Struct IndexPool

pub struct IndexPool { /* private fields */ }

A pool which manages allocation of unique indices. Acts like a psuedo-memory allocator.

Implementations

impl IndexPool

pub fn new() -> Self

Constructs an empty IndexPool. Indices will start at 0.

pub fn with_initial_index(index: usize) -> Self

Constructs an empty IndexPool. index will be the first index returned from new_id. You can logically think of this as either specifying a base index for the pool, or pre-allocating the [0..index) range. This datastructure does not care which is your usecase, and neither has any kind of performance penalty, except that in_use() will include the [0..index) range.

pub fn new_id(&mut self) -> usize

Allocates a new index for use. This is guaranteed to not be any index which has previously been returned from new_id but has not yet been passed to return_id.

pub fn request_id(&mut self, id: usize) -> Result<(), AlreadyInUse>

Attempts to allocate a specific index

pub fn return_id(&mut self, id: usize) -> Result<(), AlreadyReturned>

Gives an Id back to the pool so that it may be handed out again. Returns Err if the Id was not in use at the time. Whether ignoring such an error is okay is up to your own usecase.

pub fn maximum(&self) -> usize

Returns an upper bound on the number of IDs which have been allocated, specifically the highest numbered ID in use + 1. Useful if you’re going to e.g. create a Vec which has room for all of your IDs.

pub fn in_use(&self) -> usize

Returns the number of currently in-use indices

pub fn is_free(&self, id: usize) -> bool

Checks if a specific index is currently free

pub fn all_indices(&self) -> IndexIter<'_>

Returns an iterator over all indices which are in use

pub fn all_indices_after(&self, after: usize) -> IndexAfterIter<'_>

pub fn clear(&mut self)

Trait Implementations

impl Debug for IndexPool

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for IndexPool

fn default() -> Self

Constructs an empty IndexPool. Indices will start at 0.