fireblade-ecs/Sources/FirebladeECS/SparseSet.swift

84 lines
2.1 KiB
Swift

//
// SparseSet.swift
// FirebladeECS
//
// Created by Christian Treffs on 30.10.17.
//
public class SparseComponentSet {
public typealias Element = Component
fileprivate typealias ComponentIdx = Int
fileprivate var size: Int = 0
fileprivate var dense: ContiguousArray<Pair?>
fileprivate var sparse: [EntityIndex: ComponentIdx]
fileprivate typealias Pair = (key: EntityIndex, value: Element)
public init() {
dense = ContiguousArray<Pair?>()
sparse = [EntityIndex: ComponentIdx]()
}
deinit {
clear()
}
public var count: Int { return size }
internal var capacitySparse: Int { return sparse.capacity }
internal var capacityDense: Int { return dense.capacity }
public func contains(_ entityIdx: EntityIndex ) -> Bool {
return sparse[entityIdx] != nil &&
sparse[entityIdx]! < count &&
dense[sparse[entityIdx]!] != nil
}
@discardableResult
public func add(_ element: Element, with entityIdx: EntityIndex ) -> Bool {
if contains(entityIdx) { return false }
sparse[entityIdx] = count
let entry: Pair = Pair(key: entityIdx, value: element)
dense.append(entry)
size += 1
return true
}
public func get(at entityIdx: EntityIndex) -> Element? {
guard contains(entityIdx) else { return nil }
return dense[sparse[entityIdx]!]!.value
}
@discardableResult
public func remove(_ entityIdx: EntityIndex ) -> Element? {
guard contains(entityIdx) else { return nil }
let compIdx: ComponentIdx = sparse[entityIdx]!
let lastIdx: ComponentIdx = count-1
dense.swapAt(compIdx, lastIdx)
sparse[entityIdx] = nil
let swapped: Pair = dense[compIdx]!
sparse[swapped.key] = compIdx
let removed: Pair = dense.popLast()!!
size -= 1
if size == 0 {
clear(keepingCapacity: false)
}
return removed.value
}
public func clear(keepingCapacity: Bool = false) {
size = 0
dense.removeAll(keepingCapacity: keepingCapacity)
sparse.removeAll(keepingCapacity: keepingCapacity)
}
}
extension SparseComponentSet: Sequence {
public func makeIterator() -> AnyIterator<Element> {
var iterator = dense.makeIterator()
return AnyIterator<Element> {
iterator.next()??.value
}
}
}