Entity/enumerateHierarchy

Entity+EnumerateHierarchy.swift

//
//  Entity+EnumerateHierarchy.swift
//
//  Created by Drew Olbrich on 7/18/23.
//

import RealityKit

extension Entity {
    
    /// Executes a closure for each of the entity's child and descendant entities, as
    /// well as for the entity itself.
    func enumerateHierarchy(body: (Entity) -> Void) {
        enumerateHierarchy { entity, _ in
            body(entity)
        }
    }
    
    /// Asynchronously executes a closure for each of the entity's child and descendant
    /// entities, as well as for the entity itself.
    ///
    /// This method does not return until all asynchronous `body` closures have finished
    /// executing.
    func enumerateHierarchy(body: @escaping (Entity) async -> Void) async {
        await withTaskGroup(of: Void.self) { taskGroup in
            enumerateHierarchy { entity, _ in
                taskGroup.addTask {
                    await body(entity)
                }
            }
        }
    }
    
    /// Executes a closure for each of the entity's child and descendant entities, as
    /// well as for the entity itself.
    ///
    /// Set `stop` to true in the closure to abort further processing of the child entity subtree.
    func enumerateHierarchy(body: (Entity, UnsafeMutablePointer<Bool>) -> Void) {
        var stop = false
        func enumerate(body: (Entity, UnsafeMutablePointer<Bool>) -> Void) {
            guard !stop else {
                return
            }
            body(self, &stop)
            for child in children {
                guard !stop else {
                    break
                }
                child.enumerateHierarchy(body: body)
            }
        }
        enumerate(body: body)
    }
    
}