WIP: prototype for ManagedObjectProtocol

Sources/Setup/Dynamic Models/Entity.swift

@@ -0,0 +1,198 @@
+//
+//  Entity.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 CoreData
+import Foundation
+import ObjectiveC
+
+
+// MARK: - EntityProtocol
+
+public protocol EntityProtocol {
+    
+    var entityDescription: NSEntityDescription { get }
+}
+
+
+// MARK: Entity
+
+public struct Entity<O: ManagedObject>: EntityProtocol {
+    
+    public let entityDescription: NSEntityDescription
+    internal var dynamicClass: AnyClass {
+        
+        return NSClassFromString(self.entityDescription.managedObjectClassName!)!
+    }
+    
+    public init(_ entityName: String) {
+        
+        let dynamicClassName = String(reflecting: O.self)
+            .appending("__\(entityName)")
+            .replacingOccurrences(of: ".", with: "_")
+            .replacingOccurrences(of: "<", with: "_")
+            .replacingOccurrences(of: ">", with: "_")
+        // TODO: assign entityName through ModelVersion and
+        // TODO: set NSEntityDescription.userInfo AnyEntity
+        let newClass: AnyClass?
+        
+        if NSClassFromString(dynamicClassName) == nil {
+            
+            newClass = objc_allocateClassPair(NSManagedObject.self, dynamicClassName, 0)
+        }
+        else {
+            
+            newClass = nil
+        }
+        
+        defer {
+            
+            if let newClass = newClass {
+                
+                objc_registerClassPair(newClass)
+            }
+        }
+        
+        let entityDescription = NSEntityDescription()
+        entityDescription.userInfo = [
+            EntityIdentifier.UserInfoKey.CoreStoreManagedObjectName: String(reflecting: O.self)
+        ]
+        entityDescription.name = entityName
+        entityDescription.managedObjectClassName = NSStringFromClass(NSManagedObject.self)
+//        entityDescription.managedObjectClassName = dynamicClassName // TODO: return to NSManagedObject
+        entityDescription.properties = type(of: self).initializeAttributes(Mirror(reflecting: O.meta))
+        
+        self.entityDescription = entityDescription
+    }
+    
+    private static func initializeAttributes(_ mirror: Mirror) -> [NSAttributeDescription] {
+        
+        var attributeDescriptions: [NSAttributeDescription] = []
+        for child in mirror.children {
+            
+            guard case let property as AttributeProtocol = child.value else {
+                
+                continue
+            }
+            let attributeDescription = NSAttributeDescription()
+            attributeDescription.name = property.keyPath
+            attributeDescription.attributeType = type(of: property).attributeType
+            attributeDescription.isOptional = property.isOptional
+            attributeDescription.defaultValue = property.defaultValue
+            attributeDescriptions.append(attributeDescription)
+        }
+        if let baseEntityAttributeDescriptions = mirror.superclassMirror.flatMap(self.initializeAttributes) {
+            
+            attributeDescriptions.append(contentsOf: baseEntityAttributeDescriptions)
+        }
+        return attributeDescriptions
+    }
+}
+
+
+// MARK: - EntityIdentifier
+
+internal struct EntityIdentifier: Hashable {
+    
+    // MARK: - Category
+    
+    internal enum Category: Int {
+        
+        case coreData
+        case coreStore
+    }
+    
+    
+    // MARK: -
+    
+    internal let category: Category
+    internal let interfacedClassName: String
+    
+    internal init(_ type: NSManagedObject.Type) {
+        
+        self.category = .coreData
+        self.interfacedClassName = String(reflecting: type)
+    }
+    
+    internal init(_ type: ManagedObject.Type) {
+        
+        self.category = .coreStore
+        self.interfacedClassName = String(reflecting: type)
+    }
+    
+    internal init(_ type: ManagedObjectProtocol.Type) {
+        
+        switch type {
+            
+        case let type as NSManagedObject.Type:
+            self.init(type)
+            
+        case let type as ManagedObject.Type:
+            self.init(type)
+            
+        default:
+            CoreStore.abort("\(cs_typeName(ManagedObjectProtocol.self)) is not meant to be implemented by external types.")
+        }
+    }
+    
+    internal init(_ entityDescription: NSEntityDescription) {
+        
+        if let coreStoreManagedObjectName = entityDescription.userInfo?[EntityIdentifier.UserInfoKey.CoreStoreManagedObjectName] as! String? {
+            
+            self.category = .coreStore
+            self.interfacedClassName = coreStoreManagedObjectName
+        }
+        else {
+            
+            self.category = .coreData
+            self.interfacedClassName = entityDescription.managedObjectClassName!
+        }
+    }
+    
+    
+    // MARK: Equatable
+    
+    static func == (lhs: EntityIdentifier, rhs: EntityIdentifier) -> Bool {
+        
+        return lhs.category == rhs.category
+            && lhs.interfacedClassName == rhs.interfacedClassName
+    }
+    
+    
+    // MARK: Hashable
+    
+    var hashValue: Int {
+    
+        return self.category.hashValue
+            ^ self.interfacedClassName.hashValue
+    }
+    
+    
+    // MARK: FilePrivate
+    
+    fileprivate enum UserInfoKey {
+        
+        fileprivate static let CoreStoreManagedObjectName = "CoreStoreManagedObjectName"
+    }
+}