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140 lines
3.7 KiB
Swift
140 lines
3.7 KiB
Swift
//
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// ObjectState.swift
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// CoreStore
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//
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// Copyright © 2021 John Rommel Estropia
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in all
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// copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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// SOFTWARE.
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//
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#if canImport(Combine) && canImport(SwiftUI)
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import Combine
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import SwiftUI
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// MARK: - ObjectState
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/**
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A property wrapper type that can read `ObjectPublisher` changes.
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*/
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@propertyWrapper
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public struct ObjectState<O: DynamicObject>: DynamicProperty {
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// MARK: Public
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/**
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Creates an instance that observes `ObjectPublisher` changes and exposes an `Optional<ObjectSnapshot<O>>` value.
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```
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@ObjectState
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var person: ObjectSnapshot<Person>?
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init(objectPublisher: ObjectPublisher<Person>) {
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self._person = .init(objectPublisher)
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}
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var body: some View {
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HStack {
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AsyncImage(self.person?.$avatarURL)
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Text(self.person?.$fullName ?? "")
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}
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}
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```
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- parameter objectPublisher: The `ObjectPublisher` that the `ObjectState` will observe changes for
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*/
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public init(_ objectPublisher: ObjectPublisher<O>?) {
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self.observer = .init(objectPublisher: objectPublisher)
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}
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// MARK: @propertyWrapper
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public var wrappedValue: ObjectSnapshot<O>? {
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return self.observer.item
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}
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public var projectedValue: ObjectPublisher<O>? {
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return self.observer.objectPublisher
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}
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// MARK: DynamicProperty
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public mutating func update() {
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self._observer.update()
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}
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// MARK: Private
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@ObservedObject
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private var observer: Observer
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// MARK: - Observer
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private final class Observer: ObservableObject {
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@Published
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var item: ObjectSnapshot<O>?
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let objectPublisher: ObjectPublisher<O>?
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init(objectPublisher: ObjectPublisher<O>?) {
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guard
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let dataStack = objectPublisher?.cs_dataStack(),
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let objectPublisher = objectPublisher?.asPublisher(in: dataStack)
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else {
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self.objectPublisher = nil
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self.item = nil
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return
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}
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self.objectPublisher = objectPublisher
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self.item = objectPublisher.snapshot
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objectPublisher.addObserver(self) { [weak self] (objectPublisher) in
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guard let self = self else {
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return
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}
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self.item = objectPublisher.snapshot
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}
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}
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deinit {
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self.objectPublisher?.removeObserver(self)
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}
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}
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}
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#endif
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