@Override
public void meet(SqlCase node) throws RuntimeException {
super.meet(node);
List<Entry> entries = node.getEntries();
for (SqlCase.Entry e : entries) {
if (e.getCondition() instanceof SqlNull) {
node.removeEntry(e);
} else if (e.getCondition() instanceof FalseValue) {
node.removeEntry(e);
} else if (e.getCondition() instanceof TrueValue) {
node.truncateEntries(e);
break;
}
}
entries = node.getEntries();
if (entries.isEmpty()) {
replace(node, new SqlNull());
} else if (entries.size() == 1) {
Entry entry = entries.get(0);
if (entry.getCondition() instanceof TrueValue) {
replace(node, entry.getResult().clone());
} else if (entry.getCondition() instanceof FalseValue) {
replace(node, new SqlNull());
} else if (entry.getCondition() instanceof SqlNot) {
SqlNot not = (SqlNot) entry.getCondition();
if (not.getArg() instanceof SqlIsNull) {
SqlIsNull is = (SqlIsNull) not.getArg();
if (is.getArg().equals(entry.getResult())) {
replace(node, entry.getResult().clone());
}
}
}
}
}
@Override
public void meet(SqlIsNull node) throws RuntimeException {
super.meet(node);
SqlExpr arg = node.getArg();
if (arg instanceof SqlNull) {
replace(node, new TrueValue());
} else if (arg instanceof SqlConstant<?>) {
replace(node, new FalseValue());
} else if (arg instanceof SqlCase) {
SqlExpr rep = null;
SqlExpr prev = null;
SqlCase scase = (SqlCase) arg;
for (Entry entry : scase.getEntries()) {
SqlExpr condition = entry.getCondition();
if (rep == null) {
rep = and(condition.clone(), isNull(entry.getResult().clone()));
prev = not(condition.clone());
} else {
rep =
or(rep, and(and(prev.clone(), condition.clone()), isNull(entry.getResult().clone())));
prev = and(prev, not(condition.clone()));
}
}
replace(node, or(rep, prev.clone()));
}
}