72 lines
2.2 KiB
C++
72 lines
2.2 KiB
C++
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// Copyright (C) 2009-2012 Lorenzo Caminiti
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// Distributed under the Boost Software License, Version 1.0
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// (see accompanying file LICENSE_1_0.txt or a copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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// Home at http://www.boost.org/libs/local_function
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//[impl_tparam_tricks
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#include <boost/detail/lightweight_test.hpp>
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#include <vector>
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#include <algorithm>
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// Casting functor trick.
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struct casting_func {
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explicit casting_func(void* obj, void (*call)(void*, const int&))
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: obj_(obj), call_(call) {}
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// Unfortunately, function pointer call is not inlined.
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inline void operator()(const int& num) { call_(obj_, num); }
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private:
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void* obj_;
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void (*call_)(void*, const int&);
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};
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// Virtual functor trick.
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struct virtual_func {
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struct interface {
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// Unfortunately, virtual function call is not inlined.
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inline virtual void operator()(const int&) {}
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};
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explicit virtual_func(interface& func): func_(&func) {}
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inline void operator()(const int& num) { (*func_)(num); }
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private:
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interface* func_;
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};
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int main(void) {
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int sum = 0, factor = 10;
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// Local class for local function.
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struct local_add : virtual_func::interface {
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explicit local_add(int& _sum, const int& _factor)
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: sum_(_sum), factor_(_factor) {}
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inline void operator()(const int& num) {
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body(sum_, factor_, num);
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}
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inline static void call(void* obj, const int& num) {
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local_add* self = static_cast<local_add*>(obj);
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self->body(self->sum_, self->factor_, num);
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}
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private:
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int& sum_;
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const int& factor_;
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inline void body(int& sum, const int& factor, const int& num) {
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sum += factor * num;
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}
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} add_local(sum, factor);
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casting_func add_casting(&add_local, &local_add::call);
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virtual_func add_virtual(add_local);
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std::vector<int> v(10);
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std::fill(v.begin(), v.end(), 1);
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// std::for_each(v.begin(), v.end(), add_local); // Error but OK on C++11.
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std::for_each(v.begin(), v.end(), add_casting); // OK.
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std::for_each(v.begin(), v.end(), add_virtual); // OK.
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BOOST_TEST(sum == 200);
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return boost::report_errors();
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}
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//]
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