I have written a custom iterator based on boost::iterator_facade, and I'm trying
to use this with the std::partial_sort_copy algorithm.
However, when compiling with g++ I get an error message saying that there is no
matching function for a call to counting_iterator(Vertex<3>&). The way I
interpret this is that my code is trying to construct a Vertex_Iterator from a
Vertex object, but that was not my intenton.
Is there something obvious that I have missed in my definition of
Vertex_Iterator, which should be a bidirectional iterator? A Vertex_Iterator
iterates over the vertices of a mesh, and therefore it needs a pointer to the
mesh in question. Does an iterator which returns a Vertex<3>& when dereferenced
need a constructor which takes only a Vertex<3>& argument? If so, how can I
supply it with the pointer to its parent mesh?
I hope that some of this makes sense.
//////////////////////////////////////////////
// Some typedefs from the parent class 'Mesh':
//////////////////////////////////////////////
class Mesh
{
public:
class Vertex_Iterator;
//...
private:
friend class Vertex_Iterator;
typedef boost::property< boost::vertex_root_t, Vertex<3> > Vertex_Property;
typedef boost::adjacency_list
< boost::vecS, boost::vecS, boost::undirectedS, Vertex_Property >
Vertex_Graph;
typedef boost::property_map::type
Vertex_Data_Map;
Vertex_Data_Map its_vertex_data;
//...
};
//////////////////////////////////////////////
// Definition of my custom iterator:
//////////////////////////////////////////////
class Mesh::Vertex_Iterator:
public boost::iterator_facade
& >
{
public:
Vertex_Iterator()
{}
explicit Vertex_Iterator( const Mesh* const mesh,
Vertex_Graph::vertex_iterator p ) :
its_parent( mesh ),
its_vertex( p )
{}
private:
friend class boost::iterator_core_access;
Vertex<3>& dereference() const
{
return its_parent->its_vertex_data[*its_vertex];
}
void increment() { ++its_vertex; }
void decrement() { --its_vertex; }
bool equal( Vertex_Iterator const& other) const
{
return this->its_vertex == other.its_vertex;
}
const Mesh* const its_parent;
Vertex_Graph::vertex_iterator its_vertex;
};
//////////////////////////////////////////////
// The call with an error looks like this:
//////////////////////////////////////////////
void Mesh::subset()
{
//...
Compare_Normals compare( its_mean_normal );
Vertex<3> temp_holder[size];
Vertex_Iterator first_vertex( this, boost::vertices( its_vertices ).first );
Vertex_Iterator last_vertex( this, boost::vertices( its_vertices ).second );
std::partial_sort_copy( first_vertex, last_vertex,
temp_holder, temp_holder + size,
compare );
//...
}
//////////////////////////////////////////////
// This is gcc's error message:
//////////////////////////////////////////////
Building object file Mesh.o...
/usr/include/c++/3.3.1/bits/stl_algo.h: In function `_RandomAccessIter
std::partial_sort_copy(_InputIter, _InputIter, _RandomAccessIter,
_RandomAccessIter, _Compare) [with _InputIter = Mesh::Vertex_Iterator,
_RandomAccessIter = Vertex<3>*, _Compare = Mesh::Compare_Normals]':
/home/martin/source/scan-match/Mesh.cpp:532: instantiated from here
/usr/include/c++/3.3.1/bits/stl_algo.h:2661: error: no matching function for
call to `boost::counting_iterator::counting_iterator(Vertex<3>&)'
/usr/local/include/boost/iterator/counting_iterator.hpp:169: error: candidates
are: boost::counting_iterator::counting_iterator(Incrementable) [with Incrementable = size_t,
CategoryOrTraversal = boost::use_default, Difference = boost::use_default]
/usr/local/include/boost/iterator/counting_iterator.hpp:166: error:
boost::counting_iterator::counting_iterator(const boost::counting_iterator&) [with Incrementable = size_t,
CategoryOrTraversal = boost::use_default, Difference = boost::use_default]
/usr/local/include/boost/iterator/counting_iterator.hpp:164: error:
boost::counting_iterator::counting_iterator() [with Incrementable = size_t,
CategoryOrTraversal = boost::use_default, Difference = boost::use_default]
make[1]: *** [Mesh.o] Error 1
make: *** [default_target] Error 2
Thanks
/ martin
