Struct orx_funvec::ScalarAsVec

pub struct ScalarAsVec<T>(pub T);

Nothing but a wrapped value, a tuple struct, that allows to represent its internal scalar value as an infinite-length vector having the same value at all positions.

Examples

Say, for instance, we have a function requiring a vector, FunVec<1, i32>.

use orx_funvec::*;
fn third_element<V: FunVec<1, i32>>(vec: &V) -> Option<i32> {
    vec.at(2)
}

We might often call this function with a Vec<i32>.

let numbers = vec![1, 2, 3, 4, 5, 6];
assert_eq!(Some(3), third_element(&numbers));

There might however be special cases where our input vector is all 42s. Probably not 42s, but all zeros/ones vectors/matrices are often very useful. Following would work:

let numbers = vec![42, 42, 42, 42, 42];
assert_eq!(Some(42), third_element(&numbers));

However, this would not be the best way to achieve this:

• we allocate a vector just to return 42, and
• we make method calls just to read 42 and lose compiler optimization potential.

We can instead use ScalarAsVec wrapper which implements FunVec<1, _>:

let numbers = ScalarAsVec(42);
assert_eq!(Some(42), third_element(&numbers));

Actually, ScalarAsVec implements FunVec for all dimensions:

let numbers = ScalarAsVec(42);

assert_eq!(Some(42), numbers.at(3));
assert_eq!(Some(42), numbers.at([7, 2]));
assert_eq!(Some(42), numbers.at([14, 1, 0]));
assert_eq!(Some(42), numbers.at((4, 1, 3, 6))); // array or tuple indices can be used interchangeably

Tuple Fields

0: T

Trait Implementations

impl<const DIM: usize, T: Clone + Copy> FunVec<DIM, T> for ScalarAsVec<T>

fn at<Idx: IntoIndex<DIM>>(&self, _: Idx) -> Option<T>

Returns the value at the given index or None if the position is empty.

fn iter_over<'a, Idx, IdxIter>( &self, indices: IdxIter ) -> IterOverValues<'_, DIM, T, Idx, IdxIter, Self>

where Idx: IntoIndex<DIM>, IdxIter: Iterator<Item = Idx> + 'a,

Returns an iterator of elements of the vector for the given indices.

impl<const DIM: usize, T> FunVecRef<DIM, T> for ScalarAsVec<T>

fn ref_at<Idx: IntoIndex<DIM>>(&self, _: Idx) -> Option<&T>

Returns a reference to the element at the given index or None if the position is empty.

fn ref_iter_over<'a, Idx, IdxIter>( &self, indices: IdxIter ) -> IterOverRefs<'_, DIM, T, Idx, IdxIter, Self>

where Idx: IntoIndex<DIM>, IdxIter: Iterator<Item = Idx> + 'a,

Returns an iterator yielding references to elements of the vector for the given indices.