ceph/src/boost/libs/poly_collection/example/insertion_emplacement.cpp

   1 /* Copyright 2016-2017 Joaquin M Lopez Munoz.
   2  * Distributed under the Boost Software License, Version 1.0.
   3  * (See accompanying file LICENSE_1_0.txt or copy at
   4  * http://www.boost.org/LICENSE_1_0.txt)
   5  *
   6  * See http://www.boost.org/libs/poly_collection for library home page.
   7  */
   8
   9 /* examples of insertion and emplacement */
  10
  11 #include <algorithm>
  12 #include <array>
  13 #include <boost/poly_collection/base_collection.hpp>
  14 #include <random>
  15 #include "rolegame.hpp"
  16
  17 int main()
  18 {
  19   boost::base_collection<sprite> c;
  20
  21   // populate c
  22
  23   std::mt19937                 gen{92748}; // some arbitrary random seed
  24   std::discrete_distribution<> rnd{{1,1,1}};
  25   for(int i=0;i<8;++i){        // assign each type with 1/3 probability
  26     switch(rnd(gen)){
  27       case 0: c.insert(warrior{i});break;
  28       case 1: c.insert(juggernaut{i});break;
  29       case 2: c.insert(goblin{i});break;
  30     }
  31   }
  32
  33   auto render=[](const boost::base_collection<sprite>& c){
  34     const char* comma="";
  35     for(const sprite& s:c){
  36       std::cout<<comma;
  37       s.render(std::cout);
  38       comma=",";
  39     }
  40     std::cout<<"\n";
  41   };
  42   render(c);
  43
  44 //[insertion_emplacement_1]
  45   c.insert(c.begin(),juggernaut{8});
  46 //]
  47   render(c);
  48
  49 //[insertion_emplacement_2]
  50   c.insert(c.begin(),goblin{9});
  51 //]
  52   render(c);
  53
  54 //[insertion_emplacement_3]
  55   c.insert(c.begin<juggernaut>()+2,juggernaut{10});
  56                              // ^^ remember local iterators are random access
  57 //]
  58   render(c);
  59
  60 //[insertion_emplacement_4]
  61 //=  c.insert(c.begin(typeid(warrior)),juggernaut{11}); // undefined behavior!!
  62 //]
  63
  64 //[insertion_emplacement_5]
  65   boost::base_collection<sprite> c2;
  66
  67   c2.insert(c.begin(),c.end()); // read below
  68 //<-
  69   render(c2);
  70 //->
  71
  72   // add some more warriors
  73   std::array<warrior,3> aw={{11,12,13}};
  74   c2.insert(aw.begin(),aw.end());
  75 //<-
  76   render(c2);
  77 //->
  78
  79   // add some goblins at the beginning of their segment
  80   std::array<goblin,3> ag={{14,15,16}};
  81   c2.insert(c2.begin<goblin>(),ag.begin(),ag.end());
  82 //<-
  83   render(c2);
  84 //->
  85 //]
  86
  87 //[insertion_emplacement_6]
  88 //<-
  89   // same as line at beginning of previous snippet
  90 //->
  91   c2.insert(c.begin(),c.end());
  92 //]
  93
  94 //[insertion_emplacement_7]
  95 //=  c.emplace(11); // does not compile
  96 //]
  97
  98 //[insertion_emplacement_8]
  99   c.emplace<goblin>(11); // now it works
 100 //]
 101   render(c);
 102
 103 //[insertion_emplacement_9]
 104   c.emplace_hint<juggernaut>(c.begin(),12); // at the beginning if possible
 105   c.emplace_pos<goblin>(c.begin<goblin>()+2,13); // amidst the goblins
 106   c.emplace_pos<warrior>(c.begin(typeid(warrior)),14); // local_base_iterator
 107 //]
 108   render(c);
 109 }