bool isSubtypeOf(const Type& a, const Type& b) {
// make sure they are both in the same environment
auto& environment = a.getTypeEnvironment();
assert(environment.isType(a) && environment.isType(b));
// first check - a type is a sub-type of itself
if (a == b) return true;
// check for predefined types
if (b == environment.getNumberType())
return isNumberType(a);
if (b == environment.getSymbolType())
return isSymbolType(a);
// check primitive type chains
if (isA<PrimitiveType>(a)) {
if (isSubtypeOf(as<PrimitiveType>(a).getBaseType(), b)){
return true;
}
}
// next - if b is a union type
if (isUnion(b)) {
return isSubType(a, as<UnionType>(b));
}
// done
return false;
}
// Adds a subtype to the list, and associated it with a parent type.
//The association can happen only once, a subtype is then definitely associated to its parent type.
// If you associate "goblin" to "creature", trying to associate "goblin" to "land" afterwards will fail. "goblin" will stay associated to its first parent.
int Subtypes::add(string value, unsigned int parentType)
{
unsigned int subtype = find(value);
if (parentType && isSubType(subtype))
{
if ((unsigned int)(subtypesToType.size()) < subtype + 1)
subtypesToType.resize(1 + subtype * 2, 0); //multiplying by 2 to avoid resizing at every insertion
subtypesToType[subtype] = parentType;
}
if (isSubType(subtype) && (parentType == TYPE_CREATURE))
{
if(value != "forest" && value != "Forest")//http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=136196 one creature with a land subtype exist, but the card has special ruling.
subtypesCreature.push_back(value);
}
return subtype;
}
