c++11 - C++ unordered_map move beginner error -
sorry noob question here, don't know search on google. tried documention on move semantic still can't solve problem.
so if can give me clues, i'll thanksfull.
about code:
graph.hpp:
#ifndef graph_hpp #define graph_hpp #include <cstdlib> #include <unordered_map> #include <vector> #include <string> template<typename t, typename u> class link; template<typename t, typename u> class node; namespace graph { template<typename t, typename u> class link { public: link() = default; link(u&& data, t& node) : _data(data), _endnode(node) {} ~link() = default; private: u _data; node<t, u>& _endnode; }; template<typename t, typename u> class node { public: node() = default; node(t&& data) : _data(data) {}; ~node() = default; private: t _data; std::vector<link<t, u>> _links; }; template<typename k, typename t, typename u> class graph { public: graph() = default; ~graph() = default; private: size_t _nbnode; std::unordered_map<k, node<t, u>> _nodes; public: #include "graph.tpp" }; } #endif graph.tpp:
void add_link(const k& key1, const k& key2, u&& linkinfo) { if (!_nodes.count(key1) || !_nodes.count(key2)) throw "key doesn't exist!"; link<t, u> newlink(linkinfo, _nodes[key2]); _nodes[key1].links.push_back(newlink); } void add_node(k& key, t&& elem) { node<t, u> newnode(std::move(elem)); _nodes[key] = std::move(newnode); } main.cpp:
#include "graph.hpp" #include <string> int main() { std::string name("name"); graph::graph<std::string, std::string, std::string> graph; graph.add_node(name, "lol"); return 0; } i want add new element in unordered_map move. it's me :
clang++ -wall -wextra -std=c++14 -o2 -march=native -s -fomit-frame-pointer -c src/test.cpp -o obj/test.o -i ./src/include -i ./src/template/ clang: warning: argument unused during compilation: '-s' in file included src/test.cpp:1: in file included ./src/include/graph.hpp:15: in file included /usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/unordered_map:41: in file included /usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/tuple:39: in file included /usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/array:38: in file included /usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/stdexcept:39: in file included /usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/string:40: in file included /usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/char_traits.h:39: /usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/stl_algobase.h:336:18: error: object of type 'graph::link<std::basic_string<char>, std::basic_string<char> >' cannot assigned because copy assignment operator implicitly deleted *__result = *__first; ^ /usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/stl_algobase.h:396:36: note: in instantiation of function template specialization 'std::__copy_move<false, false, std::random_access_iterator_tag>::__copy_m<const graph::link<std::basic_string<char>, std::basic_string<char> > *, graph::link<std::basic_string<char>, std::basic_string<char> > *>' requested here _category>::__copy_m(__first, __last, __result); ^ /usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/stl_algobase.h:432:23: note: in instantiation of function template specialization 'std::__copy_move_a<false, const graph::link<std::basic_string<char>, std::basic_string<char> > *, graph::link<std::basic_string<char>, std::basic_string<char> > *>' requested here return _oi(std::__copy_move_a<_ismove>(std::__niter_base(__first), ^ /usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/stl_algobase.h:464:20: note: in instantiation of function template specialization 'std::__copy_move_a2<false, __gnu_cxx::__normal_iterator<const graph::link<std::basic_string<char>, std::basic_string<char> > *, std::vector<graph::link<std::basic_string<char>, std::basic_string<char> >, std::allocator<graph::link<std::basic_string<char>, std::basic_string<char> > > > >, __gnu_cxx::__normal_iterator<graph::link<std::basic_string<char>, std::basic_string<char> > *, std::vector<graph::link<std::basic_string<char>, std::basic_string<char> >, std::allocator<graph::link<std::basic_string<char>, std::basic_string<char> > > > > >' requested here return (std::__copy_move_a2<__is_move_iterator<_ii>::__value> ^ /usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/vector.tcc:206:27: note: in instantiation of function template specialization 'std::copy<__gnu_cxx::__normal_iterator<const graph::link<std::basic_string<char>, std::basic_string<char> > *, std::vector<graph::link<std::basic_string<char>, std::basic_string<char> >, std::allocator<graph::link<std::basic_string<char>, std::basic_string<char> > > > >, __gnu_cxx::__normal_iterator<graph::link<std::basic_string<char>, std::basic_string<char> > *, std::vector<graph::link<std::basic_string<char>, std::basic_string<char> >, std::allocator<graph::link<std::basic_string<char>, std::basic_string<char> > > > > >' requested here std::_destroy(std::copy(__x.begin(), __x.end(), begin()), ^ ./src/include/graph.hpp:40:10: note: in instantiation of member function 'std::vector<graph::link<std::basic_string<char>, std::basic_string<char> >, std::allocator<graph::link<std::basic_string<char>, std::basic_string<char> > > >::operator=' requested here class node ^ src/test.cpp:9:9: note: in instantiation of member function 'graph::graph<std::basic_string<char>, std::basic_string<char>, std::basic_string<char> >::add_node' requested here graph.add_node(name, "lol"); ^ ./src/include/graph.hpp:36:15: note: copy assignment operator of 'link<std::basic_string<char>, std::basic_string<char> >' implicitly deleted because field '_endnode' of reference type 'node<std::basic_string<char>, std::basic_string<char> > &' node<t, u>& _endnode; ^ in file included src/test.cpp:1: in file included ./src/include/graph.hpp:15: in file included /usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/unordered_map:41: in file included /usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/tuple:39: in file included /usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/array:38: in file included /usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/stdexcept:39: in file included /usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/string:40: in file included /usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/char_traits.h:39: /usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/stl_algobase.h:336:18: error: object of type 'graph::link<std::basic_string<char>, std::basic_string<char> >' cannot assigned because copy assignment operator implicitly deleted *__result = *__first; ^ /usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/stl_algobase.h:396:36: note: in instantiation of function template specialization 'std::__copy_move<false, false, std::random_access_iterator_tag>::__copy_m<graph::link<std::basic_string<char>, std::basic_string<char> > *, graph::link<std::basic_string<char>, std::basic_string<char> > *>' requested here _category>::__copy_m(__first, __last, __result); ^ /usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/stl_algobase.h:432:23: note: in instantiation of function template specialization 'std::__copy_move_a<false, graph::link<std::basic_string<char>, std::basic_string<char> > *, graph::link<std::basic_string<char>, std::basic_string<char> > *>' requested here return _oi(std::__copy_move_a<_ismove>(std::__niter_base(__first), ^ /usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/stl_algobase.h:464:20: note: in instantiation of function template specialization 'std::__copy_move_a2<false, graph::link<std::basic_string<char>, std::basic_string<char> > *, graph::link<std::basic_string<char>, std::basic_string<char> > *>' requested here return (std::__copy_move_a2<__is_move_iterator<_ii>::__value> ^ /usr/bin/../lib64/gcc/x86_64-unknown-linux-gnu/4.9.2/../../../../include/c++/4.9.2/bits/vector.tcc:211:13: note: in instantiation of function template specialization 'std::copy<graph::link<std::basic_string<char>, std::basic_string<char> > *, graph::link<std::basic_string<char>, std::basic_string<char> > *>' requested here std::copy(__x._m_impl._m_start, __x._m_impl._m_start + size(), ^ ./src/include/graph.hpp:40:10: note: in instantiation of member function 'std::vector<graph::link<std::basic_string<char>, std::basic_string<char> >, std::allocator<graph::link<std::basic_string<char>, std::basic_string<char> > > >::operator=' requested here class node ^ src/test.cpp:9:9: note: in instantiation of member function 'graph::graph<std::basic_string<char>, std::basic_string<char>, std::basic_string<char> >::add_node' requested here graph.add_node(name, "lol"); ^ ./src/include/graph.hpp:36:15: note: copy assignment operator of 'link<std::basic_string<char>, std::basic_string<char> >' implicitly deleted because field '_endnode' of reference type 'node<std::basic_string<char>, std::basic_string<char> > &' node<t, u>& _endnode; ^ 2 errors generated. makefile:43: recipe target 'obj/test.o' failed make: *** [obj/test.o] error 1 sorry trouble, have nice day.
okay. problem in line:
_nodes[key] = std::move(newnode); you trying move-assign node<t, u>. however, node not have move assignment operator implicitly declared defaulted because there user-declared destructor:
~node() = default; as result, line calls copy assignment operator of node<t, u>, performs member-wise copy. 1 of members of node<t, u> of type std::vector<link<t, u>>, link<t, u> has member variable reference. references aren't copy-assignable, copy assignment operator implicitly deleted. hence, there no copy assignment operator found, line ill-formed.
while references aren't move-assignable either, vector<link<t,u>> move-assignable, simplest solution delete line declare destructor defaulted:
//~node() = default; with that, compiler implicitly declare default move constructor/assignment, , code expect. , compile.
side-note, bad idea:
public: #include "graph.tpp" };
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