Allow purging of datasource

Sources/DiffableDataSource.CollectionViewAdapter-AppKit.swift

@@ -0,0 +1,232 @@
+//
+//  DiffableDataSource.CollectionViewAdapter-AppKit.swift
+//  CoreStore
+//
+//  Copyright © 2018 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.
+//
+
+#if canImport(AppKit) && os(macOS)
+
+import AppKit
+import CoreData
+
+
+// MARK: - DiffableDataSource
+
+extension DiffableDataSource {
+
+    // MARK: - CollectionView
+    
+    /**
+     The `DiffableDataSource.CollectionViewAdapter` serves as a `NSCollectionViewDataSource` that handles `ListPublisher` snapshots for a `NSCollectionView`. Subclasses of `DiffableDataSource.CollectionViewAdapter` may override some `NSCollectionViewDataSource` methods as needed.
+     The `DiffableDataSource.CollectionViewAdapter` instance needs to be held on (retained) for as long as the `NSCollectionView`'s lifecycle.
+     ```
+     self.dataSource = DiffableDataSource.CollectionViewAdapter<Person>(
+         collectionView: self.collectionView,
+         dataStack: CoreStoreDefaults.dataStack,
+         itemProvider: { (collectionView, indexPath, person) in
+             let item = collectionView.makeItem(withIdentifier: .collectionViewItem, for: indexPath) as! PersonItem
+             item.setPerson(person)
+             return item
+         }
+     )
+     ```
+     The dataSource can then apply changes from a `ListPublisher` as shown:
+     ```
+     listPublisher.addObserver(self) { [weak self] (listPublisher) in
+        self?.dataSource?.apply(
+            listPublisher.snapshot,
+            animatingDifferences: true
+        )
+     }
+     ```
+     `DiffableDataSource.CollectionViewAdapter` fully handles the reload animations.
+     - SeeAlso: CoreStore's DiffableDataSource implementation is based on https://github.com/ra1028/DiffableDataSources     
+     */
+    open class CollectionViewAdapter<O: DynamicObject>: BaseAdapter<O, DefaultCollectionViewTarget<NSCollectionView>>, NSCollectionViewDataSource {
+
+        // MARK: Public
+        
+        /**
+         Initializes the `DiffableDataSource.CollectionViewAdapter`. This instance needs to be held on (retained) for as long as the `NSCollectionView`'s lifecycle.
+         ```
+         self.dataSource = DiffableDataSource.CollectionViewAdapter<Person>(
+             collectionView: self.collectionView,
+             dataStack: CoreStoreDefaults.dataStack,
+             itemProvider: { (collectionView, indexPath, person) in
+                 let item = collectionView.makeItem(withIdentifier: .collectionViewItem, for: indexPath) as! PersonItem
+                 item.setPerson(person)
+                 return item
+             }
+         )
+         ```
+         - parameter collectionView: the `NSCollectionView` to set the `dataSource` of. This instance is not retained by the `DiffableDataSource.CollectionViewAdapter`.
+         - parameter dataStack: the `DataStack` instance that the dataSource will fetch objects from
+         - parameter itemProvider: a closure that configures and returns the `NSCollectionViewItem` for the object
+         */
+        @nonobjc
+        public init(collectionView: NSCollectionView, dataStack: DataStack, itemProvider: @escaping (NSCollectionView, IndexPath, O) -> NSCollectionViewItem?, supplementaryViewProvider: @escaping (NSCollectionView, String, IndexPath) -> NSView? = { _, _, _ in nil }) {
+
+            self.itemProvider = itemProvider
+            self.supplementaryViewProvider = supplementaryViewProvider
+
+            super.init(target: .init(collectionView), dataStack: dataStack)
+
+            collectionView.dataSource = self
+        }
+
+
+        // MARK: - NSCollectionViewDataSource
+
+        @objc
+        public dynamic func numberOfSections(in collectionView: NSCollectionView) -> Int {
+
+            return self.numberOfSections()
+        }
+
+        @objc
+        public dynamic func collectionView(_ collectionView: NSCollectionView, numberOfItemsInSection section: Int) -> Int {
+
+            return self.numberOfItems(inSection: section) ?? 0
+        }
+
+        @objc
+        open dynamic func collectionView(_ collectionView: NSCollectionView, itemForRepresentedObjectAt indexPath: IndexPath) -> NSCollectionViewItem {
+
+            guard let objectID = self.itemID(for: indexPath) else {
+
+                Internals.abort("Object at \(Internals.typeName(IndexPath.self)) \(indexPath) already removed from list")
+            }
+            guard let object = self.dataStack.fetchExisting(objectID) as O? else {
+
+                Internals.abort("Object at \(Internals.typeName(IndexPath.self)) \(indexPath) has been deleted")
+            }
+            guard let item = self.itemProvider(collectionView, indexPath, object) else {
+
+                Internals.abort("\(Internals.typeName(NSCollectionViewDataSource.self)) returned a `nil` item for \(Internals.typeName(IndexPath.self)) \(indexPath)")
+            }
+            return item
+        }
+
+        @objc
+        open dynamic func collectionView(_ collectionView: NSCollectionView, viewForSupplementaryElementOfKind kind: NSCollectionView.SupplementaryElementKind, at indexPath: IndexPath) -> NSView {
+
+            guard let view = self.supplementaryViewProvider(collectionView, kind, indexPath) else {
+
+                return NSView()
+            }
+            return view
+        }
+
+
+        // MARK: Private
+
+        private let itemProvider: (NSCollectionView, IndexPath, O) -> NSCollectionViewItem?
+        private let supplementaryViewProvider: (NSCollectionView, String, IndexPath) -> NSView?
+    }
+
+
+    // MARK: - DefaultCollectionViewTarget
+
+    public struct DefaultCollectionViewTarget<T: NSCollectionView>: Target {
+
+        // MARK: Public
+
+        public typealias Base = T
+
+        public private(set) weak var base: Base?
+
+        public init(_ base: Base) {
+
+            self.base = base
+        }
+
+
+        // MARK: DiffableDataSource.Target:
+
+        public var shouldSuspendBatchUpdates: Bool {
+
+            return self.base?.window == nil
+        }
+
+        public func deleteSections(at indices: IndexSet, animated: Bool) {
+
+            self.base?.deleteSections(indices)
+        }
+
+        public func insertSections(at indices: IndexSet, animated: Bool) {
+
+            self.base?.insertSections(indices)
+        }
+
+        public func reloadSections(at indices: IndexSet, animated: Bool) {
+
+            self.base?.reloadSections(indices)
+        }
+
+        public func moveSection(at index: IndexSet.Element, to newIndex: IndexSet.Element, animated: Bool) {
+
+            self.base?.moveSection(index, toSection: newIndex)
+        }
+
+        public func deleteItems(at indexPaths: [IndexPath], animated: Bool) {
+
+            self.base?.deleteItems(at: Set(indexPaths))
+        }
+
+        public func insertItems(at indexPaths: [IndexPath], animated: Bool) {
+
+            self.base?.insertItems(at: Set(indexPaths))
+        }
+
+        public func reloadItems(at indexPaths: [IndexPath], animated: Bool) {
+
+            self.base?.reloadItems(at: Set(indexPaths))
+        }
+
+        public func moveItem(at indexPath: IndexPath, to newIndexPath: IndexPath, animated: Bool) {
+
+            self.base?.moveItem(at: indexPath, to: newIndexPath)
+        }
+
+        public func performBatchUpdates(updates: () -> Void, animated: Bool) {
+
+            self.base?.animator().performBatchUpdates(updates, completionHandler: nil)
+        }
+
+        public func reloadData() {
+
+            self.base?.reloadData()
+        }
+    }
+}
+
+
+// MARK: - Deprecated
+
+extension DiffableDataSource {
+
+    @available(*, deprecated, renamed: "CollectionViewAdapter")
+    public typealias CollectionView = CollectionViewAdapter
+}
+
+
+#endif