Re: [boost] StringAlgo - (was: boost::tokenizer )

From: Dirk Gregorius (dirk_at_[hidden])
Date: 2004-10-16 08:53:37

Hi there,

> I'm not very good at explaining the things in short, but I'll try.
thanks for the explanation. I think I got it and it was not as bad as you 
maybe think.

To come back to the initial problem of string tokenizing. I am trying to 
implement the finder in terms
of ForwardIteratorT. Here is what I think I am expecting to do - also 
actually I am not very sure about it.
I justed started to read M. Austern's book and I am quite new to concepts, 
requirements and so on.
So here is what I did so far:

struct comment_finder
{
 template<typename ForwardIteratorT>
 boost::iterator_range<ForwardIteratorT> operator()( ForwardIteratorT Begin, 
ForwardIteratorT End )
 {
  ForwardIteratorT first, last;

  while ( Begin != End )
  {
   first = Begin;
   if ( *Begin++ == '/' && *Begin == '/' )
   {
    last = first;
    while ( *last++ != '\n' )
    {
     // FAILURE: Return an empty range
     if ( last == End )
      return boost::make_range( ??, ?? ); // return an empty range - HOW?
    }

    // SUCCESS: Return the range
    return boost::make_range( first, last + 1 );
   }
  }

  return boost::make_range( ??, ?? ); // return an empty range - HOW?
 }
};

Is this the way I have to implement the finder or can it be implemented 
using some facilities in your library?
This implementation is quite low-level, so I am wondering if this is 
correct.
Secondly, for the case this is correct, how should I return an empty range 
or what shall I return if didn't find a
matching range?

What are the following steps? Do I have to split two time times or how do I 
erase the comments out of the string?
Will the final token iterator be only of ForwardIteratorT or will be of the 
type of the conatiner that is
holding the tokens. ( e.g. for a vector it would be a randow access 
iterator? )

Sorry for the inconvinience and thanks for the help so far.

-Dirk