Trouble grokking iterator adaptors

From: Kris Braun (kbraun_at_[hidden])
Date: 2003-04-14 13:16:09

Hi there,

I could really use the features provided by iterator adaptors part of 
the library, but I'm having a lot of trouble getting a nested set of 
adaptors to compile. In one case, I'd like to return an iterator into 
std::map< std::string, boost::shared_ptr< ApiOption > >, and have it 
return references to options in which option->isTemplate( ) is false. 
Conceptually, I'd like a filter_iterator->indirect_iterator-
>projection_iterator chain.

I've been using this typedef to project onto the second member of the 
pair:
    typedef boost::projection_iterator_pair_generator< 
        select_second< std::string, boost::shared_ptr< ApiOption > >,
        OptionMap::iterator,
        OptionMap::const_iterator > OptionMapIterators;
but I've been at a loss to add indirect_iterator and filter_iterator 
into the mix. Can anyone help me get unstuck?

Thank you in advance,
Kris