byte_streams.h

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// 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 FLUTTER_SHELL_PLATFORM_COMMON_CLIENT_WRAPPER_INCLUDE_FLUTTER_BYTE_STREAMS_H_
#define FLUTTER_SHELL_PLATFORM_COMMON_CLIENT_WRAPPER_INCLUDE_FLUTTER_BYTE_STREAMS_H_
 
// Interfaces for interacting with a stream of bytes, for use in codecs.
 
namespace flutter {
 
// 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 flutter
 
#endif  // FLUTTER_SHELL_PLATFORM_COMMON_CLIENT_WRAPPER_INCLUDE_FLUTTER_BYTE_STREAMS_H_