| 1 | //! Pattern Matching macros. |
|---|---|
| 2 | |
| 3 | /// Returns true if an expression matches a pattern. |
| 4 | /// |
| 5 | /// # Example |
| 6 | /// |
| 7 | /// ``` |
| 8 | /// # #[macro_use] extern crate mac; |
| 9 | /// |
| 10 | /// # fn main() { |
| 11 | /// assert!(matches!(2, 1 | 2 | 3)); |
| 12 | /// assert!(matches!('x', 'a'... 'z')); |
| 13 | /// assert!(!matches!(Some(1), None)); |
| 14 | /// assert!(matches!(Some(42), Some(n) if n == 42)); |
| 15 | /// # } |
| 16 | /// ``` |
| 17 | #[macro_export] |
| 18 | macro_rules! matches { |
| 19 | ($expr:expr, $($pat:tt)+) => { |
| 20 | _tt_as_expr_hack! { |
| 21 | match $expr { |
| 22 | $($pat)+ => true, |
| 23 | _ => false |
| 24 | } |
| 25 | } |
| 26 | } |
| 27 | } |
| 28 | |
| 29 | /// Work around "error: unexpected token: `an interpolated tt`", whatever that |
| 30 | /// means. (Probably rust-lang/rust#22819.) |
| 31 | #[doc(hidden)] |
| 32 | #[macro_export] |
| 33 | macro_rules! _tt_as_expr_hack { |
| 34 | ($value:expr) => ($value) |
| 35 | } |
| 36 | |
| 37 | #[test] |
| 38 | fn test_matches() { |
| 39 | let foo = Some("-12"); |
| 40 | assert!(matches!(foo, Some(bar) if |
| 41 | matches!(bar.as_bytes()[0], b'+'| b'-') && |
| 42 | matches!(bar.as_bytes()[1], b'0'... b'9') |
| 43 | )); |
| 44 | } |
| 45 |