Macro tracing::stdlib::matches

macro_rules! matches {
    ($expression:expr, $pattern:pat $(if $guard:expr)? $(,)?) => { ... };
}

Returns whether the given expression matches the provided pattern.

The pattern syntax is exactly the same as found in a match arm. The optional if guard can be used to add additional checks that must be true for the matched value, otherwise this macro will return false.

When testing that a value matches a pattern, it’s generally preferable to use assert_matches! as it will print the debug representation of the value if the assertion fails.

Examples

let foo = 'f';
assert!(matches!(foo, 'A'..='Z' | 'a'..='z'));

let bar = Some(4);
assert!(matches!(bar, Some(x) if x > 2));