编译原理(十) SLR文法分析法(算法原理和C++实现)

前情提要

因为SLR文法分析法就是对LR(0)的一种优化，它提供了一种解决冲突的方法，所以很多之前在LR(0)提及的东西，在此只提供一个引用。
LR(0)文法分析法
算法描述

SLR文法构造分析表的主要思想是：许多冲突性的动作都可能通过考察有关非终结符的FOLLOW集而获解决。
解决冲突的方法：解决冲突的方法是分析所有含A和B的句型，考察集合FOLLOW(A)和FOLLOW(B)，如果这两个集合不相交，而且也不包含b，那么当状态I面临输入符号a时，我们可以使用如下策略：
若a=b，则移进。
若a∈FOLLOW(A)，则用产生式A→α进行归约；
若a∈FOLLOW(B)，则用产生式B→α进行归约；
此外，报错*
SLR的基本算法：
假定LR(0)规范族的一个项目集I中含有m个移进项目
A1→α•a1β1，A2→α•a2β2，…，Am→α•amβm；
同时含有n个归约项目
B1→α•，B2→α•，…，B3→α•，
如果集合{ a1,…, am}，FOLLOW(B1)，…，FOLLOW(Bn)两两不相交（包括不得有两个FOLLOW集合有#），则隐含在I中的动作冲突可以通过检查现行输入符号a属于上述n+1个集合中的哪个集合而活的解决：
- 若a是某个ai，i=1,2,…,m，则移进。
- 若a∈FOLLOW(Bi)，i=1,2,…,m，则用产生式Bi→α进行归约；
- 此外，报错
这种冲突的解决方法叫做SLR(1)解决办法。
SLR语法分析表的构造方法：
首先把G拓广为G’，对G’构造LR(0)项目集规范族C和活前缀识别自动机的状态转换函数Go。函数ACTION和GOTO可按如下方法构造：
若项目A→α•bβ属于Ik，GO(Ik,a)= Ij,a为终结符，置ACTION[k,a]为“把状态j和符号a移进栈”，简记为“sj”；
若项目A→α•属于Ik，那么，对任何非终结符a，a∈FOLLOW(A)，置ACTION[k,a]为“用产生式A→α进行归约”，简记为“rj”；其中，假定A→α为文法G’的第j个产生式
若项目S’→S•属于Ik，则置ACTION[k,#]为可“接受”，简记为“acc”；
若GO(Ik, A)= Ij，A为非终结符，则置GOTO[k, A]=j；
分析表中凡不能用规则1至4填入信息的空白格均填上“出错标志”。
语法分析器的初始状态是包含S’ →•S的项目集合的状态
SLR解决的冲突只是移进-规约冲突和规约-规约冲突
代码实现

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <cctype>
#include <vector>
#include <string>
#include <queue>
#include <map>
#include <set>
#include <sstream>
#define MAX 507
#define DEBUG
/*Author : byj*/
using namespace std;

class WF
{
    public:
    string left,right;
    int back;
    int id;
    WF ( char s1[] , char s2[] , int x , int y )
    {
        left = s1;
        right = s2;
        back = x;
        id = y;
    }
    WF ( const string& s1 , const string& s2 , int x , int y )
    {
        left = s1;
        right = s2;
        back = x;
        id = y;
    }
    bool operator < ( const WF& a ) const 
    {
        if ( left == a.left ) 
            return right < a.right;
        return left < a.left;
    }
    bool operator == ( const WF& a ) const 
    {
        return ( left == a.left )&& ( right == a.right );
    }
    void print ( )
    {
        printf ( "%s->%s\n" , left.c_str() , right.c_str() );
    }
};

class Closure
{
    public:
    vector<WF> element; 
    void print ( string str )
    {
        printf ( "%-15s%-15s\n" , "" , str.c_str());
        for ( int i = 0 ; i < element.size() ; i++ )
            element[i].print();
    }
    bool operator == ( const Closure& a ) const 
    {
        if ( a.element.size() != element.size() ) return false;
        for ( int i = 0 ; i < a.element.size() ; i++ )
            if ( element[i] == a.element[i] ) continue;
            else return false;
        return true;
    }
};

struct Content
{
    int type;
    int num;
    string out;
    Content(){ type = -1; }
    Content ( int a , int b )
        :type(a),num(b){}
};

vector<WF> wf;
map<string,vector<int> > dic;
map<string,vector<int> > VN_set;
map<string,bool>  vis;
string start = "S";
vector<Closure> collection;
vector<WF> items;
char CH = '$';
int go[MAX][MAX];
int to[MAX];
vector<char> V;
bool used[MAX];
Content action[MAX][MAX];
int Goto[MAX][MAX];
map<string,set<char> > first;
map<string,set<char> > follow;

void make_item ( )
{
    memset ( to , -1 , sizeof ( -1 ) );
    for ( int i = 0 ; i < wf.size() ; i++ )
        VN_set[wf[i].left].push_back ( i );
    for ( int i = 0 ; i < wf.size() ; i++ )
        for ( int j = 0 ; j <= wf[i].right.length() ; j++ )
        {
            string temp = wf[i].right;
            temp.insert ( temp.begin()+j , CH );
            dic[wf[i].left].push_back ( items.size() );
            if ( j )
                to[items.size()-1] = items.size();
            items.push_back ( WF ( wf[i].left , temp , i , items.size()) );
        }
#ifdef DEBUG
    puts("-------------------------项目表-------------------------");
    for ( int i = 0 ; i < items.size() ; i++ )
        printf ( "%s->%s back:%d id:%d\n" , items[i].left.c_str() , items[i].right.c_str() , items[i].back , items[i].id );
    puts("--------------------------------------------------------");
#endif
}

void dfs ( const string& x )
{
    if ( vis[x] ) return;
    vis[x] = 1;
    vector<int>& id = VN_set[x];
    for ( int i = 0 ; i < id.size() ; i++ )
    {
        string& left = wf[id[i]].left;
        string& right = wf[id[i]].right;
        for ( int j = 0 ; j < right.length() ; j++ )
            if ( isupper(right[j] ) )
            {
                dfs ( right.substr(j,1) );
                set<char>& temp = first[right.substr(j,1)];
                set<char>::iterator it = temp.begin();
                bool flag = true;
                for ( ; it != temp.end() ; it++ )
                {
                    if ( *it == '~' ) flag = false;
                    first[left].insert (*it );
                }
                if ( flag ) break;
            }
            else
            {
                first[left].insert ( right[j] );
                break;
            }
    } 
}

void make_first ( )
{
    vis.clear();
    map<string,vector<int> >::iterator it2 = dic.begin();
    for ( ; it2 != dic.end() ; it2++ )
        if ( vis[it2->first] ) continue;
        else dfs ( it2->first );
#ifdef DEBUG
    puts ("****************FIRST集***************************");
    map<string,set<char> >::iterator it = first.begin();
    for ( ; it != first.end() ; it++ )
    {
        printf ( "FIRST(%s)={" , it->first.c_str() );
        set<char> & temp = it->second;
        set<char>::iterator it1 = temp.begin();
        bool flag = false;
        for ( ; it1 != temp.end() ; it1++ )
        {
            if ( flag ) printf ( "," );
            printf ( "%c" , *it1 );
            flag = true;
        }
        puts ("}" );
    }
#endif 
}

void append ( const string& str1 , const string& str2 )
{
    set<char>& from = follow[str1];
    set<char>& to = follow[str2];
    set<char>::iterator it = from.begin();
    for ( ; it != from.end() ; it++ )
        to.insert ( *it );
}

bool _check ( const vector<int>& id, const string str )
{
    for ( int i = 0 ; i < id.size() ; i++ )
    {
        int x = id[i];
        if ( wf[x].right == str ) return true;
    }
    return false;
}

void make_follow ( )
{
    while ( true )
    {
        bool goon = false;
        map<string,vector<int> >::iterator it2 = VN_set.begin();
        for ( ; it2 != VN_set.end() ; it2++ )
        {
            vector<int>& id = it2->second;
            for ( int i = 0 ; i < id.size() ; i++ )
            {
                bool flag = true;
                WF& tt = wf[id[i]];
                string& left = tt.left;
                const string& right = tt.right;
                for ( int j = right.length()-1 ; j >= 0 ; j-- )
                    if ( isupper( right[j] ) )
                    {
                        if ( flag )
                        {
                            int tx = follow[right.substr(j,1)].size();
                            append( left , right.substr(j,1) );
                            int tx1 = follow[right.substr(j,1)].size();
                            if ( tx1 > tx ) goon = true;
                            if ( _check ( id , "~" ) )
                                flag = false;           
                        }
                        for ( int k = j+1 ; k < right.length() ; k++ )
                            if ( isupper(right[k] ) )
                            {
                                string idd = right.substr(k,1);
                                set<char>& from = first[idd];
                                set<char>& to = follow[right.substr(j,1)];
                                set<char>::iterator it1 = from.begin();
                                int tx = follow[right.substr(j,1)].size();
                                for ( ; it1 != from.end() ; it1++ )
                                    if ( *it1 != '~' )
                                        to.insert ( *it1 );
                                int tx1 = follow[right.substr(j,1)].size();
                                if ( tx1 > tx ) goon = true;
                                if ( _check ( id , "~" ) )
                                    break;
                            }
                            else
                            {
                                int tx = follow[right.substr(j,1)].size();
                                follow[right.substr(j,1)].insert ( right[k] );
                                int tx1 = follow[right.substr(j,1)].size();
                                if ( tx1 > tx ) goon = true;
                                break;        
                            }
                    }
                    else flag = false;
            }
        }
        if ( !goon ) break;
    }
#ifdef DEBUG
    puts ("***************FOLLOW集*******************");
    map<string,set<char> >::iterator it = follow.begin();
    for ( ; it != follow.end() ; it++ )
    {
        printf ( "FOLLOW(%s)={" , it->first.c_str() );
        set<char> & temp = it->second;
        //if ( it->first[0] == 'S' )
            temp.insert ( '#' );
        set<char>::iterator it1 = temp.begin();
        bool flag = false;
        for ( ; it1 != temp.end() ; it1++ )
        {
            if ( flag ) printf ( "," );
            printf ( "%c" , *it1 );
            flag = true;
        }
        puts ("}");
    }
#endif
}


void make_set ( )
{
    bool has[MAX];
    for ( int i = 0 ; i < items.size() ; i++ )
        if ( items[i].left[0] == 'S' && items[i].right[0] == CH )
        {
            Closure temp;
            string& str = items[i].right;
            vector<WF>& element = temp.element;
            element.push_back ( items[i] );
            int x = 0;
            for ( x = 0 ; x < str.length() ; x++ )
                if ( str[x] == CH )
                    break;
            /*if ( x != str.length()-1 )
            {
                string tt = str.substr(x+1,1);
                vector<int>& id = dic[tt];
                for ( int j = 0 ; j < id.size() ; j++ )
                {
                    int tx = id[j];
                    //items[tx].print();
                    if ( items[tx].right[0] == CH )
                        element.push_back ( items[tx] );
                }
            }*/
            memset ( has , 0 , sizeof ( has ) );
            has[i] = 1;
            if ( x != str.length()-1 )
            {
                queue<string> q;
                q.push( str.substr(x+1,1) );
                while ( !q.empty() )
                {
                    string u = q.front();
                    q.pop();
                    vector<int>& id = dic[u];
                    for( int j = 0 ; j < id.size() ; j++ )
                    {
                        int tx = id[j];
                        if ( items[tx].right[0] == CH )
                        {   
                            if ( has[tx] ) continue;
                            has[tx] = 1;
                            if ( isupper(items[tx].right[1] ) )
                                q.push ( items[tx].right.substr(1,1));
                            element.push_back ( items[tx] );
                        }    
                    }
                }
            }
            collection.push_back ( temp );
        }
    for ( int i = 0 ; i < collection.size() ; i++ )
    {
        map<int,Closure> temp;
        for ( int j = 0 ; j < collection[i].element.size() ; j++ )
        {
            string str = collection[i].element[j].right;
            int x = 0;
            for ( ; x < str.length() ; x++ )
               if ( str[x] == CH ) break;
            if ( x == str.length()-1 ) 
                continue;
            int y = str[x+1];
            int ii;
            //cout << i << "previous: " << str << endl;
            str.erase ( str.begin()+x);
            str.insert ( str.begin()+x+1 , CH );
            //cout << i <<"after: " << str << endl;
            WF cmp = WF ( collection[i].element[j].left , str , -1 , -1 );
            for ( int k = 0 ; k< items.size() ; k++ )
                if ( items[k] == cmp )
                {
                    ii = k;
                    break;
                }
             //string& str1 = items[ii].right;
             memset ( has , 0 , sizeof ( has ) );
             vector<WF>& element = temp[y].element;
             element.push_back ( items[ii] );
             has[ii] = 1;
             x++;
             /*if ( x != str.length()-1 )
             {
                 string tt = str.substr(x+1,1);
                 vector<int>& id = dic[tt];
                 for ( int j = 0 ; j < id.size() ; j++ )
                 {
                    int tx = id[j];
                    //items[tx].print();
                    if ( items[tx].right[0] == CH )
                        element.push_back ( items[tx] );
                 } 
             }*/
            if ( x != str.length()-1 )
            {
                queue<string> q;
                q.push( str.substr(x+1,1) );
                while ( !q.empty() )
                {
                    string u = q.front();
                    q.pop();
                    vector<int>& id = dic[u];
                    for( int j = 0 ; j < id.size() ; j++ )
                    {
                        int tx = id[j];
                        if ( items[tx].right[0] == CH )
                        {   
                            if ( has[tx] ) continue;
                            has[tx] = 1;
                            if ( isupper(items[tx].right[1] ) )
                                q.push ( items[tx].right.substr(1,1));
                            element.push_back ( items[tx] );
                        }    
                    }
                }
            }
        }
        map<int,Closure>::iterator it = temp.begin();
        for ( ; it != temp.end() ; it++ )
                collection.push_back ( it->second );
        for ( int i = 0 ; i < collection.size() ; i++ )
            sort ( collection[i].element.begin() , collection[i].element.end() );
        for ( int i = 0 ; i < collection.size() ; i++ )
            for ( int j = i+1 ; j < collection.size() ; j++ )
                if ( collection[i] == collection[j] )
                    collection.erase ( collection.begin()+j );
    }
#ifdef DEBUG
    puts ("-------------CLOSURE---------------------");
    stringstream sin;
    for ( int i = 0 ; i < collection.size() ; i++ )
    {
        sin.clear();
        string out;
        sin <<"closure-I" << i;
        sin >> out;
        collection[i].print ( out );
    }
    puts("");
#endif  
}

void make_V ( )
{
    memset ( used , 0 , sizeof ( used ) );
    for ( int i = 0 ; i < wf.size() ; i++ )
    {
        string& str = wf[i].left;
        for ( int j = 0 ; j < str.length() ; j++ )
        {
            if ( used[str[j]] ) continue;
            used[str[j]] = 1;
            V.push_back ( str[j] );
        }
        string& str1 = wf[i].right;
        for ( int j = 0 ; j < str1.length() ; j++ )
        {
            if ( used[str1[j]] ) continue;
            used[str1[j]] = 1;
            V.push_back ( str1[j] );
        }
    }
    sort ( V.begin() , V.end() );
    V.push_back ( '#' );
}

void make_cmp ( vector<WF>& cmp1 , int i  , char ch )
{
    for ( int j = 0 ; j < collection[i].element.size() ; j++ )
    {
        string str = collection[i].element[j].right;
        int k;
        for ( k = 0 ; k < str.length() ; k++ )
            if ( str[k] == CH ) 
                break;
        if ( k != str.length() - 1 && str[k+1] == ch  )
        {
            str.erase ( str.begin()+k);
            str.insert ( str.begin()+k+1 , CH );
            cmp1.push_back ( WF ( collection[i].element[j].left , str , -1 , -1 ) );
        }
    }
    sort ( cmp1.begin() , cmp1.end() );
}

void make_go ( )
{
    memset ( go , -1 , sizeof ( go ) );
    int m = collection.size();
    /*for ( int i = 0 ; i < m ; i++ )
        for ( int j = 0 ; j < collection[i].element.size() ; j++ )
        {
            string left = collection[i].element[j].left;
            string str = collection[i].element[j].right;
            int x = 0;
            for ( ; x < str.length() ; x++ )
               if ( str[x] == CH ) break;
            if ( x == str.length()-1 ) 
                continue;
            int y = str[x+1];
           //cout << "before : " << str << endl;
            str.erase ( str.begin()+x);
            str.insert ( str.begin()+x+1 , CH );
           //cout << "after : " << str << endl;
            WF cmp = WF ( collection[i].element[j].left , str , -1 , -1 );
            for ( int k = 0 ; k < m ; k++ )
            {
                bool flag = false;
                for ( int t = 0 ; t < collection[k].element.size() ; t++ )
                {
                    if ( cmp == collection[k].element[t] )
                    {                        
                        flag = true;
                        break;
                    }
                }
                if ( flag )
                {
                    go[i][y] = k;
                }
            }
        }*/
    for ( int t = 0 ; t < V.size() ; t++ )
    {
        char ch = V[t];
        for ( int i = 0 ; i < m ; i++ )
        {
            vector<WF> cmp1;
            make_cmp ( cmp1 , i , ch );
            cout << cmp1.size() << endl;
            if ( cmp1.size() == 0 ) continue;
            for ( int j = 0 ; j < m ; j++ )
            {
                vector<WF> cmp2;
                for ( int k = 0 ; k < collection[j].element.size() ; k++ )
                {
                    string& str = collection[j].element[k].right;
                    int x;
                    for ( x = 0 ; x < str.length() ; x++ )
                        if ( str[x] == CH )
                            break;
                    if ( x && str[x-1] == ch )
                       cmp2.push_back ( WF( collection[j].element[k].left , str , -1 , -1 ) ); 
                }
                sort ( cmp2.begin() , cmp2.end() );
                cout << cmp2.size() << endl;
                bool flag = true;
                if ( cmp2.size() != cmp1.size() ) continue;
                cout << cmp1.size() << endl;
                for ( int k = 0 ; k < cmp1.size() ; k++ )
                    if ( cmp1[k] == cmp2[k] ) continue; 
                    else flag = false;
                cout << "out " << endl;
                if ( flag ) 
                    go[i][ch] = j;
            }
            //cout << "YES" << endl;
        }

    }
#ifdef DEBUG
    puts ("---------------EDGE----------------------");
    stringstream sin;
    string out;
    for ( int i = 0 ; i < m ; i++ )
        for ( int j = 0 ; j < m ; j++ )
            for ( int k = 0 ; k < MAX ; k++ )
                if ( go[i][k] == j )
                {
                    sin.clear();
                    sin << "I" << i << "--" <<(char)(k)<<"--I"<<j;
                    sin >> out;
                    printf ( "%s\n" , out.c_str() );     
                }   
#endif
}

void make_table ( )
{
    memset ( Goto , -1 , sizeof ( Goto ) );
    /*memset ( used , 0 , sizeof ( used ) );
    for ( int i = 0 ; i < wf.size() ; i++ )
    {
        string& str = wf[i].left;
        for ( int j = 0 ; j < str.length() ; j++ )
        {
            if ( used[str[j]] ) continue;
            used[str[j]] = 1;
            V.push_back ( str[j] );
        }
        string& str1 = wf[i].right;
        for ( int j = 0 ; j < str1.length() ; j++ )
        {
            if ( used[str1[j]] ) continue;
            used[str1[j]] = 1;
            V.push_back ( str1[j] );
        }
    }
    sort ( V.begin() , V.end() );
    V.push_back ( '#' );*/
    //write s to the table 
    for( int i = 0 ; i < collection.size() ; i++ )
        for ( int j = 0 ; j < V.size() ; j++ )
        {
            char ch = V[j];
            int x = go[i][ch];
            if ( x == -1 ) continue;
            if ( !isupper(ch) )
                action[i][ch] = Content ( 0 , x );
            else 
                Goto[i][ch] = x;
        }
    //write r and acc to the table 
    for ( int i = 0 ; i < collection.size() ; i++ )
        for ( int j = 0 ; j < collection[i].element.size() ; j++ )
        {
            WF& tt = collection[i].element[j];
            if ( tt.right[tt.right.length()-1] == CH )
            {
                if ( tt.left[0] == 'S' )
                    action[i]['#'] = Content ( 2 , -1 );
                else 
                    for ( int k = 0 ; k < V.size() ; k++ )
                    {
                        int y = V[k];
                        //cout << "YES " << endl;
                        //cout << tt.left << "->" << tt.right << " " << tt.back << endl;
                        if ( !follow[tt.left].count( V[k] ) ) continue;
                       //cout <<tt.left << "->" << tt.right << " " <<  i << " " << V[k] << " " << tt.back << endl;
                        action[i][y] = Content ( 1, tt.back );
                    }
            }
        }
#ifdef DEBUG
    puts ( "------------------------------------------LR(0)分析表--------------------------------------------------------" );
    printf ( "%10s%5c%5s" , "|" , V[0]  , "|");
    for ( int i = 1 ; i < V.size() ; i++ )
        printf ( "%5c%5s" , V[i] , "|" );
    puts ("");
    for ( int i = 0 ; i < (V.size()+1)*10 ; i++ )
        printf ( "-" );
    puts("");
    stringstream sin;
    for ( int i = 0 ; i < collection.size() ; i++ )
    {
        printf ( "%5d%5s" , i , "|" );
        for ( int j = 0 ; j < V.size() ; j++ )
        {
            char ch = V[j];
            if ( isupper(ch) )
            {
                if ( Goto[i][ch] == -1 )
                    printf ( "%10s" , "|" );
                else 
                    printf ( "%5d%5s" , Goto[i][ch] , "|" );
            }
            else
            {
                sin.clear();
                if ( action[i][ch].type == -1 ) 
                    printf ( "%10s" , "|" ); 
                else 
                {
                    Content& temp = action[i][ch];
                    if ( temp.type == 0 ) 
                        sin << "S";
                    if ( temp.type == 1 ) 
                        sin << "R";
                    if ( temp.type == 2 )
                        sin << "acc";
                    if ( temp.num != -1 )
                        sin << temp.num;
                    sin >> temp.out;
                    printf ( "%7s%3s" , temp.out.c_str() , "|" );
                }
            }
        }
        puts ("");
    }
    for ( int i = 0 ; i < (V.size()+1)*10 ; i++ )
        printf ( "-" );
    puts("");
#endif
}

void print ( string s1 , string s2 , string s3 , string s4 , string s5 , string s6 , string s7 )
{
    printf ( "%-15s|%-15s%-15s%-20s|%-15s%-15s%-15s\n" , s1.c_str() , s2.c_str() , s3.c_str() ,s4.c_str(),s5.c_str(),
                                                        s6.c_str() , s7.c_str() );                            
}

string get_steps ( int x )
{
    stringstream sin;
    sin << x;
    string ret;
    sin >> ret;
    return ret;
}

template<class T>
string get_stk ( vector<T> stk )
{
    stringstream sin;
    for ( int i = 0 ; i < stk.size() ; i++ )
        sin << stk[i];
    string ret;
    sin >> ret;
    return ret;
}

string get_shift ( WF& temp )
{
    stringstream sin;
    sin << "reduce(" << temp.left << "->" << temp.right <<")";
    string out;
    sin >> out;
    return out;
}

void analyse ( string src )
{
    print ( "steps","op-stack" ,"input","operation","state-stack" , "ACTION" , "GOTO" );
    vector<char> op_stack;
    vector<int> st_stack;
    src+= "#";
    op_stack.push_back ( '#' );
    st_stack.push_back ( 0 );
    int steps= 1;
    for ( int i = 0 ; i < src.length() ; i++ )
    {
        char u = src[i];
        int top = st_stack[st_stack.size()-1];
        Content& act = action[top][u];
        //cout << "YES : " << i << " " << u << " " << top << " " << act.type << endl;
        if ( act.type == 0 )
        {
            print ( get_steps ( steps++ ) , get_stk ( op_stack ) , src.substr(i), "shift",  get_stk( st_stack ) , act.out , "" );
            op_stack.push_back ( u );
            st_stack.push_back ( act.num );
        }
        else if ( act.type == 1 )
        {
            WF& tt = wf[act.num];
            int y = st_stack[st_stack.size()-tt.right.length()-1];
            int x = Goto[y][tt.left[0]];
            //cout << y << " " << tt.left[0] << " " << x << endl;
            print ( get_steps ( steps++ ) , get_stk ( op_stack ) , src.substr(i) , get_shift(tt) ,get_stk( st_stack),act.out,get_steps(x));
            for ( int j = 0 ; j < tt.right.length() ; j++ )
            {
                st_stack.pop_back();
                op_stack.pop_back();
            }
            op_stack.push_back ( tt.left[0] );
            st_stack.push_back ( x );
            i--;
        }
        else if ( act.type == 2 )
        {
            print ( get_steps( steps++ ), get_stk( op_stack ) , src.substr(i) , "Accept" , get_stk(st_stack) , act.out , "" );
            //i--;
        }
        else continue;
    }
} 

int main ( )
{
    int n;
    char s[MAX];
    while ( ~scanf ( "%d" , &n ) )
    {
        for ( int i = 0 ; i < n ; i++ )
        {
            scanf ( "%s" , s );
            int len = strlen(s),j;
            for ( j = 0 ; j < len ; j++ )
                if ( s[j] == '-' ) break;
            s[j] = 0;
            wf.push_back ( WF ( s , s+j+2 ,-1 , -1 ) );
#ifdef DEBUG
            wf[wf.size()-1].print();
#endif
        }
        make_item();
        make_first();
        make_follow();
        make_set();
        make_V();
        make_go();
        make_table();
        analyse ( "(i*i)+i" );
    }
}
   
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