Rust match target_os macro

match_os.rs

/// Match target_os compile time constant.
///
/// Usage:
/// ```
/// match_os! {
///     "windows" => println!("hello from windows"),
///     "linux" | "macos" => {
///         println!("hello from unix")
///     },
///     _ => {
///         println!("hello from unhandled")
///     }
/// }
/// ```
///
/// Non exaustive match will cause compiler error when compiling for unhandled target_os.
///
#[macro_export]
macro_rules! match_os {
    {$($($sys: literal)|+ => $v: expr),+ , _ => $otherwise: expr } => {
        $(
            #[cfg(any($(target_os = $sys),+))]
            $v
        )+
        #[cfg(not(any($($(target_os = $sys),+),+)))]
        $otherwise
    };
    {$($($sys: literal)|+ => $v: expr),+} => {
        match_os!{
            $($($sys)|+ => $v),+ , _ => { compile_error!("current system not handled"); }
        }
    };
}