cffxq.cpp

词法分析器

// cffxq.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <fstream>
#include <iostream>
#include <string>
using namespace std;

class Word_analyzer
{
 public:
	 ifstream infile;
	 ofstream outfile;
	 Word_analyzer();
	 int analyze(char &c);
	 int symbol_number_analyzer(char &c,int &count);
     int number_analyzer(char &c,string &str,int &count);
     int number_loop(char &c,string &str);
     int exponent_analyzer(char &c,string &str);
     int point_analyzer(char &c,string &str);
	 int id_analyzer(char &c,int &count);
	 int id_loop(char &c,string &str);
	 int id_compare(char &c,string &str);
	 int key_analyzer(char &c,int &count);
	 int note_analyzer(char &c,int &count);
	 int other_char_analyzer(char &c);
	 int exponent_analyzer_two(char &c,string &str);

 private:
	 char a[10],b[4];
	 string key_table[6];
};


int main(int argc, char* argv[])
{
	 char c='\0';
     Word_analyzer analyzer1;
	 while(analyzer1.infile.get(c))
		 analyzer1.analyze(c);
	 analyzer1.infile.close();
	 analyzer1.outfile.close();
	 return 0;
}

Word_analyzer::Word_analyzer()
{ 
  a[0]='+';
  a[1]='-';
  a[2]=',';
  a[3]=';';
  a[4]=')';
  a[5]='[';
  a[6]=']';
  a[7]='{';
  a[8]='}';
  a[9]='*';
  b[0]='<';
  b[1]='>';
  b[2]='=';
  b[3]='!';

  key_table[0]="else";
  key_table[1]="if";
  key_table[2]="int";
  key_table[3]="return";
  key_table[4]="void";
  key_table[5]="while";
  infile.open("f1.txt",ios::in);
	if(!infile)
	{
	  cerr<<"open f1.txt error!"<<endl;
	  exit(1);
	}
	outfile.open("f2.txt",ios::out);
	if(!outfile)
	{
		cerr<<"open f2.txt error!"<<endl;
	    exit(1);
	}

}








int Word_analyzer::key_analyzer(char &c,int &count)
{
  string str="";
  count=0;
  for(int i=0;i<10;i++)
  {
    if(c==a[i])
	{
		cout<<"(专用符号 "<<c<<')'<<endl;
		outfile<<"(专用符号 "<<c<<')'<<endl;
		return 0;
	} 
  } 

  for(int j=0;j<4;j++)
  {
    if(c==b[j])
	{
	  str+=c;
	  if(infile.get(c))
	  {
	    if(c=='=')
		{
		  str+=c;
          cout<<"(专用符号 "<<str<<')'<<endl;
		  outfile<<"(专用符号 "<<str<<')'<<endl;
		  return 0;
		}
		else
		{
		  if(j==3)
		  {
			cout<<"(不可识别 "<<str<<')'<<endl;
		    outfile<<"(不可识别 "<<str<<')'<<endl;
            infile.seekg(-1,ios::cur);
            return 0;
		  }
		  else
		  {
		    cout<<"(专用符号 "<<str<<')'<<endl;
		    outfile<<"(专用符号 "<<str<<')'<<endl;
            infile.seekg(-1,ios::cur);
            return 0;
		  }
		}
	  }
	  else
	  {
	    if(j==3)
		  {
			cout<<"(不可识别 "<<str<<')'<<endl;
		    outfile<<"(不可识别 "<<str<<')'<<endl;
            infile.seekg(-1,ios::cur);
            return 0;
		  }
		  else
		  {
		    cout<<"(专用符号 "<<str<<')'<<endl;
		    outfile<<"(专用符号 "<<str<<')'<<endl;
            infile.seekg(-1,ios::cur);
            return 0;
		  }
	  } 
	}
  }
  count=1;
  return 0;
}







int Word_analyzer::number_loop(char &c,string &str)//数字循环
{ 
	 while(infile.get(c))
	  {
		 if('0'<=c&&c<='9')
			str+=c;
		 else 
		   return 0;
		 
      }
      return 0;
}



int Word_analyzer::exponent_analyzer(char &c,string &str)//指数循环
{
  if(c=='e')
  { 
	str+=c;
    if(infile.get(c))
	{
	  if(c=='+'||c=='-')
	  {
		str+=c;
	    if(infile.get(c))
		{
		  if('0'<=c&&c<='9')
		  {
		   str+=c;
           number_loop(c,str);
           cout<<"(常数符号 "<<str<<')'<<endl;
		   outfile<<"(常数符号 "<<str<<')'<<endl;
		   infile.seekg(-1,ios::cur);
           return 0;
		  }
		  else
		  {
		    cout<<"(错误常数 "<<str<<')'<<endl;
            outfile<<"(错误常数 "<<str<<')'<<endl;
            infile.seekg(-1,ios::cur);
            return 0;
		  }
		}
		else
		{
		  cout<<"(错误常数 "<<str<<')'<<endl;
          outfile<<"(错误常数 "<<str<<')'<<endl;
          return 0;
		}
	  }
	  else
	  {
	    if('0'<=c&&c<='9')
		{
		  str+=c;
          number_loop(c,str);
		  cout<<"(常数符号 "<<str<<')'<<endl;
          outfile<<"(常数符号 "<<str<<')'<<endl;
          infile.seekg(-1,ios::cur);
          return 0;
		}
		else
		{
		  cout<<"(错误常数 "<<str<<')'<<endl;
          outfile<<"(错误常数 "<<str<<')'<<endl;
          infile.seekg(-1,ios::cur);
          return 0;
		}
	  }
	}//718
	else
	{
	  cout<<"(错误常数 "<<str<<')'<<endl;
      outfile<<"(错误常数 "<<str<<')'<<endl;
      return 0;
	}
  }//715
  else
  {
    cout<<"(常数符号 "<<str<<')'<<endl;
    outfile<<"(常数符号 "<<str<<')'<<endl;
    infile.seekg(-1,ios::cur);
    return 0;///////////////////
  }
  
}



int Word_analyzer::exponent_analyzer_two(char &c,string &str)
{
  if(c=='e')
  { 
	str+=c;
    if(infile.get(c))
	{
	  if(c=='+'||c=='-')
	  {
		str+=c;
	    if(infile.get(c))
		{
		  if('0'<=c&&c<='9')
		  {
		   str+=c;
           number_loop(c,str);
           cout<<"(常数符号 "<<str<<')'<<endl;
		   outfile<<"(常数符号 "<<str<<')'<<endl;
		   infile.seekg(-1,ios::cur);
           return 0;
		  }
		  else
		  {
		    cout<<"(错误常数 "<<str<<')'<<endl;
            outfile<<"(错误常数 "<<str<<')'<<endl;
            infile.seekg(-1,ios::cur);
            return 0;
		  }
		}
		else
		{
		  cout<<"(错误常数 "<<str<<')'<<endl;
          outfile<<"(错误常数 "<<str<<')'<<endl;
          return 0;
		}
	  }
	  else
	  {
	    if('0'<=c&&c<='9')
		{
		  str+=c;
          number_loop(c,str);
          if(('A'<=c&&c<='Z')||('a'<=c&&c<='z'))
		     { 
			   str+=c;
			   id_loop(c,str);
			   cout<<"(错误标识 "<<str<<')'<<endl;
               outfile<<"(错误标识 "<<str<<')'<<endl;
               infile.seekg(-1,ios::cur);
               return 0;
			 }
             else
			 {
			   cout<<"(常数符号 "<<str<<')'<<endl;
		       outfile<<"(常数符号 "<<str<<')'<<endl;
		       infile.seekg(-1,ios::cur);
               return 0;
			 }
		  
		}
		else
		{
		  if(('A'<=c&&c<='Z')||('a'<=c&&c<='z'))
		  {
		       str+=c;
			   id_loop(c,str);
			   cout<<"(错误标识 "<<str<<')'<<endl;
               outfile<<"(错误标识 "<<str<<')'<<endl;
               infile.seekg(-1,ios::cur);
               return 0;
		  }
		  else
		  {
		  cout<<"(错误常数 "<<str<<')'<<endl;
          outfile<<"(错误常数 "<<str<<')'<<endl;
          infile.seekg(-1,ios::cur);
          return 0;
		  }
		}
	  }
	}//718
	else
	{
	  cout<<"(错误常数 "<<str<<')'<<endl;
      outfile<<"(错误常数 "<<str<<')'<<endl;
      return 0;
	}
  }//715
  else
  { 

    if(('A'<=c&&c<='Z')||('a'<=c&&c<='z'))
	{
	  str+=c;
	  id_loop(c,str);
	  cout<<"(错误标识 "<<str<<')'<<endl;
      outfile<<"(错误标识 "<<str<<')'<<endl;
      infile.seekg(-1,ios::cur);
      return 0;
	}
	else
	{
    cout<<"(常数符号 "<<str<<')'<<endl;
    outfile<<"(常数符号 "<<str<<')'<<endl;
    infile.seekg(-1,ios::cur);
    return 0;///////////////////
	}
  }
 

}






int Word_analyzer::point_analyzer(char &c,string &str)//小数点后循环
{
  if(c=='.')
  {
    str+=c;
	if(infile.get(c))
	{ 
	  if('0'<=c&&c<='9')
	  {
	    str+=c;
        number_loop(c,str);
        exponent_analyzer(c,str);
		return 0;
	  }
	  else
	  {
	    cout<<"(错误常数 "<<str<<')'<<endl;
        outfile<<"(错误常数 "<<str<<')'<<endl;
        infile.seekg(-1,ios::cur);
        return 0;
	  }
	    
	}
	else
	{
	   cout<<"(错误常数 "<<str<<')'<<endl;
       outfile<<"(错误常数 "<<str<<')'<<endl;
       return 0;
	}
  }
  else
  {
    exponent_analyzer_two(c,str);/////////////////////////////////////////////////////
	return 0;
  }
}




int Word_analyzer::number_analyzer(char &c,string &str,int &count)
{ 
  
  if('0'<=c&&c<='9')
  {
    str+=c;
	number_loop(c,str);
    point_analyzer(c,str);
    return 0;
  }//601
  else 
  {
    count=1;
	return 0;
  }
}//函数尾





int Word_analyzer::symbol_number_analyzer(char &c,int &count)
{    
	string str="";
	count=0;
    if(c=='(')
	{
	  cout<<"(专用符号 "<<c<<')'<<endl;
      outfile<<"(专用符号 "<<c<<')'<<endl;
	  if(infile.get(c))
	  {
	    if(c=='+'||c=='-')
		{
		  str+=c;
		  if(infile.get(c))
		  {
		    if('0'<=c&&c<='9')
			{
			  str+=c;
			  number_loop(c,str);
              point_analyzer(c,str);
              return 0;
			}//567
			else
			{
			  cout<<"(专用符号 "<<str<<')'<<endl;
              outfile<<"(专用符号 "<<str<<')'<<endl;
              infile.seekg(-1,ios::cur);
              return 0;
			}
		  }//565
		  else
		  {
		    cout<<"(专用符号 "<<str<<')'<<endl;
            outfile<<"(专用符号 "<<str<<')'<<endl;
			return 0;

		  }

		}//562
		else 
		{
		  number_analyzer(c,str,count);
		  return 0;
		}
	  }//560
	  else return 0;

	}//557
	else 
	{
	  number_analyzer(c,str,count);
	  return 0;
	}
    
}//函数尾








int Word_analyzer::id_loop(char &c,string &str)
{
  while(infile.get(c))
  {
    if(('0'<=c&&c<='9')||('A'<=c&&c<='Z')||('a'<=c&&c<='z'))
	  str+=c;
	else 
	  return 0;
  }//620
  return 0;
}//函数尾


int Word_analyzer::id_compare(char &c,string &str)
{
  for(int k=0;k<6;k++)
  {
    if(str==key_table[k])
	{
	   cout<<"(关键字符 "<<str<<')'<<endl;
       outfile<<"(关键字符 "<<str<<')'<<endl;
       infile.seekg(-1,ios::cur);
	   return 0;
	}
  }
  cout<<"(标识字符 "<<str<<')'<<endl;
  outfile<<"(标识字符 "<<str<<')'<<endl;
  infile.seekg(-1,ios::cur);
  return 0;
}//函数尾




int Word_analyzer::id_analyzer(char &c,int &count)
{ 
  string str="";
  count=0;
  if(('A'<=c&&c<='Z')||('a'<=c&&c<='z'))
  {
    str+=c;
    id_loop(c,str);
    id_compare(c,str);
    return 0;
  }//655
  else
  {
    if('0'<=c&&c<='9')
	{
	  str+=c;
      id_loop(c,str);
      cout<<"(错误标识 "<<str<<')'<<endl;
      outfile<<"(错误标识 "<<str<<')'<<endl;
      infile.seekg(-1,ios::cur);
	  return 0;
	}//664
	else
	{
	  count=1;
	  return 0;
	}
	
  }
}//函数尾*/



int Word_analyzer::note_analyzer(char &c,int &count)
{
  string str="";
  count=0;
  if(c=='/')
  { 
    str+=c;
    if(infile.get(c))
	{
	  if(c=='*')
	  {
	    str+=c;
        cout<<"(注释符号 "<<str<<')'<<endl;
        outfile<<"(注释符号 "<<str<<')'<<endl;
        str="";
		while(infile.get(c))
		{
		  if(c=='*')
		  {
		    str+=c;
            if(infile.get(c))
			{
			  if(c=='/')
			  {
			    str+=c;
                cout<<"(注释符号 "<<str<<')'<<endl;
                outfile<<"(注释符号 "<<str<<')'<<endl;
                return 0;
			  }
			  ;
			}//424
			;
		  }//421
		  ;
		}//419
		return 0;
	  }
	  else
	  {
	    cout<<"(专用符号 "<<str<<')'<<endl;
        outfile<<"(专用符号 "<<str<<')'<<endl;
        infile.seekg(-1,ios::cur);
	    return 0;	  
	  }
	}//411
	else
	{
	  cout<<"(专用符号 "<<str<<')'<<endl;
	  outfile<<"(专用符号 "<<str<<')'<<endl;
      return 0;
	}
  }//408
  else
  {
    count=1;
	return 0;
  }

}

int Word_analyzer::other_char_analyzer(char &c)
{  
  if(c!=' '&&c!='\n'&&c!='\t')
  {
	  cout<<"(不可识别 "<<c<<')'<<endl;
      outfile<<"(不可识别 "<<c<<')'<<endl;
  }
  return 0;
}



int Word_analyzer::analyze(char &c)
{   
	int count=0;
    symbol_number_analyzer(c,count);
    if(count==0)
	 return 0;
    else
    key_analyzer(c,count);
    if(count==0)
	 return 0;
    else
    id_analyzer(c,count);
    if(count==0)
	 return 0;
    else
    note_analyzer(c,count);
    if(count==0)
	 return 0;
    else
    other_char_analyzer(c);
    return 0;
}