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54 lines
1.4 KiB
54 lines
1.4 KiB
5 years ago
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/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*/
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#include <variant>
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#include <vector>
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namespace std_visit {
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struct A {
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int s_;
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~A() {}
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A() {}
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};
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// See https://en.cppreference.com/w/cpp/utility/variant/visit for more details
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using var_t = std::variant<float, int, A>;
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template <class... Ts>
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struct overloaded : Ts... {
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using Ts::operator()...;
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};
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template <class... Ts>
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overloaded(Ts...)->overloaded<Ts...>;
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void visit_ok(var_t x) {
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std::visit(overloaded{
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[](float a) {},
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[](int i) {},
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[](const A& a) {},
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},
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x);
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}
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void visit_all_ok(std::vector<var_t>& vec) {
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for (auto& x : vec) {
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// the overloaded { .. } construct appears as an InitListExpr in
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// the AST that the frontend needs to translate. Otherwise, since
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// children of that InitListExpr create C++ temporaries, pulse
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// will complain that they get destroyed because it never sees
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// them being created (this is only a problem in a loop where the
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// same temporary is re-used without having been re-initialized).
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std::visit(overloaded{
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[](float a) {},
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[](int i) {},
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[](const A& a) {},
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},
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x);
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}
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}
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} // namespace std_visit
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