libstdc++-v3/testsuite/ext/pb_ds/example/tree_join.cc

   1 // -*- C++ -*-
   2
   3 // Copyright (C) 2005-2024 Free Software Foundation, Inc.
   4 //
   5 // This file is part of the GNU ISO C++ Library.  This library is free
   6 // software; you can redistribute it and/or modify it under the terms
   7 // of the GNU General Public License as published by the Free Software
   8 // Foundation; either version 3, or (at your option) any later
   9 // version.
  10
  11 // This library is distributed in the hope that it will be useful, but
  12 // WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 // General Public License for more details.
  15
  16 // You should have received a copy of the GNU General Public License
  17 // along with this library; see the file COPYING3.  If not see
  18 // <http://www.gnu.org/licenses/>.
  19
  20
  21 // Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.
  22
  23 // Permission to use, copy, modify, sell, and distribute this software
  24 // is hereby granted without fee, provided that the above copyright
  25 // notice appears in all copies, and that both that copyright notice
  26 // and this permission notice appear in supporting documentation. None
  27 // of the above authors, nor IBM Haifa Research Laboratories, make any
  28 // representation about the suitability of this software for any
  29 // purpose. It is provided "as is" without express or implied
  30 // warranty.
  31
  32 /**
  33  * @file tree_join_example.cpp
  34  * An example showing how to join splay_tree_map objects.
  35  *    The code in the example is relevant to red-black trees as well.
  36  */
  37
  38 /**
  39  * This example shows how to join tree based containers, i.e., taking two
  40  *     objects with non-overlapping sets of keys and combining them into
  41  *    a single object.
  42  */
  43
  44 // For tree
  45 #include <ext/pb_ds/assoc_container.hpp>
  46 // For join_error exception.
  47 #include <ext/pb_ds/exception.hpp>
  48 // For assert
  49 #include <cassert>
  50
  51 using namespace std;
  52 using namespace __gnu_pbds;
  53 using namespace __gnu_pbds;
  54
  55 int main()
  56 {
  57   /*
  58    *
  59    */
  60   // A splay tree table mapping ints to chars.
  61   typedef tree<int, char, less<int>, splay_tree_tag> map_t;
  62
  63   // Two map_t object.
  64   map_t h0, h1;
  65
  66   // Insert some values into the first table.
  67   for (int i0 = 0; i0 < 100; ++i0)
  68     h0.insert(make_pair(i0, 'a'));
  69
  70   // Insert some values into the second table.
  71   for (int i1 = 0; i1 < 100; ++i1)
  72     h1.insert(make_pair(1000 + i1, 'b'));
  73
  74   // Since all the elements in h0 are smaller than those in h1, it is
  75   // possible to join the two tables. This is exception free.
  76   h0.join(h1);
  77
  78   // Check that h0 should now contain all entries, and h1 should be empty.
  79   assert(h0.size() == 200);
  80   assert(h1.empty());
  81
  82
  83   // Two other map_t objects.
  84   map_t h2, h3;
  85
  86   h2[1] = 'a';
  87   h2[3] = 'c';
  88
  89   h3[2] = 'b';
  90
  91   // Now perform an illegal join.
  92   // It is not true that all elements in h2 are smaller than those in
  93   // h3, nor is it true that they are all larger. Hence, attempting to
  94   // join h2, and h3 should result in an exception.
  95   bool exception_thrown = false;
  96   try
  97     {
  98       h2.join(h3);
  99     }
 100   catch (__gnu_pbds::join_error& )
 101     {
 102       exception_thrown = true;
 103     }
 104   assert(exception_thrown);
 105
 106   // Since the operation was not performed, the tables should be unaltered.
 107   assert(h2.size() == 2);
 108   assert(h3[2] == 'b');
 109
 110   return 0;
 111 }
 112