shm_dlist.cpp

实 现 了 一 个 双 向 链 表. 挺 好 用 的.

/*=================================================================
** Copyright (c)2006
** All rights reserved.
**
** 文件名称：ipc_dlist.cpp
**
** 当前版本：1.1
** 作    者：Like
** 完成日期：2006-11-24
**
===================================================================*/

#include <stdlib.h>
#include <stdio.h>
#include "shm_dlist.h"

/*****************************************************************
// 
// Based on the current node, get the next node in a dlist 
// 
******************************************************************/ 

ShmDListIter& ShmDListIter::operator ++ ()
{   
    _node = (ShmElem*) MAKE_SHM_PTR(_node->_nextOffset);
    return *this;
}

/*****************************************************************
// 
// Calculate the size of memory which a ShmDList needed.
// 
******************************************************************/ 
    
int ShmDList::BaseSpace()
{
    return sizeof(ShmDListHead);
}

/*****************************************************************
// 
// Attach to a shared memory
// 
******************************************************************/ 

void ShmDList::Attach(char* mem_addr, int flag)
{
    // ------------------------------------------------------------
    //  size (int) | list head (including prevOffset and nextOffset)
    // ------------------------------------------------------------
    ShmDListHead*   list_head = NULL;
    
    _location = mem_addr;
    
    list_head = (ShmDListHead*) _location;
    
    _size     = &(list_head->_size);
    _listHead = &(list_head->_listHead);
    
    if (flag == 1)
    {
        Init();
    } 
}
  
/*****************************************************************
// 
// 将一个空链表自环。这个函数只能被执行一次。
// 
******************************************************************/ 
  
void ShmDList::Init()
{
    int list_off = 0;
            
    list_off = MAKE_SHM_OFF(_listHead);
    
    _listHead->_nextOffset = list_off;
    _listHead->_prevOffset = list_off;

    *_size = 0;
}

/*****************************************************************
// 
// 将一个节点从链表的“头”插入一个节点
// 
******************************************************************/ 

void ShmDList::push_back(ShmElem* node)
{
    ShmElem*    tail_node = NULL;
        
    node->_nextOffset = MAKE_SHM_OFF(_listHead);                      
    node->_prevOffset = _listHead->_prevOffset;

    tail_node = (ShmElem*) MAKE_SHM_PTR(_listHead->_prevOffset);

    _listHead->_prevOffset = tail_node->_nextOffset = MAKE_SHM_OFF(node);        
      
    (*_size)++;
}

/*****************************************************************
// 
// 将一个节点从链表的“尾”插入一个节点
// 
******************************************************************/ 

void ShmDList::push_front(ShmElem* node)
{
    ShmElem*    next_node = NULL;

    node->_prevOffset = MAKE_SHM_OFF(_listHead);        
    node->_nextOffset = _listHead->_nextOffset;                      

    next_node = (ShmElem*) MAKE_SHM_PTR(_listHead->_nextOffset);

    _listHead->_nextOffset = next_node->_prevOffset = MAKE_SHM_OFF(node);        
        
    (*_size)++;
}

/*****************************************************************
// 
// Delete a node from ShmDList
// 
******************************************************************/ 

ShmDListIter ShmDList::erase(ShmDListIter& it)
{
    ShmElem*    prev_node = (ShmElem*) MAKE_SHM_PTR(it._node->_prevOffset);
    ShmElem*    next_node = (ShmElem*) MAKE_SHM_PTR(it._node->_nextOffset);
    
    prev_node->_nextOffset = it._node->_nextOffset;
    next_node->_prevOffset = it._node->_prevOffset; 

    (*_size)--;
    
    return iterator(next_node); 
}

/*****************************************************************
// 
// As its name, it is used to delete all the nodes from a ShmDList
// 
******************************************************************/ 

void ShmDList::clear()
{
    for (iterator it = begin(); it != end(); )
    {
        it = erase(it);
    }
}