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Diffstat (limited to 'absl/utility/utility_test.cc')
| -rw-r--r-- | absl/utility/utility_test.cc | 163 |
1 files changed, 163 insertions, 0 deletions
diff --git a/absl/utility/utility_test.cc b/absl/utility/utility_test.cc new file mode 100644 index 000000000000..62cb46f4d160 --- /dev/null +++ b/absl/utility/utility_test.cc @@ -0,0 +1,163 @@ +// Copyright 2017 The Abseil Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +#include "absl/utility/utility.h" + +#include <sstream> +#include <string> +#include <tuple> +#include <type_traits> +#include <vector> + +#include "gmock/gmock.h" +#include "gtest/gtest.h" +#include "absl/base/attributes.h" + +namespace { + +#ifdef _MSC_VER +// Warnings for unused variables in this test are false positives. On other +// platforms, they are suppressed by ABSL_ATTRIBUTE_UNUSED, but that doesn't +// work on MSVC. +// Both the unused variables and the name length warnings are due to calls +// to absl::make_index_sequence with very large values, creating very long type +// names. The resulting warnings are so long they make build output unreadable. +#pragma warning( push ) +#pragma warning( disable : 4503 ) // decorated name length exceeded +#pragma warning( disable : 4101 ) // unreferenced local variable +#endif // _MSC_VER + +using testing::StaticAssertTypeEq; +using testing::ElementsAre; + +TEST(IntegerSequenceTest, ValueType) { + StaticAssertTypeEq<int, absl::integer_sequence<int>::value_type>(); + StaticAssertTypeEq<char, absl::integer_sequence<char>::value_type>(); +} + +TEST(IntegerSequenceTest, Size) { + EXPECT_EQ(0, (absl::integer_sequence<int>::size())); + EXPECT_EQ(1, (absl::integer_sequence<int, 0>::size())); + EXPECT_EQ(1, (absl::integer_sequence<int, 1>::size())); + EXPECT_EQ(2, (absl::integer_sequence<int, 1, 2>::size())); + EXPECT_EQ(3, (absl::integer_sequence<int, 0, 1, 2>::size())); + EXPECT_EQ(3, (absl::integer_sequence<int, -123, 123, 456>::size())); + constexpr size_t sz = absl::integer_sequence<int, 0, 1>::size(); + EXPECT_EQ(2, sz); +} + +TEST(IntegerSequenceTest, MakeIndexSequence) { + StaticAssertTypeEq<absl::index_sequence<>, absl::make_index_sequence<0>>(); + StaticAssertTypeEq<absl::index_sequence<0>, absl::make_index_sequence<1>>(); + StaticAssertTypeEq<absl::index_sequence<0, 1>, + absl::make_index_sequence<2>>(); + StaticAssertTypeEq<absl::index_sequence<0, 1, 2>, + absl::make_index_sequence<3>>(); +} + +TEST(IntegerSequenceTest, MakeIntegerSequence) { + StaticAssertTypeEq<absl::integer_sequence<int>, + absl::make_integer_sequence<int, 0>>(); + StaticAssertTypeEq<absl::integer_sequence<int, 0>, + absl::make_integer_sequence<int, 1>>(); + StaticAssertTypeEq<absl::integer_sequence<int, 0, 1>, + absl::make_integer_sequence<int, 2>>(); + StaticAssertTypeEq<absl::integer_sequence<int, 0, 1, 2>, + absl::make_integer_sequence<int, 3>>(); +} + +template <typename... Ts> +class Counter {}; + +template <size_t... Is> +void CountAll(absl::index_sequence<Is...>) { + // We only need an alias here, but instantiate a variable to silence warnings + // for unused typedefs in some compilers. + ABSL_ATTRIBUTE_UNUSED Counter<absl::make_index_sequence<Is>...> seq; +} + +// This test verifies that absl::make_index_sequence can handle large arguments +// without blowing up template instantiation stack, going OOM or taking forever +// to compile (there is hard 15 minutes limit imposed by forge). +TEST(IntegerSequenceTest, MakeIndexSequencePerformance) { + // O(log N) template instantiations. + // We only need an alias here, but instantiate a variable to silence warnings + // for unused typedefs in some compilers. + ABSL_ATTRIBUTE_UNUSED absl::make_index_sequence<(1 << 16) - 1> seq; + // O(N) template instantiations. + CountAll(absl::make_index_sequence<(1 << 8) - 1>()); +} + +template <typename F, typename Tup, size_t... Is> +auto ApplyFromTupleImpl(F f, const Tup& tup, absl::index_sequence<Is...>) + -> decltype(f(std::get<Is>(tup)...)) { + return f(std::get<Is>(tup)...); +} + +template <typename Tup> +using TupIdxSeq = absl::make_index_sequence<std::tuple_size<Tup>::value>; + +template <typename F, typename Tup> +auto ApplyFromTuple(F f, const Tup& tup) + -> decltype(ApplyFromTupleImpl(f, tup, TupIdxSeq<Tup>{})) { + return ApplyFromTupleImpl(f, tup, TupIdxSeq<Tup>{}); +} + +template <typename T> +std::string Fmt(const T& x) { + std::ostringstream os; + os << x; + return os.str(); +} + +struct PoorStrCat { + template <typename... Args> + std::string operator()(const Args&... args) const { + std::string r; + for (const auto& e : {Fmt(args)...}) r += e; + return r; + } +}; + +template <typename Tup, size_t... Is> +std::vector<std::string> TupStringVecImpl(const Tup& tup, + absl::index_sequence<Is...>) { + return {Fmt(std::get<Is>(tup))...}; +} + +template <typename... Ts> +std::vector<std::string> TupStringVec(const std::tuple<Ts...>& tup) { + return TupStringVecImpl(tup, absl::index_sequence_for<Ts...>()); +} + +TEST(MakeIndexSequenceTest, ApplyFromTupleExample) { + PoorStrCat f{}; + EXPECT_EQ("12abc3.14", f(12, "abc", 3.14)); + EXPECT_EQ("12abc3.14", ApplyFromTuple(f, std::make_tuple(12, "abc", 3.14))); +} + +TEST(IndexSequenceForTest, Basic) { + StaticAssertTypeEq<absl::index_sequence<>, absl::index_sequence_for<>>(); + StaticAssertTypeEq<absl::index_sequence<0>, absl::index_sequence_for<int>>(); + StaticAssertTypeEq<absl::index_sequence<0, 1, 2, 3>, + absl::index_sequence_for<int, void, char, int>>(); +} + +TEST(IndexSequenceForTest, Example) { + EXPECT_THAT(TupStringVec(std::make_tuple(12, "abc", 3.14)), + ElementsAre("12", "abc", "3.14")); +} + +} // namespace + |