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]
18macro_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]
33macro_rules! _tt_as_expr_hack {
34 ($value:expr) => ($value)
35}
36
37#[test]
38fn 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