65 lines
1.8 KiB
Swift
65 lines
1.8 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 Max Desiatov on 08/04/2020.
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//
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protocol ValueStorage {
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var getter: (() -> Any)? { get set }
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var anyInitialValue: Any { get }
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}
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protocol WritableValueStorage: ValueStorage {
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var setter: ((Any, Transaction) -> ())? { get set }
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}
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@propertyWrapper
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public struct State<Value>: DynamicProperty {
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private let initialValue: Value
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var anyInitialValue: Any { initialValue }
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var getter: (() -> Any)?
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var setter: ((Any, Transaction) -> ())?
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public init(wrappedValue value: Value) {
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initialValue = value
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}
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public var wrappedValue: Value {
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get { getter?() as? Value ?? initialValue }
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nonmutating set { setter?(newValue, Transaction._active ?? .init(animation: nil)) }
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}
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public var projectedValue: Binding<Value> {
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guard let getter = getter, let setter = setter else {
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fatalError("\(#function) not available outside of `body`")
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}
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// swiftlint:disable force_cast
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return .init(
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get: { getter() as! Value },
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set: { newValue, transaction in
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setter(newValue, Transaction._active ?? transaction)
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}
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)
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// swiftlint:enable force_cast
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}
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}
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extension State: WritableValueStorage {}
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public extension State where Value: ExpressibleByNilLiteral {
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@inlinable
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init() { self.init(wrappedValue: nil) }
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}
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