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