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#[derive(Debug)]
pub struct Product<H, T: HList>(pub(crate) H, pub(crate) T);
pub type One<T> = (T,);
#[inline]
pub(crate) fn one<T>(val: T) -> One<T> {
(val,)
}
#[derive(Debug)]
pub enum Either<T, U> {
A(T),
B(U),
}
// Converts Product (and ()) into tuples.
pub trait HList: Sized {
type Tuple: Tuple<HList = Self>;
fn flatten(self) -> Self::Tuple;
}
// Typeclass that tuples can be converted into a Product (or unit ()).
pub trait Tuple: Sized {
type HList: HList<Tuple = Self>;
fn hlist(self) -> Self::HList;
#[inline]
fn combine<T>(self, other: T) -> CombinedTuples<Self, T>
where
Self: Sized,
T: Tuple,
Self::HList: Combine<T::HList>,
{
self.hlist().combine(other.hlist()).flatten()
}
}
pub type CombinedTuples<T, U> =
<<<T as Tuple>::HList as Combine<<U as Tuple>::HList>>::Output as HList>::Tuple;
// Combines Product together.
pub trait Combine<T: HList> {
type Output: HList;
fn combine(self, other: T) -> Self::Output;
}
pub trait Func<Args> {
type Output;
fn call(&self, args: Args) -> Self::Output;
}
// ===== impl Combine =====
impl<T: HList> Combine<T> for () {
type Output = T;
#[inline]
fn combine(self, other: T) -> Self::Output {
other
}
}
impl<H, T: HList, U: HList> Combine<U> for Product<H, T>
where
T: Combine<U>,
Product<H, <T as Combine<U>>::Output>: HList,
{
type Output = Product<H, <T as Combine<U>>::Output>;
#[inline]
fn combine(self, other: U) -> Self::Output {
Product(self.0, self.1.combine(other))
}
}
impl HList for () {
type Tuple = ();
#[inline]
fn flatten(self) -> Self::Tuple {}
}
impl Tuple for () {
type HList = ();
#[inline]
fn hlist(self) -> Self::HList {}
}
impl<F, R> Func<()> for F
where
F: Fn() -> R,
{
type Output = R;
#[inline]
fn call(&self, _args: ()) -> Self::Output {
(*self)()
}
}
impl<F, R> Func<crate::Rejection> for F
where
F: Fn(crate::Rejection) -> R,
{
type Output = R;
#[inline]
fn call(&self, arg: crate::Rejection) -> Self::Output {
(*self)(arg)
}
}
macro_rules! product {
($H:expr) => { Product($H, ()) };
($H:expr, $($T:expr),*) => { Product($H, product!($($T),*)) };
}
macro_rules! Product {
($H:ty) => { Product<$H, ()> };
($H:ty, $($T:ty),*) => { Product<$H, Product!($($T),*)> };
}
macro_rules! product_pat {
($H:pat) => { Product($H, ()) };
($H:pat, $($T:pat),*) => { Product($H, product_pat!($($T),*)) };
}
macro_rules! generics {
($type:ident) => {
impl<$type> HList for Product!($type) {
type Tuple = ($type,);
#[inline]
fn flatten(self) -> Self::Tuple {
(self.0,)
}
}
impl<$type> Tuple for ($type,) {
type HList = Product!($type);
#[inline]
fn hlist(self) -> Self::HList {
product!(self.0)
}
}
impl<F, R, $type> Func<Product!($type)> for F
where
F: Fn($type) -> R,
{
type Output = R;
#[inline]
fn call(&self, args: Product!($type)) -> Self::Output {
(*self)(args.0)
}
}
impl<F, R, $type> Func<($type,)> for F
where
F: Fn($type) -> R,
{
type Output = R;
#[inline]
fn call(&self, args: ($type,)) -> Self::Output {
(*self)(args.0)
}
}
};
($type1:ident, $( $type:ident ),*) => {
generics!($( $type ),*);
impl<$type1, $( $type ),*> HList for Product!($type1, $($type),*) {
type Tuple = ($type1, $( $type ),*);
#[inline]
fn flatten(self) -> Self::Tuple {
#[allow(non_snake_case)]
let product_pat!($type1, $( $type ),*) = self;
($type1, $( $type ),*)
}
}
impl<$type1, $( $type ),*> Tuple for ($type1, $($type),*) {
type HList = Product!($type1, $( $type ),*);
#[inline]
fn hlist(self) -> Self::HList {
#[allow(non_snake_case)]
let ($type1, $( $type ),*) = self;
product!($type1, $( $type ),*)
}
}
impl<F, R, $type1, $( $type ),*> Func<Product!($type1, $($type),*)> for F
where
F: Fn($type1, $( $type ),*) -> R,
{
type Output = R;
#[inline]
fn call(&self, args: Product!($type1, $($type),*)) -> Self::Output {
#[allow(non_snake_case)]
let product_pat!($type1, $( $type ),*) = args;
(*self)($type1, $( $type ),*)
}
}
impl<F, R, $type1, $( $type ),*> Func<($type1, $($type),*)> for F
where
F: Fn($type1, $( $type ),*) -> R,
{
type Output = R;
#[inline]
fn call(&self, args: ($type1, $($type),*)) -> Self::Output {
#[allow(non_snake_case)]
let ($type1, $( $type ),*) = args;
(*self)($type1, $( $type ),*)
}
}
};
}
generics! {
T1,
T2,
T3,
T4,
T5,
T6,
T7,
T8,
T9,
T10,
T11,
T12,
T13,
T14,
T15,
T16
}