C++ Lambda Function for BFS Traversal












0















Using the two functions below, how could I use a lambda function to BFS Traverse through a Graph of Thing's called x



i.e. Graph<Thing> x


which involves sending the display function to the bfsTraverse function so that the information in each Thing can be displayed.



void display(const Thing& c)
{
cout<<left<<setw(3)<<c.getKey()<<" "<<left<<setw(2)<<c.getLabel()<<endl;
}

template <typename E>
void Graph<E>::bfsTraverse(FuncType func)
{
/* some code not necessary to describe */
}


So basically, I just need to understand how to use a lambda function to tie these together here.










share|improve this question





























    0















    Using the two functions below, how could I use a lambda function to BFS Traverse through a Graph of Thing's called x



    i.e. Graph<Thing> x


    which involves sending the display function to the bfsTraverse function so that the information in each Thing can be displayed.



    void display(const Thing& c)
    {
    cout<<left<<setw(3)<<c.getKey()<<" "<<left<<setw(2)<<c.getLabel()<<endl;
    }

    template <typename E>
    void Graph<E>::bfsTraverse(FuncType func)
    {
    /* some code not necessary to describe */
    }


    So basically, I just need to understand how to use a lambda function to tie these together here.










    share|improve this question



























      0












      0








      0








      Using the two functions below, how could I use a lambda function to BFS Traverse through a Graph of Thing's called x



      i.e. Graph<Thing> x


      which involves sending the display function to the bfsTraverse function so that the information in each Thing can be displayed.



      void display(const Thing& c)
      {
      cout<<left<<setw(3)<<c.getKey()<<" "<<left<<setw(2)<<c.getLabel()<<endl;
      }

      template <typename E>
      void Graph<E>::bfsTraverse(FuncType func)
      {
      /* some code not necessary to describe */
      }


      So basically, I just need to understand how to use a lambda function to tie these together here.










      share|improve this question
















      Using the two functions below, how could I use a lambda function to BFS Traverse through a Graph of Thing's called x



      i.e. Graph<Thing> x


      which involves sending the display function to the bfsTraverse function so that the information in each Thing can be displayed.



      void display(const Thing& c)
      {
      cout<<left<<setw(3)<<c.getKey()<<" "<<left<<setw(2)<<c.getLabel()<<endl;
      }

      template <typename E>
      void Graph<E>::bfsTraverse(FuncType func)
      {
      /* some code not necessary to describe */
      }


      So basically, I just need to understand how to use a lambda function to tie these together here.







      c++ algorithm lambda graph-theory breadth-first-search






      share|improve this question















      share|improve this question













      share|improve this question




      share|improve this question








      edited Nov 22 '18 at 1:58









      Dominique Fortin

      1,665817




      1,665817










      asked Mar 21 '17 at 2:46









      RoryHectorRoryHector

      548




      548
























          1 Answer
          1






          active

          oldest

          votes


















          1














          It pretty straightforward. For example, let;s print values of vector using lambda:



          #include <algorithm>
          #include <vector>
          #include <iostream>

          int main (int argc, char* argv) {
          std::vector <int> data{1,2,3,4};

          std::for_each (data.begin (), data.end (), (const int val) { std::cout << val << std::endl;});

          return 0;
          }


          last argument (...) is the lambda.
          A function, which accepts lambdas, might look like this:



          template <typename E, typename FuncType> 
          void Graph<E>::bfsTraverse (FuncType func)
          {
          /* some code not necessary to describe */
          }


          UPDATE



          In case of a graph you should do the following. Your graph's implementation should have a method to access vertices: it might be 'getRoot', 'getSource', 'getAllNodes', it's implementation defined. I'll stick with 'getRoot'. Each vertex/node should have a method like 'getAdjacentVertices', 'getChildren', whatever. Combining all together:



          template <typename E, typename FuncType> 
          void Graph<E>::bfsTraverse (FuncType func)
          {
          std::queue<Node> q;

          auto&& root = getRoot ();

          q.push (root);

          while (not q.empty ()) {
          auto&& current = q.front ();
          q.pop ();

          func (current);

          auto&& adjacent = current.getAdjacent ();

          for (auto&& a: adjacent) {
          q.push (a);
          }
          }


          Be aware, that I deliberately omit keeping list of visited nodes and other things. But idea itself stays the same. Now you can call this function as follows:



          Graph<E> g;
          g.bfsTraverse ( (const Node& n) {
          std::cout << n.to_str () << std::endl;
          }
          );





          share|improve this answer


























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            1 Answer
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            active

            oldest

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            1 Answer
            1






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes









            1














            It pretty straightforward. For example, let;s print values of vector using lambda:



            #include <algorithm>
            #include <vector>
            #include <iostream>

            int main (int argc, char* argv) {
            std::vector <int> data{1,2,3,4};

            std::for_each (data.begin (), data.end (), (const int val) { std::cout << val << std::endl;});

            return 0;
            }


            last argument (...) is the lambda.
            A function, which accepts lambdas, might look like this:



            template <typename E, typename FuncType> 
            void Graph<E>::bfsTraverse (FuncType func)
            {
            /* some code not necessary to describe */
            }


            UPDATE



            In case of a graph you should do the following. Your graph's implementation should have a method to access vertices: it might be 'getRoot', 'getSource', 'getAllNodes', it's implementation defined. I'll stick with 'getRoot'. Each vertex/node should have a method like 'getAdjacentVertices', 'getChildren', whatever. Combining all together:



            template <typename E, typename FuncType> 
            void Graph<E>::bfsTraverse (FuncType func)
            {
            std::queue<Node> q;

            auto&& root = getRoot ();

            q.push (root);

            while (not q.empty ()) {
            auto&& current = q.front ();
            q.pop ();

            func (current);

            auto&& adjacent = current.getAdjacent ();

            for (auto&& a: adjacent) {
            q.push (a);
            }
            }


            Be aware, that I deliberately omit keeping list of visited nodes and other things. But idea itself stays the same. Now you can call this function as follows:



            Graph<E> g;
            g.bfsTraverse ( (const Node& n) {
            std::cout << n.to_str () << std::endl;
            }
            );





            share|improve this answer






























              1














              It pretty straightforward. For example, let;s print values of vector using lambda:



              #include <algorithm>
              #include <vector>
              #include <iostream>

              int main (int argc, char* argv) {
              std::vector <int> data{1,2,3,4};

              std::for_each (data.begin (), data.end (), (const int val) { std::cout << val << std::endl;});

              return 0;
              }


              last argument (...) is the lambda.
              A function, which accepts lambdas, might look like this:



              template <typename E, typename FuncType> 
              void Graph<E>::bfsTraverse (FuncType func)
              {
              /* some code not necessary to describe */
              }


              UPDATE



              In case of a graph you should do the following. Your graph's implementation should have a method to access vertices: it might be 'getRoot', 'getSource', 'getAllNodes', it's implementation defined. I'll stick with 'getRoot'. Each vertex/node should have a method like 'getAdjacentVertices', 'getChildren', whatever. Combining all together:



              template <typename E, typename FuncType> 
              void Graph<E>::bfsTraverse (FuncType func)
              {
              std::queue<Node> q;

              auto&& root = getRoot ();

              q.push (root);

              while (not q.empty ()) {
              auto&& current = q.front ();
              q.pop ();

              func (current);

              auto&& adjacent = current.getAdjacent ();

              for (auto&& a: adjacent) {
              q.push (a);
              }
              }


              Be aware, that I deliberately omit keeping list of visited nodes and other things. But idea itself stays the same. Now you can call this function as follows:



              Graph<E> g;
              g.bfsTraverse ( (const Node& n) {
              std::cout << n.to_str () << std::endl;
              }
              );





              share|improve this answer




























                1












                1








                1







                It pretty straightforward. For example, let;s print values of vector using lambda:



                #include <algorithm>
                #include <vector>
                #include <iostream>

                int main (int argc, char* argv) {
                std::vector <int> data{1,2,3,4};

                std::for_each (data.begin (), data.end (), (const int val) { std::cout << val << std::endl;});

                return 0;
                }


                last argument (...) is the lambda.
                A function, which accepts lambdas, might look like this:



                template <typename E, typename FuncType> 
                void Graph<E>::bfsTraverse (FuncType func)
                {
                /* some code not necessary to describe */
                }


                UPDATE



                In case of a graph you should do the following. Your graph's implementation should have a method to access vertices: it might be 'getRoot', 'getSource', 'getAllNodes', it's implementation defined. I'll stick with 'getRoot'. Each vertex/node should have a method like 'getAdjacentVertices', 'getChildren', whatever. Combining all together:



                template <typename E, typename FuncType> 
                void Graph<E>::bfsTraverse (FuncType func)
                {
                std::queue<Node> q;

                auto&& root = getRoot ();

                q.push (root);

                while (not q.empty ()) {
                auto&& current = q.front ();
                q.pop ();

                func (current);

                auto&& adjacent = current.getAdjacent ();

                for (auto&& a: adjacent) {
                q.push (a);
                }
                }


                Be aware, that I deliberately omit keeping list of visited nodes and other things. But idea itself stays the same. Now you can call this function as follows:



                Graph<E> g;
                g.bfsTraverse ( (const Node& n) {
                std::cout << n.to_str () << std::endl;
                }
                );





                share|improve this answer















                It pretty straightforward. For example, let;s print values of vector using lambda:



                #include <algorithm>
                #include <vector>
                #include <iostream>

                int main (int argc, char* argv) {
                std::vector <int> data{1,2,3,4};

                std::for_each (data.begin (), data.end (), (const int val) { std::cout << val << std::endl;});

                return 0;
                }


                last argument (...) is the lambda.
                A function, which accepts lambdas, might look like this:



                template <typename E, typename FuncType> 
                void Graph<E>::bfsTraverse (FuncType func)
                {
                /* some code not necessary to describe */
                }


                UPDATE



                In case of a graph you should do the following. Your graph's implementation should have a method to access vertices: it might be 'getRoot', 'getSource', 'getAllNodes', it's implementation defined. I'll stick with 'getRoot'. Each vertex/node should have a method like 'getAdjacentVertices', 'getChildren', whatever. Combining all together:



                template <typename E, typename FuncType> 
                void Graph<E>::bfsTraverse (FuncType func)
                {
                std::queue<Node> q;

                auto&& root = getRoot ();

                q.push (root);

                while (not q.empty ()) {
                auto&& current = q.front ();
                q.pop ();

                func (current);

                auto&& adjacent = current.getAdjacent ();

                for (auto&& a: adjacent) {
                q.push (a);
                }
                }


                Be aware, that I deliberately omit keeping list of visited nodes and other things. But idea itself stays the same. Now you can call this function as follows:



                Graph<E> g;
                g.bfsTraverse ( (const Node& n) {
                std::cout << n.to_str () << std::endl;
                }
                );






                share|improve this answer














                share|improve this answer



                share|improve this answer








                edited Mar 22 '17 at 0:55

























                answered Mar 21 '17 at 3:19









                CaptainTrunkyCaptainTrunky

                95821019




                95821019
































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