TypeSet getGreatestCommonSubtypes(const TypeSet& set) {
// handle the empty set
if (set.empty()) return set;
// handle the all set => empty set (since no common sub-type)
if (set.isAll()) return TypeSet();
TypeSet res;
auto it = set.begin();
res.insert(*it);
++it;
// refine sub-set step by step
for(;it != set.end(); ++it) {
TypeSet tmp;
for(const Type& cur : res) {
tmp.insert(getGreatestCommonSubtypes(cur, *it));
}
res = tmp;
}
// done
return res;
}
TypeSet getGreatestCommonSubtypes(const TypeSet& a, const TypeSet& b) {
// special cases
if (a.empty()) return a;
if (b.empty()) return b;
if (a.isAll()) return b;
if (b.isAll()) return a;
// compute pairwise greatest common sub types
TypeSet res;
for(const Type& x : a) {
for(const Type& y : b) {
res.insert(getGreatestCommonSubtypes(x,y));
}
}
return res;
}
bool isRecordType(const TypeSet& s) {
return !s.empty() && !s.isAll() && all_of(s, (bool(*)(const Type&))&isRecordType);
}
