public static Serializable diff(Object[] a, Object[] b) {
List<Object> la = Arrays.asList(a);
List<Object> lb = Arrays.asList(b);
Serializable diff = diff(la, lb);
if (diff instanceof List) {
return b;
}
ListDiff listDiff = (ListDiff) diff;
listDiff.isArray = true;
return listDiff;
}
public static Serializable diff(List<Object> a, List<Object> b) {
ListDiff listDiff = new ListDiff();
listDiff.isArray = false;
int aSize = a.size();
int bSize = b.size();
// TODO configure zero-length "a" case
boolean doRPush = aSize > 0 && aSize < bSize;
// we can use a list diff if lists are the same size,
// or we have a rpush
boolean doDiff = aSize == bSize || doRPush;
if (!doDiff) {
return (Serializable) b;
}
int len = Math.min(aSize, bSize);
List<Object> diff = new ArrayList<>(len);
int nops = 0;
int diffs = 0;
for (int i = 0; i < len; i++) {
Serializable elemDiff = diff(a.get(i), b.get(i));
if (elemDiff == NOP) {
nops++;
} else if (elemDiff instanceof StateDiff) {
diffs++;
}
// TODO if the individual element diffs are big StateDiffs,
// do a full State replacement instead
diff.add(elemDiff);
}
if (nops == len) {
// only nops
diff = null;
} else if (diffs == 0) {
// only setting elements or nops
// TODO use a higher ratio than 0% of diffs
return (Serializable) b;
}
listDiff.diff = diff;
if (doRPush) {
List<Object> rpush = new ArrayList<>(bSize - aSize);
for (int i = aSize; i < bSize; i++) {
rpush.add(b.get(i));
}
listDiff.rpush = rpush;
}
return listDiff;
}
private static final ListDiff listDiff(List<Object> diff, List<Object> rpush) {
ListDiff listDiff = new ListDiff();
listDiff.diff = diff;
listDiff.rpush = rpush;
return listDiff;
}