variant: support std::visit via apply

felixguendling · Apr 4, 2024 · a18e183 · a18e183
1 parent 251a73b
commit a18e183
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diff --git a/include/cista/containers/variant.h b/include/cista/containers/variant.h
@@ -438,6 +438,11 @@ using cista::variant;
 
 namespace std {
 
+template <typename Visitor, typename... T>
+constexpr auto visit(Visitor&& vis, cista::variant<T...>&& v) {
+  v.apply(vis);
+}
+
 using cista::get;
 
 }  // namespace std
diff --git a/test/variant_test.cc b/test/variant_test.cc
@@ -241,3 +241,15 @@ TEST_CASE("variant get_if") {
   REQUIRE(str != nullptr);
   CHECK(*str == "hello test test test test");
 }
+
+TEST_CASE("std visit") {
+  std::visit(
+      [](auto&& x) {
+        if constexpr (std::is_same_v<int, std::decay_t<decltype(x)>>) {
+          CHECK(true);
+        } else {
+          CHECK(false);
+        }
+      },
+      cista::variant<int, float>{1});
+}