xone_byte

C语言库函数的原型,有用的拿去

// xone_byte -- convert one-byte code to 16-bit wide
 #pragma once
#ifndef _CVT_XONE_BYTE_
#define _CVT_XONE_BYTE_
#ifndef RC_INVOKED
#include <locale>
#include <cwchar>

 #pragma pack(push,_CRT_PACKING)
 #pragma warning(push,3)

namespace stdext {
	namespace cvt {

typedef _CSTD mbstate_t _Statype;

		// TEMPLATE CLASS _Cvt_one_byte
template<class _Elem,
	class _Table,
	unsigned long _Maxcode = 0xffff>
	class _Cvt_one_byte
	: public _STD codecvt<_Elem, char, _Statype>
	{	// facet for converting between _Elem and one-byte sequences
public:
 	typedef _STD codecvt<_Elem, char, _Statype> _Mybase;
	typedef typename _Mybase::result result;
	typedef char _Byte;
	typedef _Elem intern_type;
	typedef _Byte extern_type;
	typedef _Statype state_type;

	explicit _Cvt_one_byte(size_t _Refs = 0)
		: _Mybase(_Refs)
		{	// construct with ref count
		}

	virtual ~_Cvt_one_byte()
		{	// destroy the object
		}

protected:
	virtual result do_in(_Statype&,
		const _Byte *_First1, const _Byte *_Last1, const _Byte *& _Mid1,
		_Elem *_First2, _Elem *_Last2, _Elem *& _Mid2) const
		{	// convert bytes [_First1, _Last1) to [_First2, _Last)
		unsigned long _Maxc = _Maxcode;	// to quiet warnings

		_Mid1 = _First1;
		_Mid2 = _First2;
		for (; _Mid1 != _Last1 && _Mid2 != _Last2; ++_Mid1)
			{	// get a byte and map it
			unsigned short _Bytecode = (unsigned char)*_Mid1;

			if (_Table::_Nlow <= _Bytecode
				&& (_Bytecode = _Table::_Btw[_Bytecode - _Table::_Nlow]) == 0
				|| _Maxc < _Bytecode)
				return (_Mybase::error);
			*_Mid2++ = (_Elem)_Bytecode;
			}

		return (_First1 == _Mid1 ? _Mybase::partial : _Mybase::ok);
		}

	virtual result do_out(_Statype&,
		const _Elem *_First1, const _Elem *_Last1, const _Elem *& _Mid1,
		_Byte *_First2, _Byte *_Last2, _Byte *& _Mid2) const
		{	// convert [_First1, _Last1) to bytes [_First2, _Last)
		unsigned long _Maxc = _Maxcode;	// to quiet warnings

		_Mid1 = _First1;
		_Mid2 = _First2;
		for (; _Mid1 != _Last1 && _Mid2 != _Last2; ++_Mid1)
			{	// get an element and map it
			unsigned long _Hugecode = (unsigned long)*_Mid1;
			unsigned short _Widecode = (unsigned short)_Hugecode;

			if (_Maxc < _Widecode)
				return (_Mybase::error);	// value too large
			else if (_Widecode < _Table::_Nlow || _Widecode < 0x100
				&& _Table::_Btw[_Widecode - _Table::_Nlow] == _Widecode)
				;	// map wide to same byte value
			else
				{	// search for a valid mapping
				unsigned long _Lo = 0;
				unsigned long _Hi = sizeof (_Table::_Wvalid)
					/ sizeof (_Table::_Wvalid[0]);

				for (; _Lo < _Hi; )
					{	// test midpoint of remaining interval
					unsigned long _Mid = (_Hi + _Lo) / 2;

					if (_Widecode < _Table::_Wvalid[_Mid])
						_Hi = _Mid;
					else if (_Widecode == _Table::_Wvalid[_Mid])
						{	// found the code, map it
						_Widecode = _Table::_Wtb[_Mid];
						break;
						}
					else
						_Lo = _Mid + 1;
					}
				if (_Hi <= _Lo)
					return (_Mybase::error);
				}
			*_Mid2++ = (_Byte)_Widecode;
			}

		return (_First1 == _Mid1 ? _Mybase::partial : _Mybase::ok);
		}

	virtual result do_unshift(_Statype&,
		_Byte *_First2, _Byte *, _Byte *& _Mid2) const
		{	// generate bytes to return to default shift state
		_Mid2 = _First2;
		return (_Mybase::ok);
		}

	virtual int do_length(const _Statype&, const _Byte *_First1,
		const _Byte *_Last1, size_t _Count) const _THROW0()
		{	// return min(_Count, converted length of bytes [_First1, _Last1))
		size_t _Wchars = _Last1 - _First1;

		return ((int)(_Wchars < _Count ? _Wchars : _Count));
		}

	virtual bool do_always_noconv() const _THROW0()
		{	// return true if conversions never change input
		return (false);
		}

	virtual int do_max_length() const _THROW0()
		{	// return maximum length required for a conversion
		return (1);	// length of sequence
		}

	virtual int do_encoding() const _THROW0()
		{	// return length of code sequence (from codecvt)
		return (1);	// >0 => fixed sequence length
		}
	};
		}	// namespace cvt
	}	// namespace stdext

 #if 0 && defined(_TEST_IT)	/* disable standalone testing */
  #define NCHARS	0x100
  #define MYWC_MAX	0xffff
  #define MYFILE	"xone_byte"
  #define MYNAME	stdext::cvt::_Cvt_one_byte<wchar_t, _TEST_TABLE >

  #ifndef _TEST_TABLE
   #define _TEST_TABLE	test_table
struct test_table {
	enum {
		_Nlow = 0xfe,
		_Nbytes = 1};
	static unsigned short _Btw[0x02];
	static unsigned short _Dbvalid[1];
	static unsigned short _Dbtw[1];
	static unsigned short _Wvalid[2];
	static unsigned char _Wtb[2];
	};

unsigned short test_table::_Btw[2] = {0x3000, 0x2000};
unsigned short test_table::_Dbvalid[1] = {0};
unsigned short test_table::_Dbtw[1] = {0};
unsigned short test_table::_Wvalid[2] = {0x2000, 0x3000};
unsigned char test_table::_Wtb[2] = {0xff, 0xfe};
  #endif /* _TEST_TABLE */

  #include <cvt/xtest>
 #endif /* 0 && defined(_TEST_IT) */

 #pragma warning(pop)
 #pragma pack(pop)

#endif /* RC_INVOKED */
#endif /* _CVT_XONE_BYTE_ */

/*
 * Copyright (c) 1992-2009 by P.J. Plauger.  ALL RIGHTS RESERVED. 
 * Consult your license regarding permissions and restrictions.
V5.20:0009 */