104 lines
3.2 KiB
Swift
104 lines
3.2 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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import Runtime
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/// A type-erased view.
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public struct AnyView: View {
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/// The type of the underlying `view`.
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let type: Any.Type
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/** The name of the unapplied generic type of the underlying `view`. `Button<Text>` and
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`Button<Image>` types are different, but when reconciling the tree of mounted views
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they are treated the same, thus the `Button` part of the type (the type constructor)
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is stored in this property.
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*/
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let typeConstructorName: String
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/// The actual `View` value wrapped within this `AnyView`.
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var view: Any
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/** Type-erased `body` of the underlying `view`. Needs to take a fresh version of `view` as an
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argument, otherwise it captures an old value of the `body` property.
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*/
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let bodyClosure: (Any) -> AnyView
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/** The type of the `body` of the underlying `view`. Used to cast the result of the applied
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`bodyClosure` property.
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*/
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let bodyType: Any.Type
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public init<V>(_ view: V) where V: View {
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if let anyView = view as? AnyView {
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self = anyView
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} else {
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type = V.self
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// FIXME: no idea if using `mangledName` is reliable, but seems to be the only way to get
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// a name of a type constructor in runtime. Should definitely check if these are different
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// across modules, otherwise can cause problems with views with same names in different
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// modules.
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// swiftlint:disable:next force_try
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typeConstructorName = try! typeInfo(of: type).mangledName
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bodyType = V.Body.self
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self.view = view
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if view is ViewDeferredToRenderer {
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bodyClosure = {
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let deferredView: Any
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if let opt = $0 as? AnyOptional, let value = opt.value {
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deferredView = value
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} else {
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deferredView = $0
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}
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// swiftlint:disable:next force_cast
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return (deferredView as! ViewDeferredToRenderer).deferredBody
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}
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} else {
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// swiftlint:disable:next force_cast
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bodyClosure = { AnyView(($0 as! V).body) }
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}
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}
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}
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public var body: Never {
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neverBody("AnyView")
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}
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}
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public func mapAnyView<T, V>(_ anyView: AnyView, transform: (V) -> T) -> T? {
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guard let view = anyView.view as? V else { return nil }
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return transform(view)
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}
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extension AnyView: ParentView {
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public var children: [AnyView] {
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(view as? ParentView)?.children ?? []
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}
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}
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public struct _AnyViewProxy {
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public var subject: AnyView
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public init(_ subject: AnyView) { self.subject = subject }
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public var type: Any.Type { subject.type }
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public var view: Any { subject.view }
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}
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