74 lines
2.0 KiB
Swift
74 lines
2.0 KiB
Swift
// Copyright 2020 Tokamak contributors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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// Created by Jed Fox on 06/30/2020.
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//
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final class NavigationContext: ObservableObject {
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@Published var destination = NavigationLinkDestination(EmptyView())
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}
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public struct NavigationView<Content>: View where Content: View {
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let content: Content
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@StateObject var context = NavigationContext()
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public init(@ViewBuilder content: () -> Content) {
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self.content = content()
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}
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public var body: Never {
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neverBody("NavigationView")
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}
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}
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/// This is a helper class that works around absence of "package private" access control in Swift
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public struct _NavigationViewProxy<Content: View> {
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public let subject: NavigationView<Content>
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public init(_ subject: NavigationView<Content>) { self.subject = subject }
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public var content: some View {
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subject.content
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.environmentObject(subject.context)
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}
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public var destination: some View {
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subject.context.destination.view
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.environmentObject(subject.context)
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}
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}
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struct NavigationDestinationKey: EnvironmentKey {
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public static let defaultValue: Binding<AnyView>? = nil
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}
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extension EnvironmentValues {
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var navigationDestination: Binding<AnyView>? {
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get {
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self[NavigationDestinationKey.self]
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}
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set {
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self[NavigationDestinationKey.self] = newValue
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}
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}
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}
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struct NavigationTitleKey: PreferenceKey {
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typealias Value = AnyView?
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static func reduce(value: inout AnyView?, nextValue: () -> AnyView?) {
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value = nextValue()
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}
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}
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