@Override
public int write(TupleIterator iter) throws TrippiException {
try {
m_out.println("<?xml version=\"1.0\" encoding=\"UTF-8\"?>");
doEntities();
m_out.println("<sparql xmlns=\"http://www.w3.org/2001/sw/DataAccess/rf1/result\">");
String[] names = iter.names();
m_out.println(" <head>");
for (int i = 0; i < names.length; i++) {
m_out.println(" <variable name=\"" + names[i] + "\"/>");
}
m_out.println(" </head>");
m_out.println(" <results>");
int count = 0;
while (iter.hasNext()) {
m_out.println(" <result>");
Map<String, Node> result = iter.next();
for (int i = 0; i < names.length; i++) {
m_out.print(" <" + names[i]);
Node n = result.get(names[i]);
if (n == null) {
m_out.println(" bound=\"false\"/>");
} else if (n instanceof URIReference) {
String uriString = ((URIReference) n).getURI().toString();
m_out.println(" uri=\"" + getURI(uriString) + "\"/>");
} else if (n instanceof BlankNode) {
String id = "blank" + n.hashCode();
m_out.println(" bnodeid=\"" + id + "\"/>");
} else if (n instanceof Literal) {
Literal lit = (Literal) n;
URI dType = lit.getDatatypeURI();
if (dType != null) {
m_out.print(" datatype=\"" + getURI(dType.toString()) + "\"");
}
String lang = lit.getLanguage();
if (lang != null) {
m_out.print(" xml:lang=\"" + lang + "\"");
}
m_out.println(">" + enc(lit.getLexicalForm()) + "</" + names[i] + ">");
} else {
throw new TrippiException("Unrecognized node type: " + n.getClass().getName());
}
}
m_out.println(" </result>");
m_out.flush();
count++;
}
m_out.println(" </results>");
m_out.println("</sparql>");
m_out.flush();
iter.close();
return count;
} catch (IOException e) {
throw new TrippiException("Error writing", e);
}
}
/**
* Determines if the object is a Literal or Resource and returns an iTQL representation.
*
* <p>Throws an Exception if the ObjectNode is a BlankNode
*
* @param node ObjectNode
* @return String
*/
protected String asString(Node node) {
if (node == null) {
throw new IllegalArgumentException("Node is null");
}
// determine type and convert to String
if (node instanceof URIReference) {
return " <" + ((URIReference) node).getURI() + ">";
} else if (node instanceof Literal) {
return " '" + escape(((Literal) node).getLexicalForm()) + "'";
} else {
// probably a BlankNode
throw new IllegalArgumentException("Unsupported Node type: " + node.getClass().getName());
}
}
/**
* Resolve a constraint against an RDF/XML document.
*
* <p>Resolution is by filtration of a URL stream, and thus very slow.
*/
public Resolution resolve(Constraint constraint) throws QueryException {
if (logger.isDebugEnabled()) {
logger.debug("Resolve " + constraint);
}
// Validate "constraint" parameter
if (constraint == null) {
throw new IllegalArgumentException("Null \"constraint\" parameter");
}
if (!(constraint.getModel() instanceof LocalNode)) {
if (logger.isDebugEnabled()) logger.debug("Ignoring solutions for " + constraint);
return new EmptyResolution(constraint, false);
}
if (!(constraint.getElement(1) instanceof LocalNode)
|| !(constraint.getElement(2) instanceof LocalNode)) {
throw new QueryException(
"Prefix resolver can only be used for fixed prefixes: " + constraint);
}
try {
long property = ((LocalNode) constraint.getElement(1)).getValue();
LocalNode object = (LocalNode) constraint.getElement(2);
Node prefixNode = resolverSession.globalize(object.getValue());
// check the constraint for consistency
if ((property != mulgaraPrefix && property != mulgaraStringPrefix)
|| !(prefixNode instanceof Literal || prefixNode instanceof URIReference)) {
logger.debug("property = " + property + ", mulgaraPrefix = " + mulgaraPrefix);
logger.debug("element(2): " + prefixNode + " [" + prefixNode.getClass().getName() + "]");
throw new QueryException(
"Prefix resolver can only be used for prefix constraints: " + constraint);
}
if (logger.isDebugEnabled()) {
logger.debug(
"Evaluating " + constraint.getElement(0) + " has prefix " + constraint.getElement(2));
}
ConstraintElement node = constraint.getElement(0);
assert node != null;
Tuples tuples;
if (node instanceof Variable) {
// convert the prefix into a string pool object
SPObjectFactory spoFact = SPObjectFactoryImpl.getInstance();
SPObject startPrefixObj = getStartObject(spoFact, prefixNode, property);
SPObject endPrefixObj = getEndObject(spoFact, prefixNode, property);
// get the extents of the prefix from the string pool
tuples = resolverSession.findStringPoolRange(startPrefixObj, true, endPrefixObj, false);
assert tuples != null;
// rename variables away from subject, predicate and object
tuples.renameVariables(constraint);
long resultSize;
try {
// Get the size of the final result.
resultSize = tuples.getRowCount();
} catch (TuplesException e) {
throw new QueryException("Unable to build result", e);
}
if (logger.isDebugEnabled()) {
try {
logger.debug(
"tuples size = " + tuples.getRowCount() + " (should be " + resultSize + ")");
} catch (TuplesException e) {
logger.debug("Error getting the length of the tuples object");
}
}
return new TuplesWrapperResolution(tuples, constraint);
} else { // if (node instanceof Variable)
// node must therefore be an instanceof LocalNode
// we can shortcut the process here
assert node instanceof LocalNode;
LocalNode n = (LocalNode) node;
// get the node out of the string pool
SPObject spo = resolverSession.findStringPoolObject(n.getValue());
// check that the node exists
if (spo == null) {
tuples = TuplesOperations.empty();
} else {
// see if the node starts with the required prefix
String prefix;
// extract the string from the literal
if (prefixNode instanceof Literal) {
prefix = ((Literal) prefixNode).getLexicalForm();
} else {
prefix = ((URIReference) prefixNode).getURI().toString();
}
if (spo.getLexicalForm().startsWith(prefix)) {
tuples = TuplesOperations.unconstrained();
} else {
tuples = TuplesOperations.empty();
}
}
}
// convert the tuples to a resolution
return new TuplesWrapperResolution(tuples, constraint);
} catch (GlobalizeException ge) {
throw new QueryException("Couldn't convert internal data into a string", ge);
} catch (StringPoolException e) {
throw new QueryException("Couldn't query constraint", e);
}
}