Add documentation for TransactionModifier

Author: Kyle-Ye

Sources/OpenSwiftUICore/Data/Transaction/TransactionModifier.swift

@@ -10,10 +10,17 @@ package import OpenGraphShims
 
 // MARK: - TransactionModifier
 
+/// Modifier to set a transaction adjustment.
 @frozen
 public struct _TransactionModifier: ViewModifier, _GraphInputsModifier, PrimitiveViewModifier {
+    /// A closure that transforms the current transaction.
+    ///
+    /// This closure receives the current transaction and can modify it in place.
     public var transform: (inout Transaction) -> ()
 
+    /// Creates a transaction modifier with the specified transform closure.
+    ///
+    /// - Parameter transform: A closure that modifies the transaction in place.
     public init(transform: @escaping (inout Transaction) -> ()) {
         self.transform = transform
     }
@@ -42,12 +49,25 @@ private struct ChildTransaction: Rule, AsyncAttribute {
 
 // MARK: - ValueTransactionModifier
 
+/// Modifier to set a transaction adjustment with a value constraint.
 @frozen
 public struct _ValueTransactionModifier<Value>: ViewModifier, _GraphInputsModifier, PrimitiveViewModifier where Value: Equatable {
+    /// The value to monitor for changes.
+    ///
+    /// When this value changes (as determined by `Equatable` conformance),
+    /// the transaction modifier will be applied.
     public var value: Value
 
+    /// A closure that transforms the current transaction.
+    ///
+    /// This closure receives the current transaction and can modify it in place.
     public var transform: (inout Transaction) -> ()
 
+    /// Creates a value transaction modifier with the specified value and transform closure.
+    ///
+    /// - Parameters:
+    ///   - value: The value to monitor for changes.
+    ///   - transform: A closure that modifies the transaction in place.
     public init(value: Value, transform: @escaping (inout Transaction) -> Void) {
         self.value = value
         self.transform = transform
@@ -76,6 +96,10 @@ public struct _ValueTransactionModifier<Value>: ViewModifier, _GraphInputsModifi
 @available(*, unavailable)
 extension _ValueTransactionModifier: Sendable {}
 
+/// A stateful rule that tracks value changes to determine when to update transactions.
+///
+/// This structure maintains state about a value being monitored, comparing new values
+/// with the previous ones to detect changes.
 struct ValueTransactionSeed<V>: StatefulRule, AsyncAttribute where V: Equatable {
     var _value: Attribute<V>
     var _transactionSeed: Attribute<UInt32>
@@ -123,13 +147,19 @@ private struct ChildValueTransaction: Rule, AsyncAttribute {
 }
 
 // MARK: - PushPopTransactionModifier
-
 @frozen
 public struct _PushPopTransactionModifier<Content>: ViewModifier, MultiViewModifier, PrimitiveViewModifier where Content: ViewModifier {
+    /// The content to which the transaction modification applies.
     public var content: Content
 
+    /// The base transaction modifier to apply.
     public var base: _TransactionModifier
 
+    /// Creates a push-pop transaction modifier with the specified content and transform closure.
+    ///
+    /// - Parameters:
+    ///   - content: The content to which the transaction modification applies.
+    ///   - transform: A closure that modifies the transaction in place.
     public init(content: Content, transform: @escaping (inout Transaction) -> Void) {
         self.content = content
         self.base = .init(transform: transform)
@@ -164,21 +194,35 @@ extension _PushPopTransactionModifier: Sendable {}
 
 extension _GraphInputs {
     private struct SavedTransactionKey: ViewInput {
+        /// The default value for saved transactions.
         static let defaultValue: [Attribute<Transaction>] = []
     }
 
+    /// The stack of saved transactions.
+    ///
+    /// This property maintains a stack of transaction contexts that can be restored
+    /// after temporary modifications.
     package var savedTransactions: [Attribute<Transaction>] {
         get { self[SavedTransactionKey.self] }
         set { self[SavedTransactionKey.self] = newValue }
     }
 }
 
 extension _ViewInputs {
+    /// The stack of saved transactions.
+    ///
+    /// This property provides access to the transaction stack from view inputs.
     package var savedTransactions: [Attribute<Transaction>] {
         get { base.savedTransactions }
         set { base.savedTransactions = newValue }
     }
 
+    /// Gets the transaction to use for geometry calculations.
+    ///
+    /// This method returns the first saved transaction if available, or the current
+    /// transaction otherwise.
+    ///
+    /// - Returns: The transaction attribute to use for geometry calculations.
     package func geometryTransaction() -> Attribute<Transaction> {
         savedTransactions.first ?? transaction
     }