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Merge pull request #141 from Babylonpartners/anders/adapter-store
Introduce `AdapterStore` and integrate it with the TableView adapters.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,31 @@ | ||
| /// Provide generic parameter agnostic access to the adapter. | ||
| internal protocol AdapterStoreAccessible: AnyObject { | ||
| var layoutMargins: UIEdgeInsets { get set } | ||
| var boundSize: CGSize { get set } | ||
| var cachesSizeInformation: Bool { get set } | ||
| } | ||
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| /// Provide a default implementation for all adapter store owners. | ||
| internal protocol AdapterStoreOwner: AdapterStoreAccessible { | ||
| associatedtype SectionID: Hashable | ||
| associatedtype ItemID: Hashable | ||
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| var store: AdapterStore<SectionID, ItemID> { get set } | ||
| } | ||
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| extension AdapterStoreOwner { | ||
| var layoutMargins: UIEdgeInsets { | ||
| get { return store.layoutMargins } | ||
| set { store.layoutMargins = newValue } | ||
| } | ||
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| var boundSize: CGSize { | ||
| get { return store.boundSize } | ||
| set { store.boundSize = newValue } | ||
| } | ||
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| var cachesSizeInformation: Bool { | ||
| get { return store.cachesSizeInformation } | ||
| set { store.cachesSizeInformation = newValue } | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,207 @@ | ||
| import FlexibleDiff | ||
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| /// The adapter store which carries the component tree, and also cached sizing information if enabled. | ||
| /// | ||
| /// The adapter computes sizing information lazily upon request, but it adjusts spaces and performs cache invalidation | ||
| /// every time a diff is applied. | ||
| /// | ||
| /// - important: While the use-as-you-go Bento uses the adapter, the size caching capability should only be enabled in | ||
| /// `SizeCachingTableView` and `SizeCachingCollectionView`, since there are specific messages that Bento | ||
| /// need to intercept for size caching to function as expected. | ||
| struct AdapterStore<SectionID: Hashable, ItemID: Hashable> { | ||
| private(set) var sections: [Section<SectionID, ItemID>] = [] | ||
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| var sizingStrategy: SizingStrategy = .fillHorizontally | ||
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| var cachesSizeInformation: Bool = false { | ||
| didSet { | ||
| if cachesSizeInformation && info.isEmpty { | ||
| resetCachedInfo() | ||
| } else { | ||
| info = [] | ||
| } | ||
| } | ||
| } | ||
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| var boundSize: CGSize = .unknown { | ||
| didSet { | ||
| if cachesSizeInformation && oldValue != boundSize { | ||
| resetCachedInfo() | ||
| } | ||
| } | ||
| } | ||
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| var layoutMargins: UIEdgeInsets = .zero { | ||
| didSet { | ||
| if cachesSizeInformation && oldValue != layoutMargins { | ||
| resetCachedInfo() | ||
| } | ||
| } | ||
| } | ||
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| /// All cached information. If it is empty, it means either there is no item, or the cache structure hasn't been | ||
| /// setup yet. | ||
| private var info: [SectionInfo] = [] | ||
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| init() {} | ||
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| mutating func size(for supplement: Supplement, inSection section: Int) -> SupplementSizingResult { | ||
| guard cachesSizeInformation else { return .cachingDisabled } | ||
| guard let component = sections[section].supplements[supplement] else { return .doesNotExist } | ||
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| let knownSize = info[section].supplements[supplement, default: .unknown] | ||
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| if knownSize == .unknown { | ||
| let size = sizingStrategy.size( | ||
| of: component, | ||
| boundSize: boundSize, | ||
| layoutMargins: layoutMargins | ||
| ) | ||
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| info[section].supplements[supplement] = size | ||
| return .size(size) | ||
| } else { | ||
| return .size(knownSize) | ||
| } | ||
| } | ||
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| mutating func size(forItemAt indexPath: IndexPath) -> CGSize? { | ||
| guard cachesSizeInformation else { return nil } | ||
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| let knownSize = info[indexPath.section].itemSizes[indexPath.item] | ||
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| if knownSize == .unknown { | ||
| let size = sizingStrategy.size( | ||
| of: sections[indexPath.section].items[indexPath.item].component, | ||
| boundSize: boundSize, | ||
| layoutMargins: layoutMargins | ||
| ) | ||
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| info[indexPath.section].itemSizes[indexPath.item] = size | ||
| return size | ||
| } else { | ||
| return knownSize | ||
| } | ||
| } | ||
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| mutating func removeItem(at indexPath: IndexPath) { | ||
| sections[indexPath.section].items.remove(at: indexPath.row) | ||
| } | ||
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| mutating func update(with sections: [Section<SectionID, ItemID>], knownSupplements: Set<Supplement>, changeset: SectionedChangeset? = nil) { | ||
| self.sections = sections | ||
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| guard cachesSizeInformation else { return } | ||
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| guard let changeset = changeset else { | ||
| resetCachedInfo() | ||
| return | ||
| } | ||
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| info.applyIgnoringMutation( | ||
| changeset.sections, | ||
| newElement: SectionInfo(), | ||
| whenInserted: { info, index in | ||
| info.itemSizes = Array(repeating: .unknown, count: sections[index].items.count) | ||
| } | ||
| ) | ||
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| // Apply changeset to the old section info for all mutated sections. | ||
| for mutatedSection in changeset.mutatedSections { | ||
| let index = mutatedSection.destination | ||
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| // NOTE: When layout equivalence is implemented, we need to update this to avoid not invalidating entries | ||
| // when layout is declared not to have changed. | ||
| info[index].supplements = [:] | ||
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| info[index].apply(mutatedSection.changeset) | ||
| } | ||
| } | ||
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| mutating func resetCachedInfo() { | ||
| info = Array(repeating: SectionInfo(), count: sections.count) | ||
| for index in info.indices { | ||
| info[index].itemSizes = Array(repeating: .unknown, count: sections[index].items.count) | ||
| } | ||
| } | ||
| } | ||
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| enum SupplementSizingResult: Equatable { | ||
| case doesNotExist | ||
| case cachingDisabled | ||
| case size(CGSize) | ||
| } | ||
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| enum SizingStrategy { | ||
| case fillHorizontally | ||
| case fillVertically | ||
| case compressed | ||
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| func size(of component: AnyRenderable, boundSize: CGSize, layoutMargins: UIEdgeInsets) -> CGSize { | ||
| switch self { | ||
| case .fillHorizontally: | ||
| return component.sizeBoundTo(width: boundSize.width, inheritedMargins: layoutMargins) | ||
| case .fillVertically: | ||
| return component.sizeBoundTo(height: boundSize.height, inheritedMargins: layoutMargins) | ||
| case .compressed: | ||
| return component.sizeBoundTo(size: UIView.layoutFittingCompressedSize, inheritedMargins: layoutMargins) | ||
| } | ||
| } | ||
| } | ||
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| private struct SectionInfo { | ||
| var supplements: [Supplement: CGSize] = [:] | ||
| var itemSizes: [CGSize] = [] | ||
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| init() {} | ||
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| mutating func apply(_ changeset: Changeset) { | ||
| itemSizes.applyIgnoringMutation(changeset, newElement: .unknown, whenInserted: { _, _ in }) | ||
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| for index in changeset.mutations { | ||
| itemSizes[index] = .unknown | ||
| } | ||
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| for move in changeset.moves where move.isMutated { | ||
| itemSizes[move.destination] = .unknown | ||
| } | ||
| } | ||
| } | ||
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| extension CGSize { | ||
| /// A sentinel size representing unknown size. This is not known to be generated by Auto Layout, and the logical | ||
| /// size is either zero or of positive decimals. | ||
| fileprivate static var unknown: CGSize { | ||
| return CGSize(width: -.infinity, height: -.infinity) | ||
| } | ||
| } | ||
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| extension Array { | ||
| mutating func applyIgnoringMutation(_ changeset: Changeset, newElement: Element, whenInserted: (inout Element, _ index: Index) -> Void) { | ||
| let old = self | ||
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| let allRemovals = changeset.removals | ||
| .union(IndexSet(changeset.moves.lazy.map { $0.source })) | ||
| let allInsertions = changeset.inserts | ||
| .union(IndexSet(changeset.moves.lazy.map { $0.destination })) | ||
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| // Remove all entries for removed sections, and moved sections at their original position. | ||
| for range in allRemovals.rangeView.reversed() { | ||
| removeSubrange(range) | ||
| } | ||
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| // Create all entries for newly inserted sections, and moved sections at their new position. | ||
| for range in allInsertions.rangeView { | ||
| insert(contentsOf: repeatElement(newElement, count: range.count), at: range.lowerBound) | ||
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| for index in range { | ||
| whenInserted(&self[index], index) | ||
| } | ||
| } | ||
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| // Copy over the old section info for moved sections. | ||
| for move in changeset.moves { | ||
| self[move.destination] = old[move.source] | ||
| } | ||
| } | ||
| } |
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