Adopt ArgumentParser for the command-line tool

.gitignore

@@ -6,3 +6,5 @@ Package.resolved
 /*.xcodeproj
 /*.sublime-project
 /*.sublime-workspace
+/.swiftpm
+

Package.swift

@@ -18,7 +18,9 @@ let package = Package(
       name: "tibs",
       targets: ["tibs"])
   ],
-  dependencies: [],
+  dependencies: [
+    .package(url: "https://github.com/apple/swift-argument-parser", from: "0.2.0"),
+  ],
   targets: [
 
     // MARK: Swift interface
@@ -45,7 +47,7 @@ let package = Package(
     // Commandline tool for working with tibs projects.
     .target(
       name: "tibs",
-      dependencies: ["ISDBTibs"]),
+      dependencies: ["ISDBTibs", "ArgumentParser"]),
 
     // Test support library, built on top of tibs.
     .target(

Sources/tibs/main.swift

@@ -12,81 +12,84 @@
 
 import ISDBTibs
 import Foundation
+import ArgumentParser
 
-extension FileHandle: TextOutputStream {
-  public func write(_ string: String) {
-    guard let data = string.data(using: .utf8) else {
-      fatalError("failed to get data from string '\(string)'")
-    }
-    self.write(data)
-  }
+struct RuntimeError: LocalizedError {
+  var errorDescription: String?
 }
 
-var stderr = FileHandle.standardError
-
-func swiftDepsMerge(output: String, _ files: [String]) {
-  var allDeps: Set<Substring> = []
-
-  for file in files {
-    guard let makefile = Makefile(path: URL(fileURLWithPath: file)) else {
-      print("error: could not read dep file '\(file)'", to: &stderr)
-      exit(1)
-    }
-
-    let allOutputs = makefile.outputs.flatMap { $0.deps }
-    allDeps.formUnion(allOutputs)
-  }
-
-  print("\(output) : \(allDeps.sorted().joined(separator: " "))")
+struct Tibs: ParsableCommand {
+  static var configuration = CommandConfiguration(
+    subcommands: [Build.self, MergeDependencies.self],
+    defaultSubcommand: Build.self)
 }
 
-func main(arguments: [String]) {
-
-  if arguments.count < 2 {
-    print("usage: tibs <project-dir>", to: &stderr)
-    exit(1)
-  }
-
-  if arguments[1] == "swift-deps-merge" {
-    if arguments.count < 4 {
-      print("usage: tibs swift-deps-merge <output> <deps1.d> [...]", to: &stderr)
-      exit(1)
+extension Tibs {
+  struct Build: ParsableCommand {
+    @Argument()
+    var projectDir: String
+
+    func run() throws {
+      let projectRoot = URL(fileURLWithPath: projectDir, isDirectory: true)
+
+      let manifest: TibsManifest
+      do {
+        manifest = try TibsManifest.load(projectRoot: projectRoot)
+      } catch {
+        throw RuntimeError(errorDescription: "could not read manifest for '\(projectRoot.path)'")
+      }
+
+      let cwd = URL(fileURLWithPath: FileManager.default.currentDirectoryPath, isDirectory: true)
+
+      let toolchain = TibsToolchain(
+        swiftc: URL(fileURLWithPath: "/usr/bin/swiftc"),
+        clang: URL(fileURLWithPath: "/usr/bin/clang"),
+        tibs: Bundle.main.bundleURL.appendingPathComponent("tibs", isDirectory: false))
+
+      let builder: TibsBuilder
+      do {
+        builder = try TibsBuilder(manifest: manifest, sourceRoot: projectRoot, buildRoot: cwd, toolchain: toolchain)
+      } catch {
+        throw RuntimeError(errorDescription: "could not resolve project at '\(projectRoot.path)'")
+      }
+
+      do {
+        try builder.writeBuildFiles()
+      } catch {
+        throw RuntimeError(errorDescription: "could not write build files")
+      }
     }
-    swiftDepsMerge(output: arguments[2], Array(arguments.dropFirst(3)))
-    return
-  }
-
-  let projectDir = URL(fileURLWithPath: arguments.last!, isDirectory: true)
-
-  let manifest: TibsManifest
-  do {
-    manifest = try TibsManifest.load(projectRoot: projectDir)
-  } catch {
-    print("error: could not read manifest for '\(projectDir.path)': \(error)", to: &stderr)
-    exit(1)
   }
+}
 
-  let cwd = URL(fileURLWithPath: FileManager.default.currentDirectoryPath, isDirectory: true)
+extension Tibs {
+  struct MergeDependencies: ParsableCommand {
+    static var configuration = CommandConfiguration(commandName: "swift-deps-merge")
 
-  let toolchain = TibsToolchain(
-    swiftc: URL(fileURLWithPath: "/usr/bin/swiftc"),
-    clang: URL(fileURLWithPath: "/usr/bin/clang"),
-    tibs: Bundle.main.bundleURL.appendingPathComponent("tibs", isDirectory: false))
+    @Argument()
+    var output: String
 
-  let builder: TibsBuilder
-  do {
-    builder = try TibsBuilder(manifest: manifest, sourceRoot: projectDir, buildRoot: cwd, toolchain: toolchain)
-  } catch {
-    print("error: could not resolve project at '\(projectDir.path)': \(error)", to: &stderr)
-    exit(1)
-  }
+    @Argument()
+    var files: [String] = []
 
-  do {
-    try builder.writeBuildFiles()
-  } catch {
-    print("error: could not write build files: \(error)", to: &stderr)
-    exit(1)
+    mutating func validate() throws {
+      if files.isEmpty {
+        throw ValidationError("No files specified")
+      }
+    }
+
+    func run() throws {
+      let allDeps = try files.flatMap { file -> [Substring] in
+        guard let makefile = Makefile(path: URL(fileURLWithPath: file)) else {
+          throw RuntimeError(errorDescription: "could not read dep file '\(file)'")
+        }
+        return makefile.outputs.flatMap { $0.deps }
+      }
+
+      let uniqueDeps = Set(allDeps).sorted()
+      print("\(output) : \(uniqueDeps.joined(separator: " "))")
+    }
   }
 }
 
-main(arguments: CommandLine.arguments)
+Tibs.main()