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7c673cae FG |
1 | //We need to declare: |
2 | // | |
3 | //2 conversions: rv<T> & and const rv<T> & | |
4 | //1 rv<T> & constructor: move constructor | |
5 | //1 const rv<T> & constructor: copy constructor | |
6 | //1 T & constructor: copy constructor | |
7 | // | |
8 | //Optimization: | |
9 | //Since RVO is better than move-construction, | |
10 | //avoid copy constructor overloading. | |
20effc67 | 11 | |
7c673cae FG |
12 | #include <boost/move/utility_core.hpp> |
13 | #include <iostream> | |
14 | ||
15 | bool moved = false; | |
16 | ||
17 | class obj | |
18 | { | |
19 | BOOST_COPYABLE_AND_MOVABLE(obj) | |
20 | public: | |
21 | ||
22 | obj() | |
23 | { | |
24 | std::cout << "constructing obj" << "\n"; | |
25 | } | |
26 | ||
27 | ~obj() | |
28 | {} | |
29 | ||
30 | obj(const obj &) | |
31 | { | |
32 | std::cout << "copy construct from const obj" << "\n"; | |
33 | } | |
34 | ||
35 | // copy construct from movable object (non-const rvalue, explicitly moved lvalue) | |
36 | obj(BOOST_RV_REF(obj)) | |
37 | { | |
38 | std::cout << "move construct from movable rvalue" << "\n"; | |
39 | } | |
40 | ||
41 | obj& operator =(BOOST_COPY_ASSIGN_REF(obj)) | |
42 | { | |
43 | std::cout << "copy assign from const obj" << "\n"; | |
44 | return *this; | |
45 | } | |
46 | ||
47 | obj& operator =(BOOST_RV_REF(obj)) | |
48 | { | |
49 | std::cout << "move assign from movable rvalue" << "\n"; | |
50 | return *this; | |
51 | } | |
52 | }; | |
53 | ||
54 | ||
55 | obj rvalue_func() { return obj(); } | |
56 | const obj const_rvalue_func() { return obj(); } | |
57 | obj& lvalue_func() { static obj o; return o; } | |
58 | const obj& const_lvalue_func() { static obj o; return o; } | |
59 | ||
60 | obj produce() { return obj(); } | |
61 | ||
62 | void consume(obj){} | |
63 | ||
64 | int main() | |
65 | { | |
66 | { consume(produce()); } | |
67 | { obj o = produce(); } | |
68 | { obj o(produce()); } | |
69 | { | |
70 | obj o1(rvalue_func()); | |
71 | obj o2 = const_rvalue_func(); | |
72 | obj o3 = lvalue_func(); | |
73 | obj o4 = const_lvalue_func(); | |
74 | // can't explicitly move temporaries | |
75 | //obj o5 = boost::move(rvalue_func()); | |
76 | obj o5; | |
77 | //Maybe missed optimization: copied | |
78 | o5 = rvalue_func(); | |
79 | //Explicit forward works OK and optimized | |
80 | o5 = boost::forward<obj>(rvalue_func()); | |
81 | ||
82 | obj o7 = boost::move(lvalue_func()); | |
83 | obj o8 = boost::move(const_lvalue_func()); | |
84 | ||
85 | obj o; | |
86 | o = rvalue_func(); | |
87 | o = const_rvalue_func(); | |
88 | o = lvalue_func(); | |
89 | o = const_lvalue_func(); | |
90 | // can't explicitly move temporaries | |
91 | //o = boost::move(rvalue_func()); | |
92 | o = boost::forward<obj>(rvalue_func()); | |
93 | o = boost::move(const_rvalue_func()); | |
94 | o = boost::move(lvalue_func()); | |
95 | o = boost::move(const_lvalue_func()); | |
96 | } | |
97 | return 0; | |
98 | } | |
99 | ||
100 | //We need to declare: | |
101 | // | |
102 | //2 conversions: rv<T> & and const rv<T> & | |
103 | //1 rv<T> & constructor: move constructor | |
104 | //1 const rv<T> & constructor: copy constructor | |
105 | //1 T & constructor: copy constructor |