Filter topics languages in articles

Sources/SwiftDocC/Model/Rendering/RenderNodeTranslator.swift

@@ -622,84 +622,120 @@ public struct RenderNodeTranslator: SemanticVisitor {
             node.primaryContentSections.append(ContentRenderSection(kind: .content, content: discussionContent, heading: title))
         }
 
-        if let topics = article.topics, !topics.taskGroups.isEmpty {
-            // Don't set an eyebrow as collections and groups don't have one; append the authored Topics section
-            node.topicSections.append(
-                contentsOf: renderGroups(
-                    topics,
-                    allowExternalLinks: false,
-                    allowedTraits: documentationNode.availableVariantTraits,
-                    contentCompiler: &contentCompiler
+        node.topicSectionsVariants = VariantCollection<[TaskGroupRenderSection]>(
+            from: documentationNode.availableVariantTraits,
+            fallbackDefaultValue: []
+        ) { trait in
+            var sections = [TaskGroupRenderSection]()
+
+            if let topics = article.topics, !topics.taskGroups.isEmpty {
+                // Don't set an eyebrow as collections and groups don't have one; append the authored Topics section
+                sections.append(
+                    contentsOf: renderGroups(
+                        topics,
+                        allowExternalLinks: false,
+                        allowedTraits: [trait],
+                        contentCompiler: &contentCompiler
+                    )
                 )
-            )
-        }
-
-        // Place "top" rendering preference automatic task groups
-        // after any user-defined task groups but before automatic curation.
-        if !article.automaticTaskGroups.isEmpty {
-            node.topicSections.append(contentsOf: renderAutomaticTaskGroupsSection(article.automaticTaskGroups.filter({ $0.renderPositionPreference == .top }), contentCompiler: &contentCompiler))
-        }
-
-        // If there are no manually curated topics, and no automatic groups, try generating automatic groups by child kind.
-        if (article.topics == nil || article.topics?.taskGroups.isEmpty == true) &&
-            article.automaticTaskGroups.isEmpty {
-            // If there are no authored child topics in docs or markdown,
-            // inspect the topic graph, find this node's children, and
-            // for the ones found curate them automatically in task groups.
-            // Automatic groups are named after the child's kind, e.g.
-            // "Methods", "Variables", etc.
-            let alreadyCurated = Set(node.topicSections.flatMap { $0.identifiers })
-            let groups = try! AutomaticCuration.topics(for: documentationNode, withTrait: nil, context: context)
-                .compactMap({ group -> AutomaticCuration.TaskGroup? in
-                    // Remove references that have been already curated.
-                    let newReferences = group.references.filter { !alreadyCurated.contains($0.absoluteString) }
-                    // Remove groups that have no uncurated references
-                    guard !newReferences.isEmpty else { return nil }
-
-                    return (title: group.title, references: newReferences)
-                })
+            }
 
-            // Collect all child topic references.
-            contentCompiler.collectedTopicReferences.append(contentsOf: groups.flatMap(\.references))
-            // Add the final groups to the node.
-            node.topicSections.append(contentsOf: groups.map(TaskGroupRenderSection.init(taskGroup:)))
-        }
+            // Place "top" rendering preference automatic task groups
+            // after any user-defined task groups but before automatic curation.
+            if !article.automaticTaskGroups.isEmpty {
+                sections.append(
+                    contentsOf: renderAutomaticTaskGroupsSection(
+                        article.automaticTaskGroups.filter { $0.renderPositionPreference == .top },
+                        contentCompiler: &contentCompiler
+                    )
+                )
+            }
+
+            // If there are no manually curated topics, and no automatic groups, try generating automatic groups by
+            // child kind.
+            if (article.topics == nil || article.topics?.taskGroups.isEmpty == true) &&
+                article.automaticTaskGroups.isEmpty {
+                // If there are no authored child topics in docs or markdown,
+                // inspect the topic graph, find this node's children, and
+                // for the ones found curate them automatically in task groups.
+                // Automatic groups are named after the child's kind, e.g.
+                // "Methods", "Variables", etc.
+                let alreadyCurated = Set(node.topicSections.flatMap { $0.identifiers })
+                let groups = try! AutomaticCuration.topics(for: documentationNode, withTrait: nil, context: context)
+                    .compactMap({ group -> AutomaticCuration.TaskGroup? in
+                        // Remove references that have been already curated.
+                        let newReferences = group.references.filter { !alreadyCurated.contains($0.absoluteString) }
+                        // Remove groups that have no uncurated references
+                        guard !newReferences.isEmpty else { return nil }
+
+                        return (title: group.title, references: newReferences)
+                    })
+
+                // Collect all child topic references.
+                contentCompiler.collectedTopicReferences.append(contentsOf: groups.flatMap(\.references))
+                // Add the final groups to the node.
+                sections.append(contentsOf: groups.map(TaskGroupRenderSection.init(taskGroup:)))
+            }
+
+            // Place "bottom" rendering preference automatic task groups
+            // after any user-defined task groups but before automatic curation.
+            if !article.automaticTaskGroups.isEmpty {
+                sections.append(
+                    contentsOf: renderAutomaticTaskGroupsSection(
+                        article.automaticTaskGroups.filter { $0.renderPositionPreference == .bottom },
+                        contentCompiler: &contentCompiler
+                    )
+                )
+            }
+
+            return sections
+        } ?? .init(defaultValue: [])
 
-        // Place "bottom" rendering preference automatic task groups
-        // after any user-defined task groups but before automatic curation.
-        if !article.automaticTaskGroups.isEmpty {
-            node.topicSections.append(contentsOf: renderAutomaticTaskGroupsSection(article.automaticTaskGroups.filter({ $0.renderPositionPreference == .bottom }), contentCompiler: &contentCompiler))
-        }
 
         if node.topicSections.isEmpty {
             // Set an eyebrow for articles
             node.metadata.roleHeading = "Article"
         }
         node.metadata.role = contentRenderer.roleForArticle(article, nodeKind: documentationNode.kind).rawValue
 
-        // Authored See Also section
-        if let seeAlso = article.seeAlso, !seeAlso.taskGroups.isEmpty {
-            node.seeAlsoSections.append(
-                contentsOf: renderGroups(
-                    seeAlso,
-                    allowExternalLinks: true,
-                    allowedTraits: documentationNode.availableVariantTraits,
-                    contentCompiler: &contentCompiler
+        node.seeAlsoSectionsVariants = VariantCollection<[TaskGroupRenderSection]>(
+            from: documentationNode.availableVariantTraits,
+            fallbackDefaultValue: []
+        ) { trait in
+            var seeAlsoSections = [TaskGroupRenderSection]()
+
+            // Authored See Also section
+            if let seeAlso = article.seeAlso, !seeAlso.taskGroups.isEmpty {
+                seeAlsoSections.append(
+                    contentsOf: renderGroups(
+                        seeAlso,
+                        allowExternalLinks: true,
+                        allowedTraits: [trait],
+                        contentCompiler: &contentCompiler
+                    )
                 )
-            )
-        }
-
-        // Automatic See Also section
-        if let seeAlso = try! AutomaticCuration.seeAlso(for: documentationNode, context: context, bundle: bundle, renderContext: renderContext, renderer: contentRenderer) {
-            contentCompiler.collectedTopicReferences.append(contentsOf: seeAlso.references)
-            node.seeAlsoSections.append(TaskGroupRenderSection(
-                title: seeAlso.title,
-                abstract: nil,
-                discussion: nil,
-                identifiers: seeAlso.references.map { $0.absoluteString },
-                generated: true
-            ))
-        }
+            }
+
+            // Automatic See Also section
+            if let seeAlso = try! AutomaticCuration.seeAlso(
+                for: documentationNode,
+                context: context,
+                bundle: bundle,
+                renderContext: renderContext,
+                renderer: contentRenderer
+            ) {
+                contentCompiler.collectedTopicReferences.append(contentsOf: seeAlso.references)
+                seeAlsoSections.append(TaskGroupRenderSection(
+                    title: seeAlso.title,
+                    abstract: nil,
+                    discussion: nil,
+                    identifiers: seeAlso.references.map { $0.absoluteString },
+                    generated: true
+                ))
+            }
+
+            return seeAlsoSections
+        } ?? .init(defaultValue: [])
 
         collectedTopicReferences.append(contentsOf: contentCompiler.collectedTopicReferences)
         node.references = createTopicRenderReferences()

Sources/SwiftDocC/Model/Rendering/Variants/VariantCollection+Coding.swift

@@ -39,15 +39,19 @@ extension KeyedEncodingContainer {
         )
     }
 
-    /// Encodes the given variant collection.
+    /// Encodes the given variant collection for its non-empty values.
     mutating func encodeVariantCollectionIfNotEmpty<Value>(
         _ variantCollection: VariantCollection<Value>,
         forKey key: Key,
         encoder: Encoder
     ) throws where Value: Collection {
         try encodeIfNotEmpty(variantCollection.defaultValue, forKey: key)
 
-        variantCollection.addVariantsToEncoder(
+        variantCollection.mapValues { value in
+            // Encode `nil` if the value is empty, so that when the patch is applied, it effectively
+            // removes the default value.
+            value.isEmpty ? nil : value
+        }.addVariantsToEncoder(
             encoder,
 
             // Add the key to the encoder's coding path, since the coding path refers to the value's parent.

Sources/SwiftDocC/Model/Rendering/Variants/VariantCollection+Variant.swift

@@ -0,0 +1,42 @@
+/*
+ This source file is part of the Swift.org open source project
+
+ Copyright (c) 2022 Apple Inc. and the Swift project authors
+ Licensed under Apache License v2.0 with Runtime Library Exception
+
+ See https://swift.org/LICENSE.txt for license information
+ See https://swift.org/CONTRIBUTORS.txt for Swift project authors
+*/
+
+import Foundation
+
+public extension VariantCollection {
+    /// A variant for a render node value.
+    struct Variant<Value: Codable> {
+        /// The traits associated with the override.
+        public var traits: [RenderNode.Variant.Trait]
+
+        /// The patch to apply as part of the override.
+        public var patch: [VariantPatchOperation<Value>]
+
+        /// Creates an override value for the given traits.
+        ///
+        /// - Parameters:
+        ///   - traits: The traits associated with this override value.
+        ///   - patch: The patch to apply as part of the override.
+        public init(traits: [RenderNode.Variant.Trait], patch: [VariantPatchOperation<Value>]) {
+            self.traits = traits
+            self.patch = patch
+        }
+
+        /// Returns a new variant collection containing the traits of this variant collection with the values transformed by the given closure.
+        public func mapPatch<TransformedValue>(
+            _ transform: (Value) -> TransformedValue
+        ) -> VariantCollection<TransformedValue>.Variant<TransformedValue> {
+            VariantCollection<TransformedValue>.Variant<TransformedValue>(
+                traits: traits,
+                patch: patch.map { patchOperation in patchOperation.map(transform) }
+            )
+        }
+    }
+}

Sources/SwiftDocC/Model/Rendering/Variants/VariantCollection.swift

@@ -91,25 +91,16 @@ public struct VariantCollection<Value: Codable>: Codable {
 
         encoder.userInfoVariantOverrides?.add(contentsOf: overrides)
     }
-}
-
-public extension VariantCollection {
-    /// A variant for a render node value.
-    struct Variant<Value: Codable> {
-        /// The traits associated with the override.
-        public var traits: [RenderNode.Variant.Trait]
-
-        /// The patch to apply as part of the override.
-        public var patch: [VariantPatchOperation<Value>]
-
-        /// Creates an override value for the given traits.
-        ///
-        /// - Parameters:
-        ///   - traits: The traits associated with this override value.
-        ///   - patch: The patch to apply as part of the override.
-        public init(traits: [RenderNode.Variant.Trait], patch: [VariantPatchOperation<Value>]) {
-            self.traits = traits
-            self.patch = patch
-        }
+
+    /// Returns a variant collection containing the results of calling the given transformation with each value of this variant collection.
+    public func mapValues<TransformedValue>(
+        _ transform: (Value) -> TransformedValue
+    ) -> VariantCollection<TransformedValue> {
+        VariantCollection<TransformedValue>(
+            defaultValue: transform(defaultValue),
+            variants: variants.map { variant in
+                variant.mapPatch(transform)
+            }
+        )
     }
 }

Sources/SwiftDocC/Model/Rendering/Variants/VariantPatchOperation.swift

@@ -17,6 +17,9 @@ public enum VariantPatchOperation<Value: Codable> {
     /// - Parameter value: The value to use in the replacement.
     case replace(value: Value)
 
+    /// An addition operation.
+    ///
+    /// - Parameter value: The value to use in the addition.
     case add(value: Value)
 
     /// A removal operation.
@@ -33,6 +36,24 @@ public enum VariantPatchOperation<Value: Codable> {
             return .remove
         }
     }
+
+    /// Returns a new patch operation with its value transformed using the given closure.
+    ///
+    /// If the patch operation doesn't have a value—for example, if it's a removal operation—the operation is returned unmodified.
+    func map<TransformedValue>(
+        _ transform: (Value) -> TransformedValue
+    ) -> VariantPatchOperation<TransformedValue> {
+        switch self {
+        case .replace(let value):
+            return VariantPatchOperation<TransformedValue>.replace(value: transform(value))
+
+        case .add(let value):
+            return VariantPatchOperation<TransformedValue>.add(value: transform(value))
+
+        case .remove:
+            return .remove
+        }
+    }
 }
 
 extension VariantCollection.Variant where Value: RangeReplaceableCollection {

Sources/SwiftDocC/Semantics/Article/Article.swift

@@ -75,7 +75,7 @@ public final class Article: Semantic, MarkupConvertible, Abstracted, Redirected,
     private(set) public var abstractSection: AbstractSection?
 
     /// The Topic curation section of the article.
-    private(set) public var topics: TopicsSection?
+    internal(set) public var topics: TopicsSection?
 
     /// The See Also section of the article.
     private(set) public var seeAlso: SeeAlsoSection?

Tests/SwiftDocCTests/Indexing/RenderIndexTests.swift

@@ -121,6 +121,22 @@ final class RenderIndexTests: XCTestCase {
                         "path": "/documentation/mixedlanguageframework/article",
                         "type": "article"
                       },
+                      {
+                        "title": "APICollection",
+                        "path": "/documentation/mixedlanguageframework/apicollection",
+                        "type": "symbol",
+                        "children": [
+                            {
+                              "title": "Objective-C–only APIs",
+                              "type": "groupMarker"
+                            },
+                            {
+                              "title": "_MixedLanguageFrameworkVersionNumber",
+                              "path": "/documentation/mixedlanguageframework/_mixedlanguageframeworkversionnumber",
+                              "type": "var"
+                            }
+                        ]
+                      },
                       {
                         "title": "Classes",
                         "type": "groupMarker"
@@ -262,6 +278,33 @@ final class RenderIndexTests: XCTestCase {
                         "path": "/documentation/mixedlanguageframework/article",
                         "type": "article"
                       },
+                      {
+                        "path": "/documentation/mixedlanguageframework/apicollection",
+                        "title": "APICollection",
+                        "type": "symbol",
+                        "children": [
+                          {
+                            "title": "Swift-only APIs",
+                            "type": "groupMarker"
+                          },
+                          {
+                            "path": "/documentation/mixedlanguageframework/swiftonlystruct",
+                            "title": "SwiftOnlyStruct",
+                            "type": "struct",
+                            "children": [
+                              {
+                                "title": "Instance Methods",
+                                "type": "groupMarker"
+                              },
+                              {
+                                "title": "func tada()",
+                                "path": "/documentation/mixedlanguageframework/swiftonlystruct/tada()",
+                                "type": "method"
+                              }
+                            ]
+                          }
+                        ]
+                      },
                       {
                         "title": "Classes",
                         "type": "groupMarker"