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#![feature(generic_const_exprs)]
#![allow(incomplete_features)]
trait TensorDimension {
const DIM: usize;
//~^ ERROR cycle detected when resolving instance
// FIXME Given the current state of the compiler its expected that we cycle here,
// but the cycle is still wrong.
const ISSCALAR: bool = Self::DIM == 0;
fn is_scalar(&self) -> bool {
Self::ISSCALAR
}
}
trait TensorSize: TensorDimension {
fn size(&self) -> [usize; Self::DIM];
fn inbounds(&self, index: [usize; Self::DIM]) -> bool {
index.iter().zip(self.size().iter()).all(|(i, s)| i < s)
}
}
trait Broadcastable: TensorSize + Sized {
type Element;
fn bget(&self, index: [usize; Self::DIM]) -> Option<Self::Element>;
fn lazy_updim<const NEWDIM: usize>(
&self,
size: [usize; NEWDIM],
) -> LazyUpdim<Self, { Self::DIM }, NEWDIM> {
assert!(
NEWDIM >= Self::DIM,
"Updimmed tensor cannot have fewer indices than the initial one."
);
LazyUpdim { size, reference: &self }
}
fn bmap<T, F: Fn(Self::Element) -> T>(&self, foo: F) -> BMap<T, Self, F, { Self::DIM }> {
BMap { reference: self, closure: foo }
}
}
struct LazyUpdim<'a, T: Broadcastable, const OLDDIM: usize, const DIM: usize> {
size: [usize; DIM],
reference: &'a T,
}
impl<'a, T: Broadcastable, const DIM: usize> TensorDimension for LazyUpdim<'a, T, { T::DIM }, DIM> {
const DIM: usize = DIM;
}
impl<'a, T: Broadcastable, const DIM: usize> TensorSize for LazyUpdim<'a, T, { T::DIM }, DIM> {
fn size(&self) -> [usize; DIM] {
self.size
}
}
impl<'a, T: Broadcastable, const DIM: usize> Broadcastable for LazyUpdim<'a, T, { T::DIM }, DIM> {
type Element = T::Element;
fn bget(&self, index: [usize; DIM]) -> Option<Self::Element> {
assert!(DIM >= T::DIM);
if !self.inbounds(index) {
return None;
}
let size = self.size();
let newindex: [usize; T::DIM] = Default::default();
self.reference.bget(newindex)
}
}
struct BMap<'a, R, T: Broadcastable, F: Fn(T::Element) -> R, const DIM: usize> {
reference: &'a T,
closure: F,
}
impl<'a, R, T: Broadcastable, F: Fn(T::Element) -> R, const DIM: usize> TensorDimension
for BMap<'a, R, T, F, DIM>
{
const DIM: usize = DIM;
}
impl<'a, R, T: Broadcastable, F: Fn(T::Element) -> R, const DIM: usize> TensorSize
for BMap<'a, R, T, F, DIM>
{
fn size(&self) -> [usize; DIM] {
self.reference.size()
}
}
impl<'a, R, T: Broadcastable, F: Fn(T::Element) -> R, const DIM: usize> Broadcastable
for BMap<'a, R, T, F, DIM>
{
type Element = R;
fn bget(&self, index: [usize; DIM]) -> Option<Self::Element> {
self.reference.bget(index).map(&self.closure)
}
}
impl<T> TensorDimension for Vec<T> {
const DIM: usize = 1;
}
impl<T> TensorSize for Vec<T> {
fn size(&self) -> [usize; 1] {
[self.len()]
}
}
impl<T: Clone> Broadcastable for Vec<T> {
type Element = T;
fn bget(&self, index: [usize; 1]) -> Option<T> {
self.get(index[0]).cloned()
}
}
fn main() {
let v = vec![1, 2, 3];
let bv = v.lazy_updim([3, 4]);
let bbv = bv.bmap(|x| x * x);
println!("The size of v is {:?}", bbv.bget([0, 2]).expect("Out of bounds."));
}
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