#[allow(unused)] // for the doc comments
use std::any::Any;
#[allow(unused)] // for the doc comments
use std::fmt::Debug;
#[allow(unused)] // for the doc comments
use std::hash::Hash;

#[allow(unused)] // for the doc comments
use dyn_clone::DynClone;

#[allow(unused)] // for the doc comments
use crate::foreign::{Atomic, ExternFn};
#[allow(unused)] // for the doc comments
use crate::representations::Primitive;
#[allow(unused)] // for the doc comments
use crate::{atomic_impl, atomic_redirect};

/// Implement [ExternFn] with a closure that produces an [Atomic] from a
/// reference to self and a closure. This can be used in conjunction with
/// [atomic_impl] and [atomic_redirect] to normalize the argument automatically
/// before using it.
///
/// See [atomic_impl] for an example.
#[macro_export]
macro_rules! externfn_impl {
  ($typ:ident, $next_atomic:expr) => {
    impl $crate::foreign::ExternFn for $typ {
      fn name(&self) -> &str { stringify!($typ) }
      fn apply(
        self: Box<Self>,
        arg: $crate::interpreted::ExprInst,
        _ctx: $crate::interpreter::Context,
      ) -> $crate::foreign::XfnResult {
        let closure = $next_atomic;
        match closure(*self, arg) {
          // ? casts the result but we want to strictly forward it
          Ok(r) => Ok($crate::interpreted::Clause::P($crate::Primitive::Atom(
            $crate::foreign::Atom::new(r),
          ))),
          Err(e) => Err(e),
        }
      }
    }
  };
}