Add ViewList and ViewTrait (#90)

* Add ViewTraitCollection implementation

* Add _ViewListOutputs related interface

Author: Kyle-Ye

Sources/OpenSwiftUI/Core/View/TODO/_ViewListCountInputs.swift

@@ -1,3 +1,10 @@
+//
+//  ViewInputs.swift
+//  OpenSwiftUI
+//
+//  Audited for RELEASE_2021
+//  Status: WIP
+
 internal import OpenGraphShims
 
 public struct _ViewInputs {

Sources/OpenSwiftUI/Core/View/TODO/_ViewListInputs.swift

@@ -0,0 +1,32 @@
+//
+//  ViewListCountInputs.swift
+//  OpenSwiftUI
+//
+//  Audited for RELEASE_2021
+//  Status: WIP
+
+public struct _ViewListCountInputs {
+    var customInputs : PropertyList
+    var options : _ViewListInputs.Options
+    var baseOptions : _GraphInputs.Options
+    
+    subscript<Input: GraphInput>(_ type: Input.Type) -> Input.Value {
+        get { customInputs[type] }
+        set { customInputs[type] = newValue }
+    }
+    
+    mutating func popLast<Input: GraphInput, Value>(_ type: Input.Type) -> Value? where Input.Value == [Value]  {
+        var values = self[type]
+        guard let value = values.popLast() else {
+            return nil
+        }
+        self[type] = values
+        return value
+    }
+    
+    mutating func append<Input: GraphInput, Value>(_ value: Value, to type: Input.Type) where Input.Value == [Value]  {
+        var values = self[type]
+        values.append(value)
+        self[type] = values
+    }
+}

Sources/OpenSwiftUI/Core/View/TODO/_ViewListOutputs.swift

@@ -0,0 +1,21 @@
+//
+//  ViewListInputs.swift
+//  OpenSwiftUI
+//
+//  Audited for RELEASE_2021
+//  Status: WIP
+
+internal import OpenGraphShims
+
+public struct _ViewListInputs {
+    var base: _GraphInputs
+    var implicitID: Int
+    var options: _ViewListInputs.Options
+    @OptionalAttribute
+    var traits: ViewTraitCollection?
+    var traitKeys: ViewTraitKeys?
+    
+    struct Options: OptionSet {
+        let rawValue: Int
+    }
+}

Sources/OpenSwiftUI/Core/View/ViewInput.swift renamed to Sources/OpenSwiftUI/Core/View/View/ViewInput.swift

@@ -0,0 +1,31 @@
+//
+//  ViewListOutputs.swift
+//  OpenSwiftUI
+//
+//  Audited for RELEASE_2021
+//  Status: WIP
+
+internal import OpenGraphShims
+
+public struct _ViewListOutputs {
+    var views: Views
+    var nextImplicitID: Int
+    var staticCount: Int?
+    
+    enum Views {
+        case staticList(_ViewList_Elements)
+        case dynamicList(Attribute<ViewList>, ListModifier?)
+    }
+    
+    class ListModifier {
+        init() {}
+        
+        func apply(to: inout ViewList)  {
+            // TODO
+        }
+    }
+}
+
+// TODO
+protocol ViewList {
+}

Sources/OpenSwiftUI/Core/View/TODO/ViewInputBoolFlag.swift renamed to Sources/OpenSwiftUI/Core/View/View/ViewInputBoolFlag.swift

@@ -0,0 +1,18 @@
+//
+//  ViewList_Elements.swift
+//  OpenSwiftUI
+//
+//  Audited for RELEASE_2021
+//  Status: WIP
+
+protocol _ViewList_Elements {
+    var count: Int { get }
+    func makeElements(
+        from: inout Int,
+        inputs: _ViewInputs,
+        indirectMap: _ViewList_IndirectMap?,
+        body: (_ViewInputs, (_ViewInputs) -> _ViewOutputs) -> (_ViewOutputs?, Bool)
+    ) -> (_ViewOutputs?, Bool)
+    func tryToReuseElement(at: Int, by: _ViewList_Elements, at: Int, indirectMap: _ViewList_IndirectMap, testOnly: Bool) -> Bool
+    func retain() -> () -> Void
+}

Sources/OpenSwiftUI/Core/View/ViewInputs.swift renamed to Sources/OpenSwiftUI/Core/View/View/ViewInputs.swift

@@ -0,0 +1,23 @@
+//
+//  ViewList_IndirectMap.swift
+//  OpenSwiftUI
+//
+//  Audited for RELEASE_2021
+//  Status: WIP
+//  ID: 70E71091E926A1B09B75AAEB38F5AA3F
+
+internal import OpenGraphShims
+
+final class _ViewList_IndirectMap {
+    let subgraph: OGSubgraph
+    #if canImport(Darwin)
+    private var map: [OGAttribute: OGAttribute]
+    #endif
+    
+    init(subgraph: OGSubgraph) {
+        self.subgraph = subgraph
+        #if canImport(Darwin)
+        self.map = [:]
+        #endif
+    }
+}

Sources/OpenSwiftUI/Core/View/ViewOutputs.swift renamed to Sources/OpenSwiftUI/Core/View/View/ViewOutputs.swift

@@ -0,0 +1,47 @@
+//
+//  ViewList_Subgraph.swift
+//  OpenSwiftUI
+//
+//  Audited for RELEASE_2021
+//  Status: WIP
+//  ID: 70E71091E926A1B09B75AAEB38F5AA3F
+
+internal import OpenGraphShims
+
+class _ViewList_Subgraph {
+    let subgraph: OGSubgraph
+    private var refcount : UInt32
+    
+    init(subgraph: OGSubgraph) {
+        self.subgraph = subgraph
+        self.refcount = 1 // TODO
+    }
+    
+    func invalidate() {}
+}
+
+extension _ViewList_Subgraph {
+    var isValid: Bool {
+        guard refcount > 0 else {
+            return false
+        }
+        return subgraph.isValid
+    }
+    
+    func retain() {
+        refcount &+= 1
+    }
+    
+    func release(isInserted: Bool) {
+        refcount &-= 1
+        guard refcount == 0 else {
+            return
+        }
+        invalidate()
+        guard subgraph.isValid else {
+            return
+        }
+        subgraph.willInvalidate(isInserted: isInserted)
+        subgraph.invalidate()
+    }
+}

Sources/OpenSwiftUI/Core/View/ViewList/ViewListCountInputs.swift

@@ -0,0 +1,63 @@
+//
+//  ViewTraitCollection.swift
+//  OpenSwiftUI
+//
+//  Audited for RELEASE_2021
+//  Status: WIP
+//  ID: 9929B476764059557433A108298EE66F
+
+struct ViewTraitCollection {
+    private var storage: [any AnyViewTrait]
+    
+    private struct AnyTrait<Key: _ViewTraitKey>: AnyViewTrait {
+        var value: Key.Value
+        
+        init(value: Key.Value) {
+            self.value = value
+        }
+        
+        var id: ObjectIdentifier { ObjectIdentifier(Key.self) }
+        
+        subscript<V>() -> V {
+            get { value as! V }
+            set { value = newValue as! Key.Value }
+        }
+    }
+    
+    subscript<Key: _ViewTraitKey>(_: Key.Type) -> Key.Value {
+        get {
+            value(for: Key.self)
+        }
+        set {
+            if let index = storage.firstIndex(where: { $0.id == ObjectIdentifier(Key.self) }) {
+                storage[index][] = newValue
+            } else {
+                storage.append(AnyTrait<Key>(value: newValue))
+            }
+        }
+    }
+    
+    func value<Key: _ViewTraitKey>(for _: Key.Type, defaultValue: Key.Value = Key.defaultValue) -> Key.Value {
+        storage.first { $0.id == ObjectIdentifier(Key.self) }?[] ?? defaultValue
+    }
+    
+    mutating func setValueIfUnset<Key: _ViewTraitKey>(_ value: Key.Value, for _: Key.Type) {
+        guard !storage.contains(where: { $0.id == ObjectIdentifier(Key.self) }) else {
+            return
+        }
+        storage.append(AnyTrait<Key>(value: value))
+    }
+    
+//    func insertInteraction(for: OnInsertInteraction.Strategy) -> OnInsertInteraction? {
+//        fatalError("TODO")
+//    }
+//    
+//    var optionalTransition: AnyTransition? {
+//        fatalError("TODO")
+//    }
+}
+
+private protocol AnyViewTrait {
+    var id: ObjectIdentifier { get }
+    subscript<V>() -> V { get set }
+}

Sources/OpenSwiftUI/Core/View/ViewList/ViewListInputs.swift

@@ -0,0 +1,11 @@
+//
+//  ViewTraitKey.swift
+//  OpenSwiftUI
+//
+//  Audited for RELEASE_2021
+//  Status: Complete
+
+protocol _ViewTraitKey {
+    associatedtype Value
+    static var defaultValue: Value { get }
+}

Sources/OpenSwiftUI/Core/View/ViewList/ViewListOutputs.swift

@@ -0,0 +1,19 @@
+//
+//  ViewTraitKeys.swift
+//  OpenSwiftUI
+//
+//  Audited for RELEASE_2021
+//  Status: Complete
+
+struct ViewTraitKeys {
+    var types: Set<ObjectIdentifier>
+    var isDataDependent: Bool
+    
+    mutating func insert<Key: _ViewTraitKey>(_ type: Key.Type) {
+        types.insert(ObjectIdentifier(type))
+    }
+    
+    func contains<Key: _ViewTraitKey>(_ type: Key.Type) -> Bool {
+        types.contains(ObjectIdentifier(type))
+    }
+}

Sources/OpenSwiftUI/Core/View/ViewList/ViewList_Elements.swift

@@ -15,7 +15,7 @@ extension AnimatableModifier {
     }
 
     public static func _makeViewList(modifier _: _GraphValue<Self>, inputs _: _ViewListInputs, body _: @escaping (_Graph, _ViewListInputs) -> _ViewListOutputs) -> _ViewListOutputs {
-        .init()
+        fatalError("TODO")
     }
 }
 
@@ -25,6 +25,6 @@ extension ViewModifier where Self: Animatable {
     }
 
     public static func _makeViewList(modifier _: _GraphValue<Self>, inputs _: _ViewListInputs, body _: @escaping (_Graph, _ViewListInputs) -> _ViewListOutputs) -> _ViewListOutputs {
-        .init()
+        fatalError("TODO")
     }
 }

Sources/OpenSwiftUI/Core/View/ViewList/ViewList_IndirectMap.swift

@@ -15,7 +15,7 @@ extension _AnimatableView {
     }
 
     public static func _makeViewList(view _: _GraphValue<Self>, inputs _: _ViewListInputs) -> _ViewListOutputs {
-        .init()
+        fatalError("TODO")
     }
 }
 
@@ -25,6 +25,6 @@ extension View where Self: Animatable {
     }
 
     public static func _makeViewList(view _: _GraphValue<Self>, inputs _: _ViewListInputs) -> _ViewListOutputs {
-        .init()
+        fatalError("TODO")
     }
 }

Sources/OpenSwiftUI/Core/View/ViewList/ViewList_Subgraph.swift

@@ -74,8 +74,7 @@ public struct AnyView: PrimitiveView {
     }
 
     public static func _makeViewList(view: _GraphValue<Self>, inputs: _ViewListInputs) -> _ViewListOutputs {
-        // TODO
-        .init()
+        fatalError("TODO")
     }
 }
 

Sources/OpenSwiftUI/Core/View/ViewTrait/ViewTraitCollection.swift

@@ -13,7 +13,7 @@ public struct EmptyView: PrimitiveView {
     }
 
     public static func _makeViewList(view: _GraphValue<EmptyView>, inputs: _ViewListInputs) -> _ViewListOutputs {
-        .init() // FIXME
+        fatalError("TODO")
     }
 
     public static func _viewListCount(inputs: _ViewListCountInputs) -> Int? {