[Feature] Add isAutolink property to Link (swiftlang#110)

rdar://106656851

Author: Kyle-Ye

Sources/Markdown/Inline Nodes/Inline Containers/Link.swift

@@ -1,7 +1,7 @@
 /*
  This source file is part of the Swift.org open source project
 
- Copyright (c) 2021 Apple Inc. and the Swift project authors
+ Copyright (c) 2021-2023 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
@@ -63,6 +63,16 @@ public extension Link {
         }
     }
 
+    var isAutolink: Bool {
+        guard let destination,
+              childCount == 1,
+              let text = child(at: 0) as? Text,
+              destination == text.string else {
+            return false
+        }
+        return true
+    }
+
     // MARK: Visitation
 
     func accept<V: MarkupVisitor>(_ visitor: inout V) -> V.Result {

Sources/Markdown/Walker/Walkers/MarkupFormatter.swift

@@ -819,11 +819,8 @@ public struct MarkupFormatter: MarkupWalker {
     public mutating func visitLink(_ link: Link) {
         let savedState = state
         if formattingOptions.condenseAutolinks,
-            let destination = link.destination,
-        link.childCount == 1,
-        let text = link.child(at: 0) as? Text,
-            // Print autolink-style
-            destination == text.string {
+           link.isAutolink,
+           let destination = link.destination {
             print("<\(destination)>", for: link)
         } else {
             func printRegularLink() {

Tests/MarkdownTests/Inline Nodes/LinkTests.swift

@@ -1,7 +1,7 @@
 /*
  This source file is part of the Swift.org open source project
 
- Copyright (c) 2021 Apple Inc. and the Swift project authors
+ Copyright (c) 2021-2023 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
@@ -34,4 +34,18 @@ class LinkTests: XCTestCase {
             """
         XCTAssertEqual(expectedDump, link.debugDescription())
     }
+    
+    func testAutoLink() {
+        let children = [Text("example.com")]
+        var link = Link(destination: "example.com", children)
+        let expectedDump = """
+            Link destination: "example.com"
+            └─ Text "example.com"
+            """
+        XCTAssertEqual(expectedDump, link.debugDescription())
+        XCTAssertTrue(link.isAutolink)
+        
+        link.destination = "test.example.com"
+        XCTAssertFalse(link.isAutolink)
+    }
 }