广义表的创建和遍历

#include<iostream> 
#include<string>
#include<cstring>
#include<cstdlib>
#include<list>
#include<map>
using namespace std;

class GLNode{
    public:
        int tag;
        string node;
        class {
            public:
                GLNode *hp, *tp;    
        } ptr;
};

typedef GLNode *GList;

class MyGList{
    public:
        static const int ERROR = -1;
        static const int OK = 1;
        static const int LIST = 2;
        static const int NODE = 3;
        list<string> sl;//广义表的描述字符串
        map<string, string>mp;
        GList L = NULL;
        MyGList(list<string> sl){
            this->sl = sl; 
            initMap();
        }
        
        void buildGList(){
            string s = *sl.begin();
            int pos = s.find_first_of("=");
            if(pos!=s.npos)
                createGList(L, s.substr(pos+1, s.length()));
        }
        
        void outGList(){
            out(L);
        }
    
    private:
        void server(string &s, string &hs){
            int k = 0;//记录尚未匹配的左括弧的个数
            int i = 0;
            for(i; i<s.length(); ++i) {
                if(s[i]=='(') ++k;
                if(s[i]==')') --k;
                if(k==0 && s[i]==',') break;
            }
            if(i < s.length()){
                hs = s.substr(0, i);
                s = s.substr(i+1, s.length()-(i+1));
            } else {
                hs = s;
                s = "";
            }
        }
        
        int initMap(){
            for(list<string>::iterator i = sl.begin(); i!=sl.end(); ++i){
                string s = *i, first, second;
                   int pos = s.find_first_of("=");
                   if(pos!=s.npos){
                       first = s.substr(0, pos);
                       second = s.substr(pos+1, s.length());
                   } else {
                       cout<<"广义表的描述字符串出错!"<<endl;
                       return ERROR;
                   }
                mp.insert(make_pair(first, second));
            }
        }
        
        void out(GList Lx){
            if(!Lx) return;
            if(Lx->tag==NODE){
                cout<<Lx->node<<endl;
                return;
            }
            for(GList p=Lx; p; p=p->ptr.tp)
                out(p->ptr.hp);
        }
        
        void createGList(GList &L, string s){
            if(s=="()"){
                //创建空表
                L = NULL; 
            } else { 
                L = new GLNode;//因为类中有string变量，不能用malloc, 否者赋值无效 
                if(s.find(",")==s.npos && s.find("(")==s.npos && s.find(")")==s.npos){//原子结点 
                    if(mp.find(s) == mp.end()){
                        L->tag = NODE;
                        L->node = s;
                    } else {//当s是只有一个大写字母组成的时候，说明它是一个子表，继续扩展 
                        createGList(L, mp[s]);//这块出了开始bug， 调了好长时间 
                    }
                } else {//非原子结点 
                    L->tag = LIST;
                    GList p = L, q;
                    s = s.substr(1, s.length()-2);
                    do{
                        string hs;
                        server(s, hs);//分离表头 
                        createGList(p->ptr.hp, hs);
                        q = p;
                        if(s!=""){//表尾不空 
                            p = new GLNode;
                            p->tag = LIST;
                            q->ptr.tp = p;    
                        }
                    }while(s!="");
                    q->ptr.tp = NULL;
                }
            }
        }
};

int main(){
    freopen("in.txt", "r", stdin);
    list<string> sl;
    string s;
    while(cin>>s){
        sl.push_back(s);
    }
    MyGList myGList(sl);
    myGList.buildGList();
    myGList.outGList();
    return 0;
}

测试数据：

D=(A,B,C)
A=()
B=(e)
C=(a,(b,c,d))