1// -*- C++ -*-
2
3// Copyright (C) 2005, 2006, 2009 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 erase_if_example.cpp
34 * A basic example showing how to use erase_if.
35 */
36
37/**
38 * The following example shows how to use a conditional-erase
39 * method of associative containers to erase some of their entries.
40 */
41
42#include <iostream>
43#include <cassert>
44#include <ext/pb_ds/assoc_container.hpp>
45
46using namespace std;
47using namespace __gnu_pbds;
48
49// The following functor takes a map's value-type object and returns
50// whether its key is between two numbers.
51struct between : public unary_function<pair<const int, char>, bool>
52{
53  // Constructor taking two numbers determining a range.
54  between(int b, int e) : m_b(b), m_e(e)
55  { assert(m_b < m_e); }
56
57  // Operator determining whether a value-type object's key is within
58  // the range.
59  inline bool
60  operator()(const pair<const int, char>& r_val)
61  { return r_val.first >= m_b&&  r_val.first < m_e; }
62
63private:
64  const int m_b;
65  const int m_e;
66};
67
68/**
69 * The following function performs a sequence of operations on an
70 * associative container object mapping integers to characters. Specifically
71 * it inserts 100 values and then uses a conditional-erase method to erase
72 * the values whose key is between 10 and 90.
73 */
74template<class Cntnr>
75void
76some_op_sequence(Cntnr r_c)
77{
78  assert(r_c.empty());
79  assert(r_c.size() == 0);
80
81  for (int i = 0; i < 100; ++i)
82    r_c.insert(make_pair(i, static_cast<char>(i)));
83  assert(r_c.size() == 100);
84
85  // Erase all values whose key is between 10 (inclusive) and 90
86  // (non-inclusive).
87  r_c.erase_if(between(10 , 90));
88
89  assert(!r_c.empty());
90  assert(r_c.size() == 20);
91}
92
93int main()
94{
95  // Perform operations on a list-update set.
96  some_op_sequence(list_update<int, char>());
97
98  // Perform operations on a collision-chaining hash set.
99  some_op_sequence(cc_hash_table<int, char>());
100
101  // Perform operations on a general-probing hash set.
102  some_op_sequence(gp_hash_table<int, char>());
103
104  // Perform operations on a red-black tree set.
105  some_op_sequence(tree<int, char>());
106
107  // Perform operations on a splay tree set.
108  some_op_sequence(tree<
109		   int,
110		   char,
111		   less<int>,
112		   splay_tree_tag>());
113
114  // Perform operations on a splay tree set.
115  some_op_sequence(tree<
116		   int,
117		   char,
118		   less<int>,
119		   ov_tree_tag>());
120
121  return 0;
122}
123