SparseSet

A set of integer ids, packed so it iterates with no gaps. Ids start at 1: removing id 0 from a set that holds ids corrupts it. Its memory follows the largest id, not how many ids it holds.

local Alive = Collections.SparseSet.new()
Alive:Add(10)
Alive:Add(20)
local Ids, Count = Alive:RawDense()
for Offset = 0, (Count - 1) * 4, 4 do
  print(buffer.readu32(Ids, Offset)) -- 10, then 20
end

Summary

Member	Description
.new()	Creates an empty set.
:Add()	Adds Id, and returns whether it was newly added.
:Remove()	Removes Id by moving the last id into its place, so arrays kept in the same order can make the same move.
:Has()	Whether Id is in the set.
:RawDense()	Returns the packed ids and their count.
:Count()	How many ids the set holds.
:Clear()	Removes every id.
SparseSet	The type SparseSet.new returns.

Functions

new

function SparseSet.new(Config: { InitialCapacity: number? }?): SparseSet

Creates an empty set.

Parameter	Type	Description
Config	{ InitialCapacity: number? }?	InitialCapacity reserves room for ids up to it, 4 by default

Methods

Add

function SparseSet:Add(Id: number): boolean

Adds Id, and returns whether it was newly added.

Remove

function SparseSet:Remove(Id: number): (number, number)

Removes Id by moving the last id into its place, so arrays kept in the same order can make the same move.

Returns	Description
number	the position Id held, from 1, or 0 if Id was not in the set
number	the id now at that position, Id itself when it was last, or 0

Has

function SparseSet:Has(Id: number): boolean

Whether Id is in the set.

RawDense

function SparseSet:RawDense(): (buffer, number)

Returns the packed ids and their count. An Add can replace the buffer, so take it again after one.

Returns	Description
buffer	the ids, a u32 each from byte 0
number	how many

Count

function SparseSet:Count(): number

How many ids the set holds.

Clear

function SparseSet:Clear()

Removes every id.

Types

SparseSet

export type SparseSet = {
	Add: (self: SparseSet, Id: number) -> boolean,
	Remove: (self: SparseSet, Id: number) -> (number, number),
	Has: (self: SparseSet, Id: number) -> boolean,
	RawDense: (self: SparseSet) -> (buffer, number),
	Count: (self: SparseSet) -> number,
	Clear: (self: SparseSet) -> (),
}

The type SparseSet.new returns.