treaty -


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use crate::{
    any::{TypeName}, effect::{Effect, Future}, higher_ranked_type, hkt::Marker, protocol::{walker::hint::{HintKnown, HintMeta}, Visitor}, Status
};

use super::VisitResult;

pub trait Recoverable<'ctx, E: Effect> {
    fn visit<'a>(
        &'a mut self,
        scope: DynRecoverableScope<'a, 'ctx, E>,
    ) -> Future<'a, VisitResult<DynRecoverableScope<'a, 'ctx, E>>, E>;
}

pub struct RecoverableProto<E: Effect>(Marker<E>);

higher_ranked_type! {
    impl TypeName {
        impl['a, 'ctx, E] type T['a, 'ctx] for RecoverableProto<E> =
            dyn Recoverable<'ctx, E> + Send + 'a
        where {
            E: Effect
        };

        impl['a, 'ctx, E] type HigherRanked['a, 'ctx] for dyn Recoverable<'ctx, E> + Send + 'a =
            RecoverableProto<E>
        where {
            E: Effect
        };
    }
}

pub trait RecoverableScope<'ctx, E: Effect> {
    fn new_walk<'a>(&'a mut self, visitor: Visitor<'a, 'ctx>) -> Future<'a, Status, E>;
}

pub type DynRecoverableScope<'a, 'ctx, E> = &'a mut (dyn RecoverableScope<'ctx, E> + Send + 'a);

pub struct RecoverableKnown;

higher_ranked_type! {
    impl HintKnown {
        impl['a] type T['a] for RecoverableKnown =
            RecoverableKnown;

        impl['a] type HigherRanked['a] for RecoverableKnown =
            RecoverableKnown;
    }
}

impl<'ctx, E: Effect> HintMeta<'ctx> for RecoverableProto<E> {
    type Known = RecoverableKnown;

    type Hint = ();
}

pub fn visit_recoverable<'a, 'ctx, E: Effect>(
    visitor: Visitor<'a, 'ctx>,
    scope: DynRecoverableScope<'a, 'ctx, E>,
) -> Future<'a, VisitResult<DynRecoverableScope<'a, 'ctx, E>>, E> {
    if let Some(object) = visitor.upcast_mut::<RecoverableProto<E>>() {
        // Allow the visitor to give a hint if it wants.
        object.visit(scope)
    } else {
        // If the visitor doesn't support request hint then we continue.
        E::ready(VisitResult::Skipped(scope))
    }
}