1
2 // Copyright (C) 2009-2012 Lorenzo Caminiti
3 // Distributed under the Boost Software License, Version 1.0
4 // (see accompanying file LICENSE_1_0.txt or a copy at
5 // http://www.boost.org/LICENSE_1_0.txt)
6 // Home at http://www.boost.org/libs/local_function
7
8 //[impl_tparam_tricks
9 #include <boost/detail/lightweight_test.hpp>
10 #include <vector>
11 #include <algorithm>
12
13 // Casting functor trick.
14 struct casting_func {
casting_funccasting_func15 explicit casting_func(void* obj, void (*call)(void*, const int&))
16 : obj_(obj), call_(call) {}
17 // Unfortunately, function pointer call is not inlined.
operator ()casting_func18 inline void operator()(const int& num) { call_(obj_, num); }
19 private:
20 void* obj_;
21 void (*call_)(void*, const int&);
22 };
23
24 // Virtual functor trick.
25 struct virtual_func {
26 struct interface {
27 // Unfortunately, virtual function call is not inlined.
operator ()virtual_func::interface28 inline virtual void operator()(const int&) {}
29 };
virtual_funcvirtual_func30 explicit virtual_func(interface& func): func_(&func) {}
operator ()virtual_func31 inline void operator()(const int& num) { (*func_)(num); }
32 private:
33 interface* func_;
34 };
35
main(void)36 int main(void) {
37 int sum = 0, factor = 10;
38
39 // Local class for local function.
40 struct local_add : virtual_func::interface {
41 explicit local_add(int& _sum, const int& _factor)
42 : sum_(_sum), factor_(_factor) {}
43 inline void operator()(const int& num) {
44 body(sum_, factor_, num);
45 }
46 inline static void call(void* obj, const int& num) {
47 local_add* self = static_cast<local_add*>(obj);
48 self->body(self->sum_, self->factor_, num);
49 }
50 private:
51 int& sum_;
52 const int& factor_;
53 inline void body(int& sum, const int& factor, const int& num) {
54 sum += factor * num;
55 }
56 } add_local(sum, factor);
57 casting_func add_casting(&add_local, &local_add::call);
58 virtual_func add_virtual(add_local);
59
60 std::vector<int> v(10);
61 std::fill(v.begin(), v.end(), 1);
62
63 // std::for_each(v.begin(), v.end(), add_local); // Error but OK on C++11.
64 std::for_each(v.begin(), v.end(), add_casting); // OK.
65 std::for_each(v.begin(), v.end(), add_virtual); // OK.
66
67 BOOST_TEST(sum == 200);
68 return boost::report_errors();
69 }
70 //]
71
72