stl_construct.h

/*
 *
 * 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>

__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.
//destroy函数调用相应类型的析构函数
template <class _Tp>
inline void destroy(_Tp* __pointer) {
  __pointer->~_Tp();
}
//在指定位置上调用相应类型的构造函数
template <class _T1, class _T2>
inline void construct(_T1* __p, const _T2& __value) {
  new (__p) _T1(__value);
}

template <class _T1>
inline void construct(_T1* __p) {
  new (__p) _T1();
}
//下面两个函数通过第三个参数进行重载;
template <class _ForwardIterator>
void
__destroy_aux(_ForwardIterator __first, _ForwardIterator __last, __false_type)
{
  for ( ; __first != __last; ++__first)
    destroy(&*__first);
}
template <class _ForwardIterator> 
inline void __destroy_aux(_ForwardIterator, _ForwardIterator, __true_type) {}

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());//根据元素类型是否为POD类型来进行区分选择调用;
}
//接口函数：destroy;只有要删除一个区间时，才需要判断元素类型有没有trivial constructor
template <class _ForwardIterator>
inline void destroy(_ForwardIterator __first, _ForwardIterator __last) {
  __destroy(__first, __last, __VALUE_TYPE(__first));
}

//trivial destructors
//特化版本;
inline void destroy(char*, char*) {}
inline void destroy(wchar_t*, wchar_t*) {}

__STL_END_NAMESPACE

#endif /* __SGI_STL_INTERNAL_CONSTRUCT_H */

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