48 lines
1.4 KiB
Swift
48 lines
1.4 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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public protocol ViewModifier {
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typealias Content = _ViewModifier_Content<Self>
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associatedtype Body: View
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func body(content: Content) -> Self.Body
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}
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public struct _ViewModifier_Content<Modifier>: View where Modifier: ViewModifier {
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public let modifier: Modifier
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public let view: AnyView
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public init(modifier: Modifier, view: AnyView) {
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self.modifier = modifier
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self.view = view
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}
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public var body: AnyView {
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view
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}
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}
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public extension View {
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func modifier<Modifier>(_ modifier: Modifier) -> ModifiedContent<Self, Modifier> {
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.init(content: self, modifier: modifier)
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}
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}
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public extension ViewModifier where Body == Never {
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func body(content: Content) -> Body {
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fatalError(
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"\(Self.self) is a primitive `ViewModifier`, you're not supposed to run `body(content:)`"
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)
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}
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}
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