Big update. Migration tools in progress

CoreStore/Migrating/MigrationResult.swift

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+//
+//  MigrationResult.swift
+//  CoreStore
+//
+//  Copyright (c) 2014 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: - MigrationType
+
+/**
+The `MigrationType` specifies the type of migration required for a store.
+*/
+public enum MigrationType: BooleanType {
+    
+    // MARK: Public
+    
+    /**
+    Indicates that the persistent store matches the latest model version and no migration is needed
+    */
+    case None
+    
+    /**
+    Indicates that the persistent store does not match the latest model version but Core Data can infer the mapping model, so a lightweight migration is needed
+    */
+    case Lightweight
+    
+    /**
+    Indicates that the persistent store does not match the latest model version and Core Data could not infer a mapping model, so a custom migration is needed
+    */
+    case Heavyweight
+    
+    
+    // MARK: BooleanType
+    
+    public var boolValue: Bool {
+        
+        switch self {
+            
+        case .None:         return false
+        case .Lightweight:  return true
+        case .Heavyweight:  return true
+        }
+    }
+}
+
+
+// MARK: - MigrationResult
+
+/**
+The `MigrationResult` indicates the result of a migration.
+The `MigrationResult` can be treated as a boolean:
+
+    CoreStore.upgradeSQLiteStoreIfNeeded { transaction in
+        // ...
+        let result = transaction.commit()
+        if result {
+            // succeeded
+        }
+        else {
+            // failed
+        }
+    }
+
+or as an `enum`, where the resulting associated object can also be inspected:
+
+    CoreStore.beginAsynchronous { transaction in
+        // ...
+        let result = transaction.commit()
+        switch result {
+        case .Success(let hasChanges):
+            // hasChanges indicates if there were changes or not
+        case .Failure(let error):
+            // error is the NSError instance for the failure
+        }
+    }
+```
+*/
+public enum MigrationResult {
+    
+    // MARK: Public
+    
+    /**
+    `MigrationResult.Success` indicates that the `commit()` for the transaction succeeded, either because the save succeeded or because there were no changes to save. The associated value `hasChanges` indicates if there were saved changes or not.
+    */
+    case Success(MigrationType)
+    
+    /**
+    `SaveResult.Failure` indicates that the `commit()` for the transaction failed. The associated object for this value is the related `NSError` instance.
+    */
+    case Failure(NSError)
+    
+    
+    // MARK: Internal
+    
+    internal init(_ migrationType: MigrationType) {
+        
+        self = .Success(migrationType)
+    }
+    
+    internal init(_ error: NSError) {
+        
+        self = .Failure(error)
+    }
+    
+    internal init(_ errorCode: CoreStoreErrorCode) {
+        
+        self.init(errorCode, userInfo: nil)
+    }
+    
+    internal init(_ errorCode: CoreStoreErrorCode, userInfo: [NSObject: AnyObject]?) {
+        
+        self.init(NSError(
+            coreStoreErrorCode: errorCode,
+            userInfo: userInfo))
+    }
+}
+
+
+// MARK: - MigrationResult: BooleanType
+
+extension MigrationResult: BooleanType {
+    
+    public var boolValue: Bool {
+        
+        switch self {
+        case .Success: return true
+        case .Failure: return false
+        }
+    }
+}