[Question]: include more than one validator about requestty HOT 2 CLOSED

macro_rules! join_validators {
    // Just uses the question mark operator to call the validators in order of which they are
    // specified, returning early if one fails
    ($($validators:expr),+ $(,)?) => {
        |val, ans| { $($validators(val, ans)?;)+ Ok(()) }
    };
}

macro_rules! join_on_key_validators {
    // Joins all the validator calls with an && as the result is boolean and all must return true
    ($($validators:expr),+ $(,)?) => {
        |val, ans| $($validators(val, ans))&&+
    };
}

macro_rules! join_filters {
    // This is slightly more complicated as the function calls need to be nested.
    //
    // The top level macro call sets up the wrapper function and calls the implementation
    ($($filters:expr),+ $(,)?) => {
        |val, ans| join_filters!(@__impl val, ans; $($filters),+ ,)
    };

    // In the general case, $val represents the filtered value so far, $ans is the answers supplied
    // to the wrapper function, $filter and $remaining are the filter functions which are yet to be called.
    //
    // join_filters! is called recursively with the new $val being $filter($val), after removing
    // $filter from the list of filters to be called.
    (@__impl $val:expr, $ans:expr; $filter:expr, $($remaining:expr,)*) => {
        join_filters!(@__impl $filter($val, $ans), $ans; $($remaining,)*)
    };

    // This is the base case where there are no more functions to call, so just return the value as it is fully filtered
    (@__impl $val:expr, $ans:expr;) => {
        $val
    };
}

pub fn join_str_validators<'a>(
    mut left: impl FnMut(&str, &Answers) -> Result<(), String> + 'a,
    mut right: impl FnMut(&str, &Answers) -> Result<(), String> + 'a,
) -> impl FnMut(&str, &Answers) -> Result<(), String> + 'a {
    move |str_value: &str, answers: &Answers| {
        if let Err(err) = left(str_value, &answers) {
            Err(err)
        } else if let Err(err) = right(str_value, &answers) {
            Err(err)
        } else {
            Ok(())
        }
    }
}

pub fn join_on_key_validator<'a>(
    mut left: impl FnMut(&str, &Answers) -> bool + 'a,
    mut right: impl FnMut(&str, &Answers) -> bool + 'a,
) -> impl FnMut(&str, &Answers) -> bool + 'a {
    move |str_value, answers| left(str_value, &answers) && right(str_value, &answers)
}