57 lines
1.5 KiB
C++
57 lines
1.5 KiB
C++
#include <cassert>
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#include <sstream>
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#include <string>
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using namespace std::string_literals;
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template <typename T> auto sum(T final) { return final; }
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template <typename T, typename... Ts> auto sum(T first, Ts... rem) {
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return first + sum<Ts...>(rem...);
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}
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class ss_sum {
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std::stringstream ss;
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public:
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template <typename T> ss_sum(T obj) : ss{} { ss << obj; }
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ss_sum(ss_sum const &rhs) : ss{} {
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std::string tmp;
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const_cast<ss_sum &>(rhs).ss >> tmp;
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const_cast<ss_sum &>(rhs).ss << tmp;
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ss << tmp;
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}
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friend ss_sum operator+(ss_sum const &lhs, ss_sum const &rhs) {
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ss_sum ret = lhs;
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ss_sum tmp = rhs;
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std::string a;
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tmp.ss >> a;
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ret.ss << a;
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return ret;
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}
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friend bool operator==(ss_sum const &lhs, ss_sum const &rhs) {
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ss_sum inner_l = lhs;
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ss_sum inner_r = rhs;
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std::string l;
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std::string r;
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inner_l.ss >> l;
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inner_r.ss >> r;
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return l == r;
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}
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};
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int main(void) {
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bool dummy = sum<double, int, int, int>(1.5, 2, 3, 10) == 16.5;
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assert(dummy);
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dummy = sum<int, int, int, int, int, int, int>(1, 5, 7, 8, 2, 3, 4) == 30;
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assert(dummy);
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dummy = sum<double>(1.5, 1, 2, 3.5) == 8.0;
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assert(dummy);
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dummy = sum<std::string>("asdf"s, "abcdefghijklmnop"s, "qrstuvwxyz"s) ==
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"asdfabcdefghijklmnopqrstuvwxyz"s;
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assert(dummy);
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// ss_sum is only associative when everything is ss_sum
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auto tmp = sum<ss_sum, ss_sum, ss_sum>(1, 2, 3);
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dummy = tmp == ss_sum{"123"};
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assert(dummy);
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}
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