Implement Logging Infrastructure

Package.swift

@@ -19,13 +19,15 @@ let package = Package(
         .package(url: "https://github.com/SwiftDocOrg/Markup.git", .upToNextMinor(from: "0.0.3")),
         .package(url: "https://github.com/NSHipster/SwiftSyntaxHighlighter.git", .revision("1.0.0")),
         .package(url: "https://github.com/apple/swift-argument-parser.git", .upToNextMinor(from: "0.0.2")),
+        .package(url: "https://github.com/apple/swift-log.git", .upToNextMinor(from: "1.2.0")),
+        .package(url: "https://github.com/NSHipster/swift-log-github-actions.git", .upToNextMinor(from: "0.0.1")),
     ],
     targets: [
         // Targets are the basic building blocks of a package. A target can define a module or a test suite.
         // Targets can depend on other targets in this package, and on products in packages which this package depends on.
         .target(
             name: "swift-doc",
-            dependencies: ["ArgumentParser", "SwiftDoc", "SwiftSemantics", "SwiftMarkup", "CommonMarkBuilder", "HypertextLiteral", "Markup", "DCOV", "GraphViz", "SwiftSyntaxHighlighter"]
+            dependencies: ["ArgumentParser", "SwiftDoc", "SwiftSemantics", "SwiftMarkup", "CommonMarkBuilder", "HypertextLiteral", "Markup", "DCOV", "GraphViz", "SwiftSyntaxHighlighter", "Logging", "LoggingGitHubActions"]
         ),
         .target(
             name: "DCOV",

Sources/swift-doc/Subcommands/Generate.swift

@@ -90,6 +90,8 @@ extension SwiftDoc {
                     let url = outputDirectoryURL.appendingPathComponent(filename)
                     try $0.value.write(to: url, format: format)
                 }
+            } catch {
+                logger.error("\(error)")
             }
         }
     }

Sources/swift-doc/Supporting Types/Components/Relationships.swift

@@ -86,7 +86,7 @@ struct Relationships: Component {
         do {
             svg = try HypertextLiteral.HTML(String(data: graph.render(using: algorithm, to: .svg), encoding: .utf8) ?? "")
         } catch {
-            print(error)
+            logger.error("\(error)")
         }
 
         return #"""

Sources/swift-doc/main.swift

@@ -1,5 +1,17 @@
 import ArgumentParser
 import Foundation
+import Logging
+import LoggingGitHubActions
+
+LoggingSystem.bootstrap { label in
+    if ProcessInfo.processInfo.environment["GITHUB_ACTIONS"] == "true" {
+        return GitHubActionsLogHandler.standardOutput(label: label)
+    } else {
+        return StreamLogHandler.standardOutput(label: label)
+    }
+}
+
+let logger = Logger(label: "org.swiftdoc.swift-doc")
 
 let fileManager = FileManager.default
 let fileAttributes: [FileAttributeKey : Any] = [.posixPermissions: 0o744]
@@ -10,8 +22,7 @@ var standardError = FileHandle.standardError
 struct SwiftDoc: ParsableCommand {
     static var configuration = CommandConfiguration(
         abstract: "A utility for generating documentation for Swift code.",
-        subcommands: [Generate.self, Coverage.self, Diagram.self],
-        defaultSubcommand: Generate.self
+        subcommands: [Generate.self, Coverage.self, Diagram.self]
     )
 }