treaty -


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use core::{any::TypeId, marker::PhantomData, ops::ControlFlow};

use crate::{
    any::{static_wrapper::OwnedStatic, LtTypeId},
    any_trait,
    effect::{Effect, Future},
    protocol::{visitor::{
        tag::{Dyn, Tag},
        value::Value, request_hint::RequestHint,
    }, self},
    DynWalker,
};

pub struct Walker<E>(usize, PhantomData<fn() -> E>);

any_trait! {
    impl['a, 'ctx, E] Walker<E> = [
        dyn RequestHint<'ctx, Effect = E> + 'a,
        dyn Tag<'ctx, Dyn, Effect = E> + 'a,
        dyn Value<'a, 'ctx, OwnedStatic<&'static str>, Effect = E> + 'a,
        dyn Value<'a, 'ctx, OwnedStatic<TypeId>, Effect = E> + 'a,
    ] else fallback where E: Effect<'ctx>
}

fn fallback(id: LtTypeId<'_>) {
    println!("Unknown trait: {}", id);
}

impl<'ctx, E: Effect<'ctx>> Walker<E> {
    pub fn new() -> Self {
        Self(0, PhantomData)
    }

    fn tab(&self) {
        for _ in 0..self.0 {
            print!("  ");
        }
    }
}

impl<'ctx, E: Effect<'ctx>> RequestHint<'ctx> for Walker<E> {
    type Effect = E;

    fn request_hint<'a>(
        &'a mut self,
        _walker: crate::protocol::Walker<'a, 'ctx>,
    ) -> Future<'a, 'ctx, ControlFlow<(), ()>, Self::Effect>
    where
        Self: 'a 
    {
        self.tab();
        println!("Visit request hint (no hint given)");
        E::wrap(async { ControlFlow::Continue(()) })
    }
}

impl<'ctx, E: Effect<'ctx>> Tag<'ctx, Dyn> for Walker<E> {
    type Effect = E;

    fn visit<'a>(
        &'a mut self,
        kind: Dyn,
        walker: &'a mut dyn DynWalker<'ctx, Effect = Self::Effect>,
    ) -> Future<'a, 'ctx, ControlFlow<(), protocol::visitor::tag::Status>, Self::Effect>
    where
        Self: 'a,
    {
        self.tab();
        println!("Visit tag: {}", kind.0);

        E::wrap(async {
            self.0 += 1;
            let result = walker.walk(self).await;
            self.0 -= 1;
            match result {
                ControlFlow::Continue(()) => ControlFlow::Continue(protocol::visitor::tag::Status::Walked),
                ControlFlow::Break(()) => ControlFlow::Break(()),
            }
        })
    }
}

impl<'a, 'ctx: 'a, E: Effect<'ctx>> Value<'a, 'ctx, OwnedStatic<&'static str>> for Walker<E> {
    type Effect = E;

    fn visit(&'a mut self, OwnedStatic(value): OwnedStatic<&'static str>) -> Future<'a, 'ctx, ControlFlow<(), ()>, Self::Effect> where Self: 'a {
        self.tab();
        println!("Visit static str: {:?}", value);
        E::wrap(async { ControlFlow::Continue(()) })
    }
}

impl<'a, 'ctx: 'a, E: Effect<'ctx>> Value<'a, 'ctx, OwnedStatic<TypeId>> for Walker<E> {
    type Effect = E;

    fn visit(&'a mut self, OwnedStatic(value): OwnedStatic<TypeId>) -> Future<'a, 'ctx, ControlFlow<(), ()>, Self::Effect> where Self: 'a {
        self.tab();
        println!("Visit type ID: {:?}", value);
        E::wrap(async { ControlFlow::Continue(()) })
    }
}