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1 | |
2 | // Copyright (C) 2006-2009, 2012 Alexander Nasonov | |
3 | // Copyright (C) 2012 Lorenzo Caminiti | |
4 | // Distributed under the Boost Software License, Version 1.0 | |
5 | // (see accompanying file LICENSE_1_0.txt or a copy at | |
6 | // http://www.boost.org/LICENSE_1_0.txt) | |
7 | // Home at http://www.boost.org/libs/scope_exit | |
8 | ||
9 | #include <boost/config.hpp> | |
10 | #ifdef BOOST_NO_CXX11_VARIADIC_MACROS | |
11 | # error "variadic macros required" | |
12 | #else | |
13 | ||
14 | #include <boost/scope_exit.hpp> | |
15 | #include <boost/foreach.hpp> | |
16 | #include <boost/typeof/typeof.hpp> | |
17 | #include <boost/typeof/std/vector.hpp> | |
18 | #include BOOST_TYPEOF_INCREMENT_REGISTRATION_GROUP() | |
19 | #include <boost/detail/lightweight_test.hpp> | |
20 | #include <vector> | |
21 | #include <iostream> | |
22 | #include <sstream> | |
23 | ||
24 | struct person { | |
25 | typedef unsigned int id_t; | |
26 | typedef unsigned int evolution_t; | |
27 | ||
28 | id_t id; | |
29 | evolution_t evolution; | |
30 | ||
31 | person(void) : id(0), evolution(0) {} | |
32 | ||
33 | friend std::ostream& operator<<(std::ostream& o, person const& p) { | |
34 | return o << "person(" << p.id << ", " << p.evolution << ")"; | |
35 | } | |
36 | }; | |
37 | BOOST_TYPEOF_REGISTER_TYPE(person) | |
38 | ||
39 | struct world { | |
40 | world(void) : next_id_(1) {} | |
41 | void add_person(person const& a_person); | |
42 | ||
43 | friend std::ostream& operator<<(std::ostream& o, world const& w) { | |
44 | o << "world(" << w.next_id_ << ", {"; | |
45 | BOOST_FOREACH(person const& p, w.persons_) { | |
46 | o << " " << p << ", "; | |
47 | } | |
48 | return o << "})"; | |
49 | } | |
50 | ||
51 | private: | |
52 | person::id_t next_id_; | |
53 | std::vector<person> persons_; | |
54 | }; | |
55 | BOOST_TYPEOF_REGISTER_TYPE(world) | |
56 | ||
57 | //[world_checkpoint | |
58 | void world::add_person(person const& a_person) { | |
59 | persons_.push_back(a_person); | |
60 | ||
61 | // This block must be no-throw. | |
62 | person& p = persons_.back(); | |
63 | person::evolution_t checkpoint = p.evolution; | |
64 | BOOST_SCOPE_EXIT(checkpoint, &p, &persons_) { | |
65 | if(checkpoint == p.evolution) persons_.pop_back(); | |
66 | } BOOST_SCOPE_EXIT_END | |
67 | ||
68 | // ... | |
69 | ||
70 | checkpoint = ++p.evolution; | |
71 | ||
72 | // Assign new identifier to the person. | |
73 | person::id_t const prev_id = p.id; | |
74 | p.id = next_id_++; | |
75 | BOOST_SCOPE_EXIT(checkpoint, &p, &next_id_, prev_id) { | |
76 | if(checkpoint == p.evolution) { | |
77 | next_id_ = p.id; | |
78 | p.id = prev_id; | |
79 | } | |
80 | } BOOST_SCOPE_EXIT_END | |
81 | ||
82 | // ... | |
83 | ||
84 | checkpoint = ++p.evolution; | |
85 | } | |
86 | //] | |
87 | ||
88 | int main(void) { | |
89 | person adam, eva; | |
90 | std::ostringstream oss; | |
91 | oss << adam; | |
92 | std::cout << oss.str() << std::endl; | |
93 | BOOST_TEST(oss.str() == "person(0, 0)"); | |
94 | ||
95 | oss.str(""); | |
96 | oss << eva; | |
97 | std::cout << oss.str() << std::endl; | |
98 | BOOST_TEST(oss.str() == "person(0, 0)"); | |
99 | ||
100 | world w; | |
101 | w.add_person(adam); | |
102 | w.add_person(eva); | |
103 | oss.str(""); | |
104 | oss << w; | |
105 | std::cout << oss.str() << std::endl; | |
106 | BOOST_TEST(oss.str() == "world(3, { person(1, 2), person(2, 2), })"); | |
107 | ||
108 | return boost::report_errors(); | |
109 | } | |
110 | ||
111 | #endif // variadic macros | |
112 |