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#[cfg(not(feature = "no-std"))]
static PANIC_HANDLER_INIT: std::sync::atomic::AtomicBool =
    std::sync::atomic::AtomicBool::new(false);

#[cfg(not(feature = "no-std"))]
#[doc(hidden)]
pub fn inital_setup() {
    if PANIC_HANDLER_INIT
        .compare_exchange(
            false,
            true,
            std::sync::atomic::Ordering::Relaxed,
            std::sync::atomic::Ordering::Relaxed,
        )
        .is_err()
    {
        return;
    }

    unsafe {
        ocaml_boxroot_sys::boxroot_setup();
    }

    ::std::panic::set_hook(Box::new(|info| unsafe {
        let err = info.payload();
        let msg = if err.is::<&str>() {
            err.downcast_ref::<&str>().unwrap()
        } else if err.is::<String>() {
            err.downcast_ref::<String>().unwrap().as_ref()
        } else {
            "rust panic"
        };

        if let Some(err) = crate::Value::named("Rust_exception") {
            crate::Error::raise_value(err, msg);
        }

        crate::Error::raise_failure(msg)
    }))
}

/// `body!` is needed to help the OCaml runtime to manage garbage collection, it should
/// be used to wrap the body of each function exported to OCaml. Panics from Rust code
/// will automatically be unwound/caught here (unless the `no-std` feature is enabled)
///
/// ```rust
/// #[no_mangle]
/// pub unsafe extern "C" fn example(a: ocaml::Value, b: ocaml::Value) -> ocaml::Value {
///     ocaml::body!(gc: {
///         let a = a.int_val();
///         let b = b.int_val();
///         ocaml::Value::int(a + b)
///     })
/// }
/// ```
#[macro_export]
#[cfg(not(feature = "no-std"))]
macro_rules! body {
    ($gc:ident: $code:block) => {{
        let $gc = unsafe { $crate::Runtime::recover_handle() };

        // Ensure panic handler is initialized
        #[cfg(not(feature = "no-std"))]
        $crate::inital_setup();

        {
            $code
        }
    }};
}

#[macro_export]
/// Convenience macro to create an OCaml array
macro_rules! array {
    ($($x:expr),*) => {{
        $crate::ToValue::to_value(&vec![$($crate::ToValue::to_value(&$x)),*])
    }}
}

#[macro_export]
/// Convenience macro to create an OCaml list
macro_rules! list {
    ($($x:expr),*) => {{
        let mut l = $crate::list::empty();
        for i in (&[$($x),*]).into_iter().rev() {
            $crate::list::push_hd(&mut l, $crate::ToValue::to_value(i));
        }
        l
    }};
}