Crate slice_map 

0.2.4 Update

SliceMap is a Rust crate driven by needs of a separate personal project. As a result, I had to go back to the idea of a Generic SliceMap that uses a Storage trait to pick different Storage structs.

Instead of SliceMap you should use the new type aliases, SlotSliceMap for SlotMap storage, SecSliceMap for SecondaryMap and SparseSliceMap for SparseSecondaryMap respectively.

To allow using SparseSecondaryMap this crate is not “no_std” anymore, but I plan to make that an optional feature and restore its no_std status!

Description

SliceMap and its type aliases provides a container that allows iterating directly all of its items, or iterating through non-overlapping slices of varying sizes. You can only insert new items in groups that will become a new slice.

Example

A good use would be storing the points for polygons with different point counts, but in a way where all those points are laid out continuously in memory. Each slice of points can be iterated separately and is effectively a new polygon. Drawing all polygons at once can be very CPU cache-friendly.

Here’s a simpler example with i32 values:

use slice_map::SlotSliceMap;

// Since SlotSLiceMap uses slotmap keys, we need to define our key in advance
slotmap::new_key_type!{
    pub struct TestKey;
}

let mut slices = SlotSliceMap::<TestKey, i32>::default();

// Adding items returns a SliceKey
let a = slices.add_items([1, 2, 3, 4, 5]);
let b = slices.add_items([6, 7]);
let c = slices.add_items([8, 9, 10]);

// Iterating over slices
let mut slice_iter = slices.iter_slices();
assert_eq!(slice_iter.next().unwrap(), [1, 2, 3, 4, 5]);
assert_eq!(slice_iter.next().unwrap(), [6, 7]);
assert_eq!(slice_iter.next().unwrap(), [8, 9, 10]);
assert_eq!(slice_iter.next(), None);
drop(slice_iter);

// Iterating over all items
let mut i = 1;
for item in slices.iter_items(){
    assert_eq!(i, *item);
    i += 1
}

 // Removing slices removes all of their items,
 // but other keys are still valid!
{
    slices.remove_slice(b);
    let slice_c = slices.get_slice(c).unwrap();
    assert_eq!(slice_c, &[8, 9, 10]);
}

// Iterating
{
    let mut slice_iter = slices.iter_slices();
    assert_eq!(slice_iter.next().unwrap(), [1, 2, 3, 4, 5]);
    assert_eq!(slice_iter.next().unwrap(), [8, 9, 10]);
}

slices.remove_slice(a);
slices.remove_slice(c);
assert!(slices.is_empty());

Structs

KeySliceIter

Iterator for SliceMap that returns slices of items along with their keys.

SliceIter

Iterator for SliceMap that returns slices of items.

SliceMap

This generic SliceMap needs to be provided a Key type, a Value type and a Storage type. Use SlotSliceMap and SecSliceMap for storage using SlotMap and SecondarySlotMap, respectively.

Traits

SliceStorage

Trait to abstract operations on storage of slices

Type Aliases

SecSliceMap

SliceMap that uses slotmap::SecondaryMap for range storage

SlotSliceMap

SliceMap that uses slotmap::SlotMap for range storage

SparseSliceMap

SliceMap that uses slotmap::SparseSecondaryMap for range storage