partials

partial.rs

macro_rules! generate_field_diff {
    (optional, $self:ident, $before:ident, $partial:ident, $field:ident) => {
        if $partial.$field.is_some() {
            $before.$field = $self.$field.clone();
        };
    };

    ($self:ident, $before:ident, $partial:ident, $field:ident) => {
        if $partial.$field.is_some() {
            $before.$field = Some($self.$field.clone());
        };
    };
}

macro_rules! generate_diff {
    (
        $self:ident,
        $before:ident,
        $partial:ident,
        (
            $(
                $(
                    $(@$optional:tt)? (optional)
                )?
                $field: ident
            ),+
            $(,)?
        )
    ) => {
        $(
            generate_field_diff!($( $($optional)? optional,)? $self, $before, $partial, $field);
        )*
    }
}