@Override
public boolean isSubtypeOf(Type type) {
// trivial base cases
if (type == null) {
return false;
} else if (this == type || type.isDynamic() || type.isDartCoreFunction()) {
return true;
} else if (!(type instanceof FunctionType)) {
return false;
} else if (this.equals(type)) {
return true;
}
FunctionType t = this;
FunctionType s = (FunctionType) type;
// normal parameter types
if (t.getNormalParameterTypes().length != s.getNormalParameterTypes().length) {
return false;
} else if (t.getNormalParameterTypes().length > 0) {
Type[] tTypes = t.getNormalParameterTypes();
Type[] sTypes = s.getNormalParameterTypes();
for (int i = 0; i < tTypes.length; i++) {
if (!tTypes[i].isAssignableTo(sTypes[i])) {
return false;
}
}
}
// optional parameter types
if (t.getOptionalParameterTypes().length > 0) {
Type[] tOpTypes = t.getOptionalParameterTypes();
Type[] sOpTypes = s.getOptionalParameterTypes();
// if k >= m is false, return false: the passed function type has more optional parameter
// types than this
if (tOpTypes.length < sOpTypes.length) {
return false;
}
for (int i = 0; i < sOpTypes.length; i++) {
if (!tOpTypes[i].isAssignableTo(sOpTypes[i])) {
return false;
}
}
if (t.getNamedParameterTypes().size() > 0 || s.getNamedParameterTypes().size() > 0) {
return false;
}
} else if (s.getOptionalParameterTypes().length > 0) {
return false;
}
// named parameter types
if (t.getNamedParameterTypes().size() > 0) {
Map<String, Type> namedTypesT = t.getNamedParameterTypes();
Map<String, Type> namedTypesS = s.getNamedParameterTypes();
// if k >= m is false, return false: the passed function type has more named parameter types
// than this
if (namedTypesT.size() < namedTypesS.size()) {
return false;
}
// Loop through each element in S verifying that T has a matching parameter name and that the
// corresponding type is assignable to the type in S.
Iterator<Entry<String, Type>> iteratorS = namedTypesS.entrySet().iterator();
while (iteratorS.hasNext()) {
Entry<String, Type> entryS = iteratorS.next();
Type typeT = namedTypesT.get(entryS.getKey());
if (typeT == null) {
return false;
}
if (!entryS.getValue().isAssignableTo(typeT)) {
return false;
}
}
} else if (s.getNamedParameterTypes().size() > 0) {
return false;
}
return s.getReturnType().equals(VoidTypeImpl.getInstance())
|| t.getReturnType().isAssignableTo(s.getReturnType());
}
