Struct Table

pub struct Table<V> { /* private fields */ }

This is a table for generating unique u32 identifiers for each element in a dynamically-changing set of resources.

This is inspired by the Table type in wasi-common and serves the same purpose: allow opaque resources and their lifetimes to be managed across an interface boundary, analogous to how file handles work across the user-kernel boundary.

Implementations

impl<V> Table<V>

pub fn new(capacity: u32) -> Self

Create a new, empty table with the specified capacity.

pub fn push(&mut self, value: V) -> Result<u32, ()>

Add the specified resource to this table.

If the table is full (i.e. there already are self.capacity resources inside), this returns Err(()). Otherwise, a new, unique identifier is allocated for the resource and returned.

This function will attempt to avoid reusing recently closed identifiers, but after 2^32 calls to this function they will start repeating.

pub fn get(&self, key: u32) -> Option<&V>

Get a reference to the resource identified by the specified key, if it exists.

pub fn get_mut(&mut self, key: u32) -> Option<&mut V>

Get a mutable reference to the resource identified by the specified key, if it exists.

pub fn remove(&mut self, key: u32) -> Option<V>

Remove the resource identified by the specified key, if present.

This makes the key eligible for eventual reuse (i.e. for a newly-pushed resource).

Trait Implementations

impl<V> Default for Table<V>

fn default() -> Self

Returns the “default value” for a type.