Complete State implementation

Author: Kyle-Ye

Package.resolved

@@ -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 +1,17 @@
+//
+//  ThreadUtils.swift
+//  
+//
+//  Created by Kyle on 2024/4/21.
+//
+
+import Foundation
+
+@inline(__always)
+func performOnMainThread(_ block: @escaping () -> Void) {
+    if Thread.isMainThread {
+        block()
+    } else {
+        RunLoop.main.perform(inModes: [.common], block: block)
+    }
+}

Sources/OpenSwiftUI/Core/Util/ThreadUtils.swift

@@ -253,19 +253,30 @@ private struct StatePropertyBox<Value>: DynamicPropertyBox {
     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 {
-        // TODO
-        false
+        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>? {
-        // TODO
-        nil
+    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

@@ -22,7 +22,7 @@ class StoredLocationBase<Value>: AnyLocation<Value>, Location {
         }
     }
 
-    private struct BeginUpdate: GraphMutation {
+    fileprivate struct BeginUpdate: GraphMutation {
         weak var box: StoredLocationBase<Value>?
 
         func apply() {
@@ -56,21 +56,19 @@ class StoredLocationBase<Value>: AnyLocation<Value>, Location {
         super.init()
     }
 
-    private var isValid: Bool {
-        true
-    }
+    fileprivate var isValid: Bool { true }
 
     // MARK: - abstract method
 
-    private var isUpdating: Bool {
+    fileprivate var isUpdating: Bool {
         fatalError("abstract")
     }
 
-    private func commit(transaction: Transaction, mutation: BeginUpdate) {
+    fileprivate func commit(transaction: Transaction, mutation: BeginUpdate) {
         fatalError("abstract")
     }
 
-    private func notifyObservers() {
+    fileprivate func notifyObservers() {
         fatalError("abstract")
     }
 
@@ -96,15 +94,26 @@ class StoredLocationBase<Value>: AnyLocation<Value>, Location {
             }
             return
         }
-        let _ = $data.withMutableData { data in
+        let shouldCommit = $data.withMutableData { data in
             guard !compareValues(data.currentValue, value) else {
                 return false
             }
             data.savedValue.append(data.currentValue)
             data.currentValue = value
             return true
         }
-        // TODO
+        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 {
@@ -130,10 +139,38 @@ class StoredLocationBase<Value>: AnyLocation<Value>, Location {
 
     private final func beginUpdate() {
         data.savedValue.removeFirst()
+        notifyObservers()
     }
 }
 
-// TODO
 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()
+    }
 }

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

@@ -22,12 +22,26 @@ public struct Transaction {
         plist = PropertyList()
     }
 
+    @inline(__always)
+    init(plist: PropertyList) {
+        self.plist = plist
+    }
+    
     @usableFromInline
     var plist: PropertyList
 
     @inline(__always)
-    @inlinable
     var isEmpty: Bool { plist.elements == nil }
+    
+    @inline(__always)
+    mutating func override(_ transaction: Transaction) {
+        plist.override(with: transaction.plist)
+    }
+    
+    @inline(__always)
+    static var current: Transaction {
+        Transaction(plist: .current)
+    }
 }
 
 extension Transaction {
@@ -55,9 +69,10 @@ public func withTransaction<Result>(
     _ body: () throws -> Result
 ) rethrows -> Result {
     try withExtendedLifetime(transaction) {
-        let data = _threadTransactionData()
-        defer { _setThreadTransactionData(data) }
-        _setThreadTransactionData(transaction.plist.elements.map { Unmanaged.passUnretained($0).toOpaque() })
+        let oldData = _threadTransactionData()
+        defer { _setThreadTransactionData(oldData) }
+        let data = transaction.plist.elements.map { Unmanaged.passUnretained($0).toOpaque() }        
+        _setThreadTransactionData(data)
         return try body()
     }
 }