Macro regexm 

macro_rules! regexm {
    (
        match $str:tt {captures($pattern:expr) => |$caps:ident| $expr:expr, $($rest:tt)*}
    ) => { ... };
    (
        match $str:tt {captures($pattern:expr) => |$caps:ident| $expr:block $($rest:tt)*}
    ) => { ... };
    (
        match $str:tt {$pattern:expr => $expr:expr, $($rest:tt)*}
    ) => { ... };
    (
        match $str:tt {$pattern:expr => $expr:block $($rest:tt)*}
    ) => { ... };
}