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use std::marker::PhantomData;
pub struct Context<Stack>(Stack);
impl Context<()> {
pub fn root() -> () {
()
}
}
impl<Stack> Context<Stack> {
pub fn stack(&self) -> &Stack {
&self.0
}
}
pub trait ContextParent: Sized {
fn add<Next>(self, next: Next) -> ContextStack<Next, Self>;
fn seal(self) -> Context<Self>;
}
impl ContextParent for () {
fn add<Next>(self, next: Next) -> ContextStack<Next, Self> {
ContextStack {
head: next,
tail: self,
}
}
fn seal(self) -> Context<Self> {
Context(self)
}
}
impl<H, T> ContextParent for ContextStack<H, T> {
fn add<Next>(self, next: Next) -> ContextStack<Next, Self> {
ContextStack {
head: next,
tail: self,
}
}
fn seal(self) -> Context<Self> {
Context(self)
}
}
pub struct ContextStack<Head, Tail> {
pub head: Head,
pub tail: Tail,
}
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<Stack, Unit, Proof> Has<Unit, Proof> for Context<Stack>
where
Stack: Has<Unit, Proof>,
{
fn get_unit(&self) -> &Unit {
self.0.get_unit()
}
fn get_unit_mut(&mut self) -> &mut Unit {
self.0.get_unit_mut()
}
}
impl<Unit, Tail> Has<Unit, ()> for ContextStack<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 ContextStack<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;