Re: urlstring testing/enhancement

[Federico Montesino Pouzols]

On Thu, Jan 09, 2003 at 05:16:39PM -0800, Chad Yates wrote:
> before I post a patch to add the new STL string functions I was wondering if
> somebody knew the prefered way of dealing with excessive temporaries.  see
> the following:
> 
> /** @relates URLStream
>  * Encode a octet stream using base64 coding into a STL string
>  * @return base 64 encoded string
>  * @param src     source buffer
>  * @param srcsize source buffer size
>  */
> CCXX_EXPORT(std::string) b64Encode(const unsigned char *src, size_t srcsize)
> {
>   size_t limit = (srcsize+2)/3*4+1;
>   char* buffer = new char[limit];
> 
>   unsigned size = b64Encode(src, srcsize, buffer, limit);
>   buffer[size] = '\0';
> 
>   std::string final = string(buffer);
>   delete buffer;
>   return final;
> }
> 
> notice that I have to not only allocate a temporary buffer (since the
> b64Encode function doesn't work with strings directly -- or some kind
> streaming), but I have to make a copy before I unallocate it, and then yet
> another on the actual return by value.  I have yet to delve into the realm
> of autoptr's.  is that the best bet?  if so, the stl autoptr, or does common
> c++ have a better one.

        I guess there is no good solution for this. The first copy
seems unavoidable and the second one, as far as I know, could only be
avoided if the core routine operated over a string object instead of
the array of char, but that would be a lot worse. Well, after all, you
loose some performance, but you can save significant space :).

        Also, what about adding an encode method that takes a string
object as argument.

> 
> thanks,
> 
> Chad
> 
> 
> 
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