126 lines
2.9 KiB
C++
126 lines
2.9 KiB
C++
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#include <cstdlib>
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#include <iostream>
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#include <string>
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#include <typeinfo>
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#include <utility>
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#include "auto_cpu_timer.hpp"
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#include <mapbox/variant.hpp>
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using namespace mapbox;
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namespace test {
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struct add;
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struct sub;
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template <typename OpTag>
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struct binary_op;
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typedef util::variant<int,
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util::recursive_wrapper<binary_op<add>>,
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util::recursive_wrapper<binary_op<sub>>>
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expression;
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template <typename Op>
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struct binary_op
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{
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expression left; // variant instantiated here...
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expression right;
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binary_op(expression&& lhs, expression&& rhs)
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: left(std::move(lhs)), right(std::move(rhs))
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{
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}
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};
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struct print
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{
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template <typename T>
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void operator()(T const& val) const
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{
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std::cerr << val << ":" << typeid(T).name() << std::endl;
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}
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};
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struct test
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{
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template <typename T>
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std::string operator()(T const& obj) const
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{
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return std::string("TYPE_ID=") + typeid(obj).name();
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}
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};
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struct calculator
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{
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public:
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int operator()(int value) const
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{
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return value;
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}
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int operator()(binary_op<add> const& binary) const
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{
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return util::apply_visitor(calculator(), binary.left) + util::apply_visitor(calculator(), binary.right);
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}
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int operator()(binary_op<sub> const& binary) const
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{
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return util::apply_visitor(calculator(), binary.left) - util::apply_visitor(calculator(), binary.right);
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}
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};
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struct to_string
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{
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public:
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std::string operator()(int value) const
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{
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return std::to_string(value);
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}
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std::string operator()(binary_op<add> const& binary) const
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{
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return util::apply_visitor(to_string(), binary.left) + std::string("+") + util::apply_visitor(to_string(), binary.right);
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}
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std::string operator()(binary_op<sub> const& binary) const
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{
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return util::apply_visitor(to_string(), binary.left) + std::string("-") + util::apply_visitor(to_string(), binary.right);
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}
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};
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} // namespace test
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int main(int argc, char** argv)
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{
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if (argc != 2)
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{
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std::cerr << "Usage" << argv[0] << " <num-iter>" << std::endl;
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return EXIT_FAILURE;
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}
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const std::size_t NUM_ITER = static_cast<std::size_t>(std::stol(argv[1]));
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test::expression sum(test::binary_op<test::add>(2, 3));
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test::expression result(test::binary_op<test::sub>(std::move(sum), 4));
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std::cerr << "TYPE OF RESULT-> " << util::apply_visitor(test::test(), result) << std::endl;
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int total = 0;
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{
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auto_cpu_timer t;
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for (std::size_t i = 0; i < NUM_ITER; ++i)
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{
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total += util::apply_visitor(test::calculator(), result);
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}
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}
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std::cerr << "total=" << total << std::endl;
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std::cerr << util::apply_visitor(test::to_string(), result) << "=" << util::apply_visitor(test::calculator(), result) << std::endl;
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return EXIT_SUCCESS;
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}
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