73 lines
2.4 KiB
C
73 lines
2.4 KiB
C
/*++
|
|
|
|
Copyright (C) 1992-2001 Microsoft Corporation
|
|
|
|
Module Name:
|
|
|
|
ELEMENTS.H
|
|
|
|
Abstract:
|
|
|
|
History:
|
|
|
|
--*/
|
|
|
|
// This is a part of the Microsoft Foundation Classes C++ library.
|
|
// Copyright (C) 1992-1993 Microsoft Corporation
|
|
// All rights reserved.
|
|
//
|
|
// This source code is only intended as a supplement to the
|
|
// Microsoft Foundation Classes Reference and Microsoft
|
|
// QuickHelp documentation provided with the library.
|
|
// See these sources for detailed information regarding the
|
|
// Microsoft Foundation Classes product.
|
|
|
|
// Collection implementation helpers
|
|
|
|
/*
|
|
* The short story:
|
|
* this file contains inline functions that make up the building blocks
|
|
* for implementing the string versions of standard parameterized
|
|
* collection shapes
|
|
*
|
|
* The long story:
|
|
* Because the implementation of collection classes moves objects around
|
|
* in various ways, it is very inefficient to use only generic C++ constructs.
|
|
* For example, in order to grow an array of FOO objects by one element,
|
|
* you would be forced to allocate a new array of appropriate size, calling
|
|
* the FOO constructor on every element. Then copy the original array, element
|
|
* by element using a possibly overloaded assignment operator. Finally destroy
|
|
* the original array element by element.
|
|
* For built-in data types (WORD, DWORD, pointer types), this is complete
|
|
* overkill. For non-trivial classes (eg: CString in particular) this is
|
|
* a terrible implementation.
|
|
*
|
|
* The bottom line: we have to special routines for doing construction
|
|
* and destruction of arrays of special elements - in particular CStrings.
|
|
* The standard templates are parameterized on 'HAS_CREATE' which is
|
|
* non-zero if the collection implementation requires a special
|
|
* construct and destruct function.
|
|
*
|
|
* Please note that these are inline overloaded operators, and do not have
|
|
* any form of runtime polymorphism (i.e. nothing is 'virtual').
|
|
*/
|
|
|
|
/////////////////////////////////////////////////////////////////////////////
|
|
// Special implementations for CStrings
|
|
// it is faster to bit-wise copy a CString than to call an official
|
|
// constructor - since an empty CString can be bit-wise copied
|
|
|
|
extern const CString afxEmptyString;
|
|
|
|
static inline void ConstructElement(CString* pNewData)
|
|
{
|
|
memcpy(pNewData, &afxEmptyString, sizeof(CString));
|
|
}
|
|
|
|
static inline void DestructElement(CString* pOldData)
|
|
{
|
|
pOldData->Empty();
|
|
}
|
|
|
|
/////////////////////////////////////////////////////////////////////////////
|