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CovertSwiftObserver.swift
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CovertSwiftObserver.swift
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//
// CovertSwiftObserver.swift
// CovertSwiftObserver
//
// Created by Alexey Demin on 2018-04-11.
// Copyright © 2018 DnV1eX. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
import Foundation
private let hash = NSHashTable<AnyObserver>.weakObjects()
public struct Group: Hashable, ExpressibleByStringLiteral {
public typealias StringLiteralType = String
public let objectIdentifier: ObjectIdentifier?
public let keyPath: AnyKeyPath?
public let id: String?
public static func by(_ object: AnyObject, _ keyPath: AnyKeyPath, id: String? = nil) -> Group {
return Group(ObjectIdentifier(object), keyPath, id)
}
public static func by(_ object: AnyObject, id: String? = nil) -> Group {
return Group(ObjectIdentifier(object), nil, id)
}
public static func by(_ keyPath: AnyKeyPath, id: String? = nil) -> Group {
return Group(nil, keyPath, id)
}
public init(stringLiteral value: StringLiteralType) {
self = Group(nil, nil, value)
}
private init(_ objectIdentifier: ObjectIdentifier?, _ keyPath: AnyKeyPath?, _ id: String?) {
self.objectIdentifier = objectIdentifier
self.keyPath = keyPath
self.id = id
}
}
public class AnyObserver {
public let group: Group?
public var all: [AnyObserver] {
if let group = group {
return hash.allObjects.filter { $0.group == group }
} else {
return [self]
}
}
fileprivate init(_ group: Group?) {
self.group = group
hash.add(self)
}
fileprivate func remove(_ handler: AnyObject) { preconditionFailure() }
fileprivate func revoke(_ group: Group) { preconditionFailure() }
}
public final class Observer<Parameter>: AnyObserver {
public final class Handler {
public typealias Closure = (AnyObject) -> (Parameter) -> Bool
public private(set) weak var object: AnyObject?
fileprivate private(set) var closure: Closure
public let group: Group?
public fileprivate(set) var count = 0
public init(_ object: AnyObject, group: Group?, _ closure: @escaping Closure) {
self.object = object
self.group = group
self.closure = closure
}
@discardableResult public func on(_ queue: DispatchQueue) -> Handler {
let closure = self.closure
self.closure = { object in
{ parameter in
queue.async {
_ = closure(object)(parameter)
}
return true
}
}
return self
}
@discardableResult public func until(_ condition: @escaping (Parameter, Int) -> Bool) -> Handler {
let closure = self.closure
self.closure = { [unowned self] object in
{ parameter in
return condition(parameter, self.count) ? closure(object)(parameter) : false
}
}
return self
}
@discardableResult public func until(_ condition: @escaping (Parameter) -> Bool) -> Handler {
return until { parameter, _ in condition(parameter) }
}
@discardableResult public func until(_ condition: @escaping () -> Bool) -> Handler {
return until { _, _ in condition() }
}
@discardableResult public func once() -> Handler {
return until { _, count in count == 0 }
}
@discardableResult public func now(_ parameter: Parameter) -> Handler {
if let object = object, closure(object)(parameter) {
count += 1
} else {
remove()
}
return self
}
public func remove() {
hash.allObjects.forEach {
$0.remove(self)
}
}
}
public private(set) var handlers = [Handler]()
private let queue = DispatchQueue(label: "ObserverQueue", qos: .userInteractive)
public init(_: Parameter.Type? = nil, group: Group? = nil) {
super.init(group)
}
@discardableResult public func bind<Object: AnyObject>(_ object: Object, _ keyPath: ReferenceWritableKeyPath<Object, Parameter>) -> Handler {
unbind(object, keyPath)
let handler = Handler(object, group: .by(object, keyPath)) { object in
{ parameter in
(object as! Object)[keyPath: keyPath] = parameter
return true
}
}
append(handler)
return handler
}
@discardableResult public func call<Object: AnyObject>(_ object: Object, group: Group? = nil, _ function: @escaping (Object) -> (Parameter) -> Void) -> Handler {
if let group = group { revokeAll(group) }
let handler = Handler(object, group: group) { object in
{ parameter in
function(object as! Object)(parameter)
return true
}
}
append(handler)
return handler
}
@discardableResult public func call<Object: AnyObject>(_ object: Object, group: Group? = nil, _ function: @escaping (Object) -> () -> Void) -> Handler {
return call(object, group: group) { object in { _ in function(object)() } }
}
@discardableResult public func run<Object: AnyObject>(_ object: Object, group: Group? = nil, _ closure: @escaping (Object, Parameter) -> Void) -> Handler {
if let group = group { revokeAll(group) }
let handler = Handler(object, group: group) { object in
{ parameter in
closure(object as! Object, parameter)
return true
}
}
append(handler)
return handler
}
@discardableResult public func run(_ object: AnyObject, group: Group? = nil, _ closure: @escaping (Parameter) -> Void) -> Handler {
return run(object, group: group) { _, parameter in closure(parameter) }
}
@discardableResult public func run(group: Group? = nil, _ closure: @escaping (Parameter) -> Void) -> Handler {
return run(self, group: group) { _, parameter in closure(parameter) }
}
/*
@discardableResult public func run(_ object: AnyObject, group: Group? = nil) -> Handler {
return run(object, group: group) { _, _ in }
}
@discardableResult public func run(group: Group? = nil) -> Handler {
return run(self, group: group) { _, _ in }
}
*/
public func notify(_ parameter: Parameter) {
var objects = [(Handler, AnyObject)]() // Retain objects
queue.sync {
objects = handlers.compactMap { handler in handler.object.map { (handler, $0) } }
handlers = objects.map { $0.0 }
}
for (handler, object) in objects {
if handler.closure(object)(parameter) {
handler.count += 1
} else {
handler.remove()
}
}
}
public func append(_ handler: Handler) {
queue.sync {
handlers.append(handler)
handlers.removeAll { $0.object == nil }
}
}
fileprivate override func remove(_ handler: AnyObject) {
if let handler = handler as? Handler {
remove(handler)
}
}
public func remove(_ handler: Handler) {
queue.sync {
handlers.removeAll { $0 === handler }
}
}
public func unbind<Object: AnyObject>(_ object: Object, _ keyPath: ReferenceWritableKeyPath<Object, Parameter>) {
revokeAll(.by(object, keyPath))
}
public func revokeAll(_ group: Group) {
all.forEach { $0.revoke(group) }
}
public override func revoke(_ group: Group) {
queue.sync {
handlers.removeAll { $0.group == group }
}
}
public func revoke() {
revoke(self)
}
public func revoke(_ object: AnyObject) {
queue.sync {
handlers.removeAll { $0.object === object && $0.group == nil }
}
}
}
public extension Observer where Parameter == Void {
convenience init(group: Group? = nil) {
self.init(Void.self, group: group)
}
@discardableResult func run<Object: AnyObject>(_ object: Object, group: Group? = nil, _ closure: @escaping (Object) -> Void) -> Handler {
return run(object, group: group) { object, _ in closure(object) }
}
func notify() {
notify(())
}
}
public extension Observer.Handler where Parameter == Void {
@discardableResult func until(_ condition: @escaping (Int) -> Bool) -> Observer.Handler {
return until { _, count in condition(count) }
}
@discardableResult func now() -> Observer.Handler {
return now(())
}
@discardableResult func now(if condition: Bool) -> Observer.Handler {
if condition {
now()
}
return self
}
}