y_combinator in C++
来源：https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0200r0.html
1. 模板
cpp <y_combinator>
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| #include <functional>
#include <utility>
template <class Fun>
class y_combinator_result {
Fun fun_;
public:
template <class T>
explicit y_combinator_result(T &&fun) : fun_(std::forward<T>(fun)) {}
template <class... Args>
decltype(auto) operator()(Args &&...args) {
return fun_(std::ref(*this), std::forward<Args>(args)...);
}
};
template <class Fun>
decltype(auto) y_combinator(Fun &&fun) {
return y_combinator_result<std::decay_t<Fun>>(std::forward<Fun>(fun));
}
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2. 用法
cpp
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| int main() {
std::vector<std::vector<int>> G;
y_combinator([&](auto dfs, int u) -> void {
for (auto v : G[u]) dfs(v);
})(1);
}
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