Files
CoreStore-JohnEstropia/Sources/Internals.DiffableDataSourceSnapshot.swift
2021-06-19 15:49:45 +09:00

941 lines
32 KiB
Swift

//
// Internals.DiffableDataSourceSnapshot.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(UIKit) || canImport(AppKit)
import CoreData
#if canImport(UIKit)
import UIKit
#elseif canImport(AppKit)
import AppKit
#endif
// MARK: - Internals
extension Internals {
// MARK: - DiffableDataSourceSnapshot
// Implementation based on https://github.com/ra1028/DiffableDataSources
internal struct DiffableDataSourceSnapshot: DiffableDataSourceSnapshotProtocol {
// MARK: Internal
init(
sections: [NSFetchedResultsSectionInfo],
sectionIndexTransformer: @escaping (_ sectionName: String?) -> String?,
fetchOffset: Int,
fetchLimit: Int
) {
self.structure = .init(
sections: sections,
sectionIndexTransformer: sectionIndexTransformer,
fetchOffset: Swift.max(0, fetchOffset),
fetchLimit: (fetchLimit > 0) ? fetchLimit : nil
)
}
var sections: [Section] {
get {
return self.structure.sections
}
set {
self.structure.sections = newValue
}
}
// MARK: DiffableDataSourceSnapshotProtocol
init() {
self.structure = .init()
}
var numberOfItems: Int {
return self.structure.allItemsCount
}
var numberOfSections: Int {
return self.structure.allSectionIDs.count
}
var sectionIdentifiers: [String] {
return self.structure.allSectionIDs
}
var itemIdentifiers: [NSManagedObjectID] {
return self.structure.allItemIDs
}
var updatedItemIdentifiers: Set<NSManagedObjectID> {
return self.structure.reloadedItems
}
func numberOfItems(inSection identifier: String) -> Int {
return self.itemIdentifiers(inSection: identifier).count
}
func itemIdentifier(atAllItemsIndex index: Int) -> NSManagedObjectID? {
guard index >= 0 else {
return nil
}
var remainingIndex = index
for section in self.structure.sections {
let elements = section.elements
let sectionCount = elements.count
if remainingIndex < sectionCount {
return elements[remainingIndex].differenceIdentifier
}
remainingIndex -= sectionCount
}
return nil
}
func itemIdentifiers(atAllItemsBounds bounds: Range<Int>) -> [NSManagedObjectID] {
var remainingIndex = bounds.lowerBound
var itemIdentifiers: [NSManagedObjectID] = []
for section in self.structure.sections {
let elements = section.elements
let sectionCount = elements.count
if remainingIndex < sectionCount {
itemIdentifiers.append(
contentsOf: elements[remainingIndex..<min(sectionCount, bounds.count)]
.map({ $0.differenceIdentifier })
)
}
else if !itemIdentifiers.isEmpty {
itemIdentifiers.append(
contentsOf: elements.prefix(bounds.count - itemIdentifiers.count)
.map({ $0.differenceIdentifier })
)
}
if itemIdentifiers.count >= bounds.count {
return itemIdentifiers
}
remainingIndex -= sectionCount
}
return itemIdentifiers
}
func itemIdentifiers(inSection identifier: String) -> [NSManagedObjectID] {
return self.structure.items(in: identifier)
}
func sectionIdentifier(containingItem identifier: NSManagedObjectID) -> String? {
return self.structure.section(containing: identifier)
}
func indexOfItem(_ identifier: NSManagedObjectID) -> Int? {
return self.structure.allItemIDs.firstIndex(of: identifier)
}
func indexOfSection(_ identifier: String) -> Int? {
return self.structure.allSectionIDs.firstIndex(of: identifier)
}
mutating func appendItems<C: Collection>(_ identifiers: C, toSection sectionIdentifier: String?) where C.Element == NSManagedObjectID {
self.structure.append(itemIDs: identifiers, to: sectionIdentifier)
}
mutating func insertItems<C: Collection>(_ identifiers: C, beforeItem beforeIdentifier: NSManagedObjectID) where C.Element == NSManagedObjectID {
self.structure.insert(itemIDs: identifiers, before: beforeIdentifier)
}
mutating func insertItems<C: Collection>(_ identifiers: C, afterItem afterIdentifier: NSManagedObjectID) where C.Element == NSManagedObjectID {
self.structure.insert(itemIDs: identifiers, after: afterIdentifier)
}
mutating func deleteItems<C: Collection>(_ identifiers: C) where C.Element == NSManagedObjectID {
self.structure.remove(itemIDs: identifiers)
}
mutating func deleteAllItems() {
self.structure.removeAllItems()
}
mutating func moveItem(_ identifier: NSManagedObjectID, beforeItem toIdentifier: NSManagedObjectID) {
self.structure.move(itemID: identifier, before: toIdentifier)
}
mutating func moveItem(_ identifier: NSManagedObjectID, afterItem toIdentifier: NSManagedObjectID) {
self.structure.move(itemID: identifier, after: toIdentifier)
}
mutating func reloadItems<C: Collection>(_ identifiers: C) where C.Element == NSManagedObjectID {
self.structure.update(itemIDs: identifiers)
}
mutating func appendSections<C: Collection>(_ identifiers: C) where C.Element == String {
self.structure.append(sectionIDs: identifiers)
}
mutating func insertSections<C: Collection>(_ identifiers: C, beforeSection toIdentifier: String) where C.Element == String {
self.structure.insert(sectionIDs: identifiers, before: toIdentifier)
}
mutating func insertSections<C: Collection>(_ identifiers: C, afterSection toIdentifier: String) where C.Element == String {
self.structure.insert(sectionIDs: identifiers, after: toIdentifier)
}
mutating func deleteSections<C: Collection>(_ identifiers: C) where C.Element == String {
self.structure.remove(sectionIDs: identifiers)
}
mutating func moveSection(_ identifier: String, beforeSection toIdentifier: String) {
self.structure.move(sectionID: identifier, before: toIdentifier)
}
mutating func moveSection(_ identifier: String, afterSection toIdentifier: String) {
self.structure.move(sectionID: identifier, after: toIdentifier)
}
mutating func reloadSections<C: Collection>(_ identifiers: C) where C.Element == String {
self.structure.update(sectionIDs: identifiers)
}
mutating func unsafeAppendItems<C: Collection>(_ identifiers: C, toSectionAt sectionIndex: Int) where C.Element == NSManagedObjectID {
self.structure.unsafeAppend(identifiers, toSectionAt: sectionIndex)
}
mutating func unsafeInsertItems<C: Collection>(_ identifiers: C, at indexPath: IndexPath) where C.Element == NSManagedObjectID {
self.structure.unsafeInsert(itemIDs: identifiers, at: indexPath)
}
mutating func unsafeDeleteItems<C: Collection>(at indexPaths: C) where C.Element == IndexPath {
self.structure.unsafeRemove(itemsAt: indexPaths)
}
mutating func unsafeMoveItem(at indexPath: IndexPath, to newIndexPath: IndexPath) {
self.structure.unsafeMove(itemAt: indexPath, to: newIndexPath)
}
mutating func unsafeReloadItems<C: Collection>(at indexPaths: C) where C.Element == IndexPath {
self.structure.unsafeUpdate(itemsAt: indexPaths)
}
mutating func unsafeInsertSections<C: Collection>(_ identifiers: C, at sectionIndex: Int) where C.Element == String {
self.structure.unsafeInsert(identifiers, at: sectionIndex)
}
mutating func unsafeDeleteSections<C: Collection>(at sectionIndices: C) where C.Element == Int {
self.structure.unsafeRemove(sectionsAt: sectionIndices)
}
mutating func unsafeMoveSection(at sectionIndex: Int, to newSectionIndex: Int) {
self.structure.unsafeMove(sectionAt: sectionIndex, to: newSectionIndex)
}
mutating func unsafeReloadSections<C: Collection>(at sectionIndices: C) where C.Element == Int {
self.structure.unsafeUpdate(sectionsAt: sectionIndices)
}
// MARK: Private
private var structure: BackingStructure
// MARK: - Section
internal struct Section: DifferentiableSection, Equatable {
let indexTitle: String?
var isReloaded: Bool
init(
differenceIdentifier: String,
indexTitle: String?,
items: [Item] = [],
isReloaded: Bool = false
) {
self.differenceIdentifier = differenceIdentifier
self.indexTitle = indexTitle
self.elements = items
self.isReloaded = isReloaded
}
// MARK: Differentiable
let differenceIdentifier: String
func isContentEqual(to source: Section) -> Bool {
return !self.isReloaded
&& self.differenceIdentifier == source.differenceIdentifier
}
// MARK: DifferentiableSection
var elements: [Item] = []
init<S: Sequence>(source: Section, elements: S) where S.Element == Item {
self.init(
differenceIdentifier: source.differenceIdentifier,
indexTitle: source.indexTitle,
items: Array(elements),
isReloaded: source.isReloaded
)
}
}
// MARK: - Item
internal struct Item: Differentiable, Equatable {
var isReloaded: Bool
init(differenceIdentifier: NSManagedObjectID, isReloaded: Bool = false) {
self.differenceIdentifier = differenceIdentifier
self.isReloaded = isReloaded
}
// MARK: Differentiable
let differenceIdentifier: NSManagedObjectID
func isContentEqual(to source: Item) -> Bool {
return !self.isReloaded
&& self.differenceIdentifier == source.differenceIdentifier
}
}
// MARK: - BackingStructure
fileprivate struct BackingStructure {
// MARK: Internal
let sectionIndexTransformer: (_ sectionName: String?) -> String?
var sections: [Section]
private(set) var reloadedItems: Set<NSManagedObjectID>
init() {
self.sectionIndexTransformer = { _ in nil }
self.sections = []
self.reloadedItems = []
}
init(
sections: [NSFetchedResultsSectionInfo],
sectionIndexTransformer: @escaping (_ sectionName: String?) -> String?,
fetchOffset: Int,
fetchLimit: Int?
) {
let sliceItems: (_ array: [Any], _ offset: Int) -> Array<Any>.SubSequence
if let fetchLimit = fetchLimit {
var remainingCount = fetchLimit
sliceItems = {
let slice = $0[$1...].prefix(remainingCount)
remainingCount -= slice.count
return slice
}
}
else {
sliceItems = { $0[$1...] }
}
var newSections: [Internals.DiffableDataSourceSnapshot.Section] = []
var ignoreCount = fetchOffset
for section in sections {
let objects = section.objects ?? []
guard objects.indices.contains(ignoreCount) else {
ignoreCount -= objects.count
continue
}
let items = sliceItems(objects, ignoreCount)
.map({ Item(differenceIdentifier: ($0 as! NSManagedObject).objectID) })
ignoreCount = 0
guard !items.isEmpty else {
continue
}
newSections.append(
Section(
differenceIdentifier: section.name,
indexTitle: section.indexTitle,
items: items
)
)
}
self.sectionIndexTransformer = sectionIndexTransformer
self.sections = newSections
self.reloadedItems = []
}
var allSectionIDs: [String] {
return self.sections.map({ $0.differenceIdentifier })
}
var allItemsCount: Int {
return self.sections.reduce(into: 0) { (result, section) in
result += section.elements.count
}
}
var allItemIDs: [NSManagedObjectID] {
return self.sections.lazy.flatMap({ $0.elements }).map({ $0.differenceIdentifier })
}
func items(in sectionID: String) -> [NSManagedObjectID] {
guard let sectionIndex = self.sectionIndex(of: sectionID) else {
Internals.abort("Section \"\(sectionID)\" does not exist")
}
return self.sections[sectionIndex].elements.map({ $0.differenceIdentifier })
}
func unsafeItem(at indexPath: IndexPath) -> NSManagedObjectID {
return self.sections[indexPath.section]
.elements[indexPath.item]
.differenceIdentifier
}
func section(containing itemID: NSManagedObjectID) -> String? {
return self.itemPositionMap(itemID)?.section.differenceIdentifier
}
mutating func append<C: Collection>(
itemIDs: C,
to sectionID: String?
) where C.Element == NSManagedObjectID {
let index: Array<Section>.Index
if let sectionID = sectionID {
guard let sectionIndex = self.sectionIndex(of: sectionID) else {
Internals.abort("Section \"\(sectionID)\" does not exist")
}
index = sectionIndex
}
else {
let section = self.sections
guard !section.isEmpty else {
Internals.abort("No sections exist")
}
index = section.index(before: section.endIndex)
}
let items = itemIDs.lazy.map({ Item(differenceIdentifier: $0) })
self.sections[index].elements.append(contentsOf: items)
}
mutating func unsafeAppend<C: Collection>(
_ itemIDs: C,
toSectionAt sectionIndex: Int?
) where C.Element == NSManagedObjectID {
let index: Array<Section>.Index
if let sectionIndex = sectionIndex {
index = sectionIndex
}
else {
let section = self.sections
index = section.index(before: section.endIndex)
}
let items = itemIDs.lazy.map({ Item(differenceIdentifier: $0) })
self.sections[index].elements.append(contentsOf: items)
}
mutating func insert<C: Collection>(
itemIDs: C,
before beforeItemID: NSManagedObjectID
) where C.Element == NSManagedObjectID {
guard let itemPosition = self.itemPositionMap(beforeItemID) else {
Internals.abort("Item \(beforeItemID) does not exist")
}
let items = itemIDs.lazy.map({ Item(differenceIdentifier: $0) })
self.sections[itemPosition.sectionIndex].elements
.insert(contentsOf: items, at: itemPosition.itemRelativeIndex)
}
mutating func insert<C: Collection>(
itemIDs: C,
after afterItemID: NSManagedObjectID
) where C.Element == NSManagedObjectID {
guard let itemPosition = self.itemPositionMap(afterItemID) else {
Internals.abort("Item \(afterItemID) does not exist")
}
let itemIndex = self.sections[itemPosition.sectionIndex].elements
.index(after: itemPosition.itemRelativeIndex)
let items = itemIDs.lazy.map({ Item(differenceIdentifier: $0) })
self.sections[itemPosition.sectionIndex].elements
.insert(contentsOf: items, at: itemIndex)
}
mutating func unsafeInsert<C: Collection>(
itemIDs: C,
at indexPath: IndexPath
) where C.Element == NSManagedObjectID {
let items = itemIDs.lazy.map({ Item(differenceIdentifier: $0) })
self.sections[indexPath.section].elements
.insert(contentsOf: items, at: indexPath.item)
}
mutating func remove<S: Sequence>(itemIDs: S) where S.Element == NSManagedObjectID {
let itemPositionMap = self.itemPositionMap()
var removeIndexSetMap: [Int: IndexSet] = [:]
for itemID in itemIDs {
guard let itemPosition = itemPositionMap[itemID] else {
continue
}
removeIndexSetMap[itemPosition.sectionIndex, default: []]
.insert(itemPosition.itemRelativeIndex)
}
for (sectionIndex, removeIndexSet) in removeIndexSetMap {
for range in removeIndexSet.rangeView.reversed() {
self.sections[sectionIndex].elements.removeSubrange(range)
}
}
}
mutating func unsafeRemove<S: Sequence>(itemsAt indexPaths: S) where S.Element == IndexPath {
var removeIndexSetMap: [Int: IndexSet] = [:]
for indexPath in indexPaths {
removeIndexSetMap[indexPath.section, default: []]
.insert(indexPath.item)
}
for (sectionIndex, removeIndexSet) in removeIndexSetMap {
for range in removeIndexSet.rangeView.reversed() {
self.sections[sectionIndex].elements.removeSubrange(range)
}
}
}
mutating func removeAllItems() {
for sectionIndex in self.sections.indices {
self.sections[sectionIndex].elements.removeAll()
}
}
mutating func removeAllEmptySections() {
self.sections.removeAll(where: { $0.elements.isEmpty })
}
mutating func move(
itemID: NSManagedObjectID,
before beforeItemID: NSManagedObjectID
) {
guard let removed = self.remove(itemID: itemID) else {
Internals.abort("Item \(itemID) does not exist")
}
guard let itemPosition = self.itemPositionMap(beforeItemID) else {
Internals.abort("Item \(beforeItemID) does not exist")
}
self.sections[itemPosition.sectionIndex].elements
.insert(removed, at: itemPosition.itemRelativeIndex)
}
mutating func move(
itemID: NSManagedObjectID,
after afterItemID: NSManagedObjectID
) {
guard let removed = self.remove(itemID: itemID) else {
Internals.abort("Item \(itemID) does not exist")
}
guard let itemPosition = self.itemPositionMap(afterItemID) else {
Internals.abort("Item \(afterItemID) does not exist")
}
let itemIndex = self.sections[itemPosition.sectionIndex].elements
.index(after: itemPosition.itemRelativeIndex)
self.sections[itemPosition.sectionIndex].elements
.insert(removed, at: itemIndex)
}
mutating func unsafeMove(
itemAt indexPath: IndexPath,
to newIndexPath: IndexPath
) {
let itemID = self.sections[indexPath.section].elements
.remove(at: indexPath.item)
self.sections[newIndexPath.section].elements
.insert(itemID, at: newIndexPath.item)
}
mutating func update<S: Sequence>(itemIDs: S) where S.Element == NSManagedObjectID {
let itemPositionMap = self.itemPositionMap()
var newItemIDs: Set<NSManagedObjectID> = []
for itemID in itemIDs {
guard let itemPosition = itemPositionMap[itemID] else {
continue
}
self.sections[itemPosition.sectionIndex]
.elements[itemPosition.itemRelativeIndex].isReloaded = true
newItemIDs.insert(itemID)
}
self.reloadedItems.formUnion(newItemIDs)
}
mutating func unsafeUpdate<S: Sequence>(itemsAt indexPaths: S) where S.Element == IndexPath {
var newItemIDs: Set<NSManagedObjectID> = []
for indexPath in indexPaths {
self.sections[indexPath.section]
.elements[indexPath.item].isReloaded = true
newItemIDs.insert(self.unsafeItem(at: indexPath))
}
self.reloadedItems.formUnion(newItemIDs)
}
mutating func append<C: Collection>(sectionIDs: C) where C.Element == String {
let sectionIndexTransformer = self.sectionIndexTransformer
let newSections = sectionIDs.lazy.map {
return Section(
differenceIdentifier: $0,
indexTitle: sectionIndexTransformer($0)
)
}
self.sections.append(contentsOf: newSections)
}
mutating func insert<C: Collection>(
sectionIDs: C,
before beforeSectionID: String
) where C.Element == String {
guard let sectionIndex = self.sectionIndex(of: beforeSectionID) else {
Internals.abort("Section \"\(beforeSectionID)\" does not exist")
}
let sectionIndexTransformer = self.sectionIndexTransformer
let newSections = sectionIDs.lazy.map {
return Section(
differenceIdentifier: $0,
indexTitle: sectionIndexTransformer($0)
)
}
self.sections.insert(contentsOf: newSections, at: sectionIndex)
}
mutating func insert<C: Collection>(
sectionIDs: C,
after afterSectionID: String
) where C.Element == String {
guard let beforeIndex = self.sectionIndex(of: afterSectionID) else {
Internals.abort("Section \"\(afterSectionID)\" does not exist")
}
let sectionIndexTransformer = self.sectionIndexTransformer
let sectionIndex = self.sections.index(after: beforeIndex)
let newSections = sectionIDs.lazy.map {
return Section(
differenceIdentifier: $0,
indexTitle: sectionIndexTransformer($0)
)
}
self.sections.insert(contentsOf: newSections, at: sectionIndex)
}
mutating func unsafeInsert<C: Collection>(
_ sectionIDs: C,
at sectionIndex: Int
) where C.Element == String {
let sectionIndexTransformer = self.sectionIndexTransformer
let newSections = sectionIDs.lazy.map {
return Section(
differenceIdentifier: $0,
indexTitle: sectionIndexTransformer($0)
)
}
self.sections.insert(contentsOf: newSections, at: sectionIndex)
}
mutating func remove<S: Sequence>(sectionIDs: S) where S.Element == String {
for sectionID in sectionIDs {
self.remove(sectionID: sectionID)
}
}
mutating func unsafeRemove<S: Sequence>(
sectionsAt sectionIndices: S
) where S.Element == Int {
for sectionIndex in sectionIndices.sorted(by: >) {
self.sections.remove(at: sectionIndex)
}
}
mutating func move(sectionID: String, before beforeSectionID: String) {
guard let removed = self.remove(sectionID: sectionID) else {
Internals.abort("Section \"\(sectionID)\" does not exist")
}
guard let sectionIndex = self.sectionIndex(of: beforeSectionID) else {
Internals.abort("Section \"\(beforeSectionID)\" does not exist")
}
self.sections.insert(removed, at: sectionIndex)
}
mutating func move(sectionID: String, after afterSectionID: String) {
guard let removed = self.remove(sectionID: sectionID) else {
Internals.abort("Section \"\(sectionID)\" does not exist")
}
guard let beforeIndex = self.sectionIndex(of: afterSectionID) else {
Internals.abort("Section \"\(afterSectionID)\" does not exist")
}
let sectionIndex = self.sections.index(after: beforeIndex)
self.sections.insert(removed, at: sectionIndex)
}
mutating func unsafeMove(
sectionAt sectionIndex: Int,
to newSectionIndex: Int
) {
self.sections.move(
fromOffsets: .init(integer: sectionIndex),
toOffset: newSectionIndex
)
}
mutating func update<S: Sequence>(
sectionIDs: S
) where S.Element == String {
for sectionID in sectionIDs {
guard let sectionIndex = self.sectionIndex(of: sectionID) else {
continue
}
self.sections[sectionIndex].isReloaded = true
}
}
mutating func unsafeUpdate<S: Sequence>(
sectionsAt sectionIndices: S
) where S.Element == Int {
for sectionIndex in sectionIndices {
self.sections[sectionIndex].isReloaded = true
}
}
// MARK: Private
private func sectionIndex(of sectionID: String) -> Array<Section>.Index? {
return self.sections.firstIndex(where: { $0.differenceIdentifier == sectionID })
}
@discardableResult
private mutating func remove(itemID: NSManagedObjectID) -> Item? {
guard let itemPosition = self.itemPositionMap(itemID) else {
return nil
}
return self.sections[itemPosition.sectionIndex].elements
.remove(at: itemPosition.itemRelativeIndex)
}
@discardableResult
private mutating func remove(sectionID: String) -> Section? {
guard let sectionIndex = self.sectionIndex(of: sectionID) else {
return nil
}
return self.sections.remove(at: sectionIndex)
}
private func itemPositionMap(_ itemID: NSManagedObjectID) -> ItemPosition? {
let sections = self.sections
for (sectionIndex, section) in sections.enumerated() {
for (itemRelativeIndex, item) in section.elements.enumerated() {
guard item.differenceIdentifier == itemID else {
continue
}
return ItemPosition(
item: item,
itemRelativeIndex: itemRelativeIndex,
section: section,
sectionIndex: sectionIndex
)
}
}
return nil
}
private func itemPositionMap() -> [NSManagedObjectID: ItemPosition] {
return self.sections.enumerated().reduce(into: [:]) { result, section in
for (itemRelativeIndex, item) in section.element.elements.enumerated() {
result[item.differenceIdentifier] = ItemPosition(
item: item,
itemRelativeIndex: itemRelativeIndex,
section: section.element,
sectionIndex: section.offset
)
}
}
}
// MARK: - ItemPosition
fileprivate struct ItemPosition {
let item: Item
let itemRelativeIndex: Int
let section: Section
let sectionIndex: Int
}
}
}
}
#endif