Making a vector of graphs in Lemon Graph Library

Question

I created a graph and added nodes and transitions to it in Lemon Graph Library

typedef ListDigraph Graph;
vector<Graph> Process;
for(temp = temp.child("role");temp;temp = temp.next_sibling("role"))
{
    Graph proc;
    for(xml_node temp1 = temp.child("states").child("state");temp1;temp1 = temp1.next_sibling())
    {
        string state = temp1.child_value();
        state = role + "_" + state;
        vertex = process.addNode();
        state_name[vertex] = state;
    }
    Process.push_back(proc);
}

If I don't push it in vector everything works fine, but when I try to push it in Process I get error. Error is 70-80 lines long, but the main point I found is:

/usr/local/include/lemon/list_graph.h:336:5: error:
lemon::ListDigraph::ListDigraph(const lemon::ListDigraph&) is private

After doing what @Magtheridon96 suggested getting the following error:

    In file included from /usr/include/c++/4.6/i686-linux-gnu/./bits/c++allocator.h:34:0,
                 from /usr/include/c++/4.6/bits/allocator.h:48,
                 from /usr/include/c++/4.6/string:43,
                 from /usr/include/c++/4.6/bits/locale_classes.h:42,
                 from /usr/include/c++/4.6/bits/ios_base.h:43,
                 from /usr/include/c++/4.6/ios:43,
                 from /usr/include/c++/4.6/ostream:40,
                 from /usr/include/c++/4.6/iostream:40,
                 from usingleda.cpp:1:
/usr/include/c++/4.6/ext/new_allocator.h: In member function ‘void __gnu_cxx::new_allocator<_Tp>::construct(__gnu_cxx::new_allocator<_Tp>::pointer, _Args&& ...) [with _Args = {std::unique_ptr<lemon::ListDigraph>&}, _Tp = std::unique_ptr<lemon::ListDigraph>, __gnu_cxx::new_allocator<_Tp>::pointer = std::unique_ptr<lemon::ListDigraph>*]’:
/usr/include/c++/4.6/bits/vector.tcc:97:6:   instantiated from ‘void std::vector<_Tp, _Alloc>::emplace_back(_Args&& ...) [with _Args = {std::unique_ptr<lemon::ListDigraph>&}, _Tp = std::unique_ptr<lemon::ListDigraph>, _Alloc = std::allocator<std::unique_ptr<lemon::ListDigraph> >]’
usingleda.cpp:134:43:   instantiated from here
/usr/include/c++/4.6/ext/new_allocator.h:114:4: error: use of deleted function ‘std::unique_ptr<_Tp, _Dp>::unique_ptr(const std::unique_ptr<_Tp, _Dp>&) [with _Tp = lemon::ListDigraph, _Dp = std::default_delete<lemon::ListDigraph>, std::unique_ptr<_Tp, _Dp> = std::unique_ptr<lemon::ListDigraph>]’
/usr/include/c++/4.6/bits/unique_ptr.h:256:7: error: declared here
In file included from /usr/include/c++/4.6/vector:70:0,
                 from /usr/local/include/lemon/core.h:22,
                 from /usr/local/include/lemon/list_graph.h:26,
                 from usingleda.cpp:3:
/usr/include/c++/4.6/bits/vector.tcc: In member function ‘void std::vector<_Tp, _Alloc>::_M_insert_aux(std::vector<_Tp, _Alloc>::iterator, _Args&& ...) [with _Args = {std::unique_ptr<lemon::ListDigraph>&}, _Tp = std::unique_ptr<lemon::ListDigraph>, _Alloc = std::allocator<std::unique_ptr<lemon::ListDigraph> >, std::vector<_Tp, _Alloc>::iterator = __gnu_cxx::__normal_iterator<std::unique_ptr<lemon::ListDigraph>*, std::vector<std::unique_ptr<lemon::ListDigraph> > >, typename std::_Vector_base<_Tp, _Alloc>::_Tp_alloc_type::pointer = std::unique_ptr<lemon::ListDigraph>*]’:
/usr/include/c++/4.6/bits/vector.tcc:102:4:   instantiated from ‘void std::vector<_Tp, _Alloc>::emplace_back(_Args&& ...) [with _Args = {std::unique_ptr<lemon::ListDigraph>&}, _Tp = std::unique_ptr<lemon::ListDigraph>, _Alloc = std::allocator<std::unique_ptr<lemon::ListDigraph> >]’
usingleda.cpp:134:43:   instantiated from here
/usr/include/c++/4.6/bits/vector.tcc:319:4: error: use of deleted function ‘std::unique_ptr<_Tp, _Dp>::unique_ptr(const std::unique_ptr<_Tp, _Dp>&) [with _Tp = lemon::ListDigraph, _Dp = std::default_delete<lemon::ListDigraph>, std::unique_ptr<_Tp, _Dp> = std::unique_ptr<lemon::ListDigraph>]’
/usr/include/c++/4.6/bits/unique_ptr.h:256:7: error: declared here

_"but when i try to push it in Process i get error"_ - What error? — awesoon, Jun 18 '13 at 13:58
error is 70-80 lines long...but the main point i found is : "/usr/local/include/lemon/list_graph.h:336:5: error: ‘lemon::ListDigraph::ListDigraph(const lemon::ListDigraph&)’ is private " — vigenere, Jun 18 '13 at 14:01
Judging by the error excerpt the copy constructor is made private to prevent copying. — Some programmer dude, Jun 18 '13 at 14:02
Also if i create a vector for map of the graph and insert it in the vector i get smthng similar error — vigenere, Jun 18 '13 at 14:03
You cannot create a vector of a class that is not copyable. You can try to use smart pointers (like `unique_ptr`) and use a vector of smart pointers of `Graph`. — Gonmator, Jun 18 '13 at 14:08
@Gonmator: Please don't just throw smart pointers at every problem. Also, you may create a vector of objects of a type that is not copyable (as long as it is moveable, and the move assignment operator is marked `nothrow`). — Lightness Races in Orbit, Jun 18 '13 at 15:58
@CatPlusPlus: it's true, `unique_ptr` is not copyable, so it's requires be emplaced instead pushed. — Gonmator, Jun 18 '13 at 17:03

user123 · Accepted Answer · 2013-06-18T15:45:57.570

2

You are not permitted to make copies of this object (This is what the author wants). The author of the library made the copy constructor private to ensure that you can't do this.

The solution is to change std::vector<Graph> to std::vector<std::unique_ptr<Graph>>

That way, you don't need to make copies of the object as the author intended.

You would then allocate and insert like this:

std::unique_ptr<Graph> graph(new Graph);
// ...
vec.emplace_back(graph);

edited Jun 18 '13 at 15:45

answered Jun 18 '13 at 14:13

user123

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You should certainly NOT push a unique_ptr of a stack allocated object by taking it's address. You should use `new` to allocate it. – Dave S Jun 18 '13 at 14:18
I'm giving him a general solution. Whether he chooses to allocate on the stack or the heap is his choice, and he should definitely be allocating on the heap. – user123 Jun 18 '13 at 14:19
I have updated the answer to take note of this so he can avoid the error. Thank you for pointing it out Dave – user123 Jun 18 '13 at 14:25
grt..thnks...solvd the prblm...can you plz jst tell me one more thing.. now i have this... vector > names; and another vector - vector state .... now i want to find out names[i][state[i]] ... that is... to which name state[i] maps to using map names[i] ... how do i do this.. – vigenere Jun 18 '13 at 14:28
1

It's best to create a new question for that. – user123 Jun 18 '13 at 14:43
If i use unique_ptr as you mentioned, then i am unable to use the functions of the Graph class. I am getting errors : "error: ‘Translator::up’ has no member named ‘addNode’" where "up" is "std::unique_ptr" – vigenere Jun 18 '13 at 16:28
1

`up->addNode` instead of `up.addNode` – user123 Jun 18 '13 at 16:29
I have edited my question to include the error i am getting after your suggested modifications. – vigenere Jun 18 '13 at 16:53
1

You have to understand that `std::unique_ptr` is non-copyable but moveable and it can be moved around with `std::move`. Until you know how to use it properly on your own, you can get this all to compile by using `std::shared_ptr` which is copyable. (You would then call `push_back` instead of `emplace_back`) – user123 Jun 18 '13 at 19:38

Making a vector of graphs in Lemon Graph Library

1 Answers1