CBSTRStream - A simple BSTR stream implementation

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  This file also includes the CEnBSTR class.

Introduction

There are several classes available that handle BSTR strings, however I have yet to find one that offers basic buffering support. The CBSTRStream class was designed to provide this feature as well as some useful data type conversion functions.

This class is not a replacement for the popular _bstr_t class, but it is designed to interoperate with it.

Usage

This class is very easy to use (as the examples below will show you). You simply use the << operator to append data to the stream. The list at the end of the article provides a more detailed overview.

Example 1 (basic usage):

		_bstr_t bstrData(L"somedata");
		_bstr_t bstrData2(L"some other data");
		GUID guid = //someguid..
		long nData = 3;
		CBSTRStream bsData; 
		bsData << bstrData << L"TEST" << nData << L"  " << bstrData2 << L"  " << guid;

Example 2 (composing SQL queries):

		long nItemId = 1;
		CBSTRStream bsSelect;
		bsSelect << L"SELECT It_Name, It_Desc FROM It_Item WHERE It_Id = " << nItemId;

Example 3 (using allocation hints):

		long nData = 14;
		long nData2 = 18;
		long nData3 = 25;
		
		CBSTRStream bsData(10, 5);  
		bsData << L"Numbers: " << nData << L", " << nData2;
		bsData << L", " << nData3;

Constructors

CBSTRStream(const CBSTRStream& bsSrc, long nInitialBufferSize = 50, long nChunkSize = 50) CBSTRStream(long nInitialBufferSize = 50, long nChunkSize = 50)
	These constructors provide you with the opportunity to set allocation hints for the stream allocator. The nInitialBufferSize sets the size used during the first buffer allocation and the nChunkSize sets the size appended during the next buffer reallocations.

Operators

CBSTRStream& operator << (const _bstr_t& bstrData) CBSTRStream& operator << (wchar_t* pstr) CBSTRStream& operator << (REFGUID src) CBSTRStream& operator << (long nData) CBSTRStream& operator << (unsigned long nData) CBSTRStream& operator << (int nData) CBSTRStream& operator << (double dValue) CBSTRStream& operator << (const CBSTRStream& bsSrc)
	These operators provide basic stream support as well as data type conversions. They will append the string representation of their respective data type to the stream.
operator ==
	Compares two CBSTRStream objects.
operator =
	Assigns a new value to an existing CBSTRStream object.
operator BSTR() operator _bstr_t()
	Extracts the pointers/objects to the encapsulated BSTR object.

Operations

void reset
	Resets the string (but keeps the buffer).
long length const
	Returns the length of the encapsulated BSTR.

Limitations

• This class is NOT threadsafe.

History

v1.0 (2001-04-13)

• Initial Release