#slot #fixed-size #data #operations #structure #constant-time

no-std slots

Fixed size data structure with constant-time operations

6 releases (3 breaking)

0.4.0 Mar 25, 2022
0.3.1 May 21, 2020
0.2.0 May 5, 2020
0.1.1 Apr 25, 2020

#1329 in Data structures

24 downloads per month

MIT license

265 lines

Slots crates.io build status codecov

This crate provides a heapless slab allocator with strict access control.

Slots implements a static friendly, fixed size, unordered data structure inspired by SlotMap. All operations are constant time.



  • Slots provide the runtime_checks feature that can be used to disable key owner verification. By default the feature is on and it is recommended to leave it enabled for development builds and disabled for release builds.

    Note: This feature requires atomic instructions, which are not generally available (for example, on ARM Cortex-M0 microcontrollers)


This crate provides a heapless, fixed size, unordered data structure, inspired by SlotMap.

The following basic operations (all of them O(1)) are defined for Slots:

  • Store: store data and retrieve a handle for later access
  • Read, modify: use the given handle to access the data without removal
  • Take: use the given handle to remove data

There are two variations of this data structure:

  • Slots, where elements can only be modified using a Key that can't be copied
  • UnrestrictedSlots, where elements are free to be modified by anyone