public Tuple<Collection<BasicOperator>, Collection<BasicOperator>> transformOperatorGraph(
final Map<String, BasicOperator> mso,
final BasicOperator rootOperator) {
final Collection<BasicOperator> deleted = new LinkedList<BasicOperator>();
final Collection<BasicOperator> added = new LinkedList<BasicOperator>();
final Generate generate = (Generate) mso.get("generate");
final TriplePattern pat = (TriplePattern) mso.get("pat");
final Item[] patItems = pat.getItems();
final Item[] generateItems = generate.getValueOrVariable();
// System.out.println(generate.toString() + "---" + pat.toString());
Filter filter = null;
final ReplaceVar replaceVar = new ReplaceVar();
replaceVar.setIntersectionVariables(new HashSet<Variable>());
replaceVar.setUnionVariables(replaceVar.getIntersectionVariables());
final LinkedList<Variable> addBindingsVar = new LinkedList<Variable>();
final LinkedList<Literal> addBindingsLit = new LinkedList<Literal>();
String filterConstraint = "Filter( ";
for (int i = 0; i < 3; i++) {
final Item patItem = patItems[i];
final Item generateItem = generateItems[i];
if ((!patItem.isVariable()) && generateItem.isVariable()) {
filterConstraint += generateItems[i].toString() + " = "
+ patItems[i].toString() + " && ";
} else if (patItem.isVariable() && generateItem.isVariable()) {
replaceVar.addSubstitution((Variable) patItem,
(Variable) generateItem);
replaceVar.getIntersectionVariables().add((Variable) patItem);
} else if (patItem.isVariable() && (!generateItem.isVariable())) {
addBindingsVar.add((Variable) patItem);
addBindingsLit.add((Literal) generateItem);
} else if (!patItem.isVariable() && !generateItem.isVariable()
&& !generateItem.equals(patItem)) {
// cannot match, remove generate.
for (final BasicOperator parent : generate
.getPrecedingOperators())
parent.removeSucceedingOperator(generate);
generate.getPrecedingOperators().clear();
generate.removeFromOperatorGraph();
return null;
}
}
// If (?x = ?a) and (?x = ?b) then (valueOf(?a) = value(?b)) must be
// fulfilled
for (int i = 0; i < 2; i++) {
for (int x = i + 1; x < 3; x++) {
if (patItems[i].equals(patItems[x])) {
filterConstraint += generateItems[i].toString() + " = "
+ generateItems[x].toString() + " && ";
}
}
}
if (!filterConstraint.equals("Filter( ")) {
filterConstraint = filterConstraint.substring(0,
filterConstraint.length() - 3)
+ ") ";
try {
final ASTFilterConstraint ASTfilter = (ASTFilterConstraint) SPARQL1_1Parser
.parseFilter(filterConstraint);
filter = new Filter(ASTfilter);
} catch (final Exception e) {
System.err
.println("This should never happen in RuleReplaceGenPat!");
System.err.println(e);
e.printStackTrace();
}
}
// Only Operators with a not empty definition are put into the
// operatorgraph
final LinkedList<BasicOperator> order = new LinkedList<BasicOperator>();
if (filter != null) {
order.add(filter);
added.add(filter);
}
final int substVar = replaceVar.getSubstitutionsVariableLeft().size();
if (substVar > 0) {
order.add(replaceVar);
added.add(replaceVar);
} else {
final Projection p = new Projection();
p.setIntersectionVariables(new HashSet<Variable>());
p.setUnionVariables(p.getUnionVariables());
order.add(p);
added.add(p);
}
if (addBindingsVar.size() > 0) {
final Iterator<Literal> lit_it = addBindingsLit.iterator();
final HashSet<Variable> hsv = new HashSet<Variable>();
hsv.addAll(replaceVar.getUnionVariables());
for (final Variable v : addBindingsVar) {
final AddBinding ab = new AddBinding(v, lit_it.next());
hsv.add(v);
ab.setIntersectionVariables((HashSet<Variable>) hsv.clone());
ab.setUnionVariables(ab.getIntersectionVariables());
order.add(ab);
added.add(ab);
}
}
// In case that Generate or TriplePattern has minimum one variable, than
// minimum one operator has to be inserted
if (order.size() > 0) {
final List<BasicOperator> pres = (List<BasicOperator>) generate
.getPrecedingOperators();
BasicOperator pre;
for (int i = 0; i < pres.size(); i++) {
pre = pres.get(i);
pre.addSucceedingOperator(new OperatorIDTuple(order.getFirst(),
0));
if (filter != null) {
Collection<Variable> vars = filter
.getIntersectionVariables();
if (vars == null)
vars = new HashSet<Variable>();
vars.addAll(pre.getIntersectionVariables());
filter.setIntersectionVariables(vars);
filter.setUnionVariables(vars);
}
pre.removeSucceedingOperator(generate);
order.getFirst().addPrecedingOperator(pre);
}
for (int i = 0; i < order.size() - 1; i++) {
order.get(i + 1).setPrecedingOperator(order.get(i));
order.get(i).setSucceedingOperator(
new OperatorIDTuple(order.get(i + 1), 0));
}
final LinkedList<OperatorIDTuple> succs = (LinkedList<OperatorIDTuple>) pat
.getSucceedingOperators();
for (int i = 0; i < succs.size(); i++) {
succs.get(i).getOperator()
.addPrecedingOperator(order.getLast());
}
final LinkedList<OperatorIDTuple> sops = new LinkedList<OperatorIDTuple>();
sops.addAll(pat.getSucceedingOperators());
order.getLast().setSucceedingOperators(sops);
} else {
final LinkedList<BasicOperator> pres = (LinkedList<BasicOperator>) generate
.getPrecedingOperators();
final LinkedList<OperatorIDTuple> succs = (LinkedList<OperatorIDTuple>) pat
.getSucceedingOperators();
BasicOperator pre;
BasicOperator succ;