private SqlExpr other(SqlExpr node, SqlExpr compare, Class<? extends BinarySqlOperator> type) {
if (type.isInstance(node)) {
BinarySqlOperator cast = type.cast(node);
SqlExpr left = cast.getLeftArg();
SqlExpr right = cast.getRightArg();
if (left.equals(compare)) return right;
if (right.equals(compare)) return left;
}
return null;
}
@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()));
}
}
@Override
public void meet(SqlAnd node) throws RuntimeException {
super.meet(node);
SqlExpr left = node.getLeftArg();
SqlExpr right = node.getRightArg();
if (left instanceof FalseValue || right instanceof FalseValue) {
replace(node, new FalseValue());
} else if (left instanceof TrueValue && right instanceof TrueValue) {
replace(node, new TrueValue());
} else if (left instanceof TrueValue) {
replace(node, right.clone());
} else if (right instanceof TrueValue) {
replace(node, left.clone());
} else if (right instanceof SqlNull || left instanceof SqlNull) {
replace(node, new SqlNull());
} else if (right instanceof SqlNot && ((SqlNot) right).getArg().equals(left)) {
replace(node, new FalseValue());
} else if (left instanceof SqlNot && ((SqlNot) left).getArg().equals(right)) {
replace(node, new FalseValue());
}
}
@Override
public void meet(SqlOr node) throws RuntimeException {
super.meet(node);
SqlExpr left = node.getLeftArg();
SqlExpr right = node.getRightArg();
if (left instanceof TrueValue || right instanceof TrueValue) {
replace(node, new TrueValue());
} else if (left instanceof FalseValue && right instanceof FalseValue) {
replace(node, new FalseValue());
} else if (left instanceof FalseValue) {
replace(node, right.clone());
} else if (right instanceof FalseValue) {
replace(node, left.clone());
} else if (right instanceof SqlNull && andAllTheWay(node)) {
replace(node, left.clone());
} else if (left instanceof SqlNull && andAllTheWay(node)) {
replace(node, right.clone());
} else if (right instanceof SqlNull && left instanceof SqlNull) {
replace(node, new SqlNull());
} else if (left instanceof SqlNull && right instanceof SqlOr) {
SqlOr r = (SqlOr) right;
SqlExpr rleft = r.getLeftArg();
SqlExpr rright = r.getRightArg();
if (rleft instanceof SqlNull || rright instanceof SqlNull) {
replace(node, right.clone());
}
} else if (right instanceof SqlNull && left instanceof SqlOr) {
SqlOr l = (SqlOr) left;
SqlExpr lleft = l.getLeftArg();
SqlExpr lright = l.getRightArg();
if (lleft instanceof SqlNull || lright instanceof SqlNull) {
replace(node, left.clone());
}
} else if (right instanceof SqlNull && left instanceof SqlAnd) {
// value IS NOT NULL AND value = ? OR NULL
// -> value = ?
SqlAnd l = (SqlAnd) left;
SqlExpr lleft = l.getLeftArg();
SqlExpr lright = l.getRightArg();
SqlExpr isNotNull = arg(arg(lleft, SqlNot.class), SqlIsNull.class);
SqlExpr isNotEq = other(lright, isNotNull, SqlEq.class);
if (isNotEq instanceof SqlConstant) {
replace(node, lright);
}
}
}
private void replace(SqlExpr before, SqlExpr after) {
before.replaceWith(after);
after.visit(this);
}
public void optimize(SqlExpr sqlExpr) {
sqlExpr.visit(this);
}