Add support for @argsfile

Summary:
added a new argument type with the format @[filename].
If supplied, ktfmt arguments will be extracted from file.

Reviewed By: cgrushko

Differential Revision: D34612728

fbshipit-source-id: 46cb237b12fd929719fcab7c05a5f42ec7d398fa

2 files changed, 13 insertions, 1 deletions

diff --git a/core/src/main/java/com/facebook/ktfmt/cli/Main.kt b/core/src/main/java/com/facebook/ktfmt/cli/Main.kt
index f71cd4c..4c965bb 100644
--- a/core/src/main/java/com/facebook/ktfmt/cli/Main.kt
+++ b/core/src/main/java/com/facebook/ktfmt/cli/Main.kt
@@ -65,12 +65,13 @@ class Main(
     }
   }
 
-  private val parsedArgs: ParsedArgs = ParsedArgs.parseOptions(err, args)
+  private val parsedArgs: ParsedArgs = ParsedArgs.processArgs(err, args)
 
   fun run(): Int {
     if (parsedArgs.fileNames.isEmpty()) {
       err.println(
           "Usage: ktfmt [--dropbox-style | --google-style | --kotlinlang-style] [--dry-run] [--set-exit-if-changed] File1.kt File2.kt ...")
+      err.println("Or: ktfmt @file")
       return 1
     }
 
diff --git a/core/src/main/java/com/facebook/ktfmt/cli/ParsedArgs.kt b/core/src/main/java/com/facebook/ktfmt/cli/ParsedArgs.kt
index bb959c8..503cb89 100644
--- a/core/src/main/java/com/facebook/ktfmt/cli/ParsedArgs.kt
+++ b/core/src/main/java/com/facebook/ktfmt/cli/ParsedArgs.kt
@@ -18,6 +18,7 @@ package com.facebook.ktfmt.cli
 
 import com.facebook.ktfmt.format.Formatter
 import com.facebook.ktfmt.format.FormattingOptions
+import java.io.File
 import java.io.PrintStream
 
 /** ParsedArgs holds the arguments passed to ktfmt on the command-line, after parsing. */
@@ -34,6 +35,15 @@ data class ParsedArgs(
     val setExitIfChanged: Boolean,
 ) {
   companion object {
+
+    fun processArgs(err: PrintStream, args: Array<String>): ParsedArgs {
+      if (args.size == 1 && args[0].startsWith("@")) {
+        return parseOptions(err, File(args[0].substring(1)).readLines().toTypedArray())
+      } else {
+        return parseOptions(err, args)
+      }
+    }
+
     /** parseOptions parses command-line arguments passed to ktfmt. */
     fun parseOptions(err: PrintStream, args: Array<String>): ParsedArgs {
       val fileNames = mutableListOf<String>()
@@ -49,6 +59,7 @@ data class ParsedArgs(
           arg == "--dry-run" || arg == "-n" -> dryRun = true
           arg == "--set-exit-if-changed" -> setExitIfChanged = true
           arg.startsWith("--") -> err.println("Unexpected option: $arg")
+          arg.startsWith("@") -> err.println("Unexpected option: $arg")
           else -> fileNames.add(arg)
         }
       }