public static Pair<Var, NodeValue> extractValueConstraint(Expr expr) {
if (!(expr instanceof ExprFunction2)) {
return null;
}
ExprFunction func = (ExprFunction) expr;
Expr a = func.getArg(1);
Expr b = func.getArg(2);
if (a.isVariable() == b.isVariable()) {
return null;
}
if (b.isVariable()) {
Expr tmp = b;
b = a;
a = tmp;
}
if (!b.isConstant()) {
return null;
}
return Pair.create(a.asVar(), b.getConstant());
}
/* @see com.hp.hpl.jena.sparql.syntax.ElementVisitorBase#visit(com.hp.hpl.jena.sparql.syntax.ElementFilter) */
@Override
public void visit(final ElementFilter elementfilter) {
final Expr expr = elementfilter.getExpr();
final BuiltinAtom atom;
try {
if (expr instanceof Expression) // RDQL
{
final Expression e = (Expression) expr;
final SWRLDataObject arg1 = makeDataObject(e.getArg(0));
final SWRLDataObject arg2 = makeDataObject(e.getArg(1));
if (e instanceof Q_Equal) atom = swrlFactory.createEqual(arg1, arg2);
else if (e instanceof Q_NotEqual) atom = swrlFactory.createNotEqual(arg1, arg2);
else if (e instanceof Q_GreaterThan) atom = swrlFactory.createGreaterThan(arg1, arg2);
else if (e instanceof Q_GreaterThanOrEqual)
atom = swrlFactory.createGreaterThanOrEqual(arg1, arg2);
else if (e instanceof Q_LessThan) atom = swrlFactory.createLessThan(arg1, arg2);
else if (e instanceof Q_LessThanOrEqual)
atom = swrlFactory.createLessThanOrEqual(arg1, arg2);
else
throw new IllegalArgumentException(
"Unsupported constraint expression " + e + " used in RDQL query.");
} else if (expr.isFunction()) // SPARQL
{
final ExprFunction f = (ExprFunction) expr;
final SWRLDataObject arg1 = makeDataObject(f.getArg(0));
final SWRLDataObject arg2 = makeDataObject(f.getArg(1));
if (f instanceof E_Equals) atom = swrlFactory.createEqual(arg1, arg2);
else if (f instanceof E_NotEquals) atom = swrlFactory.createNotEqual(arg1, arg2);
else if (f instanceof E_GreaterThan) atom = swrlFactory.createGreaterThan(arg1, arg2);
else if (f instanceof E_GreaterThanOrEqual)
atom = swrlFactory.createGreaterThanOrEqual(arg1, arg2);
else if (f instanceof E_LessThan) atom = swrlFactory.createLessThan(arg1, arg2);
else if (f instanceof E_LessThanOrEqual)
atom = swrlFactory.createLessThanOrEqual(arg1, arg2);
else
throw new IllegalArgumentException(
"Unsupported constraint (filter) " + f + " used in SPARQL query.");
} else return;
atoms = atoms.cons(atom);
} catch (final URISyntaxException e) {
throw new IllegalArgumentException(e.getInput() + " is not a valid URI!");
}
}
public static boolean containsDirectFuncChild(Expr expr, Class<?> clazz) {
if (!(expr instanceof ExprFunction)) {
return false;
}
ExprFunction func = (ExprFunction) expr;
for (Expr arg : func.getArgs()) {
if (arg == null) {
continue;
}
if (clazz.isAssignableFrom(arg.getClass())) {
return true;
}
}
return false;
}
private void visitExprFunction(ExprFunction function) {
logger.debug("visit ExprFunction " + function);
if (!convertable) {
expression.push(Expression.FALSE); // prevent stack empty exceptions when conversion
return; // fails in the middle of a multi-arg operator conversion
}
if (!extensionSupports(function)) {
conversionFailed(function);
return;
}
for (int i = 0; i < function.numArgs(); i++) function.getArg(i + 1).visit(this);
List<Expression> args = new ArrayList<Expression>(function.numArgs());
for (int i = 0; i < function.numArgs(); i++) args.add(expression.pop());
Collections.reverse(args);
extensionConvert(function, args);
}
public static Expr handle(ExprFunction expr) {
// System.out.println("Converting to DNF: [" + expr.getClass() + "]: " + expr);
// not(and(A, B)) -> or(not A, not B)
// not(or(A, B)) -> or(not A, not B)
if (expr instanceof E_LogicalNot) {
Expr tmp = ((E_LogicalNot) expr).getArg();
if (!(tmp instanceof ExprFunction)) {
return expr;
}
ExprFunction child = (ExprFunction) tmp;
Expr newExpr = expr;
if (child instanceof E_LogicalAnd) {
newExpr =
new E_LogicalOr(
eval(new E_LogicalNot(child.getArg(1))), eval(new E_LogicalNot(child.getArg(2))));
} else if (child instanceof E_LogicalOr) {
newExpr =
new E_LogicalAnd(
eval(new E_LogicalNot(child.getArg(1))), eval(new E_LogicalNot(child.getArg(2))));
} else if (child instanceof E_LogicalNot) { // Remove double negation
newExpr = eval(child.getArg(1));
} else {
return expr;
}
return eval(newExpr);
} else if (expr instanceof E_LogicalOr) {
// return expr;
// return eval(expr);
return new E_LogicalOr(eval(expr.getArg(1)), eval(expr.getArg(2)));
}
/* Given:
* (A or B) AND (C x D) becomes:
* (A and (C x D)) OR (B and (c x D))
*
*
* (A or B) AND (C or D)
*
* Goal:
* (A and C) OR (A and D) OR (B and C) OR (B and D)
*
* This method transforms any "or" children of an AND node.
* other nodes are left untouched:
* (A or B) AND (c x D) becomes:
* (A and (c x D)) OR (B and (c x D))
*/
else if (expr instanceof E_LogicalAnd) {
Expr aa = eval(expr.getArg(1));
Expr bb = eval(expr.getArg(2));
E_LogicalOr a = null;
Expr b = null;
if (aa instanceof E_LogicalOr) {
a = (E_LogicalOr) aa;
b = bb;
} else if (bb instanceof E_LogicalOr) {
a = (E_LogicalOr) bb;
b = aa;
}
if (a == null) {
return new E_LogicalAnd(aa, bb);
} else {
return new E_LogicalOr(
eval(new E_LogicalAnd(a.getArg(1), b)), eval(new E_LogicalAnd(a.getArg(2), b)));
}
} else if (expr
instanceof
E_NotEquals) { // Normalize (a != b) to !(a = b) --- this makes it easier to find "a and !a"
// cases
return new E_LogicalNot(eval(new E_Equals(expr.getArg(1), expr.getArg(2))));
}
return expr;
/*
if(expr instanceof E_LogicalNot) {
Expr tmp = ((E_LogicalNot)expr).getArg();
if (!(tmp instanceof ExprFunction))
return expr;
ExprFunction child = (ExprFunction) tmp;
String newFuncName = "";
if (child.getName().equals("and"))
newFuncName = "or";
else if (child.getName().equals("or"))
newFuncName = "and";
else if (child.getName().equals("not")) // Remove double negation
return eval(child.getChildren().get(0));
else
return expr;
FuncExpr result = new FuncExpr(newFuncName, child.getArity());
for (int i = 0; i < child.getArity(); ++i)
result.setChild(i,
new FuncExpr("not", child.getChildren().get(i)));
return eval(result);
}
if (expr.getName().equals("or")) {
List<IExpr> children = new ArrayList<IExpr>();
for (IExpr child : expr.getChildren())
children.add(eval(child));
if (!ExprUtil.containsDirectFuncChild(children, "or"))
return new FuncExpr("or", children);
// flatten or expressions
// or(or(A, B), C) becomes or(A, B, C)
List<IExpr> resultChildren = new ArrayList<IExpr>();
for (IExpr child : children)
if (ExprUtil.isFunc(child, "or"))
resultChildren.addAll(child.getChildren());
else
resultChildren.add(child);
return new FuncExpr("or", resultChildren);
}
if (expr.getName().equals("and")) {
List<IExpr> children = new ArrayList<IExpr>();
for (IExpr child : expr.getChildren())
children.add(eval(child));
// FIXME an and-node must have at least 2 children
// but maybe validation should be done somewhere else
// On the other hand it might be convenient to assume that
// whenever a binary expression only contains a single child
// it should be treated as if there was no operation at all.
// No 'or'-expression => nothing todo
if (!ExprUtil.containsDirectFuncChild(children, "or"))
return new FuncExpr("and", children);
// Collect all expressions
List<List<IExpr>> tables = new ArrayList<List<IExpr>>();
for (IExpr child : children) {
if (ExprUtil.isFunc(child, "or"))
tables.add(child.getChildren());
else
tables.add(Collections.singletonList(child));
}
Collection<List<IExpr>> joinedTable = new JoinIterable<IExpr>(
tables);
FuncExpr result = new FuncExpr("or", joinedTable.size());
// List<IExpr> resultChildren = new ArrayList<IExpr>();
int i = 0;
for (List<IExpr> row : joinedTable) {
IExpr newChild = new FuncExpr("and", row);
result.setChild(i, newChild);
++i;
}
return result;
}
// TODO Auto-generated method stub
return expr;
*/
}
/**
* Processes (at the time of writing some) known functions available in the Sparqlify-ML,
* variables and constant strings. Since arguments of the considered function can be functions,
* variables or constant strings as well, this method is called recursively to get to the most
* inner expression and build up the rest based on that.
*
* @param expr a restriction expression (com.hp.hpl.jena.sparql.expr.Expr) like a function
* (concat( ... ), uri( ... ), ...) or a variable
* @return a String containing the R2RML counterpart of these Sparqlify-ML expressions
*/
private String processRestrExpr(Expr expr) {
String exprStr = "";
/*
* functions
*/
if (expr.isFunction()) {
ExprFunction func = expr.getFunction();
// concat( ... )
if (func.getFunctionSymbol().equals(concatLabel)) {
List<Expr> args = func.getArgs();
for (Expr arg : args) {
// explicitely use string representation of IRIs get strings
// without leading and trailing angle brackets
if (arg.isConstant() && arg.toString().startsWith("<")) {
exprStr += arg.getConstant().asString();
continue;
}
exprStr += processRestrExpr(arg);
}
// uri( ... )
} else if (func.getFunctionIRI().equals(uriFunctionIRI)) {
// there should be just one argument here
Expr subExpr = func.getArgs().get(0);
exprStr += processRestrExpr(subExpr);
// plainLiteral( ... )
} else if (func.getFunctionIRI().equals(plainLiteralFunctionIRI)) {
// I am only interested in the first argument here, since a
// possible second argument containing a language tag is only
// of interest, if the plainLiteral is the most outer function
// which is handled in a different place.
Expr subExpr = func.getArgs().get(0);
exprStr += processRestrExpr(subExpr);
// typedLiteral
} else if (func.getFunctionIRI().equals(typedLiteralFunctionIRI)) {
// As above I am only interested in the first argument here
// since the second argument stating which type the first
// argument has, should be processed in a different place.
Expr subExpr = func.getArgs().get(0);
exprStr += processRestrExpr(subExpr);
} else {
// URL encode
// FIXME: no URL encoding is done here!!
Expr subExpr = func.getArgs().get(0);
exprStr += processRestrExpr(subExpr);
}
/*
* variables and strings
*/
} else {
// strings
if (expr.isConstant()) {
String constStr = expr.toString();
if (constStr.startsWith("\"")) {
// strip off the leading and trailing quote
constStr = constStr.substring(1);
if (constStr.endsWith("\"")) {
int strLength = constStr.length();
constStr = constStr.substring(0, strLength - 1);
}
}
exprStr += constStr;
// variables
} else if (expr.isVariable()) {
String varStr = expr.toString();
// strip off the leading question mark...
varStr = varStr.substring(1);
// ...and put the value in curly braces
varStr = "{" + varStr + "}";
exprStr += varStr;
}
}
return exprStr;
}