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Update StaticIf implementation
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‎Sources/OpenSwiftUI/View/StaticIf.swift

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//
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// StaticIf.swift
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// OpenSwiftUI
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//
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// Audited for iOS 18.0
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// Status: Complete
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import OpenSwiftUICore
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/// A container view that conditionally renders one of two views based on a `ViewInputPredicate`.
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///
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/// `StaticIf` makes view selection decisions based on the evaluation of a `ViewInputPredicate`
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/// against view inputs. Unlike regular conditional logic, the `ViewInputPredicate` is
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/// specifically designed to only depend on view input parameters rather than arbitrary
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/// runtime state.
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///
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/// This view facilitates optimizations in the view hierarchy by allowing the framework
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/// to make view structure decisions based on stable view properties rather than
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/// arbitrary runtime values.
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///
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/// Use this when you need conditional views based on input parameters like
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/// environment values, interface idioms, or view context properties.
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package struct StaticIf<Predicate, TrueBody, FalseBody> where Predicate: ViewInputPredicate {
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package var trueBody: TrueBody
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package var falseBody: FalseBody
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}
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extension StaticIf: PrimitiveView, View where TrueBody: View, FalseBody: View {
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/// Creates a new instance that statically selects between two views based on a predicate type.
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///
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/// - Parameters:
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/// - predicate: The predicate type used to evaluate against view inputs.
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/// - then: A closure that returns the view to display when the predicate evaluates to `true`.
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/// - else: A closure that returns the view to display when the predicate evaluates to `false`.
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package init(_ predicate: Predicate.Type, then: () -> TrueBody, else: () -> FalseBody) {
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trueBody = then()
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falseBody = `else`()
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}
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/// Creates a new instance that statically selects between two views based on a predicate instance.
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///
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/// - Parameters:
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/// - predicate: The predicate instance used to evaluate against view inputs.
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/// - then: A closure that returns the view to display when the predicate evaluates to `true`.
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/// - else: A closure that returns the view to display when the predicate evaluates to `false`.
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package init(_ predicate: Predicate, then: () -> TrueBody, else: () -> FalseBody) {
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trueBody = then()
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falseBody = `else`()
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}
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/// Creates a new instance that statically selects between two views based on an interface idiom.
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///
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/// - Parameters:
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/// - idiom: The interface idiom to evaluate against the current environment.
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/// - then: A closure that returns the view to display when the current device matches the specified idiom.
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/// - else: A closure that returns the view to display when the current device doesn't match the specified idiom.
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init<I>(idiom: I, then: () -> TrueBody, else: () -> FalseBody) where Predicate == InterfaceIdiomPredicate<I>, I: InterfaceIdiom {
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trueBody = then()
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falseBody = `else`()
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}
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/// Creates a new instance that statically selects between two views based on a style context.
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///
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/// - Parameters:
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/// - context: The style context to evaluate against the current environment.
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/// - then: A closure that returns the view to display when the current context accepts the specified style.
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/// - else: A closure that returns the view to display when the current context doesn't accept the specified style.
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package init<Context>(in context: Context, then: () -> TrueBody, else: () -> FalseBody) where Predicate == StyleContextAcceptsPredicate<Context>, Context: StyleContext {
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trueBody = then()
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falseBody = `else`()
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}
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nonisolated package static func _makeView(view: _GraphValue<Self>, inputs: _ViewInputs) -> _ViewOutputs {
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if Predicate.evaluate(inputs: inputs.base) {
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TrueBody._makeView(view: view[offset: { .of(&$0.trueBody) }], inputs: inputs)
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} else {
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FalseBody._makeView(view: view[offset: { .of(&$0.falseBody) }], inputs: inputs)
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}
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}
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nonisolated package static func _makeViewList(view: _GraphValue<Self>, inputs: _ViewListInputs) -> _ViewListOutputs {
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if Predicate.evaluate(inputs: inputs.base) {
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TrueBody._makeViewList(view: view[offset: { .of(&$0.trueBody) }], inputs: inputs)
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} else {
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FalseBody._makeViewList(view: view[offset: { .of(&$0.falseBody) }], inputs: inputs)
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}
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}
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nonisolated package static func _viewListCount(inputs: _ViewListCountInputs) -> Int? {
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if Predicate.evaluate(inputs: inputs.base) {
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TrueBody._viewListCount(inputs: inputs)
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} else {
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FalseBody._viewListCount(inputs: inputs)
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}
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}
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}
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extension StaticIf: PrimitiveViewModifier, ViewModifier where TrueBody: ViewModifier, FalseBody: ViewModifier {
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/// Creates a new modifier that statically applies one of two modifiers based on a predicate type.
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///
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/// - Parameters:
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/// - predicate: The predicate type used to evaluate against view inputs.
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/// - then: The modifier to apply when the predicate evaluates to `true`.
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/// - else: The modifier to apply when the predicate evaluates to `false`.
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package init(_ predicate: Predicate.Type, then: TrueBody, else: FalseBody) {
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trueBody = then
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falseBody = `else`
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}
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/// Creates a new modifier that statically applies a modifier when the predicate is true,
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/// and applies no modification when false.
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///
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/// - Parameters:
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/// - predicate: The predicate type used to evaluate against view inputs.
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/// - then: The modifier to apply when the predicate evaluates to `true`.
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package init(_ predicate: Predicate.Type, then: TrueBody) where FalseBody == EmptyModifier {
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trueBody = then
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falseBody = EmptyModifier()
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}
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/// Creates a new modifier that statically applies one of two modifiers based on an interface idiom.
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///
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/// - Parameters:
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/// - idiom: The interface idiom to evaluate against the current environment.
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/// - then: The modifier to apply when the current device matches the specified idiom.
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/// - else: The modifier to apply when the current device doesn't match the specified idiom.
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package init<I>(idiom: I, then: TrueBody, else: FalseBody) where Predicate == InterfaceIdiomPredicate<I>, I: InterfaceIdiom {
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trueBody = then
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falseBody = `else`
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}
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nonisolated package static func _makeView(modifier: _GraphValue<Self>, inputs: _ViewInputs, body: @escaping (_Graph, _ViewInputs) -> _ViewOutputs) -> _ViewOutputs {
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if Predicate.evaluate(inputs: inputs.base) {
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TrueBody._makeView(modifier: modifier[offset: { .of(&$0.trueBody) }], inputs: inputs, body: body)
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} else {
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FalseBody._makeView(modifier: modifier[offset: { .of(&$0.falseBody) }], inputs: inputs, body: body)
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}
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}
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nonisolated package static func _makeViewList(modifier: _GraphValue<Self>, inputs: _ViewListInputs, body: @escaping (_Graph, _ViewListInputs) -> _ViewListOutputs) -> _ViewListOutputs {
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if Predicate.evaluate(inputs: inputs.base) {
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TrueBody._makeViewList(modifier: modifier[offset: { .of(&$0.trueBody) }], inputs: inputs, body: body)
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} else {
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FalseBody._makeViewList(modifier: modifier[offset: { .of(&$0.falseBody) }], inputs: inputs, body: body)
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}
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}
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nonisolated package static func _viewListCount(inputs: _ViewListCountInputs, body: (_ViewListCountInputs) -> Int?) -> Int? {
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if Predicate.evaluate(inputs: inputs.base) {
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TrueBody._viewListCount(inputs: inputs, body: body)
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} else {
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FalseBody._viewListCount(inputs: inputs, body: body)
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}
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}
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}
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extension View {
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/// Conditionally applies a modifier to a view based on a predicate type.
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///
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/// Use this method when you want to apply a specific modifier only when the predicate
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/// evaluates to true based on view inputs, and leave the view unmodified otherwise.
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///
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/// - Parameters:
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/// - predicate: The predicate type used to evaluate against view inputs.
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/// - trueModifier: A closure that takes the current view and returns a modified view when the predicate evaluates to true.
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/// - Returns: Either the modified view or the original view, depending on the predicate result.
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package func staticIf<Predicate, TrueBody>(
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_ predicate: Predicate.Type,
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trueModifier: (Self) -> TrueBody
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) -> some View where Predicate: ViewInputPredicate, TrueBody: View {
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StaticIf(predicate) {
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trueModifier(self)
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} else: {
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self
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}
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}
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/// Conditionally applies one of two modifiers to a view based on a predicate type.
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///
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/// Use this method when you want to apply different modifiers based on the evaluation
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/// of a predicate against view inputs.
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///
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/// - Parameters:
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/// - predicate: The predicate type used to evaluate against view inputs.
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/// - trueModifier: A closure that takes the current view and returns a modified view when the predicate evaluates to true.
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/// - falseModifier: A closure that takes the current view and returns a modified view when the predicate evaluates to false.
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/// - Returns: A view that's been modified by either the true modifier or false modifier.
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package func staticIf<Predicate, TrueBody, FalseBody>(
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_ predicate: Predicate.Type,
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trueModifier: (Self) -> TrueBody,
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falseModifier: (Self) -> FalseBody
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) -> some View where Predicate: ViewInputPredicate, TrueBody: View, FalseBody: View {
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StaticIf(predicate) {
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trueModifier(self)
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} else: {
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falseModifier(self)
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}
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}
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/// Conditionally applies one of two modifiers to a view based on a style context.
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///
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/// Use this method when you want to apply different modifiers based on whether
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/// the current style context accepts a specific style.
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///
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/// - Parameters:
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/// - context: The style context to evaluate against the current environment.
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/// - trueModifier: A closure that takes the current view and returns a modified view when the context accepts the style.
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/// - falseModifier: A closure that takes the current view and returns a modified view when the context doesn't accept the style.
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/// - Returns: A view that's been modified by either the true modifier or false modifier based on the context.
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package func staticIf<Context, TrueBody, FalseBody>(
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context: Context,
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trueModifier: (Self) -> TrueBody,
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falseModifier: (Self) -> FalseBody
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) -> some View where Context: StyleContext, TrueBody: View, FalseBody: View {
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staticIf(
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StyleContextAcceptsPredicate<Context>.self,
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trueModifier: trueModifier,
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falseModifier: falseModifier
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)
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}
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}
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extension ViewModifier {
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/// Creates a conditional modifier that only applies when a predicate evaluates to true.
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///
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/// Use this method to create a modifier that is only applied when certain view input
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/// conditions are met. If the predicate evaluates to false, an empty modifier is applied instead.
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///
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/// - Parameter predicate: The predicate type used to evaluate against view inputs.
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/// - Returns: A conditional modifier that applies the current modifier only when the predicate is true.
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package func requiring<Predicate>(_ predicate: Predicate.Type) -> StaticIf<Predicate, Self, EmptyModifier> where Predicate: ViewInputPredicate {
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StaticIf(predicate, then: self)
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}
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}

‎Sources/OpenSwiftUICore/Modifier/StaticIf.swift

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This file was deleted.

‎Sources/OpenSwiftUICore/View/Style/StyleContext.swift

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//
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// StyleContext.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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// ID: 2EF43D8D991A83294E93848563DD541B (SwiftUICore)
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// MARK: - StyleContext
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package protocol StyleContext {
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static func accepts<Q>(_: Q.Type, at: Int) -> Bool
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static func acceptsAny<each Q>(_ queries: repeat (each Q).Type) -> Bool where repeat each Q: StyleContext
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static func visitStyle<V>(_ visitor: inout V) where V: StyleContextVisitor
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}
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extension StyleContext {
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package static func visitStyle<V>(_ visitor: inout V) where V: StyleContextVisitor {
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visitor.visit(Self.self)
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}
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package static func accepts<Q>(_ query: Q.Type, at: Int) -> Bool {
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Self.self == query
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}
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package static func acceptsAny<each Q>(_ queries: repeat (each Q).Type) -> Bool where repeat each Q: StyleContext {
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var visitor = QueryVisitor<Self>()
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for query in repeat each queries {
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query.visitStyle(&visitor)
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guard !visitor.accepts else {
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return true
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}
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}
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return visitor.accepts
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}
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package static func acceptsTop<Q>(_ query: Q.Type) -> Bool {
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accepts(query, at: 0)
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}
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}
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// TODO
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// MARK: - StyleContextAcceptsPredicate [WIP]
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package struct StyleContextAcceptsPredicate<Query>: ViewInputPredicate {
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package init() {}
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package static func evaluate(inputs: _GraphInputs) -> Bool {
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preconditionFailure("TODO")
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}
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}
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package struct StyleContextAcceptsAnyPredicate<each Query>: ViewInputPredicate where repeat each Query: StyleContext {
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package init() {}
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package static func evaluate(inputs: _GraphInputs) -> Bool {
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preconditionFailure("TODO")
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}
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}
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// TODO
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// MARK: - StyleContextVisitor
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package protocol StyleContextVisitor {
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mutating func visit<C>(_ context: C.Type) where C: StyleContext
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}
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// MARK: - QueryVisitor
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private struct QueryVisitor<Context>: StyleContextVisitor where Context: StyleContext {
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var accepts: Bool = false
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mutating func visit<C>(_ context: C.Type) where C : StyleContext {
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accepts = accepts ? true : Context.self == context
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}
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}

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