新建 文本文档.txt

文法如下: (1)S->aAcBe (2)A->b (3)A->Ab (4)B->d 關於lr0的語法分析

#include <stdio.h>
#include <iostream.h>
#include <stdlib.h>

#define stack_size 20
#define stackincrement 10

int p=0,q=0,zh,sh,x;
char Vn[3]={'S','A','B'};   //非终结符
char Vt[6]={'a','c','e','b','d','#'};   //终结符
typedef struct {
    char *bottom;
    char *top;
    int size;
// char data[stack_size];
}stack;

int Initstack(stack &s)        //初始化栈
{
   s.bottom=(char *)malloc(stack_size*sizeof(char));
   if(!s.bottom) exit(-1);
   s.top=s.bottom;
   s.size=stack_size;
   return(1);
}

int push(stack &s,char e)      //入栈
{
 //int i;
   if(s.top-s.bottom>=s.size){
      s.bottom=(char *)realloc(s.bottom,(stack_size+stackincrement)*sizeof(char));
      if(!s.bottom) exit(-1);
      s.top=s.bottom+s.size;
      s.size+=stackincrement;
   
   }
   *s.top++=e;
    
    cout<<e<<"进s栈";
  //  s.data[x]=e;      // 
// x++;
//输出所有元素
 //  for(i=0;i<x;i++)cout<<s.data[x];
   return(1);
}
int push2(stack &s,int e)      //入栈
{
 //int i;
   if(s.top-s.bottom>=s.size){
      s.bottom=(char *)realloc(s.bottom,(stack_size+stackincrement)*sizeof(char));
      if(!s.bottom) exit(-1);
      s.top=s.bottom+s.size;
      s.size+=stackincrement;
   
   }
   *s.top++=e;
    
    cout<<e<<"进t栈";
   return(1);
}

int pop(stack &s,char *e)       //出栈
{
   if(s.top==s.bottom) return(0);
   *e=*--s.top;
   cout<<*e<<"出s栈"<<"        ";
   return(1);
}

int pop2(stack &s,int *e)       //出栈
{
   if(s.top==s.bottom) return(0);
   *e=*--s.top;
 
   cout<<*e<<"出t栈"<<"        ";
   return(1);
}


int action(int m,int n,char a)    //ACTION表
{
  int i;
  int act[10][6]={{2,0,0,0,0,0},{0,0,0,0,0,20},
  {0,0,0,4,0,0},{0,5,0,6,0,0},{12,12,12,12,12,12},
  {0,0,0,0,8,0},{13,13,13,13,13,13},{0,0,9,0,0,0},
  {14,14,14,14,14,14},{11,11,11,11,11,11 } };
  for(i=0; i<n; i++)
     if(a==Vt[i])
   break;
  if(i==n&&a!=Vt[n-1])return(0);
  else 
  {zh=act[m][i];
   //if(zh==0)cout<<"出错"<<endl;
   //else return(zh);  
   return(zh);
  }
}
int go(int m,int n,char a)    //goto表
{
 int i;
 int go[10][3]={{1,0,0},{0,0,0},{0,3,0},{0,0,0},
 {0,0,0},{0,0,7},{0,0,0},{0,0,0},{0,0,0} };

  for(i=0; i<n; i++)
     if(a==Vn[i])
   break;
  if(i==n&&a!=Vn[n-1])return(0);
  else 
  {sh=go[m][i];
   //if(sh==0)cout<<"出错";
   //else return(sh);  
    return(sh);
  }

}


void main()
{  
   char ch,y;
   int x,v,e,u,ok=1;
   int i=0,index=0,k;
   char st[20];

   stack s;
   stack t;
  
   cout<<" 输入要分析的字符串(end by ';'):"<<endl;
   cin>>st[0];
   while(st[i]!=';'){
        i++;
     cin>>st[i];

   }  
   Initstack(s);
   Initstack(t);
   push(s,'#');
   push2(t,0);
   cout<<"\t";

   while(ok==1){
   ch=st[index];
   index++;
   cout<<endl<<ch<<"分析";
      if(ch==';')
    {ok=0;break;
    }
      
       y=ch;
    cout<<"y="<<y<<"\t";  //y是终结符
    pop2(t,&q);   //这两句主要是为了得到当前的q值
    push2(t,q);
    cout<<"q="<<q<<"\t";   //q是0~9的数字
    u=action(q,6,y);
     cout<<"u="<<u<<"\t";
       if(action(q,6,y)>0&&action(q,6,y)<10){
          push(s,ch);
          push2(t,zh);
         // q=zh;
        }
        if(action(q,6,y)>10&&action(q,6,y)<20){
          switch(zh)
          { case 11: for(i=0;i<5;i++){pop(s,&y);pop2(t,&x);}
                     push(s,'S');
           
      pop2(t,&e);
      push2(t,e);
      go(e,3,'S');  //查询GOTO表
      push2(t,sh);  //替换后的数字
      index--;

      break;
                     
            case 12: pop(s,&y);pop2(t,&x);
                     push(s,'A');

      pop2(t,&e);
      push2(t,e);
      go(e,3,'A');
      push2(t,sh);
                     index--;
                     break;
            case 13: pop(s,&y);
                     pop(s,&y);
                     pop2(t,&x);
      pop2(t,&x);
                     push(s,'A');
         pop2(t,&e);
      push2(t,e);
      go(e,3,'A');
      push2(t,sh);
      index--;
                  break;
            case 14: pop(s,&y);pop2(t,&x);
                     push(s,'B');
      pop2(t,&e);
      push2(t,e);
      go(e,3,'B');
      push2(t,sh);
      index--;
      break;

           }
         }
  if(action(q,6,y)==20)
  {cout<<"分析成功"<<endl;
  ok=0;
  }
  else if(u==0){cout<<"出错"<<endl;break;}
  }

}