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// This is a minimum implementation of multifile, which enables us to
// treat multiple files like a single concatenated file.

#ifndef MOZC_BASE_MULTIFILE_H_
#define MOZC_BASE_MULTIFILE_H_

#include <ios>
#include <memory>
#include <string>
#include <vector>

#include "absl/strings/string_view.h"
#include "base/file_stream.h"

namespace mozc {

class InputMultiFile {
 public:
  // filenames must be separated by comma(s), e.g., "foo.txt,hoge.txt".
  explicit InputMultiFile(absl::string_view filenames,
                          std::ios_base::openmode mode = std::ios_base::in);
  InputMultiFile(const InputMultiFile&) = delete;
  InputMultiFile& operator=(const InputMultiFile&) = delete;
  ~InputMultiFile() = default;

  // Reads one line. Returns false after reading all the lines.
  bool ReadLine(std::string* line);

 private:
  bool OpenNext();

  std::vector<std::string> filenames_;
  const std::ios_base::openmode mode_;
  std::vector<std::string>::iterator next_iter_;
  std::unique_ptr<InputFileStream> ifs_;
};

}  // namespace mozc

#endif  // MOZC_BASE_MULTIFILE_H_
