main_part5

来自「学习lemon语法分析的windows程序」· 代码 · 共 63 行

#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>

#define BUFS 1024


/**
 * We have to declare these here - they're not  in any header files
 * we can inclde.  yyparse() is declared with an empty argument list
 * so that it is compatible with the generated C code from bison.
 *
 */

extern FILE *yyin;
typedef struct yy_buffer_state *YY_BUFFER_STATE;

extern "C" {
  int             yylex( void );
  YY_BUFFER_STATE yy_scan_string( const char * );
  void            yy_delete_buffer( YY_BUFFER_STATE );
}


int main(int argc,char** argv)
{
  int n;
  int yv;
  char buf[BUFS+1];
  void* pParser = ParseAlloc (malloc);

  struct Token t0,t1;
  struct Token mToken;

  t0.n=0;
  t0.value=0;

  std::cout << "Enter an expression like 3+5 <return>" << std::endl;
  std::cout << "  Terminate with ^D" << std::endl;

  while ( ( n=read(fileno(stdin), buf, BUFS )) >  0)
    {
      buf[n]='\0';
      yy_scan_string(buf);
      // on EOF yylex will return 0
      while( (yv=yylex()) != 0)
        { 
          std::cout << " yylex() " << yv << " yylval.dval " << yylval.dval << std::endl;
          t0.value=yylval.dval;
          Parse (pParser, yv, t0);
        }


    }

  Parse (pParser, 0, t0);
  ParseFree(pParser, free );

}