5 releases
0.1.4 | May 18, 2023 |
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0.1.3 | May 18, 2023 |
0.1.2 | May 18, 2023 |
0.1.1 | May 18, 2023 |
0.1.0 | May 18, 2023 |
#2175 in Rust patterns
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Used in micro_ndarray
25KB
547 lines
vec_split
vec_split is a library to work with arrays of vectors as if they were instead one array for each dimension of the vector.
Example
let mut array = [[0.0, 0.0]; 10];
let [mut x_array, mut y_array] = array.vec_split_fast_mut();
for (i, item) in x_array.iter_mut().enumerate() {
*item = i as f64 / 10.0;
}
for (i, item) in y_array.iter_mut().enumerate() {
*item = i as f64 * 2.0;
}
for item in x_array.iter() {
println!("X {item}");
}
for item in y_array.iter() {
println!("Y {item}");
}
Safety and Accessor types
As is visible in the example, vec_split allows multiple mutable references to what is technically all the same array. This is SAFE because each part of the split array cannot write where the others do, meaning they are effectively separate.
FastAccessor
also uses unsafe code to do some pointer manipulation. Because
we want it to still be safe, the SizedVector trait has some special
requirements. If these are always ensured, FastAccessor IS SAFE.
SAFETY: MUST have no extra items before first dimension in memory, MUST not have padding between items!! This means Vec, for example, is NOT fit for this trait.
[T; D]
, for example, works.
This is essentially just saying that the vector MUST be an array, just like
[T; D]
. Vec<T>
however does not work for this, as it has a lot of extra
room around the items. If this is the case SafeAccessor
must be used, which
may be a small bit slower.
SafeAccessor uses no memory manipulation, so it may be slower, but it also doesn't have any way to cause UB or some other weirdness if some trait is implemented wrongly.