Re: [Boost-users] Wave: how to recover after errors?

From: Daryle Walker (darylew_at_[hidden])
Date: 2005-12-06 01:40:45

On 12/5/05 11:28 PM, "Max Motovilov" <max_at_[hidden]> wrote:

[SNIP]
> Here's my sample snippet:
> 
> try {
> wave_context::iterator_type p = ctx.begin(), last_known_good = p;
> bool done = false;
> 
> while( !done ) {
> try {
>  done = p == ctx.end();

There's a problem with the previous line.  You can't dereference "p" if
you're at the end, but you don't prevent it.

>  std::cout << p->get_value();
>  ++p;
>  last_known_good = p;
> } catch( boost::wave::preprocess_exception& err ) {
>  if( err.get_severity() >= boost::wave::util::severity_error ) throw;
>  complain( err );
>  p = last_known_good;
> }
> }
> } catch( boost::wave::cpp_exception& err ) {
> complain( err );
> return false;
> }
[TRUNCATE]

Maybe your problems are caused by dereference violation.  Try something
like:

//========================================================================
using namespace boost::wave;

try {
    typedef wave_context::iterator_type  iterator;

    iterator        last_known_good = ctx.begin();
    iterator const  e = ctx.end();

    for ( iterator i = last_known_good ; e != i ; )
    {
        try {
            std::cout << i->get_value();
            last_known_good = ++i;
        } catch ( preprocess_exception &  err ) {
            if ( err.get_severity() >= util::severity_error )
                throw;
            complain( err );
            i = last_known_good;
        }
    }
    //...
} catch ( cpp_exception &  err ) {
    complain( err );
    return false;
}
//========================================================================

Looking at this, I still don't see how you avoid reading the problem context
element over and over....

-- 
Daryle Walker
Mac, Internet, and Video Game Junkie
darylew AT hotmail DOT com