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2_2_3_stl_construct.h
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135 lines (108 loc) · 4.03 KB
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/*
*
* Copyright (c) 1994
* Hewlett-Packard Company
*
* Permission to use, copy, modify, distribute and sell this software
* and its documentation for any purpose is hereby granted without fee,
* provided that the above copyright notice appear in all copies and
* that both that copyright notice and this permission notice appear
* in supporting documentation. Hewlett-Packard Company makes no
* representations about the suitability of this software for any
* purpose. It is provided "as is" without express or implied warranty.
*
*
* Copyright (c) 1996,1997
* Silicon Graphics Computer Systems, Inc.
*
* Permission to use, copy, modify, distribute and sell this software
* and its documentation for any purpose is hereby granted without fee,
* provided that the above copyright notice appear in all copies and
* that both that copyright notice and this permission notice appear
* in supporting documentation. Silicon Graphics makes no
* representations about the suitability of this software for any
* purpose. It is provided "as is" without express or implied warranty.
*/
/* NOTE: This is an internal header file, included by other STL headers.
* You should not attempt to use it directly.
*/
#ifndef __SGI_STL_INTERNAL_CONSTRUCT_H
#define __SGI_STL_INTERNAL_CONSTRUCT_H
#include <new.h> // 使用placement new
__STL_BEGIN_NAMESPACE
// construct and destroy. These functions are not part of the C++ standard,
// and are provided for backward compatibility with the HP STL. We also
// provide internal names _Construct and _Destroy that can be used within
// the library, so that standard-conforming pieces don't have to rely on
// non-standard extensions.
// Internal names
template <class _T1, class _T2>
inline void _Construct(_T1* __p, const _T2& __value) {
new ((void*) __p) _T1(__value); // placement new; 唤起T1::T1(value)
}
template <class _T1>
inline void _Construct(_T1* __p) {
new ((void*) __p) _T1();
}
// 第一个版本，接受一个参数
template <class _Tp>
inline void _Destroy(_Tp* __pointer) {
__pointer->~_Tp(); // 调用dtor ~T()
}
// 如果元素value type 有 non-trivial destructor
template <class _ForwardIterator>
void
__destroy_aux(_ForwardIterator __first, _ForwardIterator __last, __false_type)
{
for ( ; __first != __last; ++__first)
destroy(&*__first);
}
// 如果元素value type 有 trivial destructor
template <class _ForwardIterator>
inline void __destroy_aux(_ForwardIterator, _ForwardIterator, __true_type) {}
// 判断元素value type是否有trivial destructor
template <class _ForwardIterator, class _Tp>
inline void
__destroy(_ForwardIterator __first, _ForwardIterator __last, _Tp*)
{
typedef typename __type_traits<_Tp>::has_trivial_destructor
_Trivial_destructor;
__destroy_aux(__first, __last, _Trivial_destructor());
}
// 第二个版本，接受两个迭代器，函数设法找出元素类别，进而利用 __type_traits<>使用最佳措施
template <class _ForwardIterator>
inline void _Destroy(_ForwardIterator __first, _ForwardIterator __last) {
__destroy(__first, __last, __VALUE_TYPE(__first));
}
// destroy()特化版
inline void _Destroy(char*, char*) {}
inline void _Destroy(int*, int*) {}
inline void _Destroy(long*, long*) {}
inline void _Destroy(float*, float*) {}
inline void _Destroy(double*, double*) {}
#ifdef __STL_HAS_WCHAR_T
inline void _Destroy(wchar_t*, wchar_t*) {}
#endif /* __STL_HAS_WCHAR_T */
// --------------------------------------------------
// Old names from the HP STL.
template <class _T1, class _T2>
inline void construct(_T1* __p, const _T2& __value) {
_Construct(__p, __value);
}
template <class _T1>
inline void construct(_T1* __p) {
_Construct(__p);
}
template <class _Tp>
inline void destroy(_Tp* __pointer) {
_Destroy(__pointer);
}
template <class _ForwardIterator>
inline void destroy(_ForwardIterator __first, _ForwardIterator __last) {
_Destroy(__first, __last);
}
__STL_END_NAMESPACE
#endif /* __SGI_STL_INTERNAL_CONSTRUCT_H */
// Local Variables:
// mode:C++
// End: