Re: [Boost-users] counting_iterator and iterator_adaptor problem

From: Felipe Magno de Almeida (felipe.almeida_at_[hidden])
Date: 2005-01-16 20:58:13

I´ve tried with iterator_adaptor either in this way: (the class template 
xml_basic_node continues the same)
and the iterator becomes:

template <class value>
class xml_iterator : public boost::iterator_adaptor 
<xml_iterator<value>, value>
{
   public:
   explicit xml_iterator(value node)
     : xml_iterator::iterator_adaptor_(node)
   {}
private:
   friend class boost::iterator_core_access;

   value &dereference() const {
     return base_reference();
   }
};

and it gives me the same error...
I just cant figure out how to make a mutable iterator with the boost 
library...

Jeremy Graham Siek wrote:
> Hi Felipe,
> 
> The counting_iterator is not meant to be used for creating mutable  
> iterators.
> You should use iterator_adaptor instead.
> 
> Cheers,
> Jeremy
> 
> On Jan 16, 2005, at 1:50 AM, Felipe Magno de Almeida wrote:
> 
>> I'm trying to create an iterator from a class that is almost an  
>> iterator, it worked fine for const iterator with counting_iterator,  
>> but when I needed to dereference it, it complained about this:
>> error C2440: 'return' : cannot convert from 'const  
>> xmlmanager::xml_basic_node<T>' to  'boost:: 
>> iterator_facade<Derived,Value,CategoryOrTraversal,Reference,Difference> 
>> ::reference'
>> I think it is because it is still a const iterator...
>> But I need a mutable iterator, and I have no clue in how to do it...  
>> I've tried the documentation, but it just explains what it is, but 
>> not  ho to do it. The way I'm doing the iterator is:
>>
>> template <typename T>
>> class xml_basic_node : public xml_basic_container<T>,
>>     public  boost::iterator<boost::iterator_archetypes:: 
>> readable_lvalue_iterator_t, xml_basic_node<T> >
>> {
>> public:
>>     // some specifics constructors
>>
>>     bool operator == (xml_basic_node<T> const &n) const
>>     {
>>         // compares equality
>>     }
>>
>>     xml_basic_node<T> &operator ++()
>>     {
>>         // advances...
>>         return *this;           
>>     }
>> };   
>> and the iterator through counting_iterator:
>> template <typename T>
>> class acontainer {
>>     typedef boost::counting_iterator<xml_basic_node<T> > iterator;
>> };
>>
>> If someone could, please point me where I am getting wrong... I am  
>> days already trying to figure out how to do it...
>>
>> Sorry for the size of the mail and thanks in advance.
>>
>> -- 
>>    Felipe Magno de Almeida
>>    UIN: 2113442
>>     email: felipe.almeida_at_ic unicamp br, felipe.m.almeida_at_gmail com
>> I am a C, modern C++, MFC, ODBC, Windows Services, MAPI developer
>> from synergy, and Computer Science student from State
>> University of Campinas(UNICAMP).
>> To know more about:
>> Unicamp: http://www.ic.unicamp.br
>> Synergy: http://www.synergy.com.br
>> current work: http://www.mintercept.com
>> _______________________________________________
>> Boost-users mailing list
>> Boost-users_at_[hidden]
>> http://lists.boost.org/mailman/listinfo.cgi/boost-users
>>
> _______________________________________________
> Jeremy Siek <jsiek_at_[hidden]>
> http://www.osl.iu.edu/~jsiek
> Ph.D. Candidate, Indiana University Bloomington
> C++ Booster (http://www.boost.org)
> _______________________________________________
> 
> _______________________________________________
> Boost-users mailing list
> Boost-users_at_[hidden]
> http://lists.boost.org/mailman/listinfo.cgi/boost-users
> 

-- 
    Felipe Magno de Almeida
    UIN: 2113442
     email: felipe.almeida_at_ic unicamp br, felipe.m.almeida_at_gmail com
I am a C, modern C++, MFC, ODBC, Windows Services, MAPI developer
from synergy, and Computer Science student from State
University of Campinas(UNICAMP).
To know more about:
Unicamp: http://www.ic.unicamp.br
Synergy: http://www.synergy.com.br
current work: http://www.mintercept.com