skip-comments.h

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// -*- C++ -*-

#ifndef NMWR_GB_SKIP_COMMENTS_H
#define NMWR_GB_SKIP_COMMENTS_H


#include <iostream>
#include <string>
#include <climits>
#include <cctype>

class skip_comments_istream {
public:
  skip_comments_istream(std::istream& in, 
                        char comment_begin = '#',
                        char comment_end   = '\n') 
    : in_(&in),
      comment_begin_(comment_begin), 
      comment_end_(comment_end) {}
 
  std::istream& the_istream() { return skip_comments(*in_);} 
  char begin_comment() const {return comment_begin_;}

  std::istream& skip_comments(std::istream& in) 
  {
    while(true) {
      in >> std::ws;
      if (in.peek() != comment_begin_)
        break;
      in.get();
      in.ignore(INT_MAX,comment_end_);
    }
    return in;
  } 

private:
  std::istream* in_;
  char comment_begin_, comment_end_;
};

inline std::istream& skip_comment(std::istream& in) {
  if(in) {
    skip_comments_istream sk(in);
    sk.skip_comments(in);
  }
  return in;
}

inline skip_comments_istream& operator>>(skip_comments_istream& in,
    std::string& s)
{
  std::istream& in1(in.the_istream());
  int max_len = 256;
  char* ss = new char[max_len];
  // std::string ss = "";
  int i = 0;
  char c = 'a';
  while(in1 && i < max_len-1 && (c != in.begin_comment()) && ! std::isspace(c)) {
    c = in1.get();
    ss[i] = c;
    i++;
  };
  
  if(c == in.begin_comment() || std::isspace(c)) {
    if(in1)
      in1.putback(c);
    i--;
  }

   ss[i] = '\0';
  s = ss;
  return in;
}


template<class T>
inline skip_comments_istream& operator>>(skip_comments_istream& in, T& t)
{ 
  in.the_istream() >> t;
  return in;
}




#endif

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