Struct Set 

pub struct Set { /* private fields */ }

A sparse set of entities, which assigns each Entity a unique index in a densely packed array.

The time complexity for insert, remove, index_of, and contains is O(1).

The set internally maintains two arrays: sparse and dense.

• sparse:
  • Contains indices to entities in the dense array.
  • Entities are used as indices.
  • Is sparse, meaning it may have holes.
  • Its length is based on the entity with the highest value in the set.
• dense:
  • Contains entities.
  • Is densely packed.
  • Its length is the number of entities in the set.

This should true for any entity in the set: dense[sparse[entity]] == entity

Implementations

impl Set

pub fn new() -> Self

Constructs a new Set.

pub fn len(&self) -> usize

Returns the number of elements in the set, also referred to as its ‘length’.

pub fn is_empty(&self) -> bool

Returns true if the set contains no elements.

pub fn contains(&self, entity: Entity) -> bool

Returns true if the set contains the entity.

pub fn index_of(&self, entity: Entity) -> Option<usize>

Returns the index that was assigned to the entity.

pub fn insert(&mut self, entity: Entity) -> bool

Adds the entity to the set.

Returns true if the entity was inserted into the set, returns false if the entity was already contained in the set.

pub fn remove(&mut self, entity: Entity) -> bool

Removes the entity from the set.

Returns true if the entity was removed from the set, returns false if the entity was not contained in the set.

pub fn reserve(&mut self, additional: usize)

Reserves capacity for at least additional more elements to be inserted into the set.

pub fn iter(&self) -> Iter<'_, Entity>

An iterator visiting all entities in the set.

Trait Implementations

impl Default for Set

fn default() -> Set

Returns the “default value” for a type.

impl<'a> IntoIterator for &'a Set

type IntoIter = Copied<Iter<'a, Entity>>

Which kind of iterator are we turning this into?

type Item = Entity

The type of the elements being iterated over.

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.