src/embedder/standard_message_codec/byte_streams.h

// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef SRC_EMBEDDER_STANDARD_MESSAGE_CODEC_BYTE_STREAMS_H_
#define SRC_EMBEDDER_STANDARD_MESSAGE_CODEC_BYTE_STREAMS_H_

// Interfaces for interacting with a stream of bytes, for use in codecs.

namespace standard_message_codec {

// An interface for a class that reads from a byte stream.
class ByteStreamReader {
 public:
  explicit ByteStreamReader() = default;
  virtual ~ByteStreamReader() = default;

  // Reads and returns the next byte from the stream.
  virtual uint8_t ReadByte() = 0;

  // Reads the next |length| bytes from the stream into |buffer|. The caller
  // is responsible for ensuring that |buffer| is large enough.
  virtual void ReadBytes(uint8_t* buffer, size_t length) = 0;

  // Advances the read cursor to the next multiple of |alignment| relative to
  // the start of the stream, unless it is already aligned.
  virtual void ReadAlignment(uint8_t alignment) = 0;

  // Reads and returns the next 32-bit integer from the stream.
  int32_t ReadInt32() {
    int32_t value = 0;
    ReadBytes(reinterpret_cast<uint8_t*>(&value), 4);
    return value;
  }

  // Reads and returns the next 64-bit integer from the stream.
  int64_t ReadInt64() {
    int64_t value = 0;
    ReadBytes(reinterpret_cast<uint8_t*>(&value), 8);
    return value;
  }

  // Reads and returns the next 64-bit floating point number from the stream.
  double ReadDouble() {
    double value = 0;
    ReadBytes(reinterpret_cast<uint8_t*>(&value), 8);
    return value;
  }
};

// An interface for a class that writes to a byte stream.
class ByteStreamWriter {
 public:
  explicit ByteStreamWriter() = default;
  virtual ~ByteStreamWriter() = default;

  // Writes |byte| to the stream.
  virtual void WriteByte(uint8_t byte) = 0;

  // Writes the next |length| bytes from |bytes| to the stream
  virtual void WriteBytes(const uint8_t* bytes, size_t length) = 0;

  // Writes 0s until the next multiple of |alignment| relative to the start
  // of the stream, unless the write positition is already aligned.
  virtual void WriteAlignment(uint8_t alignment) = 0;

  // Writes the given 32-bit int to the stream.
  void WriteInt32(int32_t value) { WriteBytes(reinterpret_cast<const uint8_t*>(&value), 4); }

  // Writes the given 64-bit int to the stream.
  void WriteInt64(int64_t value) { WriteBytes(reinterpret_cast<const uint8_t*>(&value), 8); }

  // Writes the given 36-bit double to the stream.
  void WriteDouble(double value) { WriteBytes(reinterpret_cast<const uint8_t*>(&value), 8); }
};

}  // namespace standard_message_codec

#endif  // SRC_EMBEDDER_STANDARD_MESSAGE_CODEC_BYTE_STREAMS_H_