Do you know a regular expression based parser in C++ that can be used to parse streams?

I would like to specify the regular expression during run-time, not开发者_Go百科 compile-time. So that is why pcre falls out. Do you know C/c++ regular expression library that can parse streams and can recognise relatively complex regular expression such as .+?

Thanks.

AFAIK boost::regex should know how to work with streams and it supports perl regular expressions

Well, there is PCRE.

Minimal grep implemented with pcre (note that the expression to search for is supplied on the command line at run time):

#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include "pcre.h"
#define OVECCOUNT 30    /* should be a multiple of 3 */

/* only needed if your libc doesn't include it! */
#include "getline.c" 

int main(int argc, char**argv){
  char *res;
  char *fname;
  const char *error;
  int erroroffset;
  pcre *re=NULL;

  /* Grab the search expression from the first command line argument */
  if (--argc) {
    res=(++argv)[0];
    re=pcre_compile(res,0,&error,&erroroffset,NULL);
    if (re==NULL) /* compilation failed, bomb out */ exit(1);
  }

  /* All further command line arguments are files to grep in */
  while (--argc) {
    FILE*f=NULL;
    fname=(++argv)[0];

    if (f=fopen(fname,"r")) {
      char *line=NULL;
      size_t l=0;
      while (-1 != getline(&line,&l,f)) {
    int ovector[OVECCOUNT];
    if ( pcre_exec(re,NULL,line,l,0,0,ovector,OVECCOUNT) > 0 ) {
      printf("%s",line);
    }

    free(line);
    line = NULL; l=0;
      }

      fclose(f);
    }
  }
  free(re);
  return 0;
}

Run it:

$ ./pcregrep char pcregrep.c
int main(int argc, char**argv){
  char *res;
  char *fname;
  const char *error;
      char *line=NULL;