public static void main(String[] args) {
// String sA = "Select * { ?s ?p ?o . Filter((?s || ?p) && ?o) . }";
// String sA = "Select * { ?s ?p ?o . Filter((?s || ?p) && !(?o || ?g)) . }";
String sA =
"Select * { ?s ?p ?o . Filter(?o != <http://Person>). Optional { { ?x ?y ?z . Filter(?x != <http://x> && ?x = ?y) . } Union { ?x a ?y . Filter(?x = <http://x>) . } } . }";
// String sA = "Select * { ?s ?p ?o . Filter(!(?s = ?p || ?p = ?o && ?s = ?o || ?o = ?s)) . }";
// String sA = "Select * { ?s ?p ?o . Filter(!(?s = ?p || ?j = <http://x>)) . }";
Query qA = QueryFactory.create(sA);
Op opA = Algebra.compile(qA);
opA = Algebra.toQuadForm(opA);
System.out.println(opA);
// How to deal with union? variables appearing in them
// System.out.println(opA.getClass());
ExprList exprs = FilterUtils.collectExprs(opA, new ExprList());
ExprList proc = eval(exprs);
System.out.println(proc);
List<ExprList> clauses = dnfToClauses(proc);
System.out.println("Mentioned vars:" + proc.getVarsMentioned());
System.out.println("Clauses: " + clauses);
}
public static ExprList eval(ExprList exprs) {
System.out.println("ExprList.size = " + exprs.size());
ExprList result = new ExprList();
for (Expr expr : exprs) {
result.add(eval(expr));
}
return result;
}
/** Place expressions around an Op */
private static Op buildFilter(ExprList exprs, Op op) {
if (exprs.isEmpty()) return op;
for (Iterator<Expr> iter = exprs.iterator(); iter.hasNext(); ) {
Expr expr = iter.next();
if (op == null) op = OpTable.unit();
op = OpFilter.filter(expr, op);
iter.remove();
}
return op;
}
/**
* Concatenates the sub exressions using Logical_And
*
* <p>and(and(and(0, 1), 2, 3)
*
* @param exprs
* @return
*/
public static Expr andifyLeftSided(ExprList exprs) {
Expr result = null;
for (Expr expr : exprs.getList()) {
result = (result == null) ? expr : new E_LogicalAnd(result, expr);
}
return result;
}
public static void collectAnd(Expr expr, ExprList list) {
if (expr instanceof E_LogicalAnd) {
E_LogicalAnd e = (E_LogicalAnd) expr;
collectAnd(e.getArg1(), list);
collectAnd(e.getArg2(), list);
} else {
list.add(expr);
}
}
public static ExprList collectExprs(Op op, ExprList result) {
if (op instanceof OpLeftJoin) {
OpLeftJoin x = (OpLeftJoin) op;
if (x.getExprs() != null) {
result.addAll(x.getExprs());
}
collectExprs(x.getLeft(), result);
collectExprs(x.getRight(), result);
} else if (op instanceof OpFilter) {
OpFilter x = (OpFilter) op;
result.addAll(x.getExprs());
collectExprs(x.getSubOp(), result);
} else if (op instanceof OpJoin) {
OpJoin x = (OpJoin) op;
collectExprs(x.getLeft(), result);
collectExprs(x.getRight(), result);
} else if (op instanceof OpUnion) {
System.out.println(
"Warning: Collecting expressions from unions. Since the same vars may appear within different (parts of) unions, it may be ambiguous to which part the expression refers.");
OpUnion x = (OpUnion) op;
collectExprs(x.getLeft(), result);
collectExprs(x.getRight(), result);
} else if (op instanceof OpQuadPattern) {
} else if (op instanceof OpSequence) {
OpSequence x = (OpSequence) op;
for (Op element : x.getElements()) {
collectExprs(element, result);
}
} else {
throw new RuntimeException("Not implemented. Type: " + op.getClass());
}
return result;
}
/** For any expression now in scope, wrap the op with a filter */
private static Op insertAnyFilter(ExprList exprs, Set<Var> patternVarsScope, Op op) {
for (Iterator<Expr> iter = exprs.iterator(); iter.hasNext(); ) {
Expr expr = iter.next();
// Cache
Set<Var> exprVars = expr.getVarsMentioned();
if (patternVarsScope.containsAll(exprVars)) {
if (op == null) op = OpTable.unit();
op = OpFilter.filter(expr, op);
iter.remove();
}
}
return op;
}
@Override
public void checkBuild(String uri, ExprList args) {
if (args.size() != 0)
throw new QueryBuildException("Function '" + Utils.className(this) + "' takes no arguments");
}
public static ExprList substitute(ExprList exprList, Binding binding) {
if (isNotNeeded(binding)) return exprList;
return exprList.copySubstitute(binding);
}