mirror of https://github.com/grpc/grpc.git
Add Match/Overload abstractions (#26640)
* match/overload abstraction * update projects * match should really not accept mutable args * typo * tests * usage comment * mutable version * build stuff * clang-format * add an escape hatch to avoid needing port_platform.h in files that do not need port_platform.h * unused args * Make it possible for a test to not depend on gpr * add tests * compile fix * sepellingpull/26659/head
Craig Tiller
3 years ago
committed by
GitHub
parent
994ee5da0c
commit
0bd70a7e3e
11 changed files with 435 additions and 5 deletions
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// Copyright 2021 gRPC authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef GRPC_CORE_LIB_GPRPP_MATCH_H |
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#define GRPC_CORE_LIB_GPRPP_MATCH_H |
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// Portable code. port_platform.h is not required.
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#include "absl/types/variant.h" |
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#include "src/core/lib/gprpp/overload.h" |
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namespace grpc_core { |
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namespace detail { |
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template <typename... Cases> |
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struct MatchPointerExtractor { |
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OverloadType<Cases...> cases; |
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template <typename T> |
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auto operator()(T& value) -> decltype(cases(&value)) { |
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return cases(&value); |
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} |
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}; |
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} // namespace detail
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/// Match on a variant.
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/// Given variant \a value, and a set of callables \a fs, call the appropriate
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/// callable based on the type contained in \a value.
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///
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/// Example (prints "hoorah"):
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/// variant<int, string> v = 42;
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/// Match(v,
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/// [](int i) { puts("hoorah"); },
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/// [](string s) { puts("boo"); });
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template <typename... Fs, typename T0, typename... Ts> |
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auto Match(const absl::variant<T0, Ts...>& value, Fs... fs) |
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-> decltype(std::declval<OverloadType<Fs...>>()(std::declval<T0>())) { |
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return absl::visit(Overload(std::move(fs)...), value); |
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} |
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/// A version of Match that takes a mutable pointer to a variant and calls its
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/// overload callables with a mutable pointer to the current variant value.
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///
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/// Example:
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/// variant<int, string> v = 42;
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/// MatchMutable(&v,
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/// [](int* i) { *i = 1; },
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/// [](string* s) { *s = "foo"; });
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/// // v now contains 1.
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template <typename... Fs, typename T0, typename... Ts> |
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auto MatchMutable(absl::variant<T0, Ts...>* value, Fs... fs) |
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-> decltype(std::declval<OverloadType<Fs...>>()(std::declval<T0*>())) { |
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return absl::visit(detail::MatchPointerExtractor<Fs...>{OverloadType<Fs...>( |
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std::move(fs)...)}, |
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*value); |
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} |
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} // namespace grpc_core
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#endif // GRPC_CORE_LIB_GPRPP_MATCH_H
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// Copyright 2021 gRPC authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef GRPC_CORE_LIB_GPRPP_OVERLOAD_H |
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#define GRPC_CORE_LIB_GPRPP_OVERLOAD_H |
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// Portable code. port_platform.h is not required.
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#include <utility> |
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namespace grpc_core { |
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template <typename... Cases> |
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struct OverloadType; |
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// Compose one overload with N more -- use inheritance to leverage using and the
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// empty base class optimization.
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template <typename Case, typename... Cases> |
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struct OverloadType<Case, Cases...> : public Case, |
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public OverloadType<Cases...> { |
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explicit OverloadType(Case&& c, Cases&&... cases) |
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: Case(std::forward<Case>(c)), |
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OverloadType<Cases...>(std::forward<Cases>(cases)...) {} |
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using Case::operator(); |
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using OverloadType<Cases...>::operator(); |
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}; |
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// Overload of a single case is just that case itself
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template <typename Case> |
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struct OverloadType<Case> : public Case { |
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explicit OverloadType(Case&& c) : Case(std::forward<Case>(c)) {} |
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using Case::operator(); |
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}; |
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/// Compose callables into a single callable.
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/// e.g. given [](int i) { puts("a"); } and [](double d) { puts("b"); },
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/// return a callable object like:
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/// struct {
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/// void operator()(int i) { puts("a"); }
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/// void operator()(double i) { puts("b"); }
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/// };
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/// Preserves all captures.
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template <typename... Cases> |
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OverloadType<Cases...> Overload(Cases... cases) { |
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return OverloadType<Cases...>(std::move(cases)...); |
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} |
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} // namespace grpc_core
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#endif // GRPC_CORE_LIB_GPRPP_OVERLOAD_H
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// Copyright 2021 gRPC authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "src/core/lib/gprpp/match.h" |
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#include <gtest/gtest.h> |
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namespace grpc_core { |
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namespace testing { |
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TEST(MatchTest, Test) { |
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EXPECT_EQ(Match( |
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absl::variant<int, double>(1.9), [](int) -> int { abort(); }, |
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[](double x) -> int { |
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EXPECT_EQ(x, 1.9); |
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return 42; |
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}), |
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42); |
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EXPECT_EQ(Match( |
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absl::variant<int, double>(3), |
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[](int x) -> int { |
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EXPECT_EQ(x, 3); |
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return 42; |
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}, |
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[](double) -> int { abort(); }), |
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42); |
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} |
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TEST(MatchTest, TestVoidReturn) { |
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bool triggered = false; |
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Match( |
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absl::variant<int, double>(1.9), [](int) { abort(); }, |
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[&triggered](double x) { |
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EXPECT_EQ(x, 1.9); |
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triggered = true; |
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}); |
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EXPECT_TRUE(triggered); |
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} |
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TEST(MatchTest, TestMutable) { |
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absl::variant<int, double> v = 1.9; |
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MatchMutable( |
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&v, [](int*) { abort(); }, [](double* x) { *x = 0.0; }); |
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EXPECT_EQ(v, (absl::variant<int, double>(0.0))); |
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} |
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TEST(MatchTest, TestMutableWithReturn) { |
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absl::variant<int, double> v = 1.9; |
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EXPECT_EQ(MatchMutable( |
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&v, [](int*) -> int { abort(); }, |
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[](double* x) -> int { |
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*x = 0.0; |
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return 1; |
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}), |
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1); |
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EXPECT_EQ(v, (absl::variant<int, double>(0.0))); |
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} |
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} // namespace testing
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} // namespace grpc_core
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int main(int argc, char** argv) { |
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::testing::InitGoogleTest(&argc, argv); |
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return RUN_ALL_TESTS(); |
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} |
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// Copyright 2021 gRPC authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "src/core/lib/gprpp/overload.h" |
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#include <gtest/gtest.h> |
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namespace grpc_core { |
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namespace testing { |
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TEST(Overload, Test) { |
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auto a = [](int x) { return x; }; |
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auto b = [](std::string x) -> int { return x.length(); }; |
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auto overload = Overload(a, b); |
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EXPECT_EQ(overload(1), 1); |
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EXPECT_EQ(overload("1"), 1); |
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EXPECT_EQ(overload("abc"), 3); |
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} |
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} // namespace testing
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} // namespace grpc_core
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int main(int argc, char** argv) { |
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::testing::InitGoogleTest(&argc, argv); |
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return RUN_ALL_TESTS(); |
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} |
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