third_party/blink/renderer/core/html/track/vtt/buffered_line_reader.h

/*
 * Copyright (C) 2013, Opera Software ASA. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *     * Neither the name of Google Inc. nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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#ifndef THIRD_PARTY_BLINK_RENDERER_CORE_HTML_TRACK_VTT_BUFFERED_LINE_READER_H_
#define THIRD_PARTY_BLINK_RENDERER_CORE_HTML_TRACK_VTT_BUFFERED_LINE_READER_H_

#include "base/macros.h"
#include "third_party/blink/renderer/core/core_export.h"
#include "third_party/blink/renderer/platform/text/segmented_string.h"
#include "third_party/blink/renderer/platform/wtf/allocator/allocator.h"
#include "third_party/blink/renderer/platform/wtf/text/string_builder.h"

namespace blink {

// Line collection helper for the WebVTT Parser.
//
// Converts a stream of data (== a sequence of Strings) into a set of
// lines. CR, LR or CRLF are considered linebreaks. Normalizes NULs (U+0000)
// to 'REPLACEMENT CHARACTER' (U+FFFD) and does not return the linebreaks as
// part of the result.
class CORE_EXPORT BufferedLineReader {
  DISALLOW_NEW();

 public:
  BufferedLineReader() : end_of_stream_(false), maybe_skip_lf_(false) {}

  // Append data to the internal buffer.
  void Append(const String& data) {
    DCHECK(!end_of_stream_);
    buffer_.Append(SegmentedString(data));
  }

  // Indicate that no more data will be appended. This will cause any
  // potentially "unterminated" line to be returned from getLine.
  void SetEndOfStream() { end_of_stream_ = true; }

  // Attempt to read a line from the internal buffer (fed via append).
  // If successful, true is returned and |line| is set to the line that was
  // read. If no line could be read false is returned.
  bool GetLine(String& line);

  // Returns true if EOS has been reached proper.
  bool IsAtEndOfStream() const { return end_of_stream_ && buffer_.IsEmpty(); }

 private:
  // Consume the next character the buffer if it is the character |c|.
  void ScanCharacter(UChar c) {
    DCHECK(!buffer_.IsEmpty());
    if (buffer_.CurrentChar() == c)
      buffer_.Advance();
  }

  SegmentedString buffer_;
  StringBuilder line_buffer_;
  bool end_of_stream_;
  bool maybe_skip_lf_;

  DISALLOW_COPY_AND_ASSIGN(BufferedLineReader);
};

}  // namespace blink

#endif