0.1.2

.swiftpm/xcode/xcshareddata/xcschemes/Turbocharger.xcscheme

@@ -0,0 +1,67 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Scheme
+   LastUpgradeVersion = "1410"
+   version = "1.3">
+   <BuildAction
+      parallelizeBuildables = "YES"
+      buildImplicitDependencies = "YES">
+      <BuildActionEntries>
+         <BuildActionEntry
+            buildForTesting = "YES"
+            buildForRunning = "YES"
+            buildForProfiling = "YES"
+            buildForArchiving = "YES"
+            buildForAnalyzing = "YES">
+            <BuildableReference
+               BuildableIdentifier = "primary"
+               BlueprintIdentifier = "Turbocharger"
+               BuildableName = "Turbocharger"
+               BlueprintName = "Turbocharger"
+               ReferencedContainer = "container:">
+            </BuildableReference>
+         </BuildActionEntry>
+      </BuildActionEntries>
+   </BuildAction>
+   <TestAction
+      buildConfiguration = "Debug"
+      selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
+      selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
+      shouldUseLaunchSchemeArgsEnv = "YES">
+      <Testables>
+      </Testables>
+   </TestAction>
+   <LaunchAction
+      buildConfiguration = "Debug"
+      selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
+      selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
+      launchStyle = "0"
+      useCustomWorkingDirectory = "NO"
+      ignoresPersistentStateOnLaunch = "NO"
+      debugDocumentVersioning = "YES"
+      debugServiceExtension = "internal"
+      allowLocationSimulation = "YES">
+   </LaunchAction>
+   <ProfileAction
+      buildConfiguration = "Release"
+      shouldUseLaunchSchemeArgsEnv = "YES"
+      savedToolIdentifier = ""
+      useCustomWorkingDirectory = "NO"
+      debugDocumentVersioning = "YES">
+      <MacroExpansion>
+         <BuildableReference
+            BuildableIdentifier = "primary"
+            BlueprintIdentifier = "Turbocharger"
+            BuildableName = "Turbocharger"
+            BlueprintName = "Turbocharger"
+            ReferencedContainer = "container:">
+         </BuildableReference>
+      </MacroExpansion>
+   </ProfileAction>
+   <AnalyzeAction
+      buildConfiguration = "Debug">
+   </AnalyzeAction>
+   <ArchiveAction
+      buildConfiguration = "Release"
+      revealArchiveInOrganizer = "YES">
+   </ArchiveAction>
+</Scheme>

Sources/Turbocharger/Sources/Alignment/VariadicAlignmentID.swift

@@ -0,0 +1,103 @@
+//
+// Copyright (c) Nathan Tannar
+//
+
+import SwiftUI
+
+/// An `AlignmentID` that is resolved from multiple values
+///
+/// > Tip: Use ``VariadicAlignmentID`` to create alignments
+/// similar to `.firstTextBaseline`
+public protocol VariadicAlignmentID: AlignmentID {
+    static func reduce(value: inout CGFloat?, n: Int, nextValue: CGFloat)
+}
+
+private struct DefaultAlignmentID: AlignmentID {
+    static func defaultValue(in context: ViewDimensions) -> CGFloat { 0 }
+}
+
+extension VariadicAlignmentID {
+    public static func reduce(value: inout CGFloat?, n: Int, nextValue: CGFloat) {
+        DefaultAlignmentID._combineExplicit(childValue: nextValue, n, into: &value)
+    }
+
+    public static func _combineExplicit(
+        childValue: CGFloat,
+        _ n: Int,
+        into parentValue: inout CGFloat?
+    ) {
+        reduce(value: &parentValue, n: n, nextValue: childValue)
+    }
+}
+
+extension View {
+
+    /// A modifier that transforms a vertical alignment to another
+    @inlinable
+    public func alignmentGuide(
+        _ g: VerticalAlignment,
+        value: VerticalAlignment
+    ) -> some View {
+        alignmentGuide(g) { $0[value] }
+    }
+
+    /// A modifier that transforms a horizontal alignment to another
+    @inlinable
+    public func alignmentGuide(
+        _ g: HorizontalAlignment,
+        value: HorizontalAlignment
+    ) -> some View {
+        alignmentGuide(g) { $0[value] }
+    }
+}
+
+// MARK: - Previews
+
+struct SecondTextBaseline: VariadicAlignmentID {
+    static func defaultValue(in context: ViewDimensions) -> CGFloat {
+        context[.firstTextBaseline]
+    }
+
+    static func reduce(value: inout CGFloat?, n: Int, nextValue: CGFloat) {
+        if n == 1 {
+            value = nextValue
+        }
+    }
+}
+
+extension VerticalAlignment {
+    static let secondTextBaseline = VerticalAlignment(SecondTextBaseline.self)
+}
+
+struct VariadicAlignmentID_Previews: PreviewProvider {
+    static var previews: some View {
+        VStack(spacing: 48) {
+            HStack(alignment: .firstTextBaseline) {
+                Text("Label")
+
+                VStack(alignment: .trailing) {
+                    Text("One")
+                    Text("Two")
+                    Text("Three")
+                }
+                .font(.title)
+            }
+
+            HStack(alignment: .secondTextBaseline) {
+                Text("Label")
+
+                VStack(alignment: .trailing) {
+                    Group {
+                        Text("One")
+                        Text("Two")
+                        Text("Three")
+                    }
+                    .alignmentGuide(.secondTextBaseline) { d in
+                        d[VerticalAlignment.firstTextBaseline]
+                    }
+                }
+                .font(.title)
+            }
+        }
+    }
+}

Sources/Turbocharger/Sources/DynamicProperty/BindingTransform.swift

@@ -5,6 +5,7 @@
 import SwiftUI
 import os.log
 
+/// A protocol for defining a transform for a `Binding`
 public protocol BindingTransform {
     associatedtype Input
     associatedtype Output
@@ -14,6 +15,8 @@ public protocol BindingTransform {
 }
 
 extension Binding {
+
+    /// Projects a `Binding` with the `transform`
     @inlinable
     public func projecting<Transform: BindingTransform>(
         _ transform: Transform

Sources/Turbocharger/Sources/DynamicProperty/FormatTransform.swift

@@ -4,6 +4,8 @@
 
 import SwiftUI
 
+/// A ``BindingTransform`` that transforms the value
+/// with a `ParseableFormatStyle`
 @available(iOS 15.0, macOS 12.0, tvOS 15.0, watchOS 8.0, *)
 public struct FormatTransform<F: ParseableFormatStyle>: BindingTransform where F.FormatInput: Equatable, F.FormatOutput == String {
     public typealias Input = F.FormatInput

Sources/Turbocharger/Sources/DynamicProperty/IsNilTransform.swift

@@ -4,6 +4,10 @@
 
 import SwiftUI
 
+/// A ``BindingTransform`` that transforms the value to a `Bool`
+///
+/// The transform will return `true` when the value is `nil`. If the projected
+/// value is set to `true`, the value will be set to `nil`.
 @frozen
 public struct IsNilTransform<Input>: BindingTransform {
 
@@ -23,6 +27,8 @@ public struct IsNilTransform<Input>: BindingTransform {
 }
 
 extension Binding {
+
+    /// A ``BindingTransform`` that transforms the value to `true` when `nil`
     @inlinable
     public func isNil<Wrapped>() -> Binding<Bool> where Optional<Wrapped> == Value {
         projecting(IsNilTransform())

Sources/Turbocharger/Sources/DynamicProperty/IsNotNilTransform.swift

@@ -4,6 +4,10 @@
 
 import SwiftUI
 
+/// A ``BindingTransform`` that transforms the value to a `Bool`
+///
+/// The transform will return `true` when the value is not `nil`. If the projected
+/// value is set to `false`, the value will be set to `nil`.
 @frozen
 public struct IsNotNilTransform<Input>: BindingTransform {
 
@@ -23,6 +27,8 @@ public struct IsNotNilTransform<Input>: BindingTransform {
 }
 
 extension Binding {
+
+    /// A ``BindingTransform`` that transforms the value to `true` when not `nil`
     @inlinable
     public func isNotNil<Wrapped>() -> Binding<Bool> where Optional<Wrapped> == Value {
         projecting(IsNotNilTransform())

Sources/Turbocharger/Sources/DynamicProperty/MapTransform.swift

@@ -4,6 +4,7 @@
 
 import SwiftUI
 
+/// A ``BindingTransform`` that transforms the value from a `WritableKeyPath`
 @frozen
 public struct MapTransform<Input, Output>: BindingTransform {
 
@@ -27,6 +28,8 @@ public struct MapTransform<Input, Output>: BindingTransform {
 }
 
 extension Binding {
+
+    /// A ``BindingTransform`` that transforms the value from a `WritableKeyPath`
     @inlinable
     public func map<T>(_ keyPath: WritableKeyPath<Value, T>) -> Binding<T> {
         projecting(MapTransform(keyPath: keyPath))

Sources/Turbocharger/Sources/DynamicProperty/OptionalObservedObject.swift

@@ -0,0 +1,57 @@
+//
+// Copyright (c) Nathan Tannar
+//
+
+import SwiftUI
+import Combine
+
+/// A property wrapper that subscribes to an optional observable
+/// object and invalidates a view whenever the observable object changes.
+@propertyWrapper
+@frozen
+public struct OptionalObservedObject<ObjectType: ObservableObject>: DynamicProperty {
+
+    @usableFromInline
+    class Storage: ObservableObject {
+        weak var value: ObjectType? {
+            didSet {
+                if oldValue !== value {
+                    value.map { bind(to: $0) }
+                    objectWillChange.send()
+                }
+            }
+        }
+
+        var cancellable: AnyCancellable?
+
+        @usableFromInline
+        init(value: ObjectType?) {
+            self.value = value
+            value.map { bind(to: $0) }
+        }
+
+        func bind(to object: ObjectType) {
+            cancellable = object.objectWillChange
+                .sink { [unowned self] _ in
+                    self.objectWillChange.send()
+                }
+        }
+    }
+
+    @usableFromInline
+    var storage: ObservedObject<Storage>
+
+    @inlinable
+    public init(wrappedValue: ObjectType?) {
+        storage = ObservedObject<Storage>(wrappedValue: Storage(value: wrappedValue))
+    }
+
+    public var wrappedValue: ObjectType? {
+        get { storage.wrappedValue.value }
+        nonmutating set { storage.wrappedValue.value = newValue }
+    }
+
+    public var projectedValue: Binding<ObjectType?> {
+        storage.projectedValue.value
+    }
+}