Add support for transforming Doxygen discussion/note tags

Sources/SwiftDocC/Model/Rendering/RenderContentCompiler.swift

@@ -354,6 +354,29 @@ struct RenderContentCompiler: MarkupVisitor {
         return renderableDirective.render(blockDirective, with: &self)
     }
 
+    mutating func visitDoxygenDiscussion(_ doxygenDiscussion: DoxygenDiscussion) -> [RenderContent] {
+        doxygenDiscussion.children.flatMap { self.visit($0) }
+    }
+
+    mutating func visitDoxygenNote(_ doxygenNote: DoxygenNote) -> [RenderContent] {
+        let content: [RenderBlockContent] = doxygenNote.children
+            .flatMap { self.visit($0) }
+            .map {
+                switch $0 {
+                case let inlineContent as RenderInlineContent:
+                    return .paragraph(.init(inlineContent: [inlineContent]))
+                case let blockContent as RenderBlockContent:
+                    return blockContent
+                default:
+                    fatalError("Unexpected content type in note: \(type(of: $0))")
+                }
+            }
+        return [RenderBlockContent.aside(.init(
+            style: .init(asideKind: .note),
+            content: content
+        ))]
+    }
+
     func defaultVisit(_ markup: Markup) -> [RenderContent] {
         return []
     }

Sources/SwiftDocC/Semantics/MarkupReferenceResolver.swift

@@ -40,7 +40,7 @@ fileprivate func removedLinkDestinationProblem(reference: ResolvedTopicReference
 }
 
 /**
- Rewrites a ``Markup`` tree to resolve ``UnresolvedTopicReference`s using a ``DocumentationContext``.
+ Rewrites a ``Markup`` tree to resolve ``UnresolvedTopicReference``s using a ``DocumentationContext``.
  */
 struct MarkupReferenceResolver: MarkupRewriter {
     var context: DocumentationContext

Tests/SwiftDocCTests/Semantics/DoxygenTests.swift

@@ -0,0 +1,150 @@
+/*
+ This source file is part of the Swift.org open source project
+
+ Copyright (c) 2024 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
+
+import XCTest
+@testable import SwiftDocC
+import SwiftDocCTestUtilities
+@testable import SymbolKit
+
+class DoxygenTests: XCTestCase {
+    func testDoxygenDiscussionAndNote() throws {
+        let documentationLines: [SymbolGraph.LineList.Line] = """
+            This is an abstract.
+
+            @discussion This is a discussion linking to ``AnotherClass`` and ``AnotherClass/prop``.
+
+            @note This is a note linking to ``Class3`` and ``Class3/prop2``.
+            """
+            .splitByNewlines
+            .enumerated()
+            .map { index, line in
+                SymbolGraph.LineList.Line(
+                    text: line,
+                    range: .init(start: .init(line: 1 + index, character: 1), end: .init(line: 1 + index, character: 1 + line.utf8.count))
+                )
+            }
+
+        let tempURL = try createTempFolder(content: [
+            Folder(name: "unit-test.docc", content: [
+                JSONFile(name: "ModuleName.symbols.json", content: makeSymbolGraph(
+                    moduleName: "ModuleName",
+                    symbols: [
+                        SymbolGraph.Symbol(
+                            identifier: .init(precise: "some-class-id", interfaceLanguage: SourceLanguage.swift.id),
+                            names: .init(title: "SomeClass", navigator: nil, subHeading: nil, prose: nil),
+                            pathComponents: ["SomeClass"],
+                            docComment: .init(documentationLines),
+                            accessLevel: .public,
+                            kind: .init(parsedIdentifier: .class, displayName: "Kind Display Name"),
+                            mixins: [:]
+                        ),
+                        SymbolGraph.Symbol(
+                            identifier: .init(precise: "another-class-id", interfaceLanguage: SourceLanguage.swift.id),
+                            names: .init(title: "AnotherClass", navigator: nil, subHeading: nil, prose: nil),
+                            pathComponents: ["AnotherClass"],
+                            docComment: nil,
+                            accessLevel: .public,
+                            kind: .init(parsedIdentifier: .class, displayName: "Kind Display Name"),
+                            mixins: [:]
+                        ),
+                        SymbolGraph.Symbol(
+                            identifier: .init(precise: "another-class-prop-id", interfaceLanguage: SourceLanguage.swift.id),
+                            names: .init(title: "prop", navigator: nil, subHeading: nil, prose: nil),
+                            pathComponents: ["AnotherClass", "prop"],
+                            docComment: nil,
+                            accessLevel: .public,
+                            kind: .init(parsedIdentifier: .property, displayName: "Kind Display Name"),
+                            mixins: [:]
+                        ),
+                        SymbolGraph.Symbol(
+                            identifier: .init(precise: "class3-id", interfaceLanguage: SourceLanguage.swift.id),
+                            names: .init(title: "Class3", navigator: nil, subHeading: nil, prose: nil),
+                            pathComponents: ["Class3"],
+                            docComment: nil,
+                            accessLevel: .public,
+                            kind: .init(parsedIdentifier: .class, displayName: "Kind Display Name"),
+                            mixins: [:]
+                        ),
+                        SymbolGraph.Symbol(
+                            identifier: .init(precise: "class3-prop-id", interfaceLanguage: SourceLanguage.swift.id),
+                            names: .init(title: "prop", navigator: nil, subHeading: nil, prose: nil),
+                            pathComponents: ["Class3", "prop"],
+                            docComment: nil,
+                            accessLevel: .public,
+                            kind: .init(parsedIdentifier: .property, displayName: "Kind Display Name"),
+                            mixins: [:]
+                        ),
+                    ]
+                )),
+            ])
+        ])
+
+        let (_, bundle, context) = try loadBundle(from: tempURL)
+        let reference = ResolvedTopicReference(bundleIdentifier: bundle.identifier, path: "/documentation/ModuleName/SomeClass", sourceLanguage: .swift)
+
+        // Verify the expected content in the in-memory model
+        let node = try context.entity(with: reference)
+        let symbol = try XCTUnwrap(node.semantic as? Symbol)
+
+        XCTAssertEqual(symbol.abstract?.format(), "This is an abstract.")
+        XCTAssertEqual(symbol.discussion?.content.map { $0.format() }, [
+            #"\discussion This is a discussion linking to ``doc://unit-test/documentation/ModuleName/AnotherClass`` and ``doc://unit-test/documentation/ModuleName/AnotherClass/prop``."#,
+            #"\note This is a note linking to ``doc://unit-test/documentation/ModuleName/Class3`` and ``Class3/prop2``."#
+        ])
+
+        // Verify the expected content in the render model
+        var translator = RenderNodeTranslator(context: context, bundle: bundle, identifier: node.reference, source: nil)
+        let renderNode = try XCTUnwrap(translator.visit(node.semantic) as? RenderNode)
+
+        XCTAssertEqual(renderNode.abstract, [.text("This is an abstract.")])
+        XCTAssertEqual(renderNode.primaryContentSections.count, 1)
+
+        let overviewSection = try XCTUnwrap(renderNode.primaryContentSections.first as? ContentRenderSection)
+        XCTAssertEqual(overviewSection.content.count, 3)
+        XCTAssertEqual(overviewSection.content, [
+            .heading(.init(level: 2, text: "Overview", anchor: "overview")),
+
+            .paragraph(.init(inlineContent: [
+                .text("This is a discussion linking to "),
+                .reference(
+                    identifier: .init("doc://unit-test/documentation/ModuleName/AnotherClass"),
+                    isActive: true,
+                    overridingTitle: nil,
+                    overridingTitleInlineContent: nil
+                ),
+                .text(" and "),
+                .reference(
+                    identifier: .init("doc://unit-test/documentation/ModuleName/AnotherClass/prop"),
+                    isActive: true,
+                    overridingTitle: nil,
+                    overridingTitleInlineContent: nil
+                ),
+                .text(".")
+            ])),
+
+            .aside(.init(style: .init(asideKind: .note), content: [
+                .paragraph(.init(inlineContent: [
+                    .text("This is a note linking to "),
+                    .reference(
+                        identifier: .init("doc://unit-test/documentation/ModuleName/Class3"),
+                        isActive: true,
+                        overridingTitle: nil,
+                        overridingTitleInlineContent: nil
+                    ),
+                    .text(" and "),
+                    .codeVoice(code: "Class3/prop2"),
+                    .text(".")
+                ]))
+            ])),
+        ])
+    }
+}