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1 | // -*- C++ -*- |
2 | ||
3 | // Copyright (C) 2005, 2006 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 2, 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 COPYING. If not, write to | |
18 | // the Free Software Foundation, 59 Temple Place - Suite 330, Boston, | |
19 | // MA 02111-1307, USA. | |
20 | ||
21 | // As a special exception, you may use this file as part of a free | |
22 | // software library without restriction. Specifically, if other files | |
23 | // instantiate templates or use macros or inline functions from this | |
24 | // file, or you compile this file and link it with other files to | |
25 | // produce an executable, this file does not by itself cause the | |
26 | // resulting executable to be covered by the GNU General Public | |
27 | // License. This exception does not however invalidate any other | |
28 | // reasons why the executable file might be covered by the GNU General | |
29 | // Public License. | |
30 | ||
31 | // Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL. | |
32 | ||
33 | // Permission to use, copy, modify, sell, and distribute this software | |
34 | // is hereby granted without fee, provided that the above copyright | |
35 | // notice appears in all copies, and that both that copyright notice | |
36 | // and this permission notice appear in supporting documentation. None | |
37 | // of the above authors, nor IBM Haifa Research Laboratories, make any | |
38 | // representation about the suitability of this software for any | |
39 | // purpose. It is provided "as is" without express or implied | |
40 | // warranty. | |
41 | ||
42 | /** | |
43 | * @file erase_if_example.cpp | |
44 | * A basic example showing how to use erase_if. | |
45 | */ | |
46 | ||
47 | /** | |
48 | * The following example shows how to use a conditional-erase | |
49 | * method of associative containers to erase some of their entries. | |
50 | */ | |
51 | ||
52 | #include <iostream> | |
53 | #include <cassert> | |
54 | #include <ext/pb_ds/assoc_container.hpp> | |
55 | ||
56 | using namespace std; | |
5e11f978 | 57 | using namespace __gnu_pbds; |
4569a895 AT |
58 | |
59 | // The following functor takes a map's value-type object and returns | |
60 | // whether its key is between two numbers. | |
61 | struct between : public unary_function<pair<const int, char>, bool> | |
62 | { | |
63 | // Constructor taking two numbers determining a range. | |
64 | between(int b, int e) : m_b(b), m_e(e) | |
65 | { assert(m_b < m_e); } | |
66 | ||
67 | // Operator determining whether a value-type object's key is within | |
68 | // the range. | |
69 | inline bool | |
70 | operator()(const pair<const int, char>& r_val) | |
71 | { return r_val.first >= m_b&& r_val.first < m_e; } | |
72 | ||
73 | private: | |
74 | const int m_b; | |
75 | const int m_e; | |
76 | }; | |
77 | ||
78 | /** | |
79 | * The following function performs a sequence of operations on an | |
80 | * associative container object mapping integers to characters. Specifically | |
81 | * it inserts 100 values and then uses a conditional-erase method to erase | |
82 | * the values whose key is between 10 and 90. | |
83 | */ | |
84 | template<class Cntnr> | |
85 | void | |
86 | some_op_sequence(Cntnr r_c) | |
87 | { | |
88 | assert(r_c.empty()); | |
89 | assert(r_c.size() == 0); | |
90 | ||
91 | for (int i = 0; i < 100; ++i) | |
92 | r_c.insert(make_pair(i, static_cast<char>(i))); | |
93 | assert(r_c.size() == 100); | |
94 | ||
95 | // Erase all values whose key is between 10 (inclusive) and 90 | |
96 | // (non-inclusive). | |
97 | r_c.erase_if(between(10 , 90)); | |
98 | ||
99 | assert(!r_c.empty()); | |
100 | assert(r_c.size() == 20); | |
101 | } | |
102 | ||
103 | int main() | |
104 | { | |
105 | // Perform operations on a list-update set. | |
106 | some_op_sequence(list_update<int, char>()); | |
107 | ||
108 | // Perform operations on a collision-chaining hash set. | |
109 | some_op_sequence(cc_hash_table<int, char>()); | |
110 | ||
111 | // Perform operations on a general-probing hash set. | |
112 | some_op_sequence(gp_hash_table<int, char>()); | |
113 | ||
114 | // Perform operations on a red-black tree set. | |
115 | some_op_sequence(tree<int, char>()); | |
116 | ||
117 | // Perform operations on a splay tree set. | |
118 | some_op_sequence(tree< | |
119 | int, | |
120 | char, | |
121 | less<int>, | |
122 | splay_tree_tag>()); | |
123 | ||
124 | // Perform operations on a splay tree set. | |
125 | some_op_sequence(tree< | |
126 | int, | |
127 | char, | |
128 | less<int>, | |
129 | ov_tree_tag>()); | |
130 | ||
131 | return 0; | |
132 | } |