/**
* During the join process, there might be cycle. It means the ECR <code>
* root</code> might be set to <code>freshType</code>. The type-union should take care of it --
* union <code>freshType</code> to <code>unionType</code>. In particular, <code>freshType</code>
* is an object type, while <code>
* unionType</code> is a struct type, then <code>unionType</code> should be collapsed before union
* with <code>freshType</code>.
*
* @param root
* @param unionType
* @param freshType
* @return unified type
*/
private ValueType resolveType(ECR root, ValueType unionType, ValueType freshType) {
Preconditions.checkArgument(!unionType.isLambda());
Preconditions.checkArgument(!freshType.isLambda());
Pair<ValueType, ValueType> pair = swap(unionType, freshType);
ValueType t1 = pair.fst(), t2 = pair.snd();
if (t1.isSimple() && t2.isStruct()) {
Collection<ECR> elems = t2.asStruct().getFieldMap().asMapOfRanges().values();
ValueType resType = t1;
for (ECR elem : elems) {
ECR elemLoc = getLoc(elem);
ValueType elemLocType = getType(elemLoc);
Parent parent = elemLocType.getParent().removeECR(root);
elemLocType.setParent(parent);
if (elemLocType.isStruct()) {
elemLocType = collapseStruct(elemLoc, elemLocType.asStruct());
}
union(root, elemLoc);
resType = unify(resType, elemLocType);
}
return resType;
}
return unify(t1, t2);
}
/**
* Swap <code>t1</code> and <code>t2</code> if <code> kind(t1) > kind(t2)
* </code>
*
* @param t1
* @param t2
* @return the pair of value types <code>(t1', t2')</code> that <code>kind(t1') <= kind(t2')
* </code>
*/
private Pair<ValueType, ValueType> swap(ValueType t1, ValueType t2) {
if (t1.isBottom()) return Pair.of(t1, t2);
if (t2.isBottom()) return Pair.of(t2, t1);
if (t1.isLambda()) {
assert t2.isLambda();
return Pair.of(t1, t2);
}
if (t2.isLambda()) {
assert t1.isLambda();
return Pair.of(t1, t2);
}
ValueTypeKind kind1 = t1.getKind();
ValueTypeKind kind2 = t2.getKind();
switch (kind1) {
case BOTTOM:
return Pair.of(t1, t2);
case BLANK:
switch (kind2) {
case BOTTOM:
case BLANK:
return Pair.of(t2, t1);
default:
return Pair.of(t1, t2);
}
case SIMPLE:
switch (kind2) {
case BLANK:
case BOTTOM:
case SIMPLE:
return Pair.of(t2, t1);
default:
return Pair.of(t1, t2);
}
default: // case STRUCT:
switch (kind2) {
case BLANK:
case BOTTOM:
case SIMPLE:
case STRUCT:
return Pair.of(t2, t1);
default:
return Pair.of(t1, t2);
}
}
}
/**
* Unify value types <code>t1</code> and <code>t2</code>
*
* @param t1
* @param t2
* @return a unified value type
*/
ValueType unify(ValueType t1, ValueType t2) {
Pair<ValueType, ValueType> pair = swap(t1, t2);
t1 = pair.fst();
t2 = pair.snd();
if (t1.equals(t2)) return t1;
if (t1.isBottom()) {
if (t1.hasOpTag()) t2.enableOpTag();
return t2;
}
Parent parent = Parent.getLUB(t1.getParent(), t2.getParent());
Size size = Size.getLUB(t1.getSize(), t2.getSize());
boolean hasOpTag = t1.hasOpTag() || t2.hasOpTag();
switch (t1.getKind()) {
case BLANK:
{
switch (t2.getKind()) {
case BLANK:
return ValueType.blank(size, parent, hasOpTag);
case SIMPLE:
{
return ValueType.simple(
t2.asSimple().getLoc(), t2.asSimple().getFunc(), size, parent, hasOpTag);
}
default:
{ // case STRUCT:
return ValueType.struct(t2.asStruct().getFieldMap(), size, parent, hasOpTag);
}
}
}
case SIMPLE:
{
switch (t2.getKind()) {
case SIMPLE:
{
ECR loc1 = t1.asSimple().getLoc();
ECR loc2 = t2.asSimple().getLoc();
ECR func1 = t1.asSimple().getFunc();
ECR func2 = t2.asSimple().getFunc();
ECR loc = join(loc1, loc2);
ECR func = join(func1, func2);
return ValueType.simple(loc, func, size, parent, hasOpTag);
}
default: // case STRUCT:
throw new IllegalArgumentException();
}
}
case STRUCT:
{
if (ValueTypeKind.STRUCT.equals(t2.getKind())) {
RangeMap<Long, ECR> map = getCompatibleMap(t1.asStruct(), t2.asStruct());
return ValueType.struct(map, size, parent, hasOpTag);
} else {
throw new IllegalArgumentException();
}
}
default:
{ // Lambda
assert (t2.isLambda());
List<ECR> params = Lists.newArrayList();
Iterator<ECR> paramItr1 = t1.asLambda().getParams().iterator();
Iterator<ECR> paramItr2 = t2.asLambda().getParams().iterator();
while (paramItr1.hasNext() && paramItr2.hasNext()) {
ECR param1 = paramItr1.next();
ECR param2 = paramItr2.next();
ECR param = join(param1, param2);
params.add(param);
}
while (paramItr1.hasNext()) params.add(paramItr1.next());
while (paramItr2.hasNext()) params.add(paramItr2.next());
ECR ret1 = t1.asLambda().getRet();
ECR ret2 = t2.asLambda().getRet();
ECR ret = join(ret1, ret2);
return ValueType.lam(ret, params, parent);
}
}
}