treaty -


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use effectful::{
    effective::{Canonical, Effective}, environment::{Environment, InEnvironment}, higher_ranked::Rank1, DynBind
};

use crate::{
    any::type_name,
    protocol::{walker::hint::HintMeta, DynVisitor},
    Status,
};

use super::VisitResult;

pub trait Recoverable<'src, E: Environment>: DynBind<E> {
    fn visit<'r>(
        &'r mut self,
        scope: DynRecoverableScope<'r, 'src, E>,
    ) -> Canonical<'r, VisitResult, E>;
}

impl<'u, 'src, E: 'static> type_name::Lower<'u, 'src, &'u &'src ()> for dyn Recoverable<'static, E> {
    type Lowered = dyn Recoverable<'src, E> + 'u;
}

impl<'u, 'src, E: 'static> type_name::Raise<'u, 'src, &'u &'src ()>
    for dyn Recoverable<'src, E> + 'u
{
    type Raised = dyn Recoverable<'static, E>;
}

impl<E: Environment> HintMeta for dyn Recoverable<'static, E> {
    type Known = Rank1<()>;

    type Hint = Rank1<()>;
}

impl<E: Environment> InEnvironment for dyn Recoverable<'static, E> {
    type Env = E;
}

pub trait RecoverableScope<'src, E: Environment>: DynBind<E> {
    fn new_walk<'r>(
        &'r mut self,
        visitor: DynVisitor<'r, 'src, E>,
    ) -> Canonical<'r, Status, E>;
}

pub type DynRecoverableScope<'r, 'src, E> = &'r mut dyn RecoverableScope<'src, E>;

pub fn visit_recoverable<'r, 'src, E: Environment>(
    visitor: DynVisitor<'r, 'src, E>,
    scope: DynRecoverableScope<'r, 'src, E>,
) -> Canonical<'r, VisitResult, E> {
    if let Some(object) = visitor
        .into_inner()
        .as_any_trait_mut()
        .upcast_mut::<dyn Recoverable<'src, E> + 'r>()
    {
        // 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::value(VisitResult::Skipped(())).cast()
    }
}