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#ifndef SQL_PLIST_H
#define SQL_PLIST_H
/* Copyright (C) 2008 MySQL AB
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
#include <my_global.h>
template <typename T, typename B> class I_P_List_iterator;
/**
Intrusive parameterized list.
Unlike I_List does not require its elements to be descendant of ilink
class and therefore allows them to participate in several such lists
simultaneously.
Unlike List is doubly-linked list and thus supports efficient deletion
of element without iterator.
@param T Type of elements which will belong to list.
@param B Class which via its methods specifies which members
of T should be used for participating in this list.
Here is typical layout of such class:
struct B
{
static inline T **next_ptr(T *el)
{
return &el->next;
}
static inline T ***prev_ptr(T *el)
{
return &el->prev;
}
};
*/
template <typename T, typename B>
class I_P_List
{
T *first;
/*
Do not prohibit copying of I_P_List object to simplify their usage in
backup/restore scenarios. Note that performing any operations on such
is a bad idea.
*/
public:
I_P_List() : first(NULL) { };
inline void empty() { first= NULL; }
inline bool is_empty() { return (first == NULL); }
inline void push_front(T* a)
{
*B::next_ptr(a)= first;
if (first)
*B::prev_ptr(first)= B::next_ptr(a);
first= a;
*B::prev_ptr(a)= &first;
}
inline void remove(T *a)
{
T *next= *B::next_ptr(a);
if (next)
*B::prev_ptr(next)= *B::prev_ptr(a);
**B::prev_ptr(a)= next;
}
inline T* head() { return first; }
void swap(I_P_List<T,B> &rhs)
{
swap_variables(T *, first, rhs.first);
if (first)
*B::prev_ptr(first)= &first;
if (rhs.first)
*B::prev_ptr(rhs.first)= &rhs.first;
}
#ifndef _lint
friend class I_P_List_iterator<T, B>;
#endif
};
/**
Iterator for I_P_List.
*/
template <typename T, typename B>
class I_P_List_iterator
{
I_P_List<T, B> *list;
T *current;
public:
I_P_List_iterator(I_P_List<T, B> &a) : list(&a), current(a.first) {}
inline void init(I_P_List<T, B> &a)
{
list= &a;
current= a.first;
}
inline T* operator++(int)
{
T *result= current;
if (result)
current= *B::next_ptr(current);
return result;
}
inline void rewind()
{
current= list->first;
}
};
#endif
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