poco/Foundation/include/Poco/BinaryReader.h

//
// BinaryReader.h
//
// $Id: //poco/1.4/Foundation/include/Poco/BinaryReader.h#3 $
//
// 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 "Poco/Foundation.h"
#include "Poco/Buffer.h"
#include "Poco/MemoryStream.h"
#include "Poco/ByteOrder.h"
#include <vector>
#include <istream>


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_HAVE_INT64) && !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.

#if defined(POCO_HAVE_INT64)
	void read7BitEncoded(UInt64& value);
		/// Reads a 64-bit unsigned integer in compressed format.
		/// See BinaryWriter::write7BitEncoded() for a description
		/// of the compression algorithm.
#endif

	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 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:
	template<typename T>
	BinaryReader& read(T& value, bool flipBytes)
	{
		_istr.read((char*) &value, sizeof(value));
		if (flipBytes) value = ByteOrder::flipBytes(value);
		return *this;
	}

	template<typename T>
	void read7BitEncoded(T& value)
	{
		char c;
		value = 0;
		int s = 0;
		do
		{
			c = 0;
			_istr.read(&c, 1);
			T x = (c & 0x7F);
			x <<= s;
			value += x;
			s += 7;
		}
		while (c & 0x80);
	}

	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>& dataBuffer, StreamByteOrder order = NATIVE_BYTE_ORDER):
		BinaryReader(_istr, order),
		_data(dataBuffer),
		_istr(dataBuffer.begin(), dataBuffer.capacity())
	{
	}

	BasicMemoryBinaryReader(const Buffer<T>& dataBuffer, TextEncoding& encoding, StreamByteOrder order = NATIVE_BYTE_ORDER):
		BinaryReader(_istr, encoding, order),
		_data(dataBuffer),
		_istr(dataBuffer.begin(), dataBuffer.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