Introduce ArgParseResult

We introduce a sealed interface ArgParseResult so we can separate
parsing of arguments and error reporting

core/src/main/java/com/facebook/ktfmt/cli/Main.kt

@@ -36,7 +36,7 @@ class Main(
  private val input: InputStream,
  private val out: PrintStream,
  private val err: PrintStream,
- args: Array<String>
+ private val args: Array<String>
 ) {
  companion object {
  @JvmStatic
@@ -69,9 +69,13 @@ class Main(
  }
  }
 
- private val parsedArgs: ParsedArgs = ParsedArgs.processArgs(err, args)
+
 
  fun run(): Int {
+ val parsedArgs = when (val argParseResult = ParsedArgs.processArgs(err, args)) {
+ is ArgParseResult.Ok -> argParseResult.parsedArgs
+ is ArgParseResult.Error -> exitFatal(argParseResult.errorMessage, 1)
+ }
  if (parsedArgs.fileNames.isEmpty()) {
  err.println(
  "Usage: ktfmt [--dropbox-style | --google-style | --kotlinlang-style] [--dry-run] [--set-exit-if-changed] [--stdin-name=<name>] [--do-not-remove-unused-imports] File1.kt File2.kt ...")
@@ -81,7 +85,7 @@ class Main(
 
  if (parsedArgs.fileNames.size == 1 && parsedArgs.fileNames[0] == "-") {
  return try {
- val alreadyFormatted = format(null)
+ val alreadyFormatted = format(null,parsedArgs)
  if (!alreadyFormatted && parsedArgs.setExitIfChanged) 1 else 0
  } catch (e: Exception) {
  1
@@ -107,7 +111,7 @@ class Main(
  val retval = AtomicInteger(0)
  files.parallelStream().forEach {
  try {
- if (!format(it) && parsedArgs.setExitIfChanged) {
+ if (!format(it, parsedArgs) && parsedArgs.setExitIfChanged) {
  retval.set(1)
  }
  } catch (e: Exception) {
@@ -126,17 +130,17 @@ class Main(
  * @param file The file to format. If null, the code is read from <stdin>.
  * @return true iff input is valid and already formatted.
  */
- private fun format(file: File?): Boolean {
- val fileName = file?.toString() ?: parsedArgs.stdinName ?: "<stdin>"
+ private fun format(file: File?, args: ParsedArgs): Boolean {
+ val fileName = file?.toString() ?: args.stdinName ?: "<stdin>"
  try {
  val bytes = if (file == null) input else FileInputStream(file)
  val code = BufferedReader(InputStreamReader(bytes, UTF_8)).readText()
- val formattedCode = Formatter.format(parsedArgs.formattingOptions, code)
+ val formattedCode = Formatter.format(args.formattingOptions, code)
  val alreadyFormatted = code == formattedCode
 
  // stdin
  if (file == null) {
- if (parsedArgs.dryRun) {
+ if (args.dryRun) {
  if (!alreadyFormatted) {
  out.println(fileName)
  }
@@ -146,7 +150,7 @@ class Main(
  return alreadyFormatted
  }
 
- if (parsedArgs.dryRun) {
+ if (args.dryRun) {
  if (!alreadyFormatted) {
  out.println(fileName)
  }
@@ -173,4 +177,11 @@ class Main(
  throw e
  }
  }
+
+ fun exitFatal(message: String, returnCode: Int): Nothing {
+ err.println(message)
+ exitProcess(returnCode)
+ }
+
 }
+

core/src/main/java/com/facebook/ktfmt/cli/ParsedArgs.kt

@@ -39,11 +39,11 @@ data class ParsedArgs(
 ) {
  companion object {
 
- fun processArgs(err: PrintStream, args: Array<String>): ParsedArgs {
+ fun processArgs(err: PrintStream, args: Array<String>): ArgParseResult {
  if (args.size == 1 && args[0].startsWith("@")) {
- return parseOptions(err, File(args[0].substring(1)).readLines(UTF_8).toTypedArray())
+ return ArgParseResult.Ok(parseOptions(err, File(args[0].substring(1)).readLines(UTF_8).toTypedArray()))
  } else {
- return parseOptions(err, args)
+ return ArgParseResult.Ok(parseOptions(err, args))
  }
  }
 
@@ -90,3 +90,8 @@ data class ParsedArgs(
  }
  }
 }
+
+sealed interface ArgParseResult {
+ data class Ok(val parsedArgs: ParsedArgs): ArgParseResult
+ data class Error(val errorMessage: String): ArgParseResult
+}

core/src/test/java/com/facebook/ktfmt/cli/ParsedArgsTest.kt

@@ -177,7 +177,10 @@ class ParsedArgsTest {
  val file = root.resolve("existing-file")
  file.writeText("--google-style\n--dry-run\n--set-exit-if-changed\nFile1.kt\nFile2.kt\n")
 
- val parsed = ParsedArgs.processArgs(PrintStream(out), arrayOf("@" + file.absolutePath))
+ val result = ParsedArgs.processArgs(PrintStream(out), arrayOf("@" + file.absolutePath))
+ assertThat(result).isInstanceOf(ArgParseResult.Ok::class.java)
+
+ val parsed = (result as ArgParseResult.Ok).parsedArgs
 
  assertThat(parsed.formattingOptions).isEqualTo(Formatter.GOOGLE_FORMAT)
  assertThat(parsed.dryRun).isTrue()