Avoid converting HTML to attributed string twice when displaying a status cell for the first time

Now, when Filterer performs the conversion, the status cell can reuse
the attributed string.

Tusker.xcodeproj/project.pbxproj

@@ -67,6 +67,7 @@
 		D61F75B7293C119700C0B37F /* Filterer.swift in Sources */ = {isa = PBXBuildFile; fileRef = D61F75B6293C119700C0B37F /* Filterer.swift */; };
 		D61F75B9293C15A000C0B37F /* ZeroHeightCollectionViewCell.swift in Sources */ = {isa = PBXBuildFile; fileRef = D61F75B8293C15A000C0B37F /* ZeroHeightCollectionViewCell.swift */; };
 		D61F75BB293C183100C0B37F /* HTMLConverter.swift in Sources */ = {isa = PBXBuildFile; fileRef = D61F75BA293C183100C0B37F /* HTMLConverter.swift */; };
+		D61F75BD293D099600C0B37F /* Lazy.swift in Sources */ = {isa = PBXBuildFile; fileRef = D61F75BC293D099600C0B37F /* Lazy.swift */; };
 		D620483423D3801D008A63EF /* LinkTextView.swift in Sources */ = {isa = PBXBuildFile; fileRef = D620483323D3801D008A63EF /* LinkTextView.swift */; };
 		D620483623D38075008A63EF /* ContentTextView.swift in Sources */ = {isa = PBXBuildFile; fileRef = D620483523D38075008A63EF /* ContentTextView.swift */; };
 		D620483823D38190008A63EF /* StatusContentTextView.swift in Sources */ = {isa = PBXBuildFile; fileRef = D620483723D38190008A63EF /* StatusContentTextView.swift */; };
@@ -450,6 +451,7 @@
 		D61F75B6293C119700C0B37F /* Filterer.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Filterer.swift; sourceTree = "<group>"; };
 		D61F75B8293C15A000C0B37F /* ZeroHeightCollectionViewCell.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ZeroHeightCollectionViewCell.swift; sourceTree = "<group>"; };
 		D61F75BA293C183100C0B37F /* HTMLConverter.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = HTMLConverter.swift; sourceTree = "<group>"; };
+		D61F75BC293D099600C0B37F /* Lazy.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Lazy.swift; sourceTree = "<group>"; };
 		D620483323D3801D008A63EF /* LinkTextView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = LinkTextView.swift; sourceTree = "<group>"; };
 		D620483523D38075008A63EF /* ContentTextView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ContentTextView.swift; sourceTree = "<group>"; };
 		D620483723D38190008A63EF /* StatusContentTextView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = StatusContentTextView.swift; sourceTree = "<group>"; };
@@ -1463,6 +1465,7 @@
 				D6E4269C2532A3E100C02E1C /* FuzzyMatcher.swift */,
 				D61F75BA293C183100C0B37F /* HTMLConverter.swift */,
 				D6B30E08254BAF63009CAEE5 /* ImageGrayscalifier.swift */,
+				D61F75BC293D099600C0B37F /* Lazy.swift */,
 				D60E2F2B24423EAD005F8713 /* LazilyDecoding.swift */,
 				D64D0AAC2128D88B005A6F37 /* LocalData.swift */,
 				D61DC84528F498F200B82C6E /* Logging.swift */,
@@ -2004,6 +2007,7 @@
 				D6420AEE26BED18B00ED8175 /* PublicTimelineDescriptionTableViewCell.swift in Sources */,
 				D6E0DC8E216EDF1E00369478 /* Previewing.swift in Sources */,
 				D6B93667281D937300237D0E /* MainSidebarMyProfileCollectionViewCell.swift in Sources */,
+				D61F75BD293D099600C0B37F /* Lazy.swift in Sources */,
 				D6BED174212667E900F02DA0 /* TimelineStatusTableViewCell.swift in Sources */,
 				D69693F42585941A00F4E116 /* UIWindowSceneDelegate+Close.swift in Sources */,
 				D6C143DA253510F4007DC240 /* ComposeEmojiTextField.swift in Sources */,

Tusker/Filterer.swift

@@ -42,7 +42,7 @@ class Filterer {
     
     var filtersChanged: ((Bool) -> Void)?
     
-    private let htmlConverter = HTMLConverter()
+    var htmlConverter = HTMLConverter()
     private var hasSetup = false
     private var matchers = [(NSRegularExpression, Result)]()
     private var allFiltersObserver: AnyCancellable?
@@ -114,16 +114,16 @@ class Filterer {
     }
     
     // Use a closure for the status in case the result is cached and we don't need to look it up
-    func resolve(state: FilterState, status: () -> StatusMO) -> Filterer.Result {
+    func resolve(state: FilterState, status: () -> StatusMO) -> (Filterer.Result, NSAttributedString?) {
         switch state.state {
         case .known(_, generation: let knownGen) where knownGen < generation:
             fallthrough
         case .unknown:
-            let result = doResolve(status: status())
+            let (result, attributedString) = doResolve(status: status())
             state.state = .known(result, generation: generation)
-            return result
+            return (result, attributedString)
         case .known(let result, _):
-            return result
+            return (result, nil)
         }
     }
     
@@ -131,21 +131,21 @@ class Filterer {
         state.state = .known(result, generation: generation)
     }
     
-    private func doResolve(status: StatusMO) -> Result {
+    private func doResolve(status: StatusMO) -> (Result, NSAttributedString?) {
         if !hasSetup {
             setupFilters(filters: mastodonController.filters)
         }
         if matchers.isEmpty {
-            return .allow
+            return (.allow, nil)
         }
-        lazy var text = htmlConverter.convert(status.content).string
+        @Lazy var text = self.htmlConverter.convert(status.content)
         for (regex, result) in matchers {
             if (!status.spoilerText.isEmpty && regex.numberOfMatches(in: status.spoilerText, range: NSRange(location: 0, length: status.spoilerText.utf16.count)) > 0)
-                || regex.numberOfMatches(in: text, range: NSRange(location: 0, length: text.utf16.count)) > 0 {
+                || regex.numberOfMatches(in: text.string, range: NSRange(location: 0, length: text.length)) > 0 {
-                return result
+                return (result, _text.valueIfInitialized)
             }
         }
-        return .allow
+        return (.allow, _text.valueIfInitialized)
     }
     
     enum Result: Equatable {

Tusker/Lazy.swift

@@ -0,0 +1,54 @@
+//
+//  Lazy.swift
+//  Tusker
+//
+//  Created by Shadowfacts on 12/4/22.
+//  Copyright © 2022 Shadowfacts. All rights reserved.
+//
+
+import Foundation
+
+/// A lazy initialization property wrapper that allows checking the initialization state.
+@propertyWrapper
+enum Lazy<Value> {
+    case uninitialized(() -> Value)
+    case initialized(Value)
+    
+    init(wrappedValue: @autoclosure @escaping () -> Value) {
+        self = .uninitialized(wrappedValue)
+    }
+    
+    /// Returns the contained value, initializing it if the value hasn't been accessed before.
+    var wrappedValue: Value {
+        mutating get {
+            switch self {
+            case .uninitialized(let closure):
+                let value = closure()
+                self = .initialized(value)
+                return value
+            case .initialized(let value):
+                return value
+            }
+        }
+    }
+    
+    /// Whether this Lazy has been initialized yet.
+    var isInitialized: Bool {
+        switch self {
+        case .uninitialized(_):
+            return false
+        case .initialized(_):
+            return true
+        }
+    }
+    
+    /// If this Lazy is initialized, this returns the value. Otherwise, it returns `nil`.
+    var valueIfInitialized: Value? {
+        switch self {
+        case .uninitialized(_):
+            return nil
+        case .initialized(let value):
+            return value
+        }
+    }
+}

Tusker/Logging.swift

@@ -13,6 +13,7 @@ struct Logging {
     private init() {}
     
     static let general = Logger(subsystem: Bundle.main.bundleIdentifier!, category: "General")
+    static let generalSignposter = OSSignposter(logger: general)
     
     static func getLogData() -> Data? {
         do {

Tusker/Screens/Explore/TrendingStatusesViewController.swift

@@ -65,7 +65,7 @@ class TrendingStatusesViewController: UIViewController {
         let statusCell = UICollectionView.CellRegistration<TimelineStatusCollectionViewCell, (String, CollapseState)> { [unowned self] cell, indexPath, item in
             cell.delegate = self
             // TODO: filter these
-            cell.updateUI(statusID: item.0, state: item.1, filterResult: .allow)
+            cell.updateUI(statusID: item.0, state: item.1, filterResult: .allow, precomputedContent: nil)
         }
         let loadingCell = UICollectionView.CellRegistration<LoadingCollectionViewCell, Void> { cell, _, _ in
             cell.indicator.startAnimating()

Tusker/Screens/Profile/ProfileStatusesViewController.swift

@@ -40,6 +40,8 @@ class ProfileStatusesViewController: UIViewController, TimelineLikeCollectionVie
         self.owner = owner
         self.mastodonController = owner.mastodonController
         self.filterer = Filterer(mastodonController: mastodonController, context: .account)
+        self.filterer.htmlConverter.font = TimelineStatusCollectionViewCell.contentFont
+        self.filterer.htmlConverter.paragraphStyle = TimelineStatusCollectionViewCell.contentParagraphStyle
         
         super.init(nibName: nil, bundle: nil)
         
@@ -116,10 +118,10 @@ class ProfileStatusesViewController: UIViewController, TimelineLikeCollectionVie
     
     private func createDataSource() -> UICollectionViewDiffableDataSource<Section, Item> {
         collectionView.register(ProfileHeaderCollectionViewCell.self, forCellWithReuseIdentifier: "headerCell")
-        let statusCell = UICollectionView.CellRegistration<TimelineStatusCollectionViewCell, (String, CollapseState, Filterer.Result, Bool)> { [unowned self] cell, indexPath, item in
+        let statusCell = UICollectionView.CellRegistration<TimelineStatusCollectionViewCell, (String, CollapseState, Filterer.Result, NSAttributedString?, Bool)> { [unowned self] cell, indexPath, item in
             cell.delegate = self
-            cell.showPinned = item.3
+            cell.showPinned = item.4
-            cell.updateUI(statusID: item.0, state: item.1, filterResult: item.2)
+            cell.updateUI(statusID: item.0, state: item.1, filterResult: item.2, precomputedContent: item.3)
         }
         return UICollectionViewDiffableDataSource(collectionView: collectionView) { [unowned self] collectionView, indexPath, itemIdentifier in
             switch itemIdentifier {
@@ -146,8 +148,8 @@ class ProfileStatusesViewController: UIViewController, TimelineLikeCollectionVie
                     return cell
                 }
             case .status(id: let id, collapseState: let collapseState, filterState: let filterState, pinned: let pinned):
-                let result = filterResult(state: filterState, statusID: id)
+                let (result, precomputedContent) = filterResult(state: filterState, statusID: id)
-                return collectionView.dequeueConfiguredReusableCell(using: statusCell, for: indexPath, item: (id, collapseState, result, pinned))
+                return collectionView.dequeueConfiguredReusableCell(using: statusCell, for: indexPath, item: (id, collapseState, result, precomputedContent, pinned))
             case .loadingIndicator:
                 return loadingIndicatorCell(for: indexPath)
             case .confirmLoadMore:
@@ -245,7 +247,7 @@ class ProfileStatusesViewController: UIViewController, TimelineLikeCollectionVie
         await apply(snapshot, animatingDifferences: true)
     }
     
-    private func filterResult(state: FilterState, statusID: String) -> Filterer.Result {
+    private func filterResult(state: FilterState, statusID: String) -> (Filterer.Result, NSAttributedString?) {
         let status = {
             let status = self.mastodonController.persistentContainer.status(for: statusID)!
             // if the status is a reblog of another one, filter based on that one

Tusker/Screens/Status Action Account List/StatusActionAccountListViewController.swift

@@ -80,7 +80,7 @@ class StatusActionAccountListViewController: UIViewController {
     private func createDataSource() -> UICollectionViewDiffableDataSource<Section, Item> {
         let statusCell = UICollectionView.CellRegistration<TimelineStatusCollectionViewCell, Void> { [unowned self] cell, indexPath, _ in
             cell.delegate = self
-            cell.updateUI(statusID: self.statusID, state: self.statusState, filterResult: .allow)
+            cell.updateUI(statusID: self.statusID, state: self.statusState, filterResult: .allow, precomputedContent: nil)
         }
         let accountCell = UICollectionView.CellRegistration<AccountCollectionViewCell, String> { [unowned self] cell, indexPath, item in
             cell.delegate = self

Tusker/Screens/Timeline/InstanceTimelineViewController.swift

@@ -69,10 +69,10 @@ class InstanceTimelineViewController: TimelineViewController {
         toggleSaveButton.title = toggleSaveButtonTitle
     }
     
-    override func configureStatusCell(_ cell: TimelineStatusCollectionViewCell, id: String, state: CollapseState, filterResult: Filterer.Result) {
+    override func configureStatusCell(_ cell: TimelineStatusCollectionViewCell, id: String, state: CollapseState, filterResult: Filterer.Result, precomputedContent: NSAttributedString?) {
         cell.delegate = browsingEnabled ? self : nil
         cell.overrideMastodonController = mastodonController
-        cell.updateUI(statusID: id, state: state, filterResult: filterResult)
+        cell.updateUI(statusID: id, state: state, filterResult: filterResult, precomputedContent: precomputedContent)
     }
     
     override func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {

Tusker/Screens/Timeline/TimelineViewController.swift

@@ -37,6 +37,8 @@ class TimelineViewController: UIViewController, TimelineLikeCollectionViewContro
             filterContext = .public
         }
         self.filterer = Filterer(mastodonController: mastodonController, context: filterContext)
+        self.filterer.htmlConverter.font = TimelineStatusCollectionViewCell.contentFont
+        self.filterer.htmlConverter.paragraphStyle = TimelineStatusCollectionViewCell.contentParagraphStyle
         
         super.init(nibName: nil, bundle: nil)
         
@@ -69,7 +71,8 @@ class TimelineViewController: UIViewController, TimelineLikeCollectionViewContro
                 config.topSeparatorVisibility = .hidden
                 config.bottomSeparatorVisibility = .hidden
             } else if case .status(id: let id, collapseState: _, filterState: let filterState) = item,
-                      case .hide = filterResult(state: filterState, statusID: id) {
+                      case (.hide, _) = filterResult(state: filterState, statusID: id) {
+                // this runs after the cell is setup, so the filter state is already known and this check is cheap
                 config.topSeparatorVisibility = .hidden
                 config.bottomSeparatorVisibility = .hidden
             } else {
@@ -116,19 +119,19 @@ class TimelineViewController: UIViewController, TimelineLikeCollectionViewContro
     }
     
     // separate method because InstanceTimelineViewController needs to be able to customize it
-    func configureStatusCell(_ cell: TimelineStatusCollectionViewCell, id: String, state: CollapseState, filterResult: Filterer.Result) {
+    func configureStatusCell(_ cell: TimelineStatusCollectionViewCell, id: String, state: CollapseState, filterResult: Filterer.Result, precomputedContent: NSAttributedString?) {
         cell.delegate = self
         if case .home = timeline {
             cell.showFollowedHashtags = true
         } else {
             cell.showFollowedHashtags = false
         }
-        cell.updateUI(statusID: id, state: state, filterResult: filterResult)
+        cell.updateUI(statusID: id, state: state, filterResult: filterResult, precomputedContent: precomputedContent)
     }
     
     private func createDataSource() -> UICollectionViewDiffableDataSource<Section, Item> {
-        let statusCell = UICollectionView.CellRegistration<TimelineStatusCollectionViewCell, (String, CollapseState, Filterer.Result)> { [unowned self] cell, indexPath, item in
+        let statusCell = UICollectionView.CellRegistration<TimelineStatusCollectionViewCell, (String, CollapseState, Filterer.Result, NSAttributedString?)> { [unowned self] cell, indexPath, item in
-            self.configureStatusCell(cell, id: item.0, state: item.1, filterResult: item.2)
+            self.configureStatusCell(cell, id: item.0, state: item.1, filterResult: item.2, precomputedContent: item.3)
         }
         let zeroHeightCell = UICollectionView.CellRegistration<ZeroHeightCollectionViewCell, Void> { _, _, _ in
         }
@@ -148,10 +151,10 @@ class TimelineViewController: UIViewController, TimelineLikeCollectionViewContro
         return UICollectionViewDiffableDataSource(collectionView: collectionView) { [unowned self] collectionView, indexPath, itemIdentifier in
             switch itemIdentifier {
             case .status(id: let id, collapseState: let state, filterState: let filterState):
-                let result = filterResult(state: filterState, statusID: id)
+                let (result, attributedString) = filterResult(state: filterState, statusID: id)
                 switch result {
                 case .allow, .warn(_):
-                    return collectionView.dequeueConfiguredReusableCell(using: statusCell, for: indexPath, item: (id, state, result))
+                    return collectionView.dequeueConfiguredReusableCell(using: statusCell, for: indexPath, item: (id, state, result, nil))
                 case .hide:
                     return collectionView.dequeueConfiguredReusableCell(using: zeroHeightCell, for: indexPath, item: ())
                 }
@@ -329,7 +332,7 @@ class TimelineViewController: UIViewController, TimelineLikeCollectionViewContro
         isShowingTimelineDescription = false
     }
     
-    private func filterResult(state: FilterState, statusID: String) -> Filterer.Result {
+    private func filterResult(state: FilterState, statusID: String) -> (Filterer.Result, NSAttributedString?) {
         let status = {
             let status = self.mastodonController.persistentContainer.status(for: statusID)!
             // if the status is a reblog of another one, filter based on that one

Tusker/Views/Status/StatusCollectionViewCell.swift

@@ -76,14 +76,14 @@ extension StatusCollectionViewCell {
             .store(in: &cancellables)
     }
     
-    func doUpdateUI(status: StatusMO) {
+    func doUpdateUI(status: StatusMO, precomputedContent: NSAttributedString? = nil) {
         statusID = status.id
         accountID = status.account.id
         
         updateAccountUI(account: status.account)
         updateUIForPreferences(status: status)
         
-        contentContainer.contentTextView.setTextFrom(status: status)
+        contentContainer.contentTextView.setTextFrom(status: status, precomputed: precomputedContent)
         contentContainer.contentTextView.navigationDelegate = delegate
         contentContainer.attachmentsView.delegate = self
         contentContainer.attachmentsView.updateUI(status: status)
@@ -173,7 +173,7 @@ extension StatusCollectionViewCell {
     func updateGrayscaleableUI(status: StatusMO) {
         isGrayscale = Preferences.shared.grayscaleImages
         if contentContainer.contentTextView.hasEmojis {
-            contentContainer.contentTextView.setTextFrom(status: status)
+            contentContainer.contentTextView.setEmojis(status.emojis, identifier: status.id)
         }
         displayNameLabel.updateForAccountDisplayName(account: status.account)
     }

Tusker/Views/Status/StatusContentContainer.swift

@@ -11,7 +11,6 @@ import UIKit
 class StatusContentContainer: UIView {
 
      let contentTextView = StatusContentTextView().configure {
-         $0.defaultFont = UIFontMetrics(forTextStyle: .body).scaledFont(for: .systemFont(ofSize: 16))
          $0.adjustsFontForContentSizeCategory = true
          $0.isScrollEnabled = false
          $0.backgroundColor = nil

Tusker/Views/Status/TimelineStatusCollectionViewCell.swift

@@ -16,6 +16,8 @@ private let hashtagIcon = UIImage(systemName: "number")
 class TimelineStatusCollectionViewCell: UICollectionViewListCell, StatusCollectionViewCell {
     
     static let separatorInsets = NSDirectionalEdgeInsets(top: 0, leading: 16, bottom: 0, trailing: 0)
+    static let contentFont = UIFontMetrics(forTextStyle: .body).scaledFont(for: .systemFont(ofSize: 16))
+    static let contentParagraphStyle = HTMLConverter.defaultParagraphStyle
     
     // MARK: Subviews
     
@@ -164,6 +166,8 @@ class TimelineStatusCollectionViewCell: UICollectionViewListCell, StatusCollecti
     }
     
     let contentContainer = StatusContentContainer().configure {
+        $0.contentTextView.font = TimelineStatusCollectionViewCell.contentFont
+        $0.contentTextView.paragraphStyle = TimelineStatusCollectionViewCell.contentParagraphStyle
         $0.setContentHuggingPriority(.defaultLow, for: .vertical)
     }
     private var contentTextView: StatusContentTextView {
@@ -478,8 +482,7 @@ class TimelineStatusCollectionViewCell: UICollectionViewListCell, StatusCollecti
         }
     }
     
-    
+    func updateUI(statusID: String, state: CollapseState, filterResult: Filterer.Result, precomputedContent: NSAttributedString?) {
-    func updateUI(statusID: String, state: CollapseState, filterResult: Filterer.Result) {
         guard var status = mastodonController.persistentContainer.status(for: statusID) else {
             fatalError()
         }
@@ -531,7 +534,7 @@ class TimelineStatusCollectionViewCell: UICollectionViewListCell, StatusCollecti
         mainContainerTopToReblogLabelConstraint.isActive = !hideTimelineReason
         mainContainerTopToSelfConstraint.isActive = hideTimelineReason
         
-        doUpdateUI(status: status)
+        doUpdateUI(status: status, precomputedContent: precomputedContent)
         
         doUpdateTimestamp(status: status)
         timestampLabel.isHidden = showPinned

Tusker/Views/StatusContentTextView.swift

@@ -14,9 +14,13 @@ class StatusContentTextView: ContentTextView {
 
     private var statusID: String?
     
-    func setTextFrom(status: StatusMO) {
+    func setTextFrom(status: StatusMO, precomputed attributedText: NSAttributedString? = nil) {
         statusID = status.id
+        if let attributedText {
+            self.attributedText = attributedText
+        } else {
             setTextFromHtml(status.content)
+        }
         setEmojis(status.emojis, identifier: status.id)
     }