| Expand `$(..)` repetition in macro_rules 3d4a7d2 nandithebull 8h ago | 1 | // `$(..)` repetition — 28% of the `macro_rules!` in a 400-crate sample. The |
| 2 | // matcher binds each fragment once per iteration, and the transcriber emits |
| 3 | // its body once per iteration, joined by the separator. |
| 4 | |
| 5 | macro_rules! sum_all { |
| 6 | ($($x:expr),*) => { |
| 7 | 0 $(+ $x)* |
| 8 | }; |
| 9 | } |
| 10 | |
| 11 | macro_rules! max_of { |
| 12 | ($first:expr $(, $rest:expr)*) => {{ |
| 13 | let mut m = $first; |
| 14 | $( if $rest > m { m = $rest; } )* |
| 15 | m |
| 16 | }}; |
| 17 | } |
| 18 | |
| 19 | macro_rules! count_args { |
| 20 | ($($x:expr),*) => { |
| 21 | 0 $(+ { let _ = $x; 1 })* |
| 22 | }; |
| 23 | } |
| 24 | |
| 25 | macro_rules! pairs_sum { |
| 26 | ($($a:expr => $b:expr),*) => { |
| 27 | 0 $(+ $a * $b)* |
| 28 | }; |
| 29 | } |
| 30 | |
| 31 | fn main() { |
| 32 | println!("{}", sum_all!()); |
| 33 | println!("{}", sum_all!(1)); |
| 34 | println!("{}", sum_all!(1, 2, 3, 4)); |
| 35 | // Precedence survives: each capture is parenthesised. |
| 36 | println!("{}", sum_all!(1 + 1, 2 * 3)); |
| 37 | |
| 38 | println!("{}", max_of!(3)); |
| 39 | println!("{}", max_of!(3, 9, 2)); |
| 40 | println!("{}", max_of!(-5, -9, -1)); |
| 41 | |
| 42 | println!("{}", count_args!(7, 8, 9)); |
| 43 | println!("{}", count_args!()); |
| 44 | |
| 45 | println!("{}", pairs_sum!(2 => 3, 4 => 5)); |
| 46 | } |