102 lines
3.3 KiB
Swift
102 lines
3.3 KiB
Swift
//
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// Preference.swift
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// TuskerPreferences
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//
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// Created by Shadowfacts on 4/13/24.
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//
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import Foundation
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import Combine
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// TODO: once we target iOS 17, use Observable for this
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@propertyWrapper
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final class Preference<Key: PreferenceKey>: Codable {
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@Published private(set) var storedValue: Key.Value?
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var wrappedValue: Key.Value {
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get {
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storedValue ?? Key.defaultValue
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}
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set {
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fatalError("unreachable")
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}
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}
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init() {
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self.storedValue = nil
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}
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init(from decoder: any Decoder) throws {
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if let keyType = Key.self as? any CustomCodablePreferenceKey.Type {
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self.storedValue = try keyType.decode(from: decoder) as! Key.Value?
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} else if let container = try? decoder.singleValueContainer() {
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self.storedValue = try? container.decode(Key.Value.self)
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}
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}
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func encode(to encoder: any Encoder) throws {
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if let storedValue {
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if let keyType = Key.self as? any CustomCodablePreferenceKey.Type {
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func encode<K: CustomCodablePreferenceKey>(_: K.Type) throws {
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try K.encode(value: storedValue as! K.Value, to: encoder)
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}
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return try _openExistential(keyType, do: encode)
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} else {
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var container = encoder.singleValueContainer()
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try container.encode(storedValue)
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}
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}
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}
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static subscript(
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_enclosingInstance instance: PreferenceStore,
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wrapped wrappedKeyPath: ReferenceWritableKeyPath<PreferenceStore, Key.Value>,
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storage storageKeyPath: ReferenceWritableKeyPath<PreferenceStore, Preference>
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) -> Key.Value {
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get {
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get(enclosingInstance: instance, storage: storageKeyPath)
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}
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set {
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set(enclosingInstance: instance, storage: storageKeyPath, newValue: newValue)
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Key.didSet(in: instance, newValue: newValue)
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}
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}
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// for testing only
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@inline(__always)
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static func get<Enclosing>(
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enclosingInstance: Enclosing,
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storage: KeyPath<Enclosing, Preference>
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) -> Key.Value where Enclosing: ObservableObject, Enclosing.ObjectWillChangePublisher == ObservableObjectPublisher {
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let pref = enclosingInstance[keyPath: storage]
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return pref.storedValue ?? Key.defaultValue
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}
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// for testing only
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@inline(__always)
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static func set<Enclosing>(
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enclosingInstance: Enclosing,
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storage: KeyPath<Enclosing, Preference>,
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newValue: Key.Value
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) where Enclosing: ObservableObject, Enclosing.ObjectWillChangePublisher == ObservableObjectPublisher {
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enclosingInstance.objectWillChange.send()
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let pref = enclosingInstance[keyPath: storage]
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pref.storedValue = newValue
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}
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var projectedValue: PreferencePublisher<Key> {
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.init(preference: self)
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}
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}
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public struct PreferencePublisher<Key: PreferenceKey>: Publisher {
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public typealias Output = Key.Value
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public typealias Failure = Never
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let preference: Preference<Key>
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public func receive<S>(subscriber: S) where S : Subscriber, Never == S.Failure, Key.Value == S.Input {
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preference.$storedValue.map { $0 ?? Key.defaultValue }.receive(subscriber: subscriber)
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}
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}
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