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

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


#ifndef Foundation_BinaryReader_INCLUDED
#define Foundation_BinaryReader_INCLUDED


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


namespace Poco
{


class TextEncoding;
class TextConverter;


class Foundation_API BinaryReader
/// This class reads basic types (and std::vectors thereof)
/// in binary form into an input stream.
/// It provides an extractor-based interface similar to istream.
/// The reader also supports automatic conversion from big-endian
/// (network byte order) to little-endian and vice-versa.
/// Use a BinaryWriter to create a stream suitable for a BinaryReader.
{
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
        UNSPECIFIED_BYTE_ORDER = 4 /// unknown, byte-order will be determined by reading the byte-order mark
    };

    BinaryReader(std::istream & istr, StreamByteOrder byteOrder = NATIVE_BYTE_ORDER);
    /// Creates the BinaryReader.

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

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

    BinaryReader & operator>>(bool & value);
    BinaryReader & operator>>(char & value);
    BinaryReader & operator>>(unsigned char & value);
    BinaryReader & operator>>(signed char & value);
    BinaryReader & operator>>(short & value);
    BinaryReader & operator>>(unsigned short & value);
    BinaryReader & operator>>(int & value);
    BinaryReader & operator>>(unsigned int & value);
    BinaryReader & operator>>(long & value);
    BinaryReader & operator>>(unsigned long & value);
    BinaryReader & operator>>(float & value);
    BinaryReader & operator>>(double & value);

#if !defined(POCO_LONG_IS_64_BIT)
    BinaryReader & operator>>(Int64 & value);
    BinaryReader & operator>>(UInt64 & value);
#endif

    BinaryReader & operator>>(std::string & value);

    template <typename T>
    BinaryReader & operator>>(std::vector<T> & value)
    {
        Poco::UInt32 size(0);
        T elem;

        *this >> size;
        if (!good())
            return *this;
        value.reserve(size);
        while (this->good() && size-- > 0)
        {
            *this >> elem;
            value.push_back(elem);
        }
        return *this;
    }

    void read7BitEncoded(UInt32 & value);
    /// Reads a 32-bit unsigned integer in compressed format.
    /// See BinaryWriter::write7BitEncoded() for a description
    /// of the compression algorithm.

    void read7BitEncoded(UInt64 & value);
    /// Reads a 64-bit unsigned integer in compressed format.
    /// See BinaryWriter::write7BitEncoded() for a description
    /// of the compression algorithm.

    void readRaw(std::streamsize length, std::string & value);
    /// Reads length bytes of raw data into value.

    void readRaw(char * buffer, std::streamsize length);
    /// Reads length bytes of raw data into buffer.

    void readCString(std::string& value);
		/// Reads zero-terminated C-string into value.

    void readBOM();
    /// Reads a byte-order mark from the stream and configures
    /// the reader for the encountered byte order.
    /// A byte-order mark is a 16-bit integer with a value of 0xFEFF,
    /// written in host byte order.

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

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

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

    bool eof();
    /// Returns _istr.eof();

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

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

    void setExceptions(std::ios_base::iostate st = (std::istream::failbit | std::istream::badbit));
    /// Sets the stream to throw exception on specified state (default failbit and badbit);

    std::streamsize available() const;
    /// Returns the number of available bytes in the stream.

private:
    std::istream & _istr;
    bool _flipBytes;
    TextConverter * _pTextConverter;
};


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

    BasicMemoryBinaryReader(const Buffer<T> & data, TextEncoding & encoding, StreamByteOrder byteOrder = NATIVE_BYTE_ORDER)
        : BinaryReader(_istr, encoding, byteOrder), _data(data), _istr(data.begin(), data.capacity())
    {
    }

    ~BasicMemoryBinaryReader() { }

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

    const MemoryInputStream & stream() const { return _istr; }

    MemoryInputStream & stream() { return _istr; }

private:
    const Buffer<T> & _data;
    MemoryInputStream _istr;
};


typedef BasicMemoryBinaryReader<char> MemoryBinaryReader;


//
// inlines
//


inline bool BinaryReader::good()
{
    return _istr.good();
}


inline bool BinaryReader::fail()
{
    return _istr.fail();
}


inline bool BinaryReader::bad()
{
    return _istr.bad();
}


inline bool BinaryReader::eof()
{
    return _istr.eof();
}


inline std::istream & BinaryReader::stream() const
{
    return _istr;
}


inline BinaryReader::StreamByteOrder BinaryReader::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
}


inline void BinaryReader::setExceptions(std::ios_base::iostate st)
{
    _istr.exceptions(st);
}


inline std::streamsize BinaryReader::available() const
{
    return _istr.rdbuf()->in_avail();
}


} // namespace Poco


#endif // Foundation_BinaryReader_INCLUDED