changed keyPath string utility to use String initializer

Sources/DynamicKeyPath.swift

@@ -0,0 +1,193 @@
+//
+//  DynamicKeyPath.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: - DynamicKeyPath
+
+/**
+ Used only for utility methods.
+ */
+public protocol DynamicKeyPath {
+    
+    /**
+     The DynamicObject type
+     */
+    associatedtype ObjectType
+    
+    /**
+     The Value type
+     */
+    associatedtype ValueType
+    
+    /**
+     The keyPath string
+     */
+    var cs_keyPathString: String { get }
+}
+
+
+// MARK: - KeyPathString
+
+public extension KeyPathString {
+    
+    /**
+     Extracts the keyPath string from the property.
+     ```
+     let keyPath = String(keyPath: \Person.nickname)
+     ```
+     */
+    public init<O: NSManagedObject, V>(keyPath: KeyPath<O, V>) {
+        
+        self = keyPath.cs_keyPathString
+    }
+    
+    /**
+     Extracts the keyPath string from the property.
+     ```
+     let keyPath = String(keyPath: \Person.nickname)
+     ```
+     */
+    public init<O: CoreStoreObject, K: DynamicKeyPath>(keyPath: KeyPath<O, K>) {
+        
+        self = O.meta[keyPath: keyPath].cs_keyPathString
+    }
+}
+
+
+// MARK: - KeyPath: DynamicKeyPath
+
+// TODO: SE-0143 is not implemented: https://github.com/apple/swift-evolution/blob/master/proposals/0143-conditional-conformances.md
+//extension KeyPath: DynamicKeyPath where Root: NSManagedObject, Value: ImportableAttributeType {
+extension KeyPath: DynamicKeyPath {
+
+    public typealias ObjectType = Root
+    public typealias ValueType = Value
+    
+    public var cs_keyPathString: String {
+        
+        return self._kvcKeyPathString!
+    }
+}
+
+
+// MARK: - ValueContainer.Required: DynamicKeyPath
+
+extension ValueContainer.Required: DynamicKeyPath {
+    
+    public typealias ObjectType = O
+    public typealias ValueType = V
+    
+    public var cs_keyPathString: String {
+        
+        return self.keyPath
+    }
+}
+
+
+// MARK: - ValueContainer.Optional: DynamicKeyPath
+
+extension ValueContainer.Optional: DynamicKeyPath {
+    
+    public typealias ObjectType = O
+    public typealias ValueType = V
+    
+    public var cs_keyPathString: String {
+        
+        return self.keyPath
+    }
+}
+
+
+// MARK: - TransformableContainer.Required: DynamicKeyPath
+
+extension TransformableContainer.Required: DynamicKeyPath {
+    
+    public typealias ObjectType = O
+    public typealias ValueType = V
+    
+    public var cs_keyPathString: String {
+        
+        return self.keyPath
+    }
+}
+
+
+// MARK: - TransformableContainer.Optional: DynamicKeyPath
+
+extension TransformableContainer.Optional: DynamicKeyPath {
+    
+    public typealias ObjectType = O
+    public typealias ValueType = V
+    
+    public var cs_keyPathString: String {
+        
+        return self.keyPath
+    }
+}
+
+
+// MARK: - RelationshipContainer.ToOne: DynamicKeyPath
+
+extension RelationshipContainer.ToOne: DynamicKeyPath {
+    
+    public typealias ObjectType = O
+    public typealias ValueType = D
+    
+    public var cs_keyPathString: String {
+        
+        return self.keyPath
+    }
+}
+
+
+// MARK: - RelationshipContainer.ToManyOrdered: DynamicKeyPath
+
+extension RelationshipContainer.ToManyOrdered: DynamicKeyPath {
+    
+    public typealias ObjectType = O
+    public typealias ValueType = D
+    
+    public var cs_keyPathString: String {
+        
+        return self.keyPath
+    }
+}
+
+
+// MARK: - RelationshipContainer.ToManyUnordered: DynamicKeyPath
+
+extension RelationshipContainer.ToManyUnordered: DynamicKeyPath {
+    
+    public typealias ObjectType = O
+    public typealias ValueType = D
+    
+    public var cs_keyPathString: String {
+        
+        return self.keyPath
+    }
+}
+