Internal refactoring (#61)

* Refactor internal APIs

* Add modifier context

* Update docc

Author: ra1028

Sources/Atoms/Atom/ModifiedAtom.swift

@@ -1,7 +1,7 @@
 /// An atom type that applies a modifier to an atom.
 ///
 /// Use ``Atom/modifier(_:)`` instead of using this atom directly.
-public struct ModifiedAtom<Node: Atom, Modifier: AtomModifier>: Atom where Node.Loader.Value == Modifier.Value {
+public struct ModifiedAtom<Node: Atom, Modifier: AtomModifier>: Atom where Node.Loader.Value == Modifier.BaseValue {
     /// A type representing the stable identity of this atom.
     public struct Key: Hashable {
         private let atomKey: Node.Key

Sources/Atoms/Atoms.docc/Atoms.md

@@ -56,8 +56,9 @@ SwiftUI Atom Properties offers practical capabilities to manage the complexity o
 - ``AtomWatchableContext``
 - ``AtomTransactionContext``
 - ``AtomViewContext``
-- ``AtomUpdatedContext``
 - ``AtomTestContext``
+- ``AtomUpdatedContext``
+- ``AtomModifierContext``
 
 ### Internal System
 

Sources/Atoms/Context/AtomModifierContext.swift

@@ -0,0 +1,28 @@
+/// A context structure for notifying modifier value updates.
+@MainActor
+public struct AtomModifierContext<Value> {
+    internal let _transaction: Transaction
+    internal let _update: @MainActor (Value) -> Void
+
+    internal init(
+        transaction: Transaction,
+        update: @escaping @MainActor (Value) -> Void
+    ) {
+        _transaction = transaction
+        _update = update
+    }
+
+    /// Notifies value updates.
+    ///
+    /// - Parameter value: An updated value.
+    public func update(with value: Value) {
+        _update(value)
+    }
+
+    /// Add a termination action to be performed when atom value is updated or released.
+    ///
+    /// - Parameter termination: A termination action.
+    public func addTermination(_ termination: @MainActor @escaping () -> Void) {
+        _transaction.addTermination(termination)
+    }
+}

Sources/Atoms/Core/Loader/AsyncSequenceAtomLoader.swift

@@ -13,7 +13,7 @@ public struct AsyncSequenceAtomLoader<Node: AsyncSequenceAtom>: RefreshableAtomL
     }
 
     /// Returns a new value for the corresponding atom.
-    public func get(context: Context) -> Value {
+    public func value(context: Context) -> Value {
         let sequence = context.transaction(atom.sequence)
         let task = Task {
             do {
@@ -35,8 +35,8 @@ public struct AsyncSequenceAtomLoader<Node: AsyncSequenceAtom>: RefreshableAtomL
         return .suspending
     }
 
-    /// Refreshes and awaits until the asynchronous is finished and returns a final value.
-    public func handle(context: Context, with value: Value) -> Value {
+    /// Associates given value and handle updates and cancellations.
+    public func associateOverridden(value: Value, context: Context) -> Value {
         value
     }
 
@@ -70,7 +70,7 @@ public struct AsyncSequenceAtomLoader<Node: AsyncSequenceAtom>: RefreshableAtomL
 
     /// Refreshes and awaits for the passed value to be finished to yield values
     /// and returns a final value.
-    public func refresh(context: Context, with value: Value) async -> Value {
+    public func refreshOverridden(value: Value, context: Context) async -> Value {
         value
     }
 }

Sources/Atoms/Core/Loader/AtomLoader.swift

@@ -11,18 +11,18 @@ public protocol AtomLoader {
     typealias Context = AtomLoaderContext<Value, Coordinator>
 
     /// Returns a new value for the corresponding atom.
-    func get(context: Context) -> Value
+    func value(context: Context) -> Value
 
-    /// Handles updates or cancellation of the passed value.
-    func handle(context: Context, with value: Value) -> Value
+    /// Associates given value and handle updates and cancellations.
+    func associateOverridden(value: Value, context: Context) -> Value
 
     /// Returns a boolean value indicating whether it should notify updates to downstream
     /// by checking the equivalence of the given old value and new value.
-    func shouldNotifyUpdate(newValue: Value, oldValue: Value) -> Bool
+    func shouldUpdate(newValue: Value, oldValue: Value) -> Bool
 }
 
 public extension AtomLoader {
-    func shouldNotifyUpdate(newValue: Value, oldValue: Value) -> Bool {
+    func shouldUpdate(newValue: Value, oldValue: Value) -> Bool {
         true
     }
 }
@@ -35,7 +35,7 @@ public protocol RefreshableAtomLoader: AtomLoader {
 
     /// Refreshes and awaits for the passed value to be finished to yield values
     /// and returns a final value.
-    func refresh(context: Context, with value: Value) async -> Value
+    func refreshOverridden(value: Value, context: Context) async -> Value
 }
 
 /// A loader protocol that represents an actual implementation of the corresponding atom

Sources/Atoms/Core/Loader/AtomLoaderContext.swift

@@ -1,13 +1,9 @@
 /// The context structure that to interact with an atom store.
 @MainActor
 public struct AtomLoaderContext<Value, Coordinator> {
-    @usableFromInline
     internal let _store: StoreContext
-    @usableFromInline
     internal let _transaction: Transaction
-    @usableFromInline
     internal let _coordinator: Coordinator
-    @usableFromInline
     internal let _update: @MainActor (Value, Bool) -> Void
 
     internal init(
@@ -22,6 +18,12 @@ public struct AtomLoaderContext<Value, Coordinator> {
         _update = update
     }
 
+    internal var modifierContext: AtomModifierContext<Value> {
+        AtomModifierContext(transaction: _transaction) { value in
+            update(with: value)
+        }
+    }
+
     internal func update(with value: Value, needsEnsureValueUpdate: Bool = false) {
         _update(value, needsEnsureValueUpdate)
     }

Sources/Atoms/Core/Loader/ModifiedAtomLoader.swift

@@ -1,7 +1,7 @@
 /// A loader protocol that represents an actual implementation of `ModifiedAtom`.
-public struct ModifiedAtomLoader<Node: Atom, Modifier: AtomModifier>: AtomLoader where Node.Loader.Value == Modifier.Value {
+public struct ModifiedAtomLoader<Node: Atom, Modifier: AtomModifier>: AtomLoader where Node.Loader.Value == Modifier.BaseValue {
     /// A type of value to provide.
-    public typealias Value = Modifier.ModifiedValue
+    public typealias Value = Modifier.Value
 
     /// A type to coordinate with the atom.
     public typealias Coordinator = Void
@@ -15,19 +15,19 @@ public struct ModifiedAtomLoader<Node: Atom, Modifier: AtomModifier>: AtomLoader
     }
 
     /// Returns a new value for the corresponding atom.
-    public func get(context: Context) -> Value {
+    public func value(context: Context) -> Value {
         let value = context.transaction { $0.watch(atom) }
-        return modifier.value(context: context, with: value)
+        return modifier.modify(value: value, context: context.modifierContext)
     }
 
-    /// Handles updates or cancellation of the passed value.
-    public func handle(context: Context, with value: Modifier.ModifiedValue) -> Modifier.ModifiedValue {
-        modifier.handle(context: context, with: value)
+    /// Associates given value and handle updates and cancellations.
+    public func associateOverridden(value: Value, context: Context) -> Value {
+        modifier.associateOverridden(value: value, context: context.modifierContext)
     }
 
     /// Returns a boolean value indicating whether it should notify updates to downstream
     /// by checking the equivalence of the given old value and new value.
-    public func shouldNotifyUpdate(newValue: Modifier.ModifiedValue, oldValue: Modifier.ModifiedValue) -> Bool {
-        modifier.shouldNotifyUpdate(newValue: newValue, oldValue: oldValue)
+    public func shouldUpdate(newValue: Value, oldValue: Value) -> Bool {
+        modifier.shouldUpdate(newValue: newValue, oldValue: oldValue)
     }
 }

Sources/Atoms/Core/Loader/ObservableObjectAtomLoader.swift

@@ -16,23 +16,23 @@ public struct ObservableObjectAtomLoader<Node: ObservableObjectAtom>: AtomLoader
     }
 
     /// Returns a new value for the corresponding atom.
-    public func get(context: Context) -> Value {
+    public func value(context: Context) -> Value {
         let object = context.transaction(atom.object)
-        return handle(context: context, with: object)
+        return associateOverridden(value: object, context: context)
     }
 
-    /// Handles updates or cancellation of the passed value.
-    public func handle(context: Context, with object: Value) -> Value {
-        let cancellable = object.objectWillChange.sink { [weak object] _ in
-            guard let object else {
+    /// Associates given value and handle updates and cancellations.
+    public func associateOverridden(value: Value, context: Context) -> Value {
+        let cancellable = value.objectWillChange.sink { [weak value] _ in
+            guard let value else {
                 return
             }
 
-            context.update(with: object, needsEnsureValueUpdate: true)
+            context.update(with: value, needsEnsureValueUpdate: true)
         }
 
         context.addTermination(cancellable.cancel)
 
-        return object
+        return value
     }
 }

Sources/Atoms/Core/Loader/PublisherAtomLoader.swift

@@ -15,7 +15,7 @@ public struct PublisherAtomLoader<Node: PublisherAtom>: RefreshableAtomLoader {
     }
 
     /// Returns a new value for the corresponding atom.
-    public func get(context: Context) -> Value {
+    public func value(context: Context) -> Value {
         let results = context.transaction(atom.publisher).results
         let task = Task {
             for await result in results {
@@ -30,8 +30,8 @@ public struct PublisherAtomLoader<Node: PublisherAtom>: RefreshableAtomLoader {
         return .suspending
     }
 
-    /// Handles updates or cancellation of the passed value.
-    public func handle(context: Context, with value: Value) -> Value {
+    /// Associates given value and handle updates and cancellations.
+    public func associateOverridden(value: Value, context: Context) -> Value {
         value
     }
 
@@ -59,7 +59,7 @@ public struct PublisherAtomLoader<Node: PublisherAtom>: RefreshableAtomLoader {
 
     /// Refreshes and awaits for the passed value to be finished to yield values
     /// and returns a final value.
-    public func refresh(context: Context, with value: Value) async -> Value {
+    public func refreshOverridden(value: Value, context: Context) async -> Value {
         value
     }
 }

Sources/Atoms/Core/Loader/StateAtomLoader.swift

@@ -13,12 +13,12 @@ public struct StateAtomLoader<Node: StateAtom>: AtomLoader {
     }
 
     /// Returns a new value for the corresponding atom.
-    public func get(context: Context) -> Value {
+    public func value(context: Context) -> Value {
         context.transaction(atom.defaultValue)
     }
 
-    /// Handles updates or cancellation of the passed value.
-    public func handle(context: Context, with value: Value) -> Value {
+    /// Associates given value and handle updates and cancellations.
+    public func associateOverridden(value: Value, context: Context) -> Value {
         value
     }
 }