yucefenxi.java

输出该文法的LL（1）分析表 每行输入一个表达式 输出该表达式的预测分析步骤

/***********************************************************************
*文件名:YUCEFENXI.java
*文件描叙:预测分析程序.分析如下方法:
* E ：：=T|E+T|E-T
        T ：：=F|T*F|T/F
        F ：：=P|（E）
        P ：：=G
        G ：：= i
*为了方便把G ：：= a|b|c|d|e|f|g|h|i|j|k|l|m|n|o|p|q|r|s|t|u|v|w|x|y|z
*简化为G：：= i
*输出:输出该文法的LL（1）分析表
*输入:每行输入一个表达式
*输出:输出该表达式的预测分析步骤
************************************************************************/
import java.io.*; 
import java.util.*;
public class YUCEFENXI       
{public static String[] wenfa={"E->TA","A->+TA","A->-TA","A->ε","T->FB","B->*FB","B->/FB","B->ε","F->P","F->(E)","P->G","G->i"};
  static String s1;
  static String s2;  
  static String[] followE={")","#"}; //下面定义E，E1，T，T1，F，P，G的FOLLOW集
  static String[] followE1={")","#"};
  static String[] followT={"+","-","#"};
  static String[] followT1={"+","-","#"};
  static String[] followF={"*","/","#"};
  static String[] followP={"*","/","#"};
  static String[] followG={"*","/","#"};
  static String[] firstTE1={"(","i"}; //下面定义各个产生式的first集
  static String[] firstTE2={"+"};
  static String[] firstTE3={"-"};
  static String[] firstFT1={"(","i"};
  static String[] firstFT2={"*"};
  static String[] firstFT3={"/"};
  static String[] firstP={"i"};
  static String[] firstE1={"("};
  static String[] firstG={"i"};
  static String[] firsti={"i"};
   static String Sender;
  static String biao[][]={{" ","i","+","-","*","/","(",")","#"},
                         {"E","    ","    ","    ","    ","    ","    ","    "," "},
                         {"A","    ","    ","    ","    ","    ","    ","    ","    "},
                         {"T","    ","    ","    ","    ","    ","    ","    ","    "},
                         {"B","    ","    ","    ","    ","    ","    ","    ","    "},
                         {"F","    ","    ","    ","    ","    ","    ","    ","    "},
                         {"P","    ","    ","    ","    ","    ","    ","    ","    "},
                         {"G","    ","    ","    ","    ","    ","    ","    ","    "}};
  //**********************************************************************************************************
  public static void main(String[] args)throws IOException
{  
	System.out.println("要分析的文法为:");//输出文法信息
	System.out.println("E->T|E+T|E-T");
	System.out.println("T->F|T*F|T/F");
	System.out.println("F->P|(E)");
	System.out.println("P->G");
	System.out.println("G->i");
	System.out.println("该文法的LL（1）分析表为：");
    String sre=new String("该文法的LL（1）分析表是");
    String sr;
	JIANBIAO();
	int len=biao.length;       
	for(int s=0;s<len;s++)
	{int len1=biao[s].length;
	  for(int n=0;n<len1;n++)
	  {
	  	 System.out.print(biao[s][n]);
	  	 sr=biao[s][n];
	    System.out.print("\t");
	 
	  	}
	  	
	  System.out.print("\n");
	  	System.out.print("\n");
	  		}
	
  try{
    
  
    FileReader read=new FileReader("fenxi.txt");  //从fenxi.txt取出算术表达式
    
    BufferedReader in=new BufferedReader(read);
    while((Sender=in.readLine())!=null)
    { System.out.println("请输入算式表达式");
	System.out.println(Sender);  
	System.out.print("\n");
	System.out.println("请进行预测分析！");    
	System.out.print("步骤"+"\t"+"\t"+"符号栈"+"\t"+"\t"+"输入串"+"\t"+"\t"+"所用产生式");
	System.out.print("\n");                       
    FENXI();                                        //对取得的算术表达式进行预测分析
     }
	in.close();
	read.close();
     }
    
     catch(IOException e)
	      {
		     System.out.println(e);
	         	}
     }
  //对每个终结符a属于first(b),把A->b加至M[A，a]中，若ε属于first(b)，且c属于FOLLOW(A)把A->b加至M[A，a]中
//*******************************************************************************************************
public static void JIANBIAO()                 //构造分析表
{

	{for(int i=0;i<firstTE1.length;i++)        
	 {s1=firstTE1[i];
	 for(int j=0;j<biao[0].length;j++)
	 { 
	 
	 s2=biao[0][j];
	    if(s1.equals(s2))
	    {
	        biao[1][j]=wenfa[0];
		}
		 }
	}
	}

	 for(int i=0;i<firstTE2.length;i++)
	 {s1=firstTE2[i];
	 for(int j=0;j<biao[0].length;j++)
	 {s2=biao[0][j];
	    if(s1.equals(s2))
	    {
	        biao[2][j]=wenfa[1];
		}
	}
	}
	
	for(int i=0;i<firstTE3.length;i++)
	 {s1=firstTE3[i];
	 for(int j=0;j<biao[0].length;j++)
	 {s2=biao[0][j];
	    if(s1.equals(s2))
	    {
	        biao[2][j]=wenfa[2];
		}
	}
	}
	
	for(int i=0;i<firstFT1.length;i++)
	 {s1=firstFT1[i];
	 for(int j=0;j<biao[0].length;j++)
	 {s2=biao[0][j];
	    if(s1.equals(s2))
	    {
	        biao[3][j]=wenfa[4];
		}
	}
	}
	
	
	for(int i=0;i<firstFT2.length;i++)
	 {s1=firstFT2[i];
	 for(int j=0;j<biao[0].length;j++)
	 {s2=biao[0][j];
	    if(s1.equals(s2))
	    {
	        biao[4][j]=wenfa[5];
		}
	}
	}
	
	for(int i=0;i<firstFT3.length;i++)
	 {s1=firstFT3[i];
	 for(int j=0;j<biao[0].length;j++)
	 {s2=biao[0][j];
	    if(s1.equals(s2))
	    {
	        biao[4][j]=wenfa[6];
		}
	}
	}
	
	for(int i=0;i<firstP.length;i++)
	 {s1=firstP[i];
	 for(int j=0;j<biao[0].length;j++)
	 {s2=biao[0][j];
	    if(s1.equals(s2))
	    {
	        biao[5][j]=wenfa[8];
		}
	}
	}
	
	for(int i=0;i<firstE1.length;i++)
	 {s1=firstE1[i];
	 for(int j=0;j<biao[0].length;j++)
	 {s2=biao[0][j];
	    if(s1.equals(s2))
	    {
	        biao[5][j]=wenfa[9];
		}
	}
	}
	
	for(int i=0;i<firstG.length;i++)
	 {s1=firstG[i];
	 for(int j=0;j<biao[0].length;j++)
	 {s2=biao[0][j];
	    if(s1.equals(s2))
	    {
	        biao[6][j]=wenfa[10];
		}
	}
	}
	
	for(int i=0;i<firsti.length;i++)
	 {s1=firsti[i];
	 for(int j=0;j<biao[0].length;j++)
	 {s2=biao[0][j];
	    if(s1.equals(s2))
	    {
	        biao[7][j]=wenfa[11];
		}
	}
	}
	
	for(int i=0;i<followE1.length;i++)
	{s1=followE1[i];
	 for(int j=0;j<biao[0].length;j++)
	 {
	 	s2=biao[0][j];
	 	if(s1.equals(s2))
	 	{
	 		biao[2][j]=wenfa[3];
	 		}}
		}
		
		
 for(int i=0;i<followT1.length;i++)
	{s1=followT1[i];
	 for(int j=0;j<biao[0].length;j++)
	 {
	 	s2=biao[0][j];
	 	if(s1.equals(s2))
	 	{
	 		biao[4][j]=wenfa[7];
	 		}}
		}		
	}
	//*************************************************************************************************
public static void FENXI()	             //对算术表达式进行分析
{ String fuhao=new String("#E");
  String str=new String(" ");
  String str1=new String(" ");
  String str2=new String(" ");
  String str3=new String(" ");
  String str4=new String(Sender);
	  int len1;
	  int con=0;
	  int len2;
	  int len3;
	  int i=0;
	  int len=Sender.length();
	 System.out.print(con+"\t"+"\t"+fuhao+"\t"+"\t"+Sender+"\t"+"\t"+str2);//首先输出初始的符号栈和输入串
	 System.out.print("\n");
	str=Sender.substring(0,1);    
	str1=fuhao.substring(1,2);
    fuhao=fuhao.substring(0,1);
  p1:while(!str1.equals("#")) 
	{   
     if(str1.equals(str))
	   {
	   
	   	     ++i;
	   	  str=Sender.substring(i,i+1); //如果符号栈里的最后一个字符与输入串里的字符相等，则两个字符都弹出栈  
	   	  str4=Sender.substring(i);
	        con++;
	       System.out.print(con+"\t"+"\t"+fuhao+"\t"+"\t"+str4+"\t"+"\t");
	       System.out.print("\n"); 
	       
	        
	       
	  	   }
	  	   
	  	else
	  	{
	  		 for(int v=0;v<8;v++)    //符号栈里的字符和分析表对照，把对应的产生式，放入符号栈里
	  	 {  
	  	 if(str1.equals(biao[v][0])) 
	  	  { for(int s=0;s<9;s++)
	  	 	{ 
	  	 	 if(str.equals(biao[0][s]))
	  	 	  str2=biao[v][s];
	  	 		}
	  		} 	
	  	 	}
	  	 
	  	   len1=str2.length();
	  	  for(int t=len1;t>3;t--)
	  	  { 
	  	  	str3=str2.substring(t-1,t);
	  	    if(str3.equals(" "))
	  	     {
	  	     	System.out.println("error"); //如果对应的产生式是空字，则输出error
	  	    	 break p1; 
	  	    	  }     
	  	   if(!str3.equals("ε"))       //如果对应的字符不是ε，则把对应的字符串反序输入符号栈
	  	   {
	  	  	fuhao=fuhao.concat(str3);
	  	  	   }	  	
	  	  	 }	
	  	  con++;
	  	 
	  	  System.out.print(con+"\t"+"\t"+fuhao+"\t"+"\t"+str4+"\t"+"\t"+str2);
          System.out.print("\n");
           	 	 	    	      
	    	 }
	     len2=fuhao.length();
	     str1=fuhao.substring(len2-1,len2);
	     fuhao=fuhao.substring(0,len2-1);     
	    	 }
	    p2:while(str1.equals("#"))       //如果符号栈的字符与输入串里的字符都等于#时，输出accept
	    {if(str1.equals("#"))
	     { if(str.equals("#"))
	     {
	     	System.out.println("accept");  
	        break p2;
	           } 
	        
	         }
	    	}
	    	}
         }