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use std::marker::PhantomData;
pub trait Context: Sized {
fn add<Unit>(self, unit: Unit) -> NestedContext<Unit, Self>;
}
impl<T> Context for T {
fn add<Unit>(self, unit: Unit) -> NestedContext<Unit, Self> {
NestedContext {
head: unit,
tail: self,
}
}
}
pub struct NestedContext<Head, Tail> {
pub head: Head,
pub tail: Tail,
}
impl NestedContext<(), ()> {
pub fn root() -> () {
()
}
}
pub struct Next<T>(PhantomData<T>);
pub trait Has<Unit, Proof> {
fn get_unit(&self) -> &Unit;
fn get_unit_mut(&mut self) -> &mut Unit;
}
impl<Unit, Tail> Has<Unit, ()> for NestedContext<Unit, Tail> {
fn get_unit(&self) -> &Unit {
&self.head
}
fn get_unit_mut(&mut self) -> &mut Unit {
&mut self.head
}
}
impl<Unit, Head, Tail, TailProof> Has<Unit, Next<TailProof>> for NestedContext<Head, Tail>
where
Tail: Has<Unit, TailProof>,
{
fn get_unit(&self) -> &Unit {
self.tail.get_unit()
}
fn get_unit_mut(&mut self) -> &mut Unit {
self.tail.get_unit_mut()
}
}
#[cfg(test)]
mod tests;