private void checkVariance(
boolean covariant,
boolean contravariant,
Declaration declaration,
List<TypeParameter> errors) {
// TODO: fix this to allow reporting multiple errors!
if (getDeclaration() instanceof TypeParameter) {
TypeParameter tp = (TypeParameter) getDeclaration();
boolean ok =
tp.getDeclaration().equals(declaration)
|| ((covariant || !tp.isCovariant()) && (contravariant || !tp.isContravariant()));
if (!ok) {
// a covariant type parameter appears in a contravariant location, or
// a contravariant type parameter appears in a covariant location.
errors.add(tp);
}
} else if (getDeclaration() instanceof UnionType) {
for (ProducedType ct : getCaseTypes()) {
ct.checkVariance(covariant, contravariant, declaration, errors);
}
} else if (getDeclaration() instanceof IntersectionType) {
for (ProducedType ct : getSatisfiedTypes()) {
ct.checkVariance(covariant, contravariant, declaration, errors);
}
} else {
for (TypeParameter tp : getDeclaration().getTypeParameters()) {
ProducedType pt = getTypeArguments().get(tp);
if (pt != null) {
if (tp.isCovariant()) {
pt.checkVariance(covariant, contravariant, declaration, errors);
} else if (tp.isContravariant()) {
if (covariant | contravariant) {
pt.checkVariance(!covariant, !contravariant, declaration, errors);
} else {
// else if we are in a nonvariant position, it stays nonvariant
pt.checkVariance(covariant, contravariant, declaration, errors);
}
} else {
pt.checkVariance(false, false, declaration, errors);
}
}
}
}
}
/**
* Determine if this is a decidable supertype, i.e. if it obeys the restriction that types with
* contravariant type parameters may only appear in covariant positions.
*
* @return a list of type parameters which appear in illegal positions
*/
public List<TypeDeclaration> checkDecidability() {
List<TypeDeclaration> errors = new ArrayList<TypeDeclaration>();
for (TypeParameter tp : getDeclaration().getTypeParameters()) {
ProducedType pt = getTypeArguments().get(tp);
if (pt != null) {
pt.checkDecidability(tp.isCovariant(), tp.isContravariant(), errors);
}
}
return errors;
}
private void checkDecidability(
boolean covariant, boolean contravariant, List<TypeDeclaration> errors) {
if (getDeclaration() instanceof TypeParameter) {
// nothing to do
} else if (getDeclaration() instanceof UnionType) {
for (ProducedType ct : getCaseTypes()) {
ct.checkDecidability(covariant, contravariant, errors);
}
} else if (getDeclaration() instanceof IntersectionType) {
for (ProducedType ct : getSatisfiedTypes()) {
ct.checkDecidability(covariant, contravariant, errors);
}
} else {
for (TypeParameter tp : getDeclaration().getTypeParameters()) {
if (!covariant && tp.isContravariant()) {
// a type with contravariant parameters appears at
// a contravariant location in satisfies / extends
errors.add(getDeclaration());
}
ProducedType pt = getTypeArguments().get(tp);
if (pt != null) {
if (tp.isCovariant()) {
pt.checkDecidability(covariant, contravariant, errors);
} else if (tp.isContravariant()) {
if (covariant | contravariant) {
pt.checkDecidability(!covariant, !contravariant, errors);
} else {
// else if we are in a nonvariant position, it stays nonvariant
pt.checkDecidability(covariant, contravariant, errors);
}
} else {
pt.checkDecidability(false, false, errors);
}
}
}
}
}
/** Is this type a subtype of the given type? Ignore a certain self type constraint. */
public boolean isSubtypeOf(ProducedType type, TypeDeclaration selfTypeToIgnore) {
if (getDeclaration() instanceof BottomType) {
return true;
} else if (type.getDeclaration() instanceof BottomType) {
return false;
} else if (getDeclaration() instanceof UnionType) {
for (ProducedType ct : getInternalCaseTypes()) {
if (ct == null || !ct.isSubtypeOf(type, selfTypeToIgnore)) {
return false;
}
}
return true;
} else if (type.getDeclaration() instanceof UnionType) {
for (ProducedType ct : type.getInternalCaseTypes()) {
if (ct != null && isSubtypeOf(ct, selfTypeToIgnore)) {
return true;
}
}
return false;
} else if (type.getDeclaration() instanceof IntersectionType) {
for (ProducedType ct : type.getInternalSatisfiedTypes()) {
if (ct != null && !isSubtypeOf(ct, selfTypeToIgnore)) {
return false;
}
}
return true;
} else if (getDeclaration() instanceof IntersectionType) {
for (ProducedType ct : getInternalSatisfiedTypes()) {
if (ct == null || ct.isSubtypeOf(type, selfTypeToIgnore)) {
return true;
}
}
return false;
} else {
ProducedType st = getSupertype(type.getDeclaration(), selfTypeToIgnore);
if (st == null) {
return false;
} else {
ProducedType stqt = st.getQualifyingType();
ProducedType tqt = type.getQualifyingType();
if (stqt == null) {
if (tqt != null) {
// probably extraneous!
return false;
}
} else {
if (tqt == null) {
// probably extraneous!
return false;
} else {
// note that the qualifying type of the
// given type may be an invariant subtype
// of the type that declares the member
// type, as long as it doesn't refine the
// member type
TypeDeclaration totd = (TypeDeclaration) type.getDeclaration().getContainer();
ProducedType tqts = tqt.getSupertype(totd);
if (!stqt.isSubtypeOf(tqts)) {
return false;
}
}
}
for (TypeParameter p : type.getDeclaration().getTypeParameters()) {
ProducedType arg = st.getTypeArguments().get(p);
ProducedType otherArg = type.getTypeArguments().get(p);
if (arg == null || otherArg == null) {
/*throw new RuntimeException("Missing type argument for type parameter: " +
p.getName() + " of " +
type.getDeclaration().getName());*/
return false;
} else if (p.isCovariant()) {
if (!arg.isSubtypeOf(otherArg)) {
return false;
}
} else if (p.isContravariant()) {
if (!otherArg.isSubtypeOf(arg)) {
return false;
}
} else {
if (!arg.isExactly(otherArg)) {
return false;
}
}
}
return true;
}
}
}
