46 lines
1.5 KiB
Swift
46 lines
1.5 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 Carson Katri on 11/26/20.
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//
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public struct _PreferenceActionModifier<Key>: _PreferenceWritingModifierProtocol
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where Key: PreferenceKey, Key.Value: Equatable
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{
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public let action: (Key.Value) -> ()
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public init(action: @escaping (Key.Value) -> Swift.Void) {
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self.action = action
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}
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public func body(_ content: Content, with preferenceStore: inout _PreferenceStore) -> AnyView {
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let value = preferenceStore.value(forKey: Key.self)
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let previousValue = value.reduce(value.valueList.dropLast())
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if previousValue != value.value {
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action(value.value)
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}
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return content.view
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}
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}
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public extension View {
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func onPreferenceChange<K>(
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_ key: K.Type = K.self,
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perform action: @escaping (K.Value) -> ()
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) -> some View
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where K: PreferenceKey, K.Value: Equatable
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{
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modifier(_PreferenceActionModifier<K>(action: action))
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}
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}
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