| 45 | const auto asMulDs = asDsVia<Mul>(&Mul::lhs, &Mul::rhs); |
| 46 | |
| 47 | int eval(const Expr &ex) |
| 48 | { |
| 49 | Id<int> i; |
| 50 | Id<Expr> e, l, r; |
| 51 | return match(ex)( |
| 52 | // clang-format off |
| 53 | // FIXME: Expr{5} won't match the following line. |
| 54 | pattern | as<int>(i) = expr(i), |
| 55 | pattern | asNegDs(some(e)) = [&]{ return -eval(*e); }, |
| 56 | pattern | asAddDs(some(l), some(r)) = [&]{ return eval(*l) + eval(*r); }, |
| 57 | // Optimize multiplication by 0. |
| 58 | pattern | asMulDs(some(as<int>(0)), _) = expr(0), |
| 59 | pattern | asMulDs(_, some(as<int>(0))) = expr(0), |
| 60 | pattern | asMulDs(some(l), some(r)) = [&]{ return eval(*l) * eval(*r); }, |
| 61 | pattern | _ = expr(-1) |
| 62 | // clang-format on |
| 63 | ); |
| 64 | } |
| 65 | |
| 66 | int32_t main() |
| 67 | { |