最近遇到一个了问题，就是要从普通文本文件中读取数据，这些数据是自定义的格式的层次结构，要把这些数据转化成嵌套的链表存储起来。
数据格式如下：
begin
111
begin
222
begin
333
end
444
begin
555
end
666
end
777
begin
888
end
999
begin
000
end
aaa
end
如果用缩进表示就是下面的样子了：
begin
111
begin
222
begin
333
end
444
begin
555
end
666
end
777
begin
888
end
999
begin
000
end
aaa
end
我的解析程序如下：
- #include <string>
- #include <iostream>
- #include <fstream>
- #include <stack>
- #include <list>
- using namespace std;
- typedef struct tagNode Node;
- typedef struct tagNode
- {
- string str;
- list<Node*>* pSubList;
- } Node;
- void PrintList(list<Node*>* pList, int* piCnt)
- {
- ++*piCnt;
- for (list<Node*>::iterator it = pList->begin(); it != pList->end(); ++it)
- {
- for (int i = 0; i < *piCnt; ++i)
- cout << "/t";
- cout << (*it)->str << endl;
- if ((*it)->pSubList != NULL)
- {
- PrintList((*it)->pSubList, piCnt);
- --*piCnt;
- }
- }
- }
- int main()
- {
- ifstream cin("data");
- stack<Node*> stk;
- list<Node*>* pList = NULL;
- string str;
- Node* pParent = NULL;
- Node* pNew = NULL;
- cin >> str;
- if (str == "begin")
- {
- cin >> str;
- pNew = new Node;
- pNew->str = str;
- pNew->pSubList = NULL;
- pList = new list<Node*>;
- pList->insert(pList->begin(), pNew);
- stk.push(pNew);
- }
- while (!stk.empty())
- {
- cin >> str;
- if (str == "begin")
- {
- cin >> str;
- pNew = new Node;
- pNew->str = str;
- pNew->pSubList = NULL;
- pParent = stk.top();
- pParent->pSubList = new list<Node*>;
- pParent->pSubList->insert(pParent->pSubList->begin(), pNew);
- stk.push(pNew);
- }
- else if (str == "end")
- {
- stk.pop();
- }
- else
- {
- stk.pop();
- pNew = new Node;
- pNew->str = str;
- pNew->pSubList = NULL;
- if (stk.size() > 0)
- {
- pParent = stk.top();
- pParent->pSubList->insert(pParent->pSubList->end(), pNew);
- }
- else
- {
- pList->insert(pList->end(), pNew);
- }
- stk.push(pNew);
- }
- }
- int iCnt = -1;
- PrintList(pList, &iCnt);
- return 0;
- }
运行结果如下：
