WIP

Sources/Transactions/AsynchronousDataTransaction.swift

@@ -34,6 +34,11 @@ import CoreData
  */
 public final class AsynchronousDataTransaction: BaseDataTransaction {
     
+    public func cancel() throws -> Never {
+        
+        throw CoreStoreError.userCancelled
+    }
+    
     /**
      Saves the transaction changes. This method should not be used after the `commit()` method was already called once.
      

Sources/Transactions/BaseDataTransaction.swift

@@ -36,12 +36,6 @@ public /*abstract*/ class BaseDataTransaction {
     
     // MARK: Object management
     
-    
-    public func cancel() throws -> Never {
-        
-        throw CoreStoreError.userCancelled
-    }
-    
     /**
      Indicates if the transaction has pending changes
      */

Sources/Transactions/DataStack+Transaction.swift

@@ -31,6 +31,16 @@ import CoreData
 
 public extension DataStack {
     
+    
+    public func perform<T>(asynchronous task: @escaping (_ transaction: AsynchronousDataTransaction) throws -> T, completion: @escaping (TransactionResult<T>) -> Void) {
+        
+        self.perform(
+            asynchronous: task,
+            success: { completion(TransactionResult(userInfo: $0)) },
+            failure: { completion(TransactionResult(error: $0)) }
+        )
+    }
+    
     public func perform<T>(asynchronous task: @escaping (_ transaction: AsynchronousDataTransaction) throws -> T, success: @escaping (T) -> Void, failure: @escaping (CoreStoreError) -> Void) {
         
         let transaction = AsynchronousDataTransaction(
@@ -40,28 +50,28 @@ public extension DataStack {
         )
         transaction.transactionQueue.cs_async {
             
+            let userInfo: T
             do {
                 
-                let extraInfo = try task(transaction)
-                transaction.commit { (result) in
-                    
-                    switch result {
-                        
-                    case .success:
-                        success(extraInfo)
-                        
-                    case .failure(let error):
-                        failure(error)
-                    }
-                }
+                userInfo = try task(transaction)
             }
             catch let error as CoreStoreError {
                 
                 DispatchQueue.main.async { failure(error) }
+                return
             }
             catch let error {
                 
                 DispatchQueue.main.async { failure(.userError(error: error)) }
+                return
+            }
+            transaction.commit { (result) in
+                
+                switch result {
+                    
+                case .success: success(userInfo)
+                case .failure(let error): failure(error)
+                }
             }
         }
     }
@@ -75,10 +85,10 @@ public extension DataStack {
         )
         return try transaction.transactionQueue.cs_sync {
             
-            let extraInfo: T
+            let userInfo: T
             do {
                 
-                extraInfo = try task(transaction)
+                userInfo = try task(transaction)
             }
             catch let error as CoreStoreError {
                 
@@ -88,17 +98,13 @@ public extension DataStack {
                 
                 throw CoreStoreError.userError(error: error)
             }
-            
             let result = waitForObserverNotifications
                 ? transaction.commitAndWait()
                 : transaction.commit()
             switch result {
                 
-            case .success:
-                return extraInfo
-                
-            case .failure(let error):
-                throw error
+            case .success: return userInfo
+            case .failure(let error): throw error
             }
         }
     }

Sources/Transactions/SynchronousDataTransaction.swift

@@ -34,6 +34,11 @@ import CoreData
  */
 public final class SynchronousDataTransaction: BaseDataTransaction {
     
+    public func cancel() throws -> Never {
+        
+        throw CoreStoreError.userCancelled
+    }
+    
     /**
      Saves the transaction changes and waits for completion synchronously. This method should not be used after the `commit()` or `commitAndWait()` method was already called once.
      - Important: Unlike `SynchronousDataTransaction.commit()`, this method waits for all observers to be notified of the changes before returning. This results in more predictable data update order, but may risk triggering deadlocks.

Sources/Transactions/TransactionResult.swift

@@ -0,0 +1,58 @@
+//
+//  TransactionResult.swift
+//  CoreStore
+//
+//  Copyright © 2017 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import Foundation
+
+
+// MARK: - TransactionResult
+
+public enum TransactionResult<T> {
+
+    case success(T)
+
+    case failure(CoreStoreError)
+
+    public var boolValue: Bool {
+
+        switch self {
+
+        case .success: return true
+        case .failure: return false
+        }
+    }
+
+
+    // MARK: Internal
+
+    internal init(userInfo: T) {
+
+        self = .success(userInfo)
+    }
+
+    internal init(error: CoreStoreError) {
+
+        self = .failure(error)
+    }
+}