`record!` macro

record.rs

#[macro_export]
macro_rules! record {
    ($($fields:tt)+) => {
        let fieldset = tracing::fieldset!($($fields)+);
        $crate::valueset!(fieldset, $($fields)+);
    };
}

#[macro_export]
macro_rules! valueset {

    // === exit ===
    (@ { $(,)* $($val:expr),* $(,)* }, $next:expr $(,)*) => {
        let span = tracing::Span::current();
        $(
            let (__k, __v) = $val;
            tracing::Span::current().record(*__k, __v);
        )*
    };

    // Handle identity keys
    (@ { $(,)* $($out:expr),* }, $next:expr, $($k:ident).+ = ?$val:expr, $($rest:tt)*) => {
        $crate::valueset!(
            @ { $($out),*, ($next, debug(&$val)) },
            $next,
            $($rest)*
        );
    };
    (@ { $(,)* $($out:expr),* }, $next:expr, $($k:ident).+ = %$val:expr, $($rest:tt)*) => {
        $crate::valueset!(
            @ { $($out),*, ($next, display(&$val)) },
            $next,
            $($rest)*
        )
    };
    (@ { $(,)* $($out:expr),* }, $next:expr, $($k:ident).+ = $val:expr, $($rest:tt)*) => {
        $crate::valueset!(
            @ { $($out),*, ($next, &$val) },
            $next,
            $($rest)*
        )
    };
    (@ { $(,)* $($out:expr),* }, $next:expr, ?$($k:ident).+, $($rest:tt)*) => {
        $crate::valueset!(
            @ { $($out),*, ($next, debug(&$($k).+)) },
            $next,
            $($rest)*
        );
    };
    (@ { $(,)* $($out:expr),* }, $next:expr, %$($k:ident).+, $($rest:tt)*) => {
        $crate::valueset!(
            @ { $($out),*, ($next, display(&$($k).+)) },
            $next,
            $($rest)*
        );
    };
    (@ { $(,)* $($out:expr),* }, $next:expr, $($k:ident).+ = ?$val:expr) => {
        $crate::valueset!(
            @ { $($out),*, ($next, debug(&$val)) },
            $next,
        );
    };
    (@ { $(,)* $($out:expr),* }, $next:expr, $($k:ident).+ = %$val:expr) => {
        $crate::valueset!(
            @ { $($out),*, ($next, display(&$val)) },
            $next,
        );
    };
    (@ { $(,)* $($out:expr),* }, $next:expr, ?$($k:ident).+) => {
        $crate::valueset!(
            @ { $($out),*, ($next, debug(&$($k).+)) },
            $next,
        );
    };
    (@ { $(,)* $($out:expr),* }, $next:expr, %$($k:ident).+) => {
        $crate::valueset!(
            @ { $($out),*, ($next, display(&$($k).+)) },
            $next,
        );
    };

    // Handle literal names
    (@ { $(,)* $($out:expr),* }, $next:expr, $k:literal = ?$val:expr, $($rest:tt)*) => {
        $crate::valueset!(
            @ { $($out),*, ($next, debug(&$val)) },
            $next,
            $($rest)*
        );
    };
    (@ { $(,)* $($out:expr),* }, $next:expr, $k:literal = %$val:expr, $($rest:tt)*) => {
        $crate::valueset!(
            @ { $($out),*, ($next, display(&$val)) },
            $next,
            $($rest)*
        );
    };
    (@ { $(,)* $($out:expr),* }, $next:expr, $k:literal = $val:expr, $($rest:tt)*) => {
        $crate::valueset!(
            @ { $($out),*, ($next, display(&$val)) },
            $next,
            $($rest)*
        );
    };
    (@ { $(,)* $($out:expr),* }, $next:expr, $k:literal = ?$val:expr) => {
        $crate::valueset!(
            @ { $($out),*, ($next, debug(&$val)) },
            $next,
        );
    };
    (@ { $(,)* $($out:expr),* }, $next:expr, $k:literal = %$val:expr) => {
        $crate::valueset!(
            @ { $($out),*, ($next, display(&$val)) },
            $next,
        );
    };
    (@ { $(,)* $($out:expr),* }, $next:expr, $k:literal = $val:expr) => {
        $crate::valueset!(
            @ { $($out),*, ($next, &$val) },
            $next,
        );
    };
    // Remainder is unparsable, but exists --- must be format args!
    (@ { $(,)* $($out:expr),* }, $next:expr, $($rest:tt)+) => {
        $crate::valueset!(@ { ($next, &format_args!($($rest)+)), $($out),* }, $next, );
    };

    // === entry ===
    ($fieldset: expr, $($fields:tt)+) => {
        {
            #[allow(unused_imports)]
            use tracing::field::{debug, display, Value};
            let mut iter = $fieldset.iter();
            $crate::valueset!(
                @ { },
                iter.next().expect("FieldSet corrupted (this is a bug)"),
                $($fields)+
            );
        }
    };
}