main.cc

一个模拟flex的应用程序 主要实现词法分析 语义分析

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

void RecognizeFirstSection(fstream* in,fstream* out)
{
      char first,second;
      (*in).get(first);
      (*in).get(second);
      
      if(first=='%'&&second=='{')
      {
         (*in).get(second);
        while(second!='%')
        {
            (*out).put(second);
            (*in).get(second);
        }
        (*in).get(second);
      }
      else 
      {
         (*in).putback(second);
          (*in).putback(first);
      }
}

int main(int argc,char * argv[])
{
       fstream infile,code,outfile;
        char temp[128];
        //open input file and output file
        if (argc == 1)
        {   
             cout<<"usage: "<< argv[0] <<" <filename>\n";
             exit(1);
       }
       else if(argc==2)
      {
        strcpy(temp,argv[1]) ;
        infile.open(temp);
        if (! infile)
	{
		cout << "Opening file:  failed！" << endl;
		exit(1);
	}
	
	outfile.open("myLex.cc", ios::out|ios::trunc);
	if (! outfile)
	{
		cout << "\nCreating file  failed！" << endl;
		exit(1);
	}
	//RecognizeFirstSection
      char first,second;
      infile.get(first);
      infile.get(second);
      
      if(first=='%'&&second=='{')
      {
         infile.get(second);
        while(second!='%')
        {
            outfile.put(second);
           infile.get(second);
        }
       infile.get(second);
      }
      else 
      {
         infile.putback(second);
         infile.putback(first);
      }
     //RecognizeSecondSection
	code.open("code");
	char line[256];
     outfile<<"void invoke();\n";
	while(!code.eof())
	{
	    code.getline(line,256);
	    outfile<<line<<endl;
      }
      char ch='%';
      while(ch=='%')
       {
           infile.get(ch);
       }
         while(ch!='{')
         {
           infile.get(ch);
         }     
            infile.get(ch);//omit {
            int i=0;        //find regular expression
          while(ch!='}')
           {
              temp[i++]=ch;
              infile.get(ch);
           }
           temp[i]='\0';
           outfile<<"         DFA d;\n";
           outfile<<"         char* x=new char[128];\n";
           outfile<<"         strcpy(x,\""<<temp<<"\");\n";
           outfile<<"         d.prepare(x,"<<"argv[1]);\n";
           outfile<<"         return 0;\n}\n";
           outfile<<"void invoke(){\n";
         while(ch!='{')
         {
           infile.get(ch);
          }    
          infile.get(ch);//omit {
           while(ch!='}')
           {
              outfile<<ch;
              infile.get(ch);
           }
           outfile<<"}\n";   
           infile.get(ch);//omit {
           while(ch!='%')
           {
              infile.get(ch);
           }
          while(ch=='%')
           {
              infile.get(ch);
           }
           //RecognizeSecondSection
           while(!infile.eof())
             {
              outfile<<ch;
              infile.get(ch);
             }
    }
 }