LineReader.h

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/*
 * Copyright 2013-present Facebook, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#pragma once

#include <cstddef>

#include <boost/noncopyable.hpp>

#include <folly/Range.h>

namespace folly {
namespace symbolizer {

class LineReader : private boost::noncopyable {
 public:
  LineReader(int fd, char* buf, size_t bufSize);

  enum State {
    kReading,
    kEof,
    kError,
  };
  State readLine(StringPiece& line);

 private:
  int const fd_;
  char* const buf_;
  char* const bufEnd_;

  // buf_ <= bol_ <= eol_ <= end_ <= bufEnd_
  //
  // [buf_, end_): current buffer contents (read from file)
  //
  // [buf_, bol_): free (already processed, can be discarded)
  // [bol_, eol_): current line, including \n if it exists, eol_ points
  //               1 character past the \n
  // [eol_, end_): read, unprocessed
  // [end_, bufEnd_): free

  char* bol_;
  char* eol_;
  char* end_;
  State state_;
};
} // namespace symbolizer
} // namespace folly