47 lines
1.5 KiB
Swift
47 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 7/11/21.
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//
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/// A modifier that resolves to a concrete modifier in an environment.
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public protocol EnvironmentalModifier: ViewModifier {
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associatedtype ResolvedModifier: ViewModifier
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func resolve(in environment: EnvironmentValues) -> ResolvedModifier
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static var _requiresMainThread: Bool { get }
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}
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private struct EnvironmentalModifierResolver<M>: ViewModifier, _EnvironmentReader
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where M: EnvironmentalModifier
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{
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let modifier: M
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var resolved: M.ResolvedModifier!
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func body(content: Content) -> some View {
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content.modifier(resolved)
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}
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mutating func _setContent(from values: EnvironmentValues) {
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resolved = modifier.resolve(in: values)
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}
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}
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public extension EnvironmentalModifier {
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static var _requiresMainThread: Bool { true }
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func body(content: _ViewModifier_Content<Self>) -> some View {
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content.modifier(EnvironmentalModifierResolver(modifier: self))
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}
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}
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