1 // -*- C++ -*-
2
3 // Copyright (C) 2005-2021 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
main()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
113