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Update ViewTrait (#219)
* Update ViewTrait path * Update ViewTrait
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-21
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3 files changed

+183
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‎Sources/OpenSwiftUICore/Layout/LayoutPriorityLayout.swift

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//
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// LayoutPriorityLayout.swift
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// OpenSwiftUICore
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//
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// Audited for iOS 18.0
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// Status: WIP
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extension View {
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/// Sets the priority by which a parent layout should apportion space to
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/// this child.
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///
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/// Views typically have a default priority of `0` which causes space to be
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/// apportioned evenly to all sibling views. Raising a view's layout
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/// priority encourages the higher priority view to shrink later when the
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/// group is shrunk and stretch sooner when the group is stretched.
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///
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/// HStack {
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/// Text("This is a moderately long string.")
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/// .font(.largeTitle)
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/// .border(Color.gray)
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///
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/// Spacer()
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///
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/// Text("This is a higher priority string.")
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/// .font(.largeTitle)
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/// .layoutPriority(1)
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/// .border(Color.gray)
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/// }
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///
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/// In the example above, the first ``Text`` element has the default
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/// priority `0` which causes its view to shrink dramatically due to the
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/// higher priority of the second ``Text`` element, even though all of their
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/// other attributes (font, font size and character count) are the same.
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///
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/// ![A screenshot showing twoText views different layout
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/// priorities.](OpenSwiftUI-View-layoutPriority.png)
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///
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/// A parent layout offers the child views with the highest layout priority
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/// all the space offered to the parent minus the minimum space required for
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/// all its lower-priority children.
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///
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/// - Parameter value: The priority by which a parent layout apportions
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/// space to the child.
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@inlinable
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nonisolated public func layoutPriority(_ value: Double) -> some View {
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_trait(LayoutPriorityTraitKey.self, value)
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}
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}
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@usableFromInline
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package struct LayoutPriorityTraitKey: _ViewTraitKey {
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@inlinable
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package static var defaultValue: Double { .zero }
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}
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@available(*, unavailable)
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extension LayoutPriorityTraitKey: Sendable {}
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// FIXME
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protocol UnaryLayout: ViewModifier {
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static func makeViewImpl(
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modifier: _GraphValue<Self>,
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inputs: _ViewInputs,
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body: @escaping (_Graph, _ViewInputs) -> _ViewOutputs
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) -> _ViewOutputs
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}
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// FIXME
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package struct LayoutPriorityLayout: UnaryLayout {
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static func makeViewImpl(modifier: _GraphValue<LayoutPriorityLayout>, inputs: _ViewInputs, body: @escaping (_Graph, _ViewInputs) -> _ViewOutputs) -> _ViewOutputs {
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.init()
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}
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}

‎Sources/OpenSwiftUICore/View/Variadic/ViewTrait.swift renamed to ‎Sources/OpenSwiftUICore/View/ViewTrait.swift

Lines changed: 110 additions & 21 deletions
Original file line numberDiff line numberDiff line change
@@ -1,9 +1,9 @@
11
//
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// ViewTrait.swift
3-
// OpenSwiftUI
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// OpenSwiftUICore
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//
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// Audited for iOS 18.0
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// Status: Blocked by ViewList
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// Status: Complete
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// ID: 9929B476764059557433A108298EE66F (SwiftUI)
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// ID: 48526BA25CDCBF890FA91D018A5421B4 (SwiftUICore)
99

@@ -21,11 +21,11 @@ public protocol _ViewTraitKey {
2121
static var defaultValue: Value { get }
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}
2323

24-
// MARK: - _TraitWritingModifier [TODO]
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// MARK: - _TraitWritingModifier
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2626
/// A view content adapter that associates a trait with its base content.
2727
@frozen
28-
public struct _TraitWritingModifier<Trait>: PrimitiveViewModifier where Trait : _ViewTraitKey {
28+
public struct _TraitWritingModifier<Trait>: PrimitiveViewModifier where Trait: _ViewTraitKey {
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public let value: Trait.Value
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3131
@inlinable
@@ -38,23 +38,47 @@ public struct _TraitWritingModifier<Trait>: PrimitiveViewModifier where Trait :
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inputs: _ViewInputs,
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body: @escaping (_Graph, _ViewInputs) -> _ViewOutputs
4040
) -> _ViewOutputs {
41-
preconditionFailure("TODO")
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if Trait.self == LayoutPriorityTraitKey.self {
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LayoutPriorityLayout.makeViewImpl(
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modifier: modifier.unsafeCast(),
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inputs: inputs,
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body: body
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)
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} else {
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body(_Graph(), inputs)
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}
4250
}
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4352
nonisolated public static func _makeViewList(
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modifier: _GraphValue<Self>,
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inputs: _ViewListInputs,
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body: @escaping (_Graph, _ViewListInputs) -> _ViewListOutputs
4756
) -> _ViewListOutputs {
48-
preconditionFailure("TODO")
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}
50-
51-
nonisolated public static func _viewListCount(inputs: _ViewListCountInputs, body: (_ViewListCountInputs) -> Int?) -> Int? {
52-
preconditionFailure("TODO")
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var inputs = inputs
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if Trait.self == LayoutPriorityTraitKey.self,
59+
!inputs.options.contains(.layoutPriorityIsTrait) {
60+
let attribute = modifier.value.unsafeBitCast(to: _TraitWritingModifier<LayoutPriorityTraitKey>.self)
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var outputs = body(_Graph(), inputs)
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outputs.multiModifier(_GraphValue(attribute), inputs: inputs)
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return outputs
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} else {
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let addTrait = AddTrait(modifier: modifier.value, traits: OptionalAttribute(inputs.traits))
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let attribute = Attribute(addTrait)
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inputs.addTraitKey(Trait.self)
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inputs.traits = attribute
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return body(_Graph(), inputs)
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}
5371
}
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55-
private struct AddTrait {
73+
private struct AddTrait: Rule {
5674
@Attribute var modifier: _TraitWritingModifier
5775
@OptionalAttribute var traits: ViewTraitCollection?
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77+
var value: ViewTraitCollection {
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var traits = traits ?? ViewTraitCollection()
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traits[Trait.self] = modifier.value
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return traits
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}
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}
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}
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@@ -65,16 +89,17 @@ extension View {
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/// Associate a trait `value` for the given `key` for this view content.
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@inlinable
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nonisolated public func _trait<K>(_ key: K.Type, _ value: K.Value) -> some View where K: _ViewTraitKey {
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return modifier(_TraitWritingModifier<K>(value: value))
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modifier(_TraitWritingModifier<K>(value: value))
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}
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}
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72-
// MARK: - _ConditionalTraitWritingModifier [TODO]
96+
// MARK: - _ConditionalTraitWritingModifier
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/// Conditionally writes a trait.
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@frozen
76100
public struct _ConditionalTraitWritingModifier<Trait>: PrimitiveViewModifier where Trait : _ViewTraitKey {
77101
public var value: Trait.Value
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78103
public var isEnabled: Bool
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80105
@_alwaysEmitIntoClient
@@ -88,26 +113,56 @@ public struct _ConditionalTraitWritingModifier<Trait>: PrimitiveViewModifier whe
88113
inputs: _ViewInputs,
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body: @escaping (_Graph, _ViewInputs) -> _ViewOutputs
90115
) -> _ViewOutputs {
91-
preconditionFailure("TODO")
116+
_TraitWritingModifier<Trait>._makeView(
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modifier: _GraphValue(Attribute(identifier: AnyAttribute.nil)),
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inputs: inputs,
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body: body
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)
92121
}
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93123
nonisolated public static func _makeViewList(
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modifier: _GraphValue<Self>,
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inputs: _ViewListInputs,
96126
body: @escaping (_Graph, _ViewListInputs) -> _ViewListOutputs
97127
) -> _ViewListOutputs {
98-
preconditionFailure("TODO")
128+
var inputs = inputs
129+
if Trait.self == LayoutPriorityTraitKey.self,
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!inputs.options.contains(.layoutPriorityIsTrait) {
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let attribute = modifier.value.unsafeBitCast(to: _TraitWritingModifier<LayoutPriorityTraitKey>.self)
132+
var outputs = body(_Graph(), inputs)
133+
outputs.multiModifier(_GraphValue(attribute), inputs: inputs)
134+
return outputs
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} else {
136+
let addTrait = ConditionalAddTrait(modifier: modifier.value, traits: OptionalAttribute(inputs.traits))
137+
let attribute = Attribute(addTrait)
138+
inputs.addTraitKey(Trait.self)
139+
inputs.traits = attribute
140+
return body(_Graph(), inputs)
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}
99142
}
100143

101-
nonisolated public static func _viewListCount(inputs: _ViewListCountInputs, body: (_ViewListCountInputs) -> Int?) -> Int? {
102-
preconditionFailure("TODO")
144+
private struct ConditionalAddTrait: Rule {
145+
@Attribute var modifier: _ConditionalTraitWritingModifier
146+
@OptionalAttribute var traits: ViewTraitCollection?
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148+
var value: ViewTraitCollection {
149+
var traits = traits ?? ViewTraitCollection()
150+
if modifier.isEnabled {
151+
traits[Trait.self] = modifier.value
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}
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return traits
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}
103155
}
104156
}
105157

106158
@available(*, unavailable)
107159
extension _ConditionalTraitWritingModifier: Sendable {}
108160

109161
extension View {
162+
/// Conditionally writes a trait.
110163
@_alwaysEmitIntoClient
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@MainActor
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@preconcurrency
111166
public func _trait<K>(_ key: K.Type = K.self, _ value: K.Value, isEnabled: Bool) -> some View where K: _ViewTraitKey {
112167
modifier(_ConditionalTraitWritingModifier<K>(
113168
value: value,
@@ -116,15 +171,49 @@ extension View {
116171
}
117172
}
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119-
// MARK: - TraitTransformerModifier [TODO]
174+
// MARK: - TraitTransformerModifier
120175

121-
struct TraitTransformerModifier {
122-
176+
struct TraitTransformerModifier<Trait>: PrimitiveViewModifier where Trait: _ViewTraitKey {
177+
var transform: (inout Trait.Value) -> Void
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179+
nonisolated public static func _makeView(
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modifier: _GraphValue<Self>,
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inputs: _ViewInputs,
182+
body: @escaping (_Graph, _ViewInputs) -> _ViewOutputs
183+
) -> _ViewOutputs {
184+
body(_Graph(), inputs)
185+
}
186+
187+
nonisolated public static func _makeViewList(
188+
modifier: _GraphValue<Self>,
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inputs: _ViewListInputs,
190+
body: @escaping (_Graph, _ViewListInputs) -> _ViewListOutputs
191+
) -> _ViewListOutputs {
192+
var inputs = inputs
193+
let trait = TransformTrait(modifier: modifier.value, traits: OptionalAttribute(inputs.traits))
194+
let attribute = Attribute(trait)
195+
inputs.traits = attribute
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return body(_Graph(), inputs)
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}
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199+
private struct TransformTrait: Rule {
200+
@Attribute var modifier: TraitTransformerModifier
201+
@OptionalAttribute var traits: ViewTraitCollection?
202+
203+
var value: ViewTraitCollection {
204+
var traits = traits ?? ViewTraitCollection()
205+
let transform = modifier.transform
206+
var value = traits.value(for: Trait.self)
207+
transform(&value)
208+
traits[Trait.self] = value
209+
return traits
210+
}
211+
}
123212
}
124213

125214
extension View {
126215
package func transformTrait<K>(_ key: K.Type = K.self, transform: @escaping (inout K.Value) -> Void) -> some View where K: _ViewTraitKey {
127-
preconditionFailure("TODO")
216+
modifier(TraitTransformerModifier<K>(transform: transform))
128217
}
129218
}
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‎Tests/OpenSwiftUICoreTests/View/Variadic/ViewTraitTests.swift renamed to ‎Tests/OpenSwiftUICoreTests/View/ViewTraitTests.swift

File renamed without changes.

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