ProjectionSpec> it = typedNodeMaker.projectionSpecs().iterator();
if (!it.hasNext()) {
logger.debug("no projection spec for " + exprVar + ", assuming constant");
Node node = typedNodeMaker.makeNode(null);
result.add(new ConstantEx(NodeValue.makeNode(node).asString(), node));
}
while (it.hasNext()) {
ProjectionSpec projectionSpec = it.next();
if (projectionSpec == null) return Collections.emptyList();
if (projectionSpec instanceof Attribute) {
result.add(new AttributeExprEx((Attribute) projectionSpec, nodeMaker));
} else {
// projectionSpec is a ExpressionProjectionSpec
ExpressionProjectionSpec expressionProjectionSpec =
(ExpressionProjectionSpec) projectionSpec;
Expression expression = expressionProjectionSpec.toExpression();
if (expression instanceof SQLExpression) result.add(((SQLExpression) expression));
else return Collections.emptyList();
}
}
} else if (nodeMaker instanceof FixedNodeMaker) {
FixedNodeMaker fixedNodeMaker = (FixedNodeMaker) nodeMaker;
Node node = fixedNodeMaker.makeNode(null);
result.add(new ConstantEx(NodeValue.makeNode(node).asString(), node));
}
}
return result;
}
static NodeMaker cast(NodeMaker nodeMaker, RDFDatatype datatype) {
if (nodeMaker instanceof TypedNodeMaker)
return new TypedNodeMaker(
TypedNodeMaker.typedLiteral(datatype),
((TypedNodeMaker) nodeMaker).valueMaker(),
nodeMaker.isUnique());
if (nodeMaker instanceof FixedNodeMaker) {
Node node = nodeMaker.makeNode(null);
return new FixedNodeMaker(XSD.cast(node, datatype), nodeMaker.isUnique());
}
throw new RuntimeException("unknown nodeMaker type");
}
