Make converting a Link to a Locator synchronous

CHANGELOG.md

@@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file. Take a look
 
 ## [Unreleased]
 
+### Changed
+
+#### Shared
+
+* Converting a `Link` to a `Locator` is now synchronous: `await publication.locate(link)` becomes `publication.locator(for: link)`. The logic moved to `Manifest`, so it is also available as `manifest.locator(for: link)` without a `Publication`.
+
 ### Fixed
 
 #### Navigator

Sources/Navigator/Audiobook/AudioNavigator.swift

@@ -519,7 +519,7 @@ public final class AudioNavigator: Navigator, Configurable, AudioSessionUser, Lo
     }
 
     public func go(to link: Link, options: NavigatorGoOptions) async -> Bool {
-        guard let locator = await publication.locate(link) else {
+        guard let locator = publication.locator(for: link) else {
             return false
         }
         return await go(to: locator, options: options)

Sources/Navigator/EPUB/EPUBNavigatorViewController.swift

@@ -666,10 +666,10 @@ open class EPUBNavigatorViewController: InputObservableViewController,
         let (locator, viewport) = await EPUBViewportAndLocationCalculator.compute(
             readingOrderIndices: spreadView.spread.readingOrderIndices,
             progression: { spreadView.progression(in: $0) },
+            manifest: publication.manifest,
             readingOrder: readingOrder,
             positionsByReadingOrder: positionsByReadingOrder,
-            tableOfContentsTitleByHref: tableOfContentsTitleByHref,
-            fallbackLocator: { [publication] in await publication.locate($0) }
+            tableOfContentsTitleByHref: tableOfContentsTitleByHref
         )
         return (locator, viewport)
     }
@@ -727,7 +727,7 @@ open class EPUBNavigatorViewController: InputObservableViewController,
     }
 
     public func go(to link: Link, options: NavigatorGoOptions) async -> Bool {
-        guard let locator = await publication.locate(link) else {
+        guard let locator = publication.locator(for: link) else {
             return false
         }
         return await go(to: locator, options: options)

Sources/Navigator/EPUB/EPUBViewportAndLocationCalculator.swift

@@ -9,7 +9,6 @@ import ReadiumShared
 
 /// Computes the current `Locator` and `Viewport` from a spread's visible
 /// progressions and the publication's position list.
-@MainActor
 enum EPUBViewportAndLocationCalculator {
     /// Computes the locator and viewport for the currently visible spread.
     ///
@@ -20,22 +19,23 @@ enum EPUBViewportAndLocationCalculator {
     ///   - progression: Returns the visible scroll progression range (0–1)
     ///     for a given reading-order index. For fixed-layout resources this
     ///     is always `0...1`.
-    ///   - readingOrder: The publication's reading order links.
+    ///   - manifest: The publication's manifest, used to build a basic locator
+    ///     for the first visible link when no positions are available.
+    ///   - readingOrder: The links displayed by the navigator, indexed by
+    ///     `readingOrderIndices`. May differ from the manifest's reading order
+    ///     when the navigator was given a custom one.
     ///   - positionsByReadingOrder: Positions grouped by reading-order index.
     ///     May be empty if the publication has no positions.
     ///   - tableOfContentsTitleByHref: Mapping from resource URL to its table-
     ///     of-contents title, used to populate `Locator.title`.
-    ///   - fallbackLocator: Called with the first visible link when no
-    ///     positions are available; should return a basic locator for that
-    ///     link (e.g. from `Publication.locate(_:)`).
     static func compute(
         readingOrderIndices: ClosedRange<Int>,
         progression: (Int) -> ClosedRange<Double>,
+        manifest: Manifest,
         readingOrder: [Link],
         positionsByReadingOrder: [[Locator]],
-        tableOfContentsTitleByHref: [AnyURL: String],
-        fallbackLocator: (Link) async -> Locator?
-    ) async -> (locator: Locator?, viewport: NavigatorViewport) {
+        tableOfContentsTitleByHref: [AnyURL: String]
+    ) -> (locator: Locator?, viewport: NavigatorViewport) {
         let firstIndex = readingOrderIndices.lowerBound
         let lastIndex = readingOrderIndices.upperBound
         let firstProgressionInFirstResource = min(max(progression(firstIndex).lowerBound, 0.0), 1.0)
@@ -117,7 +117,7 @@ enum EPUBViewportAndLocationCalculator {
             return (locator, viewport)
 
         } else {
-            locator = await fallbackLocator(link)?.copy(
+            locator = manifest.locator(for: link)?.copy(
                 locations: { $0.progression = firstProgressionInFirstResource }
             )
 

Sources/Navigator/PDF/PDFNavigatorViewController.swift

@@ -728,7 +728,7 @@ open class PDFNavigatorViewController:
     }
 
     public func go(to link: Link, options: NavigatorGoOptions) async -> Bool {
-        guard let locator = await publication.locate(link) else {
+        guard let locator = publication.locator(for: link) else {
             return false
         }
 

Sources/Shared/Publication/Manifest.swift

@@ -171,4 +171,31 @@ public struct Manifest: Hashable, Sendable, JSONValueDecodable, JSONObjectEncoda
     public func linksMatching(_ predicate: (Link) -> Bool) -> [Link] {
         (readingOrder + resources + links).filter(predicate)
     }
+
+    /// Creates a new `Locator` pointing to the resource targeted by the given
+    /// `link`.
+    ///
+    /// Returns `nil` if the resource is not found in the manifest.
+    public func locator(for link: Link) -> Locator? {
+        let originalHREF = link.url()
+        let fragment = originalHREF.fragment
+        let href = originalHREF.removingFragment()
+
+        guard
+            let resourceLink = linkWithHREF(href),
+            let mediaType = resourceLink.mediaType
+        else {
+            return nil
+        }
+
+        return Locator(
+            href: href,
+            mediaType: mediaType,
+            title: resourceLink.title ?? link.title,
+            locations: Locator.Locations(
+                fragments: Array(ofNotNil: fragment),
+                progression: (fragment == nil) ? 0.0 : nil
+            )
+        )
+    }
 }

Sources/Shared/Publication/Publication.swift

@@ -104,6 +104,19 @@ public final class Publication: Sendable, Loggable {
         manifest.linksWithRel(rel)
     }
 
+    /// Creates a new `Locator` pointing to the resource targeted by the given
+    /// `link`.
+    ///
+    /// Returns `nil` if the resource is not found in the publication.
+    public func locator(for link: Link) -> Locator? {
+        manifest.locator(for: link)
+    }
+
+    @available(*, unavailable, renamed: "locator(for:)")
+    public func locate(_ link: Link) async -> Locator? {
+        fatalError()
+    }
+
     /// Returns the resource targeted by the given `link`.
     public func get(_ link: Link) -> Resource? {
         assert(!link.templated, "You must expand templated links before calling `Publication.get`")

Sources/Shared/Publication/Services/Content/Iterators/PublicationContentIterator.swift

@@ -126,7 +126,7 @@ public actor PublicationContentIterator: ContentIterator, Loggable {
         let link = publication.readingOrder[index]
         guard
             let resource = publication.get(link),
-            let locator = await location.toLocator(to: link, in: publication)
+            let locator = location.toLocator(to: link, in: publication)
         else {
             return nil
         }
@@ -149,12 +149,12 @@ private enum LocatorOrProgression {
     case locator(Locator)
     case progression(Double)
 
-    func toLocator(to link: Link, in publication: Publication) async -> Locator? {
+    func toLocator(to link: Link, in publication: Publication) -> Locator? {
         switch self {
         case let .locator(locator):
             return locator
         case let .progression(progression):
-            return await publication.locate(link)?.copy(locations: { $0.progression = progression })
+            return publication.locator(for: link)?.copy(locations: { $0.progression = progression })
         }
     }
 }

Sources/Shared/Publication/Services/Locator/DefaultLocatorService.swift

@@ -41,27 +41,9 @@ public final class DefaultLocatorService: Sendable, LocatorService, Loggable {
         return nil
     }
 
+    @available(*, unavailable, message: "Use `Publication.locator(for:)` instead.")
     public func locate(_ link: Link) async -> Locator? {
-        let originalHREF = link.url()
-        let fragment = originalHREF.fragment
-        let href = originalHREF.removingFragment()
-
-        guard
-            let resourceLink = publication()?.linkWithHREF(href),
-            let type = resourceLink.mediaType
-        else {
-            return nil
-        }
-
-        return Locator(
-            href: href,
-            mediaType: type,
-            title: resourceLink.title ?? link.title,
-            locations: Locator.Locations(
-                fragments: Array(ofNotNil: fragment),
-                progression: (fragment == nil) ? 0.0 : nil
-            )
-        )
+        fatalError()
     }
 
     public func locate(progression totalProgression: Double) async -> Locator? {

Sources/Shared/Publication/Services/Locator/LocatorService.swift

@@ -19,9 +19,6 @@ public protocol LocatorService: PublicationService {
     /// Locates the target of the given `locator`.
     func locate(_ locator: Locator) async -> Locator?
 
-    /// Locates the target of the given `link`.
-    func locate(_ link: Link) async -> Locator?
-
     /// Locates the target at the given `progression` relative to the whole publication.
     func locate(progression: Double) async -> Locator?
 }
@@ -31,10 +28,6 @@ public extension LocatorService {
         nil
     }
 
-    func locate(_ link: Link) async -> Locator? {
-        nil
-    }
-
     func locate(progression: Double) async -> Locator? {
         nil
     }
@@ -52,11 +45,6 @@ public extension Publication {
     func locate(progression: Double) async -> Locator? {
         await findService(LocatorService.self)?.locate(progression: progression)
     }
-
-    /// Locates the target of the given `link`.
-    func locate(_ link: Link) async -> Locator? {
-        await findService(LocatorService.self)?.locate(link)
-    }
 }
 
 // MARK: PublicationServicesBuilder Helpers

Sources/Streamer/Parser/Audio/Services/AudioLocatorService.swift

@@ -27,16 +27,13 @@ final class AudioLocatorService: LocatorService {
     /// Total duration of the publication.
     private let totalDuration: Double?
 
-    private let locatorService: DefaultLocatorService
-
     init(readingOrder: [Link], publication: Weak<Publication>) {
         self.publication = publication
         self.readingOrder = readingOrder
         let durations = readingOrder.map { $0.duration ?? 0 }
         self.durations = durations
         let total = durations.reduce(0, +)
         totalDuration = (total > 0) ? total : nil
-        locatorService = DefaultLocatorService(publication: publication)
     }
 
     func locate(_ locator: Locator) async -> Locator? {
@@ -50,8 +47,8 @@ final class AudioLocatorService: LocatorService {
 
         // Routes the `totalProgression` fallback through this service's audio
         // `locate(progression:)`, which is duration-based. Delegating to
-        // `locatorService.locate(locator)` would instead use the default
-        // positions-based progression and lose the audio behavior.
+        // `DefaultLocatorService` would instead use the default positions-based
+        // progression and lose the audio behavior.
         if
             let totalProgression = locator.locations.totalProgression,
             let target = await locate(progression: totalProgression)
@@ -65,10 +62,6 @@ final class AudioLocatorService: LocatorService {
         return nil
     }
 
-    func locate(_ link: Link) async -> Locator? {
-        await locatorService.locate(link)
-    }
-
     func locate(progression: Double) async -> Locator? {
         guard let totalDuration = totalDuration else {
             return nil

TestApp/Sources/Reader/Common/Outline/OutlineTableView.swift

@@ -60,10 +60,8 @@ struct OutlineTableView: View {
                             .frame(maxWidth: .infinity, alignment: .leading)
                             .contentShape(Rectangle())
                             .onTapGesture {
-                                Task {
-                                    if let locator = await publication.locate(item.link) {
-                                        locatorSubject.send(locator)
-                                    }
+                                if let locator = publication.locator(for: item.link) {
+                                    locatorSubject.send(locator)
                                 }
                             }
                     }

TestApp/Sources/Reader/Common/VisualReaderViewController.swift

@@ -362,10 +362,10 @@ class VisualReaderViewController<N: UIViewController & Navigator>: ReaderViewCon
     /// description of the image.
     private func openFromImagePreview(_ link: ReadiumShared.Link) {
         Task {
-            // `locate` runs first: the href is only inspected once it comes
-            // back nil, so a remote publication whose in-publication links are
-            // themselves absolute is not misrouted to the browser.
-            let locator = await publication.locate(link)
+            // `locator(for:)` runs first: the href is only inspected once it
+            // comes back nil, so a remote publication whose in-publication
+            // links are themselves absolute is not misrouted to the browser.
+            let locator = publication.locator(for: link)
             let externalURL = (locator == nil) ? link.httpURL : nil
             if locator == nil, externalURL == nil {
                 log(.error, "Cannot locate the extended description at \(link.href)")
@@ -416,7 +416,7 @@ extension VisualReaderViewController {
         for (index, link) in publication.pageList.enumerated() {
             guard
                 let title = link.title,
-                let locator = await publication.locate(link)
+                let locator = publication.locator(for: link)
             else {
                 continue
             }