ClickHouse/base/poco/Foundation/include/Poco/BinaryWriter.h

//
// BinaryWriter.h
//
// Library: Foundation
// Package: Streams
// Module:  BinaryReaderWriter
//
// Definition of the BinaryWriter class.
//
// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier:	BSL-1.0
//


#ifndef Foundation_BinaryWriter_INCLUDED
#define Foundation_BinaryWriter_INCLUDED


#include <ostream>
#include <vector>
#include "Poco/Buffer.h"
#include "Poco/Foundation.h"
#include "Poco/MemoryStream.h"


namespace Poco
{


class TextEncoding;
class TextConverter;


class Foundation_API BinaryWriter
/// This class writes basic types (and std::vectors of these)
/// in binary form into an output stream.
/// It provides an inserter-based interface similar to ostream.
/// The writer also supports automatic conversion from big-endian
/// (network byte order) to little-endian and vice-versa.
/// Use a BinaryReader to read from a stream created by a BinaryWriter.
/// Be careful when exchanging data between systems with different
/// data type sizes (e.g., 32-bit and 64-bit architectures), as the sizes
/// of some of the basic types may be different. For example, writing a
/// long integer on a 64-bit system and reading it on a 32-bit system
/// may yield an incorrect result. Use fixed-size types (Int32, Int64, etc.)
/// in such a case.
{
public:
    enum StreamByteOrder
    {
        NATIVE_BYTE_ORDER = 1, /// the host's native byte-order
        BIG_ENDIAN_BYTE_ORDER = 2, /// big-endian (network) byte-order
        NETWORK_BYTE_ORDER = 2, /// big-endian (network) byte-order
        LITTLE_ENDIAN_BYTE_ORDER = 3 /// little-endian byte-order
    };

    BinaryWriter(std::ostream & ostr, StreamByteOrder byteOrder = NATIVE_BYTE_ORDER);
    /// Creates the BinaryWriter.

    BinaryWriter(std::ostream & ostr, TextEncoding & encoding, StreamByteOrder byteOrder = NATIVE_BYTE_ORDER);
    /// Creates the BinaryWriter using the given TextEncoding.
    ///
    /// Strings will be converted from the currently set global encoding
    /// (see Poco::TextEncoding::global()) to the specified encoding.

    ~BinaryWriter();
    /// Destroys the BinaryWriter.

    BinaryWriter & operator<<(bool value);
    BinaryWriter & operator<<(char value);
    BinaryWriter & operator<<(unsigned char value);
    BinaryWriter & operator<<(signed char value);
    BinaryWriter & operator<<(short value);
    BinaryWriter & operator<<(unsigned short value);
    BinaryWriter & operator<<(int value);
    BinaryWriter & operator<<(unsigned int value);
    BinaryWriter & operator<<(long value);
    BinaryWriter & operator<<(unsigned long value);
    BinaryWriter & operator<<(float value);
    BinaryWriter & operator<<(double value);

#if !defined(POCO_LONG_IS_64_BIT)
    BinaryWriter & operator<<(Int64 value);
    BinaryWriter & operator<<(UInt64 value);
#endif

    BinaryWriter & operator<<(const std::string & value);
    BinaryWriter & operator<<(const char * value);

    template <typename T>
    BinaryWriter & operator<<(const std::vector<T> & value)
    {
        Poco::UInt32 size(static_cast<Poco::UInt32>(value.size()));

        *this << size;
        for (typename std::vector<T>::const_iterator it = value.begin(); it != value.end(); ++it)
        {
            *this << *it;
        }

        return *this;
    }

    void write7BitEncoded(UInt32 value);
    /// Writes a 32-bit unsigned integer in a compressed format.
    /// The value is written out seven bits at a time, starting
    /// with the seven least-significant bits.
    /// The high bit of a byte indicates whether there are more bytes to be
    /// written after this one.
    /// If value will fit in seven bits, it takes only one byte of space.
    /// If value will not fit in seven bits, the high bit is set on the first byte and
    /// written out. value is then shifted by seven bits and the next byte is written.
    /// This process is repeated until the entire integer has been written.

    void write7BitEncoded(UInt64 value);
    /// Writes a 64-bit unsigned integer in a compressed format.
    /// The value written out seven bits at a time, starting
    /// with the seven least-significant bits.
    /// The high bit of a byte indicates whether there are more bytes to be
    /// written after this one.
    /// If value will fit in seven bits, it takes only one byte of space.
    /// If value will not fit in seven bits, the high bit is set on the first byte and
    /// written out. value is then shifted by seven bits and the next byte is written.
    /// This process is repeated until the entire integer has been written.

    void writeRaw(const std::string & rawData);
    /// Writes the string as-is to the stream.

    void writeRaw(const char * buffer, std::streamsize length);
    /// Writes length raw bytes from the given buffer to the stream.

    void writeBOM();
    /// Writes a byte-order mark to the stream. A byte order mark is
    /// a 16-bit integer with a value of 0xFEFF, written in host byte-order.
    /// A BinaryReader uses the byte-order mark to determine the byte-order
    /// of the stream.

    void flush();
    /// Flushes the underlying stream.

    bool good();
    /// Returns _ostr.good();

    bool fail();
    /// Returns _ostr.fail();

    bool bad();
    /// Returns _ostr.bad();

    std::ostream & stream() const;
    /// Returns the underlying stream.

    StreamByteOrder byteOrder() const;
    /// Returns the byte ordering used by the writer, which is
    /// either BIG_ENDIAN_BYTE_ORDER or LITTLE_ENDIAN_BYTE_ORDER.

private:
    std::ostream & _ostr;
    bool _flipBytes;
    TextConverter * _pTextConverter;
};


template <typename T>
class BasicMemoryBinaryWriter : public BinaryWriter
/// A convenient wrapper for using Buffer and MemoryStream with BinarWriter.
{
public:
    BasicMemoryBinaryWriter(Buffer<T> & data, StreamByteOrder byteOrder = NATIVE_BYTE_ORDER)
        : BinaryWriter(_ostr, byteOrder), _data(data), _ostr(data.begin(), data.capacity())
    {
    }

    BasicMemoryBinaryWriter(Buffer<T> & data, TextEncoding & encoding, StreamByteOrder byteOrder = NATIVE_BYTE_ORDER)
        : BinaryWriter(_ostr, encoding, byteOrder), _data(data), _ostr(data.begin(), data.capacity())
    {
    }

    ~BasicMemoryBinaryWriter()
    {
        try
        {
            flush();
        }
        catch (...)
        {
            poco_unexpected();
        }
    }

    Buffer<T> & data() { return _data; }

    const Buffer<T> & data() const { return _data; }

    const MemoryOutputStream & stream() const { return _ostr; }

    MemoryOutputStream & stream() { return _ostr; }

private:
    Buffer<T> & _data;
    MemoryOutputStream _ostr;
};


typedef BasicMemoryBinaryWriter<char> MemoryBinaryWriter;


//
// inlines
//


inline std::ostream & BinaryWriter::stream() const
{
    return _ostr;
}


inline bool BinaryWriter::good()
{
    return _ostr.good();
}


inline bool BinaryWriter::fail()
{
    return _ostr.fail();
}


inline bool BinaryWriter::bad()
{
    return _ostr.bad();
}


inline BinaryWriter::StreamByteOrder BinaryWriter::byteOrder() const
{
#if defined(POCO_ARCH_BIG_ENDIAN)
    return _flipBytes ? LITTLE_ENDIAN_BYTE_ORDER : BIG_ENDIAN_BYTE_ORDER;
#else
    return _flipBytes ? BIG_ENDIAN_BYTE_ORDER : LITTLE_ENDIAN_BYTE_ORDER;
#endif
}


} // namespace Poco


#endif // Foundation_BinaryWriter_INCLUDED