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Sources/Fetching and Querying/Concrete Clauses/GroupBy.swift

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+//
+//  GroupBy.swift
+//  CoreStore
+//
+//  Copyright © 2015 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
+import CoreData
+
+
+// MARK: - GroupBy
+
+/**
+ The `GroupBy` clause specifies that the result of a query be grouped accoording to the specified key path.
+ */
+public struct GroupBy: QueryClause {
+    
+    /**
+     Initializes a `GroupBy` clause with a list of key path strings
+     
+     - parameter keyPaths: a list of key path strings to group results with
+     */
+    public init(_ keyPaths: [KeyPath]) {
+        
+        self.keyPaths = keyPaths
+    }
+    
+    /**
+     Initializes a `GroupBy` clause with an empty list of key path strings
+     */
+    public init() {
+        
+        self.init([])
+    }
+    
+    /**
+     Initializes a `GroupBy` clause with a list of key path strings
+     
+     - parameter keyPath: a key path string to group results with
+     - parameter keyPaths: a series of key path strings to group results with
+     */
+    public init(_ keyPath: KeyPath, _ keyPaths: KeyPath...) {
+        
+        self.init([keyPath] + keyPaths)
+    }
+    
+    public let keyPaths: [KeyPath]
+    
+    
+    // MARK: QueryClause
+    
+    public func applyToFetchRequest(fetchRequest: NSFetchRequest) {
+        
+        if let keyPaths = fetchRequest.propertiesToGroupBy as? [String] where keyPaths != self.keyPaths {
+            
+            CoreStore.log(
+                .Warning,
+                message: "An existing \"propertiesToGroupBy\" for the \(typeName(NSFetchRequest)) was overwritten by \(typeName(self)) query clause."
+            )
+        }
+        
+        fetchRequest.propertiesToGroupBy = self.keyPaths
+    }
+}