src/main/java/com/android/tools/r8/utils/FlagFile.java

// Copyright (c) 2018, the R8 project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

package com.android.tools.r8.utils;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.List;

public class FlagFile {
  public static String[] expandFlagFiles(String[] args) throws IOException {
    List<String> flags = new ArrayList<>(args.length);
    for (String arg : args) {
      if (arg.startsWith("@")) {
        flags.addAll(Files.readAllLines(Paths.get(arg.substring(1))));
      } else {
        flags.add(arg);
      }
    }
    return flags.toArray(new String[flags.size()]);
  }
}