use crate::syn::ast::{Stmt, Expr};

pub trait Visit {
    type Out;
    fn visit<A: Accept<Self>>(&mut self, acceptor: &A) -> Self::Out
        where Self: Sized
    {
        acceptor.accept(self)
    }

    fn visit_stmt(&mut self, stmt: &Stmt) -> Self::Out;
    fn visit_expr(&mut self, expr: &Expr) -> Self::Out;
}

pub trait Accept<V: Visit> {
    fn accept(&self, visitor: &mut V) -> V::Out;
}

impl<V: Visit> Accept<V> for Stmt {
    fn accept(&self, visitor: &mut V) -> V::Out {
        visitor.visit_stmt(self)
    }
}

impl<V: Visit> Accept<V> for Expr {
    fn accept(&self, visitor: &mut V) -> V::Out {
        visitor.visit_expr(self)
    }
}