treaty -


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use std::{collections::VecDeque, future::Future, ops::ControlFlow, pin::Pin};
use treaty::{
    any::{any_trait, static_wrapper::OwnedStatic},
    async_build_with, build_with, into_walker,
    protocol::{
        visitor::{Sequence, SequenceScope, Status, Value},
        AsyncEffect, ControlFlowFor, Visitor,
    },
    Builder, Walk, Walker,
};

#[tokio::test]
async fn demo() {
    let a = Data::Sequence(vec![
        Data::Bool(true),
        Data::Sequence(vec![Data::Bool(false), Data::Bool(true)]),
        Data::Bool(false),
    ]);

    let s = async_build_with::<JsonLike, _>(into_walker(a))
        .await
        .unwrap();

    assert_eq!(s, "[true,[false,true,],false,]");
}

#[derive(Debug)]
enum Data {
    Bool(bool),
    Sequence(Vec<Data>),
}

const _: () = {
    struct Impl(Data);

    impl From<Data> for Impl {
        fn from(value: Data) -> Self {
            Self(value)
        }
    }

    impl<'ctx> Walk<'ctx> for Data {
        type Walker = Impl;
    }

    impl<'ctx> Walker<'ctx> for Impl {
        type Effect = AsyncEffect;

        type Error = ();

        type Output = ();

        fn walk<'a>(self, visitor: &'a mut Visitor<'a, 'ctx>) -> ControlFlowFor<'a, AsyncEffect> {
            Box::pin(async {
                match self.0 {
                    Data::Bool(value) => walk_bool(value, visitor),
                    Data::Sequence(value) => walk_vec(value, visitor).await,
                }
                core::ops::ControlFlow::Continue(())
            })
        }
    }
};

fn walk_bool(value: bool, visitor: &mut Visitor<'_, '_>) {
    visitor
        .upcast_mut::<dyn Value<OwnedStatic<bool>>>()
        .unwrap()
        .visit(OwnedStatic(value));
}

async fn walk_vec(value: Vec<Data>, visitor: &mut Visitor<'_, '_>) {
    struct Scope(VecDeque<Data>);

    impl<'ctx> SequenceScope<'ctx, AsyncEffect> for Scope {
        fn next<'a>(
            &'a mut self,
            visitor: &'a mut Visitor<'a, 'ctx>,
        ) -> ControlFlowFor<'a, AsyncEffect, Status> {
            Box::pin(async {
                if let Some(value) = self.0.pop_front() {
                    into_walker(value).walk(visitor).await;

                    ControlFlow::Continue(Status::Continue)
                } else {
                    ControlFlow::Continue(Status::Done)
                }
            })
        }
    }

    let mut scope = Scope(value.into());

    visitor
        .upcast_mut::<dyn Sequence<'_, AsyncEffect>>()
        .unwrap()
        .visit(&mut scope)
        .await;
}

#[derive(Default)]
struct JsonLike(String);

impl<'ctx> Builder<'ctx> for JsonLike {
    type Error = ();

    type Value = String;

    fn as_visitor(&mut self) -> &mut Visitor<'_, 'ctx> {
        self
    }

    fn build(self) -> Result<Self::Value, Self::Error> {
        Ok(self.0)
    }
}

any_trait! {
    impl['a, 'ctx] JsonLike = [
        dyn Value<'a, OwnedStatic<bool>> + 'a,
        dyn Sequence<'ctx, AsyncEffect> + 'a,
    ];
}

impl Value<'_, OwnedStatic<bool>> for JsonLike {
    fn visit(&mut self, value: OwnedStatic<bool>) -> core::ops::ControlFlow<()> {
        self.0.push_str(&format!("{}", value.0));
        std::ops::ControlFlow::Continue(())
    }
}

impl<'ctx> Sequence<'ctx, AsyncEffect> for JsonLike {
    fn visit<'a>(
        &'a mut self,
        scope: &'a mut dyn SequenceScope<'ctx, AsyncEffect>,
    ) -> ControlFlowFor<'a, AsyncEffect> {
        Box::pin(async {
            self.0.push_str("[");
            while let std::ops::ControlFlow::Continue(treaty::protocol::visitor::Status::Continue) =
                scope.next(self).await
            {
                self.0.push_str(",");
            }
            self.0.push_str("]");
            std::ops::ControlFlow::Continue(())
        })
    }
}