@Override
public Type union(final Type t) {
if (instanceOf(t)) return t;
if (t instanceof ArrayType) {
final ArrayType mt = (ArrayType) t;
return mt.instanceOf(this) ? this : get(retType.union(mt.retType));
}
return t instanceof MapType ? ANY_FUN : t instanceof FuncType ? t.union(this) : AtomType.ITEM;
}
@Override
public ArrayType intersect(final Type t) {
// case for item() and compatible FuncType, e.g. function(xs:anyAtomicType) as item()*
// also excludes FuncType.ANY_FUN
if (instanceOf(t)) return this;
if (t instanceof ArrayType) {
final ArrayType mt = (ArrayType) t;
if (mt.instanceOf(this)) return mt;
final SeqType rt = retType.intersect(mt.retType);
return rt == null ? null : get(rt);
}
if (t instanceof FuncType) {
final FuncType ft = (FuncType) t;
if (ft.argTypes.length == 1 && ft.argTypes[0].instanceOf(SeqType.ITR)) {
final SeqType rt = retType.intersect(ft.retType);
return rt == null ? null : get(rt);
}
}
return null;
}