Add State implementation (#75)

* Add State _makeProperty implementation

* Add StoredLocationBase implementation

* Update StoredLocationBase implementation

* Complete State implementation

* FIx WASI build issue

Author: Kyle-Ye

.github/workflows/wasm.yml

@@ -15,6 +15,12 @@ jobs:
         swift_version: ["5.10-SNAPSHOT-2024-03-30-a"] # "5.10-RELEASE" is not release for WASM, tracked via https://github.com/swiftwasm/swift/issues/5570
         os: [ubuntu-22.04]
     runs-on: ${{ matrix.os }}
+    env:
+      OPENSWIFTUI_WERROR: 1
+      OPENSWIFTUI_SWIFT_TESTING: 0
+      OPENGRAPH_ATTRIBUTEGRAPH: 0
+      OPENSWIFTUI_COMPATIBILITY_TEST: 0
+      OPENSWIFTUI_SWIFT_LOG: 1
     steps:
       - uses: actions/checkout@v4
       - uses: swiftwasm/setup-swiftwasm@v1

Package.resolved

@@ -7,7 +7,7 @@
       "location" : "https://github.com/OpenSwiftUIProject/OpenGraph",
       "state" : {
         "branch" : "main",
-        "revision" : "315468c6339cdbcbaf7d8797b866745d5bf11d8e"
+        "revision" : "036b8d28a8a1220a768a81bbc20624759094137c"
       }
     },
     {

Sources/OpenSwiftUI/Core/Data/Location/AnyLocation.swift

@@ -16,7 +16,7 @@ class AnyLocation<Value>: AnyLocationBase {
     }
     func get() -> Value { fatalError() }
     func set(_ value: Value, transaction: Transaction) { fatalError() }
-    func projecting<P>(_ p: P) -> AnyLocation<P.Projected> where P: Projection, P.Base == Value {
+    func projecting<P: Projection>(_ p: P) -> AnyLocation<P.Projected> where Value == P.Base {
         fatalError()
     }
     func update() -> (Value, Bool) { fatalError() }

Sources/OpenSwiftUI/Core/Data/Location/LocationBox.swift

@@ -27,8 +27,8 @@ class LocationBox<L: Location>: AnyLocation<L.Value> {
         location.set(value, transaction: transaction)
     }
 
-    override func projecting<P>(_ p: P) -> AnyLocation<P.Projected> where L.Value == P.Base, P : Projection {
-        cache.reference(for: p, on: location)
+    override func projecting<P: Projection>(_ projection: P) -> AnyLocation<P.Projected> where L.Value == P.Base {
+        cache.reference(for: projection, on: location)
     }
 
     override func update() -> (L.Value, Bool) {

Sources/OpenSwiftUI/Core/Data/Location/TODO/StoredLocationBase.swift

@@ -6,6 +6,7 @@
 //  Status: Blocked by merge
 //  ID: 2B32D570B0B3D2A55DA9D4BFC1584D20
 
+internal import COpenSwiftUI
 internal import OpenGraphShims
 
 // MARK: - PropertyList
@@ -18,6 +19,11 @@ struct PropertyList: CustomStringConvertible {
 
     @inlinable
     init() { elements = nil }
+    
+    @inline(__always)
+    init(elements: Element?) {
+        self.elements = elements
+    }
 
     @usableFromInline
     var description: String {
@@ -86,13 +92,23 @@ struct PropertyList: CustomStringConvertible {
         fatalError("TODO")
     }
 
-    mutating private func override(with plist: PropertyList) {
+    mutating func override(with plist: PropertyList) {
         if let element = elements {
             elements = element.byPrepending(plist.elements)
         } else {
             elements = plist.elements
         }
     }
+    
+    @inline(__always)
+    static var current: PropertyList {
+        if let data = _threadTransactionData() {
+            // FIXME: swift_dynamicCastClassUnconditional
+            PropertyList(elements: data.assumingMemoryBound(to: Element.self).pointee)
+        } else {
+            PropertyList()
+        }
+    }
 }
 
 // MARK: - PropertyList Help functions

Sources/OpenSwiftUI/Core/Data/Property/PropertyList.swift

@@ -0,0 +1,22 @@
+//
+//  ThreadUtils.swift
+//  
+//
+//  Created by Kyle on 2024/4/21.
+//
+
+import Foundation
+
+@inline(__always)
+func performOnMainThread(_ block: @escaping () -> Void) {
+    #if os(WASI)
+    // See #76: Thread and RunLoopMode.common is not available on WASI currently
+    block()
+    #else
+    if Thread.isMainThread {
+        block()
+    } else {
+        RunLoop.main.perform(inModes: [.common], block: block)
+    }
+    #endif
+}

Sources/OpenSwiftUI/Core/Util/ThreadUtils.swift

@@ -343,7 +343,12 @@ extension Binding: DynamicProperty {
         }
     }
 
-    public static func _makeProperty<V>(in buffer: inout _DynamicPropertyBuffer, container: _GraphValue<V>, fieldOffset: Int, inputs: inout _GraphInputs) {
+    public static func _makeProperty<V>(
+        in buffer: inout _DynamicPropertyBuffer,
+        container _: _GraphValue<V>,
+        fieldOffset: Int,
+        inputs _: inout _GraphInputs
+    ) {
         buffer.append(Box(), fieldOffset: fieldOffset)
     }
 }

Sources/OpenSwiftUI/Data/Model/Binding/Binding.swift

@@ -8,7 +8,7 @@
 protocol DynamicPropertyBox<Property>: DynamicProperty {
     associatedtype Property: DynamicProperty
     func destroy()
-    func reset()
+    mutating func reset()
     mutating func update(property: inout Property, phase: _GraphInputs.Phase) -> Bool
     func getState<Value>(type: Value.Type) -> Binding<Value>?
 }

Sources/OpenSwiftUI/Data/Model/DynamicProperty/DynamicPropertyBox.swift

@@ -3,9 +3,11 @@
 //  OpenSwiftUI
 //
 //  Audited for RELEASE_2021
-//  Status: Blocked by DynamicProperty
+//  Status: Complete
 //  ID: 08168374F4710A99DCB15B5E8768D632
 
+internal import OpenGraphShims
+
 /// A property wrapper type that can read and write a value managed by OpenSwiftUI.
 ///
 /// Use state as the single source of truth for a given value type that you
@@ -206,11 +208,6 @@ public struct State<Value> {
     }
 }
 
-extension State: DynamicProperty {
-    // TODO:
-    public static func _makeProperty(in _: inout _DynamicPropertyBuffer, container _: _GraphValue<some Any>, fieldOffset _: Swift.Int, inputs _: inout _GraphInputs) {}
-}
-
 extension State where Value: ExpressibleByNilLiteral {
     /// Creates a state property without an initial value.
     ///
@@ -237,3 +234,49 @@ extension State {
         }
     }
 }
+
+extension State: DynamicProperty {
+    public static func _makeProperty<V>(
+        in buffer: inout _DynamicPropertyBuffer,
+        container _: _GraphValue<V>,
+        fieldOffset: Int,
+        inputs _: inout _GraphInputs
+    ) {
+        let attribute = Attribute(value: ())
+        let box = StatePropertyBox<Value>(signal: WeakAttribute(attribute))
+        buffer.append(box, fieldOffset: fieldOffset)
+    }
+}
+
+private struct StatePropertyBox<Value>: DynamicPropertyBox {
+    let signal: WeakAttribute<Void>
+    var location: StoredLocation<Value>?
+
+    typealias Property = State<Value>
+    func destroy() {}
+    mutating func reset() { location = nil }
+    mutating func update(property: inout State<Value>, phase: _GraphInputs.Phase) -> Bool {
+        let locationChanged = location == nil
+        if location == nil {
+            location = property._location as? StoredLocation ?? StoredLocation(
+                initialValue: property._value,
+                host: .currentHost,
+                signal: signal
+            )
+        }
+        let signalChanged = signal.changedValue()?.changed ?? false
+        property._value = location!.updateValue
+        property._location = location!
+        return (signalChanged ? location!.wasRead : false) || locationChanged
+    }
+    func getState<V>(type _: V.Type) -> Binding<V>? {
+        guard Value.self == V.self,
+              let location
+        else {
+            return nil
+        }
+        let value = location.get()
+        let binding = Binding(value: value, location: location)
+        return binding as? Binding<V>
+    }
+}

Sources/OpenSwiftUI/Data/Model/State/State.swift

@@ -0,0 +1,176 @@
+//
+//  StoredLocation.swift
+//  OpenSwiftUI
+//
+//  Audited for RELEASE_2021
+//  Status: WIP
+//  ID: EBDC911C9EE054BAE3D86F947C24B7C3
+
+internal import OpenGraphShims
+internal import COpenSwiftUI
+
+class StoredLocationBase<Value>: AnyLocation<Value>, Location {
+    private struct LockedData {
+        var currentValue: Value
+        var savedValue: [Value]
+        var cache: LocationProjectionCache
+        
+        init(currentValue: Value, savedValue: [Value], cache: LocationProjectionCache = LocationProjectionCache()) {
+            self.currentValue = currentValue
+            self.savedValue = savedValue
+            self.cache = cache
+        }
+    }
+    
+    fileprivate struct BeginUpdate: GraphMutation {
+        weak var box: StoredLocationBase<Value>?
+        
+        func apply() {
+            box?.beginUpdate()
+        }
+        
+        func combine<Mutation: GraphMutation>(with mutation: Mutation) -> Bool {
+            guard let otherBeginUpdate = mutation as? BeginUpdate,
+                  let box,
+                  let otherBox = otherBeginUpdate.box,
+                  box === otherBox
+            else {
+                return false
+            }
+            
+            box.$data.withMutableData { data in
+                _ = data.savedValue.removeFirst()
+            }
+            return true
+        }
+    }
+    
+    @UnsafeLockedPointer
+    private var data: LockedData
+    
+    var _wasRead: Bool
+    
+    init(initialValue value: Value) {
+        _wasRead = false
+        _data = UnsafeLockedPointer(wrappedValue: LockedData(currentValue: value, savedValue: []))
+        super.init()
+    }
+    
+    fileprivate var isValid: Bool { true }
+    
+    // MARK: - abstract method
+    
+    fileprivate var isUpdating: Bool {
+        fatalError("abstract")
+    }
+    
+    fileprivate func commit(transaction: Transaction, mutation: BeginUpdate) {
+        fatalError("abstract")
+    }
+    
+    fileprivate func notifyObservers() {
+        fatalError("abstract")
+    }
+    
+    // MARK: - AnyLocation
+    
+    override var wasRead: Bool {
+        get { _wasRead }
+        set { _wasRead = newValue }
+    }
+    
+    override func get() -> Value {
+        data.currentValue
+    }
+    
+    override func set(_ value: Value, transaction: Transaction) {
+        guard !isUpdating else {
+            Log.runtimeIssues("Modifying state during view update, this will cause undefined behavior.")
+            return
+        }
+        guard isValid else {
+            $data.withMutableData { data in
+                data.savedValue.removeAll()
+            }
+            return
+        }
+        let shouldCommit = $data.withMutableData { data in
+            guard !compareValues(data.currentValue, value) else {
+                return false
+            }
+            data.savedValue.append(data.currentValue)
+            data.currentValue = value
+            return true
+        }
+        guard shouldCommit else {
+            return
+        }
+        var newTransaction = transaction
+        newTransaction.override(.current)
+        performOnMainThread { [weak self] in
+            guard let self else {
+                return
+            }
+            let update = BeginUpdate(box: self)
+            commit(transaction: newTransaction, mutation: update)
+        }
+    }
+    
+    override func projecting<P: Projection>(_ projection: P) -> AnyLocation<P.Projected> where Value == P.Base {
+        data.cache.reference(for: projection, on: self)
+    }
+    
+    override func update() -> (Value, Bool) {
+        _wasRead = true
+        return (updateValue, true)
+    }
+    
+    // MARK: - final properties and methods
+    
+    deinit {
+        $data.destroy()
+    }
+    
+    final var updateValue: Value {
+        $data.withMutableData { data in
+            data.savedValue.first ?? data.currentValue
+        }
+    }
+    
+    private final func beginUpdate() {
+        data.savedValue.removeFirst()
+        notifyObservers()
+    }
+}
+
+final class StoredLocation<Value>: StoredLocationBase<Value> {
+    weak var host: GraphHost?
+    @WeakAttribute var signal: Void?
+    
+    init(initialValue value: Value, host: GraphHost?, signal: WeakAttribute<Void>) {
+        self.host = host
+        _signal = signal
+        super.init(initialValue: value)
+    }
+    
+    override fileprivate var isValid: Bool {
+        host?.isValid ?? false
+    }
+    
+    override fileprivate var isUpdating: Bool {
+        host?.isUpdating ?? false
+    }
+    
+    override fileprivate func commit(transaction: Transaction, mutation: StoredLocationBase<Value>.BeginUpdate) {
+        host?.asyncTransaction(
+            transaction,
+            mutation: mutation,
+            style: ._1,
+            mayDeferUpdate: true
+        )
+    }
+    
+    override fileprivate func notifyObservers() {
+        $signal?.invalidateValue()
+    }
+}