62 lines
1.7 KiB
Swift
62 lines
1.7 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 7/10/21.
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//
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public protocol _ViewTraitKey {
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associatedtype Value
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static var defaultValue: Value { get }
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}
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public protocol _TraitWritingModifierProtocol {
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func modifyViewTraitStore(_ viewTraitStore: inout _ViewTraitStore)
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}
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@frozen public struct _TraitWritingModifier<Trait>: ViewModifier, _TraitWritingModifierProtocol
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where Trait: _ViewTraitKey
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{
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public let value: Trait.Value
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@inlinable
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public init(value: Trait.Value) {
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self.value = value
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}
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public func body(content: Content) -> some View {
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content
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}
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public func modifyViewTraitStore(_ viewTraitStore: inout _ViewTraitStore) {
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viewTraitStore.insert(value, forKey: Trait.self)
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}
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}
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extension ModifiedContent: _TraitWritingModifierProtocol
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where Modifier: _TraitWritingModifierProtocol
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{
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public func modifyViewTraitStore(_ viewTraitStore: inout _ViewTraitStore) {
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modifier.modifyViewTraitStore(&viewTraitStore)
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}
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}
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public extension View {
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@inlinable
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func _trait<K>(
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_ key: K.Type,
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_ value: K.Value
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) -> some View where K: _ViewTraitKey {
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modifier(_TraitWritingModifier<K>(value: value))
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}
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}
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