Macro verify_regex 

verify_regex!() { /* proc-macro */ }

Compiles the given regex using the fancy_regex crate and tries to match the given value. If the value matches the regex, the macro will expand to the first expression. Otherwise it will expand to the second expression.

It is designed to be used within other macros to produce compile time errors when the regex doesn’t match but it might work for other use-cases as well.

libcnb_proc_macros::verify_regex!(
    "^A-Z+$",
    "foobar",
    println!("It did match!"),
    println!("It did not match!")
);