Update PreferenceNode

Sources/OpenSwiftUI/DataAndStorage/Preferences/Internal/PreferenceList.swift

@@ -5,6 +5,7 @@
 //  Created by Kyle on 2023/1/5.
 //  Lastest Version: iOS 15.5
 //  Status: WIP
+//  ID: C1C63C2F6F2B9F3EB30DD747F0605FBD
 
 struct PreferenceList {
     private var first: PreferenceNode?
@@ -13,6 +14,18 @@ struct PreferenceList {
         get { fatalError("TODO") }
         set { fatalError("TODO") }
     }
+
+    func valueIfPresent<Key: PreferenceKey>(_ keyType: Key.Type) -> Value<Key.Value>? {
+        fatalError("TODO")
+    }
+
+    func modifyValue() {
+        fatalError("TODO")
+    }
+
+    func removeValue() {
+        fatalError("TODO")
+    }
 }
 
 extension PreferenceList {
@@ -22,13 +35,94 @@ extension PreferenceList {
     }
 }
 
-private class PreferenceNode {
+private class PreferenceNode: CustomStringConvertible {
     let keyType: Any.Type
     let seed: VersionSeed
     let mergedSeed: VersionSeed
     let next: PreferenceNode?
 
     init(keyType: Any.Type, seed: VersionSeed, next: PreferenceNode?) {
-        fatalError("TODO")
+        self.keyType = keyType
+        self.seed = seed
+        let seedResult: VersionSeed
+        if let next {
+            seedResult = next.mergedSeed.merge(seed)
+        } else {
+            seedResult = seed
+        }
+        self.mergedSeed = seedResult
+        self.next = next
+    }
+
+    final func forEach(_ body:(PreferenceNode) -> ()) {
+        var node = self
+        repeat {
+            body(node)
+            if let next = node.next {
+                node = next
+            } else {
+                break
+            }
+        } while true
+    }
+
+    final func find<Key: PreferenceKey>(key: Key.Type) -> _PreferenceNode<Key>? {
+        var node = self
+        repeat {
+            if node.keyType == key {
+                return node as? _PreferenceNode<Key>
+            } else {
+                if let next = node.next {
+                    node = next
+                } else {
+                    break
+                }
+            }
+        } while true
+        return nil
+    }
+
+    func find(from: PreferenceNode?) -> PreferenceNode? { fatalError() }
+    func combine(from: PreferenceNode?, next: PreferenceNode?) -> PreferenceNode? { fatalError() }
+    func copy(next: PreferenceNode?) -> PreferenceNode { fatalError() }
+    var description: String { fatalError() }
+}
+
+private class _PreferenceNode<Key: PreferenceKey>: PreferenceNode {
+    let value: Key.Value
+
+    init(value: Key.Value, seed: VersionSeed, next: PreferenceNode?) {
+        self.value = value
+        super.init(keyType: Key.self, seed: seed, next: next)
+    }
+
+    override func find(from: PreferenceNode?) -> PreferenceNode? {
+        from?.find(key: Key.self)
+    }
+
+    override func combine(from: PreferenceNode?, next: PreferenceNode?) -> PreferenceNode? {
+        var currentNode = from
+        while let node = currentNode {
+            if keyType == node.keyType {
+                var value = self.value
+                var seed = self.seed
+                Key.reduce(value: &value) {
+                    seed = seed.merge(node.seed)
+                    return (node as! _PreferenceNode).value
+                }
+                return _PreferenceNode(value: value, seed: seed, next: next)
+            } else {
+                currentNode = node.next
+            }
+        }
+        return nil
+    }
+
+    override func copy(next: PreferenceNode?) -> PreferenceNode {
+        _PreferenceNode(value: value, seed: seed, next: next)
+    }
+
+    override var description: String {
+        "\(Key.self) = \(value)"
     }
 }

Sources/OpenSwiftUI/Internal/Graph/VersionSeed.swift

@@ -26,7 +26,13 @@ struct VersionSeed: CustomStringConvertible {
     @_transparent
     @inline(__always)
     func merge(_ seed: VersionSeed) -> VersionSeed {
-        VersionSeed(value: merge32(value, seed.value))
+        if isValid, seed.value == .zero {
+            self
+        } else if value == .zero, seed.isValid {
+            seed
+        } else {
+            VersionSeed(value: merge32(value, seed.value))
+        }
     }
 }
 

Tests/OpenSwiftUITests/Internal/VersionSeed/VersionSeedTests.swift

@@ -20,11 +20,11 @@ struct VersionSeedTests {
     }
 
     @Test(arguments: [
-        (0x0000_0000, 0x0000_0000, 0x9C35_2659),
+        (0x0000_0000, 0x0000_0000, 0x0000_0000),
         (0xFFFF_FFFF, 0x0000_0000, 0x17F8_3A02),
         (0xFFFF_FFFF, 0xFFFF_FFFF, 0x3258_2C16),
-        (0xAABB_CCDD, 0x0000_0000, 0x8B94_7A49),
-        (0x0000_0000, 0xAABB_CCDD, 0x7B38_F912),
+        (0xAABB_CCDD, 0x0000_0000, 0xAABB_CCDD),
+        (0x0000_0000, 0xAABB_CCDD, 0xAABB_CCDD),
         (0xAABB_CCDD, 0xAABB_CCDD, 0x1AAD_F11C),
         (0xFFFF_FFFF, 0xAABB_CCDD, 0x4C96_0643),
         (0xAABB_CCDD, 0xFFFF_FFFF, 0x13DA_25CE),