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Posted to commits@marmotta.apache.org by ss...@apache.org on 2018/04/29 19:35:33 UTC
[04/51] [partial] marmotta git commit: * Replace gtest with upstream
version,
including LICENSE header. * Include absl library for faster and safer string
operations. * Update license headers where needed. * Removed custom code
replaced by absl.
http://git-wip-us.apache.org/repos/asf/marmotta/blob/0eb556da/libraries/ostrich/backend/3rdparty/abseil/absl/types/optional_test.cc
----------------------------------------------------------------------
diff --git a/libraries/ostrich/backend/3rdparty/abseil/absl/types/optional_test.cc b/libraries/ostrich/backend/3rdparty/abseil/absl/types/optional_test.cc
new file mode 100644
index 0000000..179bfd6
--- /dev/null
+++ b/libraries/ostrich/backend/3rdparty/abseil/absl/types/optional_test.cc
@@ -0,0 +1,1625 @@
+// 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/types/optional.h"
+
+#include <string>
+#include <type_traits>
+#include <utility>
+
+#include "gtest/gtest.h"
+#include "absl/base/config.h"
+#include "absl/base/internal/raw_logging.h"
+#include "absl/meta/type_traits.h"
+#include "absl/strings/string_view.h"
+
+struct Hashable {};
+
+namespace std {
+template <>
+struct hash<Hashable> {
+ size_t operator()(const Hashable&) { return 0; }
+};
+} // namespace std
+
+struct NonHashable {};
+
+namespace {
+
+std::string TypeQuals(std::string&) { return "&"; }
+std::string TypeQuals(std::string&&) { return "&&"; }
+std::string TypeQuals(const std::string&) { return "c&"; }
+std::string TypeQuals(const std::string&&) { return "c&&"; }
+
+struct StructorListener {
+ int construct0 = 0;
+ int construct1 = 0;
+ int construct2 = 0;
+ int listinit = 0;
+ int copy = 0;
+ int move = 0;
+ int copy_assign = 0;
+ int move_assign = 0;
+ int destruct = 0;
+ int volatile_copy = 0;
+ int volatile_move = 0;
+ int volatile_copy_assign = 0;
+ int volatile_move_assign = 0;
+};
+
+// Suppress MSVC warnings.
+// 4521: multiple copy constructors specified
+// 4522: multiple assignment operators specified
+// We wrote multiple of them to test that the correct overloads are selected.
+#ifdef _MSC_VER
+#pragma warning( push )
+#pragma warning( disable : 4521)
+#pragma warning( disable : 4522)
+#endif
+struct Listenable {
+ static StructorListener* listener;
+
+ Listenable() { ++listener->construct0; }
+ explicit Listenable(int /*unused*/) { ++listener->construct1; }
+ Listenable(int /*unused*/, int /*unused*/) { ++listener->construct2; }
+ Listenable(std::initializer_list<int> /*unused*/) { ++listener->listinit; }
+ Listenable(const Listenable& /*unused*/) { ++listener->copy; }
+ Listenable(const volatile Listenable& /*unused*/) {
+ ++listener->volatile_copy;
+ }
+ Listenable(volatile Listenable&& /*unused*/) { ++listener->volatile_move; }
+ Listenable(Listenable&& /*unused*/) { ++listener->move; }
+ Listenable& operator=(const Listenable& /*unused*/) {
+ ++listener->copy_assign;
+ return *this;
+ }
+ Listenable& operator=(Listenable&& /*unused*/) {
+ ++listener->move_assign;
+ return *this;
+ }
+ // use void return type instead of volatile T& to work around GCC warning
+ // when the assignment's returned reference is ignored.
+ void operator=(const volatile Listenable& /*unused*/) volatile {
+ ++listener->volatile_copy_assign;
+ }
+ void operator=(volatile Listenable&& /*unused*/) volatile {
+ ++listener->volatile_move_assign;
+ }
+ ~Listenable() { ++listener->destruct; }
+};
+#ifdef _MSC_VER
+#pragma warning( pop )
+#endif
+
+StructorListener* Listenable::listener = nullptr;
+
+// ABSL_HAVE_NO_CONSTEXPR_INITIALIZER_LIST is defined to 1 when the standard
+// library implementation doesn't marked initializer_list's default constructor
+// constexpr. The C++11 standard doesn't specify constexpr on it, but C++14
+// added it. However, libstdc++ 4.7 marked it constexpr.
+#if defined(_LIBCPP_VERSION) && \
+ (_LIBCPP_STD_VER <= 11 || defined(_LIBCPP_HAS_NO_CXX14_CONSTEXPR))
+#define ABSL_HAVE_NO_CONSTEXPR_INITIALIZER_LIST 1
+#endif
+
+struct ConstexprType {
+ enum CtorTypes {
+ kCtorDefault,
+ kCtorInt,
+ kCtorInitializerList,
+ kCtorConstChar
+ };
+ constexpr ConstexprType() : x(kCtorDefault) {}
+ constexpr explicit ConstexprType(int i) : x(kCtorInt) {}
+#ifndef ABSL_HAVE_NO_CONSTEXPR_INITIALIZER_LIST
+ constexpr ConstexprType(std::initializer_list<int> il)
+ : x(kCtorInitializerList) {}
+#endif
+ constexpr ConstexprType(const char*) // NOLINT(runtime/explicit)
+ : x(kCtorConstChar) {}
+ int x;
+};
+
+struct Copyable {
+ Copyable() {}
+ Copyable(const Copyable&) {}
+ Copyable& operator=(const Copyable&) { return *this; }
+};
+
+struct MoveableThrow {
+ MoveableThrow() {}
+ MoveableThrow(MoveableThrow&&) {}
+ MoveableThrow& operator=(MoveableThrow&&) { return *this; }
+};
+
+struct MoveableNoThrow {
+ MoveableNoThrow() {}
+ MoveableNoThrow(MoveableNoThrow&&) noexcept {}
+ MoveableNoThrow& operator=(MoveableNoThrow&&) noexcept { return *this; }
+};
+
+struct NonMovable {
+ NonMovable() {}
+ NonMovable(const NonMovable&) = delete;
+ NonMovable& operator=(const NonMovable&) = delete;
+ NonMovable(NonMovable&&) = delete;
+ NonMovable& operator=(NonMovable&&) = delete;
+};
+
+TEST(optionalTest, DefaultConstructor) {
+ absl::optional<int> empty;
+ EXPECT_FALSE(empty);
+ constexpr absl::optional<int> cempty;
+ static_assert(!cempty.has_value(), "");
+ EXPECT_TRUE(
+ std::is_nothrow_default_constructible<absl::optional<int>>::value);
+}
+
+TEST(optionalTest, nulloptConstructor) {
+ absl::optional<int> empty(absl::nullopt);
+ EXPECT_FALSE(empty);
+
+#ifdef ABSL_HAVE_STD_OPTIONAL
+ constexpr absl::optional<int> cempty{absl::nullopt};
+#else
+ // Creating a temporary absl::nullopt_t object instead of using absl::nullopt
+ // because absl::nullopt cannot be constexpr and have external linkage at the
+ // same time.
+ constexpr absl::optional<int> cempty{absl::nullopt_t(absl::nullopt_t::init)};
+#endif
+ static_assert(!cempty.has_value(), "");
+ EXPECT_TRUE((std::is_nothrow_constructible<absl::optional<int>,
+ absl::nullopt_t>::value));
+}
+
+TEST(optionalTest, CopyConstructor) {
+ {
+ absl::optional<int> empty, opt42 = 42;
+ absl::optional<int> empty_copy(empty);
+ EXPECT_FALSE(empty_copy);
+ absl::optional<int> opt42_copy(opt42);
+ EXPECT_TRUE(opt42_copy);
+ EXPECT_EQ(42, *opt42_copy);
+ }
+ {
+ absl::optional<const int> empty, opt42 = 42;
+ absl::optional<const int> empty_copy(empty);
+ EXPECT_FALSE(empty_copy);
+ absl::optional<const int> opt42_copy(opt42);
+ EXPECT_TRUE(opt42_copy);
+ EXPECT_EQ(42, *opt42_copy);
+ }
+ {
+ absl::optional<volatile int> empty, opt42 = 42;
+ absl::optional<volatile int> empty_copy(empty);
+ EXPECT_FALSE(empty_copy);
+ absl::optional<volatile int> opt42_copy(opt42);
+ EXPECT_TRUE(opt42_copy);
+ EXPECT_EQ(42, *opt42_copy);
+ }
+ // test copyablility
+ EXPECT_TRUE(std::is_copy_constructible<absl::optional<int>>::value);
+ EXPECT_TRUE(std::is_copy_constructible<absl::optional<Copyable>>::value);
+ EXPECT_FALSE(
+ std::is_copy_constructible<absl::optional<MoveableThrow>>::value);
+ EXPECT_FALSE(
+ std::is_copy_constructible<absl::optional<MoveableNoThrow>>::value);
+ EXPECT_FALSE(std::is_copy_constructible<absl::optional<NonMovable>>::value);
+
+ EXPECT_FALSE(
+ absl::is_trivially_copy_constructible<absl::optional<Copyable>>::value);
+#if defined(ABSL_HAVE_STD_OPTIONAL) && defined(__GLIBCXX__)
+ // libstdc++ std::optional implementation (as of 7.2) has a bug: when T is
+ // trivially copyable, optional<T> is not trivially copyable (due to one of
+ // its base class is unconditionally nontrivial).
+#define ABSL_GLIBCXX_OPTIONAL_TRIVIALITY_BUG 1
+#endif
+#ifndef ABSL_GLIBCXX_OPTIONAL_TRIVIALITY_BUG
+ EXPECT_TRUE(
+ absl::is_trivially_copy_constructible<absl::optional<int>>::value);
+ EXPECT_TRUE(
+ absl::is_trivially_copy_constructible<absl::optional<const int>>::value);
+#ifndef _MSC_VER
+ // See defect report "Trivial copy/move constructor for class with volatile
+ // member" at
+ // http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#2094
+ // A class with non-static data member of volatile-qualified type should still
+ // have a trivial copy constructor if the data member is trivial.
+ // Also a cv-qualified scalar type should be trivially copyable.
+ EXPECT_TRUE(absl::is_trivially_copy_constructible<
+ absl::optional<volatile int>>::value);
+#endif // _MSC_VER
+#endif // ABSL_GLIBCXX_OPTIONAL_TRIVIALITY_BUG
+
+ // constexpr copy constructor for trivially copyable types
+ {
+ constexpr absl::optional<int> o1;
+ constexpr absl::optional<int> o2 = o1;
+ static_assert(!o2, "");
+ }
+ {
+ constexpr absl::optional<int> o1 = 42;
+ constexpr absl::optional<int> o2 = o1;
+ static_assert(o2, "");
+ static_assert(*o2 == 42, "");
+ }
+ {
+ struct TrivialCopyable {
+ constexpr TrivialCopyable() : x(0) {}
+ constexpr explicit TrivialCopyable(int i) : x(i) {}
+ int x;
+ };
+ constexpr absl::optional<TrivialCopyable> o1(42);
+ constexpr absl::optional<TrivialCopyable> o2 = o1;
+ static_assert(o2, "");
+ static_assert((*o2).x == 42, "");
+#ifndef ABSL_GLIBCXX_OPTIONAL_TRIVIALITY_BUG
+ EXPECT_TRUE(absl::is_trivially_copy_constructible<
+ absl::optional<TrivialCopyable>>::value);
+ EXPECT_TRUE(absl::is_trivially_copy_constructible<
+ absl::optional<const TrivialCopyable>>::value);
+#endif
+ // When testing with VS 2017 15.3, there seems to be a bug in MSVC
+ // std::optional when T is volatile-qualified. So skipping this test.
+ // Bug report:
+ // https://connect.microsoft.com/VisualStudio/feedback/details/3142534
+#if defined(ABSL_HAVE_STD_OPTIONAL) && defined(_MSC_VER) && _MSC_VER >= 1911
+#define ABSL_MSVC_OPTIONAL_VOLATILE_COPY_BUG 1
+#endif
+#ifndef ABSL_MSVC_OPTIONAL_VOLATILE_COPY_BUG
+ EXPECT_FALSE(std::is_copy_constructible<
+ absl::optional<volatile TrivialCopyable>>::value);
+#endif
+ }
+}
+
+TEST(optionalTest, MoveConstructor) {
+ absl::optional<int> empty, opt42 = 42;
+ absl::optional<int> empty_move(std::move(empty));
+ EXPECT_FALSE(empty_move);
+ absl::optional<int> opt42_move(std::move(opt42));
+ EXPECT_TRUE(opt42_move);
+ EXPECT_EQ(42, opt42_move);
+ // test movability
+ EXPECT_TRUE(std::is_move_constructible<absl::optional<int>>::value);
+ EXPECT_TRUE(std::is_move_constructible<absl::optional<Copyable>>::value);
+ EXPECT_TRUE(std::is_move_constructible<absl::optional<MoveableThrow>>::value);
+ EXPECT_TRUE(
+ std::is_move_constructible<absl::optional<MoveableNoThrow>>::value);
+ EXPECT_FALSE(std::is_move_constructible<absl::optional<NonMovable>>::value);
+ // test noexcept
+ EXPECT_TRUE(std::is_nothrow_move_constructible<absl::optional<int>>::value);
+#ifndef ABSL_HAVE_STD_OPTIONAL
+ EXPECT_EQ(
+ absl::default_allocator_is_nothrow::value,
+ std::is_nothrow_move_constructible<absl::optional<MoveableThrow>>::value);
+#endif
+ EXPECT_TRUE(std::is_nothrow_move_constructible<
+ absl::optional<MoveableNoThrow>>::value);
+}
+
+TEST(optionalTest, Destructor) {
+ struct Trivial {};
+
+ struct NonTrivial {
+ NonTrivial(const NonTrivial&) {}
+ NonTrivial& operator=(const NonTrivial&) { return *this; }
+ ~NonTrivial() {}
+ };
+
+ EXPECT_TRUE(std::is_trivially_destructible<absl::optional<int>>::value);
+ EXPECT_TRUE(std::is_trivially_destructible<absl::optional<Trivial>>::value);
+ EXPECT_FALSE(
+ std::is_trivially_destructible<absl::optional<NonTrivial>>::value);
+}
+
+TEST(optionalTest, InPlaceConstructor) {
+ constexpr absl::optional<ConstexprType> opt0{absl::in_place_t()};
+ static_assert(opt0, "");
+ static_assert((*opt0).x == ConstexprType::kCtorDefault, "");
+ constexpr absl::optional<ConstexprType> opt1{absl::in_place_t(), 1};
+ static_assert(opt1, "");
+ static_assert((*opt1).x == ConstexprType::kCtorInt, "");
+#ifndef ABSL_HAVE_NO_CONSTEXPR_INITIALIZER_LIST
+ constexpr absl::optional<ConstexprType> opt2{absl::in_place_t(), {1, 2}};
+ static_assert(opt2, "");
+ static_assert((*opt2).x == ConstexprType::kCtorInitializerList, "");
+#endif
+
+ // TODO(absl-team): uncomment these when std::is_constructible<T, Args&&...>
+ // SFINAE is added to optional::optional(absl::in_place_t, Args&&...).
+ // struct I {
+ // I(absl::in_place_t);
+ // };
+
+ // EXPECT_FALSE((std::is_constructible<absl::optional<I>,
+ // absl::in_place_t>::value));
+ // EXPECT_FALSE((std::is_constructible<absl::optional<I>, const
+ // absl::in_place_t&>::value));
+}
+
+// template<U=T> optional(U&&);
+TEST(optionalTest, ValueConstructor) {
+ constexpr absl::optional<int> opt0(0);
+ static_assert(opt0, "");
+ static_assert(*opt0 == 0, "");
+ EXPECT_TRUE((std::is_convertible<int, absl::optional<int>>::value));
+ // Copy initialization ( = "abc") won't work due to optional(optional&&)
+ // is not constexpr. Use list initialization instead. This invokes
+ // absl::optional<ConstexprType>::absl::optional<U>(U&&), with U = const char
+ // (&) [4], which direct-initializes the ConstexprType value held by the
+ // optional via ConstexprType::ConstexprType(const char*).
+ constexpr absl::optional<ConstexprType> opt1 = {"abc"};
+ static_assert(opt1, "");
+ static_assert(ConstexprType::kCtorConstChar == (*opt1).x, "");
+ EXPECT_TRUE(
+ (std::is_convertible<const char*, absl::optional<ConstexprType>>::value));
+ // direct initialization
+ constexpr absl::optional<ConstexprType> opt2{2};
+ static_assert(opt2, "");
+ static_assert(ConstexprType::kCtorInt == (*opt2).x, "");
+ EXPECT_FALSE(
+ (std::is_convertible<int, absl::optional<ConstexprType>>::value));
+
+ // this invokes absl::optional<int>::optional(int&&)
+ // NOTE: this has different behavior than assignment, e.g.
+ // "opt3 = {};" clears the optional rather than setting the value to 0
+ // According to C++17 standard N4659 [over.ics.list] 16.3.3.1.5, (9.2)- "if
+ // the initializer list has no elements, the implicit conversion is the
+ // identity conversion", so `optional(int&&)` should be a better match than
+ // `optional(optional&&)` which is a user-defined conversion.
+ // Note: GCC 7 has a bug with this overload selection when compiled with
+ // `-std=c++17`.
+#if defined(__GNUC__) && !defined(__clang__) && __GNUC__ == 7 && \
+ __cplusplus == 201703L
+#define ABSL_GCC7_OVER_ICS_LIST_BUG 1
+#endif
+#ifndef ABSL_GCC7_OVER_ICS_LIST_BUG
+ constexpr absl::optional<int> opt3({});
+ static_assert(opt3, "");
+ static_assert(*opt3 == 0, "");
+#endif
+
+ // this invokes the move constructor with a default constructed optional
+ // because non-template function is a better match than template function.
+ absl::optional<ConstexprType> opt4({});
+ EXPECT_FALSE(opt4);
+}
+
+struct Implicit {};
+
+struct Explicit {};
+
+struct Convert {
+ Convert(const Implicit&) // NOLINT(runtime/explicit)
+ : implicit(true), move(false) {}
+ Convert(Implicit&&) // NOLINT(runtime/explicit)
+ : implicit(true), move(true) {}
+ explicit Convert(const Explicit&) : implicit(false), move(false) {}
+ explicit Convert(Explicit&&) : implicit(false), move(true) {}
+
+ bool implicit;
+ bool move;
+};
+
+struct ConvertFromOptional {
+ ConvertFromOptional(const Implicit&) // NOLINT(runtime/explicit)
+ : implicit(true), move(false), from_optional(false) {}
+ ConvertFromOptional(Implicit&&) // NOLINT(runtime/explicit)
+ : implicit(true), move(true), from_optional(false) {}
+ ConvertFromOptional(
+ const absl::optional<Implicit>&) // NOLINT(runtime/explicit)
+ : implicit(true), move(false), from_optional(true) {}
+ ConvertFromOptional(absl::optional<Implicit>&&) // NOLINT(runtime/explicit)
+ : implicit(true), move(true), from_optional(true) {}
+ explicit ConvertFromOptional(const Explicit&)
+ : implicit(false), move(false), from_optional(false) {}
+ explicit ConvertFromOptional(Explicit&&)
+ : implicit(false), move(true), from_optional(false) {}
+ explicit ConvertFromOptional(const absl::optional<Explicit>&)
+ : implicit(false), move(false), from_optional(true) {}
+ explicit ConvertFromOptional(absl::optional<Explicit>&&)
+ : implicit(false), move(true), from_optional(true) {}
+
+ bool implicit;
+ bool move;
+ bool from_optional;
+};
+
+TEST(optionalTest, ConvertingConstructor) {
+ absl::optional<Implicit> i_empty;
+ absl::optional<Implicit> i(absl::in_place);
+ absl::optional<Explicit> e_empty;
+ absl::optional<Explicit> e(absl::in_place);
+ {
+ // implicitly constructing absl::optional<Convert> from
+ // absl::optional<Implicit>
+ absl::optional<Convert> empty = i_empty;
+ EXPECT_FALSE(empty);
+ absl::optional<Convert> opt_copy = i;
+ EXPECT_TRUE(opt_copy);
+ EXPECT_TRUE(opt_copy->implicit);
+ EXPECT_FALSE(opt_copy->move);
+ absl::optional<Convert> opt_move = absl::optional<Implicit>(absl::in_place);
+ EXPECT_TRUE(opt_move);
+ EXPECT_TRUE(opt_move->implicit);
+ EXPECT_TRUE(opt_move->move);
+ }
+ {
+ // explicitly constructing absl::optional<Convert> from
+ // absl::optional<Explicit>
+ absl::optional<Convert> empty(e_empty);
+ EXPECT_FALSE(empty);
+ absl::optional<Convert> opt_copy(e);
+ EXPECT_TRUE(opt_copy);
+ EXPECT_FALSE(opt_copy->implicit);
+ EXPECT_FALSE(opt_copy->move);
+ EXPECT_FALSE((std::is_convertible<const absl::optional<Explicit>&,
+ absl::optional<Convert>>::value));
+ absl::optional<Convert> opt_move{absl::optional<Explicit>(absl::in_place)};
+ EXPECT_TRUE(opt_move);
+ EXPECT_FALSE(opt_move->implicit);
+ EXPECT_TRUE(opt_move->move);
+ EXPECT_FALSE((std::is_convertible<absl::optional<Explicit>&&,
+ absl::optional<Convert>>::value));
+ }
+ {
+ // implicitly constructing absl::optional<ConvertFromOptional> from
+ // absl::optional<Implicit> via
+ // ConvertFromOptional(absl::optional<Implicit>&&) check that
+ // ConvertFromOptional(Implicit&&) is NOT called
+ static_assert(
+ std::is_convertible<absl::optional<Implicit>,
+ absl::optional<ConvertFromOptional>>::value,
+ "");
+ absl::optional<ConvertFromOptional> opt0 = i_empty;
+ EXPECT_TRUE(opt0);
+ EXPECT_TRUE(opt0->implicit);
+ EXPECT_FALSE(opt0->move);
+ EXPECT_TRUE(opt0->from_optional);
+ absl::optional<ConvertFromOptional> opt1 = absl::optional<Implicit>();
+ EXPECT_TRUE(opt1);
+ EXPECT_TRUE(opt1->implicit);
+ EXPECT_TRUE(opt1->move);
+ EXPECT_TRUE(opt1->from_optional);
+ }
+ {
+ // implicitly constructing absl::optional<ConvertFromOptional> from
+ // absl::optional<Explicit> via
+ // ConvertFromOptional(absl::optional<Explicit>&&) check that
+ // ConvertFromOptional(Explicit&&) is NOT called
+ absl::optional<ConvertFromOptional> opt0(e_empty);
+ EXPECT_TRUE(opt0);
+ EXPECT_FALSE(opt0->implicit);
+ EXPECT_FALSE(opt0->move);
+ EXPECT_TRUE(opt0->from_optional);
+ EXPECT_FALSE(
+ (std::is_convertible<const absl::optional<Explicit>&,
+ absl::optional<ConvertFromOptional>>::value));
+ absl::optional<ConvertFromOptional> opt1{absl::optional<Explicit>()};
+ EXPECT_TRUE(opt1);
+ EXPECT_FALSE(opt1->implicit);
+ EXPECT_TRUE(opt1->move);
+ EXPECT_TRUE(opt1->from_optional);
+ EXPECT_FALSE(
+ (std::is_convertible<absl::optional<Explicit>&&,
+ absl::optional<ConvertFromOptional>>::value));
+ }
+}
+
+TEST(optionalTest, StructorBasic) {
+ StructorListener listener;
+ Listenable::listener = &listener;
+ {
+ absl::optional<Listenable> empty;
+ EXPECT_FALSE(empty);
+ absl::optional<Listenable> opt0(absl::in_place);
+ EXPECT_TRUE(opt0);
+ absl::optional<Listenable> opt1(absl::in_place, 1);
+ EXPECT_TRUE(opt1);
+ absl::optional<Listenable> opt2(absl::in_place, 1, 2);
+ EXPECT_TRUE(opt2);
+ }
+ EXPECT_EQ(1, listener.construct0);
+ EXPECT_EQ(1, listener.construct1);
+ EXPECT_EQ(1, listener.construct2);
+ EXPECT_EQ(3, listener.destruct);
+}
+
+TEST(optionalTest, CopyMoveStructor) {
+ StructorListener listener;
+ Listenable::listener = &listener;
+ absl::optional<Listenable> original(absl::in_place);
+ EXPECT_EQ(1, listener.construct0);
+ EXPECT_EQ(0, listener.copy);
+ EXPECT_EQ(0, listener.move);
+ absl::optional<Listenable> copy(original);
+ EXPECT_EQ(1, listener.construct0);
+ EXPECT_EQ(1, listener.copy);
+ EXPECT_EQ(0, listener.move);
+ absl::optional<Listenable> move(std::move(original));
+ EXPECT_EQ(1, listener.construct0);
+ EXPECT_EQ(1, listener.copy);
+ EXPECT_EQ(1, listener.move);
+}
+
+TEST(optionalTest, ListInit) {
+ StructorListener listener;
+ Listenable::listener = &listener;
+ absl::optional<Listenable> listinit1(absl::in_place, {1});
+ absl::optional<Listenable> listinit2(absl::in_place, {1, 2});
+ EXPECT_EQ(2, listener.listinit);
+}
+
+TEST(optionalTest, AssignFromNullopt) {
+ absl::optional<int> opt(1);
+ opt = absl::nullopt;
+ EXPECT_FALSE(opt);
+
+ StructorListener listener;
+ Listenable::listener = &listener;
+ absl::optional<Listenable> opt1(absl::in_place);
+ opt1 = absl::nullopt;
+ EXPECT_FALSE(opt1);
+ EXPECT_EQ(1, listener.construct0);
+ EXPECT_EQ(1, listener.destruct);
+
+ EXPECT_TRUE((
+ std::is_nothrow_assignable<absl::optional<int>, absl::nullopt_t>::value));
+ EXPECT_TRUE((std::is_nothrow_assignable<absl::optional<Listenable>,
+ absl::nullopt_t>::value));
+}
+
+TEST(optionalTest, CopyAssignment) {
+ const absl::optional<int> empty, opt1 = 1, opt2 = 2;
+ absl::optional<int> empty_to_opt1, opt1_to_opt2, opt2_to_empty;
+
+ EXPECT_FALSE(empty_to_opt1);
+ empty_to_opt1 = empty;
+ EXPECT_FALSE(empty_to_opt1);
+ empty_to_opt1 = opt1;
+ EXPECT_TRUE(empty_to_opt1);
+ EXPECT_EQ(1, empty_to_opt1.value());
+
+ EXPECT_FALSE(opt1_to_opt2);
+ opt1_to_opt2 = opt1;
+ EXPECT_TRUE(opt1_to_opt2);
+ EXPECT_EQ(1, opt1_to_opt2.value());
+ opt1_to_opt2 = opt2;
+ EXPECT_TRUE(opt1_to_opt2);
+ EXPECT_EQ(2, opt1_to_opt2.value());
+
+ EXPECT_FALSE(opt2_to_empty);
+ opt2_to_empty = opt2;
+ EXPECT_TRUE(opt2_to_empty);
+ EXPECT_EQ(2, opt2_to_empty.value());
+ opt2_to_empty = empty;
+ EXPECT_FALSE(opt2_to_empty);
+
+ EXPECT_FALSE(std::is_copy_assignable<absl::optional<const int>>::value);
+ EXPECT_TRUE(std::is_copy_assignable<absl::optional<Copyable>>::value);
+ EXPECT_FALSE(std::is_copy_assignable<absl::optional<MoveableThrow>>::value);
+ EXPECT_FALSE(std::is_copy_assignable<absl::optional<MoveableNoThrow>>::value);
+ EXPECT_FALSE(std::is_copy_assignable<absl::optional<NonMovable>>::value);
+
+ EXPECT_TRUE(absl::is_trivially_copy_assignable<int>::value);
+ EXPECT_TRUE(absl::is_trivially_copy_assignable<volatile int>::value);
+
+ struct Trivial {
+ int i;
+ };
+ struct NonTrivial {
+ NonTrivial& operator=(const NonTrivial&) { return *this; }
+ int i;
+ };
+
+ EXPECT_TRUE(absl::is_trivially_copy_assignable<Trivial>::value);
+ EXPECT_FALSE(std::is_copy_assignable<const Trivial>::value);
+ EXPECT_FALSE(std::is_copy_assignable<volatile Trivial>::value);
+ EXPECT_TRUE(std::is_copy_assignable<NonTrivial>::value);
+ EXPECT_FALSE(absl::is_trivially_copy_assignable<NonTrivial>::value);
+
+ // std::optional doesn't support volatile nontrivial types.
+#ifndef ABSL_HAVE_STD_OPTIONAL
+ {
+ StructorListener listener;
+ Listenable::listener = &listener;
+
+ absl::optional<volatile Listenable> empty, set(absl::in_place);
+ EXPECT_EQ(1, listener.construct0);
+ absl::optional<volatile Listenable> empty_to_empty, empty_to_set,
+ set_to_empty(absl::in_place), set_to_set(absl::in_place);
+ EXPECT_EQ(3, listener.construct0);
+ empty_to_empty = empty; // no effect
+ empty_to_set = set; // copy construct
+ set_to_empty = empty; // destruct
+ set_to_set = set; // copy assign
+ EXPECT_EQ(1, listener.volatile_copy);
+ EXPECT_EQ(0, listener.volatile_move);
+ EXPECT_EQ(1, listener.destruct);
+ EXPECT_EQ(1, listener.volatile_copy_assign);
+ }
+#endif // ABSL_HAVE_STD_OPTIONAL
+}
+
+TEST(optionalTest, MoveAssignment) {
+ {
+ StructorListener listener;
+ Listenable::listener = &listener;
+
+ absl::optional<Listenable> empty1, empty2, set1(absl::in_place),
+ set2(absl::in_place);
+ EXPECT_EQ(2, listener.construct0);
+ absl::optional<Listenable> empty_to_empty, empty_to_set,
+ set_to_empty(absl::in_place), set_to_set(absl::in_place);
+ EXPECT_EQ(4, listener.construct0);
+ empty_to_empty = std::move(empty1);
+ empty_to_set = std::move(set1);
+ set_to_empty = std::move(empty2);
+ set_to_set = std::move(set2);
+ EXPECT_EQ(0, listener.copy);
+ EXPECT_EQ(1, listener.move);
+ EXPECT_EQ(1, listener.destruct);
+ EXPECT_EQ(1, listener.move_assign);
+ }
+ // std::optional doesn't support volatile nontrivial types.
+#ifndef ABSL_HAVE_STD_OPTIONAL
+ {
+ StructorListener listener;
+ Listenable::listener = &listener;
+
+ absl::optional<volatile Listenable> empty1, empty2, set1(absl::in_place),
+ set2(absl::in_place);
+ EXPECT_EQ(2, listener.construct0);
+ absl::optional<volatile Listenable> empty_to_empty, empty_to_set,
+ set_to_empty(absl::in_place), set_to_set(absl::in_place);
+ EXPECT_EQ(4, listener.construct0);
+ empty_to_empty = std::move(empty1); // no effect
+ empty_to_set = std::move(set1); // move construct
+ set_to_empty = std::move(empty2); // destruct
+ set_to_set = std::move(set2); // move assign
+ EXPECT_EQ(0, listener.volatile_copy);
+ EXPECT_EQ(1, listener.volatile_move);
+ EXPECT_EQ(1, listener.destruct);
+ EXPECT_EQ(1, listener.volatile_move_assign);
+ }
+#endif // ABSL_HAVE_STD_OPTIONAL
+ EXPECT_FALSE(std::is_move_assignable<absl::optional<const int>>::value);
+ EXPECT_TRUE(std::is_move_assignable<absl::optional<Copyable>>::value);
+ EXPECT_TRUE(std::is_move_assignable<absl::optional<MoveableThrow>>::value);
+ EXPECT_TRUE(std::is_move_assignable<absl::optional<MoveableNoThrow>>::value);
+ EXPECT_FALSE(std::is_move_assignable<absl::optional<NonMovable>>::value);
+
+ EXPECT_FALSE(
+ std::is_nothrow_move_assignable<absl::optional<MoveableThrow>>::value);
+ EXPECT_TRUE(
+ std::is_nothrow_move_assignable<absl::optional<MoveableNoThrow>>::value);
+}
+
+struct NoConvertToOptional {
+ // disable implicit conversion from const NoConvertToOptional&
+ // to absl::optional<NoConvertToOptional>.
+ NoConvertToOptional(const NoConvertToOptional&) = delete;
+};
+
+struct CopyConvert {
+ CopyConvert(const NoConvertToOptional&);
+ CopyConvert& operator=(const CopyConvert&) = delete;
+ CopyConvert& operator=(const NoConvertToOptional&);
+};
+
+struct CopyConvertFromOptional {
+ CopyConvertFromOptional(const NoConvertToOptional&);
+ CopyConvertFromOptional(const absl::optional<NoConvertToOptional>&);
+ CopyConvertFromOptional& operator=(const CopyConvertFromOptional&) = delete;
+ CopyConvertFromOptional& operator=(const NoConvertToOptional&);
+ CopyConvertFromOptional& operator=(
+ const absl::optional<NoConvertToOptional>&);
+};
+
+struct MoveConvert {
+ MoveConvert(NoConvertToOptional&&);
+ MoveConvert& operator=(const MoveConvert&) = delete;
+ MoveConvert& operator=(NoConvertToOptional&&);
+};
+
+struct MoveConvertFromOptional {
+ MoveConvertFromOptional(NoConvertToOptional&&);
+ MoveConvertFromOptional(absl::optional<NoConvertToOptional>&&);
+ MoveConvertFromOptional& operator=(const MoveConvertFromOptional&) = delete;
+ MoveConvertFromOptional& operator=(NoConvertToOptional&&);
+ MoveConvertFromOptional& operator=(absl::optional<NoConvertToOptional>&&);
+};
+
+// template <typename U = T> absl::optional<T>& operator=(U&& v);
+TEST(optionalTest, ValueAssignment) {
+ absl::optional<int> opt;
+ EXPECT_FALSE(opt);
+ opt = 42;
+ EXPECT_TRUE(opt);
+ EXPECT_EQ(42, opt.value());
+ opt = absl::nullopt;
+ EXPECT_FALSE(opt);
+ opt = 42;
+ EXPECT_TRUE(opt);
+ EXPECT_EQ(42, opt.value());
+ opt = 43;
+ EXPECT_TRUE(opt);
+ EXPECT_EQ(43, opt.value());
+ opt = {}; // this should clear optional
+ EXPECT_FALSE(opt);
+
+ opt = {44};
+ EXPECT_TRUE(opt);
+ EXPECT_EQ(44, opt.value());
+
+ // U = const NoConvertToOptional&
+ EXPECT_TRUE((std::is_assignable<absl::optional<CopyConvert>&,
+ const NoConvertToOptional&>::value));
+ // U = const absl::optional<NoConvertToOptional>&
+ EXPECT_TRUE((std::is_assignable<absl::optional<CopyConvertFromOptional>&,
+ const NoConvertToOptional&>::value));
+ // U = const NoConvertToOptional& triggers SFINAE because
+ // std::is_constructible_v<MoveConvert, const NoConvertToOptional&> is false
+ EXPECT_FALSE((std::is_assignable<absl::optional<MoveConvert>&,
+ const NoConvertToOptional&>::value));
+ // U = NoConvertToOptional
+ EXPECT_TRUE((std::is_assignable<absl::optional<MoveConvert>&,
+ NoConvertToOptional&&>::value));
+ // U = const NoConvertToOptional& triggers SFINAE because
+ // std::is_constructible_v<MoveConvertFromOptional, const
+ // NoConvertToOptional&> is false
+ EXPECT_FALSE((std::is_assignable<absl::optional<MoveConvertFromOptional>&,
+ const NoConvertToOptional&>::value));
+ // U = NoConvertToOptional
+ EXPECT_TRUE((std::is_assignable<absl::optional<MoveConvertFromOptional>&,
+ NoConvertToOptional&&>::value));
+ // U = const absl::optional<NoConvertToOptional>&
+ EXPECT_TRUE(
+ (std::is_assignable<absl::optional<CopyConvertFromOptional>&,
+ const absl::optional<NoConvertToOptional>&>::value));
+ // U = absl::optional<NoConvertToOptional>
+ EXPECT_TRUE(
+ (std::is_assignable<absl::optional<MoveConvertFromOptional>&,
+ absl::optional<NoConvertToOptional>&&>::value));
+}
+
+// template <typename U> absl::optional<T>& operator=(const absl::optional<U>&
+// rhs); template <typename U> absl::optional<T>& operator=(absl::optional<U>&&
+// rhs);
+TEST(optionalTest, ConvertingAssignment) {
+ absl::optional<int> opt_i;
+ absl::optional<char> opt_c('c');
+ opt_i = opt_c;
+ EXPECT_TRUE(opt_i);
+ EXPECT_EQ(*opt_c, *opt_i);
+ opt_i = absl::optional<char>();
+ EXPECT_FALSE(opt_i);
+ opt_i = absl::optional<char>('d');
+ EXPECT_TRUE(opt_i);
+ EXPECT_EQ('d', *opt_i);
+
+ absl::optional<std::string> opt_str;
+ absl::optional<const char*> opt_cstr("abc");
+ opt_str = opt_cstr;
+ EXPECT_TRUE(opt_str);
+ EXPECT_EQ(std::string("abc"), *opt_str);
+ opt_str = absl::optional<const char*>();
+ EXPECT_FALSE(opt_str);
+ opt_str = absl::optional<const char*>("def");
+ EXPECT_TRUE(opt_str);
+ EXPECT_EQ(std::string("def"), *opt_str);
+
+ // operator=(const absl::optional<U>&) with U = NoConvertToOptional
+ EXPECT_TRUE(
+ (std::is_assignable<absl::optional<CopyConvert>,
+ const absl::optional<NoConvertToOptional>&>::value));
+ // operator=(const absl::optional<U>&) with U = NoConvertToOptional
+ // triggers SFINAE because
+ // std::is_constructible_v<MoveConvert, const NoConvertToOptional&> is false
+ EXPECT_FALSE(
+ (std::is_assignable<absl::optional<MoveConvert>&,
+ const absl::optional<NoConvertToOptional>&>::value));
+ // operator=(absl::optional<U>&&) with U = NoConvertToOptional
+ EXPECT_TRUE(
+ (std::is_assignable<absl::optional<MoveConvert>&,
+ absl::optional<NoConvertToOptional>&&>::value));
+ // operator=(const absl::optional<U>&) with U = NoConvertToOptional triggers
+ // SFINAE because std::is_constructible_v<MoveConvertFromOptional, const
+ // NoConvertToOptional&> is false. operator=(U&&) with U = const
+ // absl::optional<NoConverToOptional>& triggers SFINAE because
+ // std::is_constructible<MoveConvertFromOptional,
+ // absl::optional<NoConvertToOptional>&&> is true.
+ EXPECT_FALSE(
+ (std::is_assignable<absl::optional<MoveConvertFromOptional>&,
+ const absl::optional<NoConvertToOptional>&>::value));
+}
+
+TEST(optionalTest, ResetAndHasValue) {
+ StructorListener listener;
+ Listenable::listener = &listener;
+ absl::optional<Listenable> opt;
+ EXPECT_FALSE(opt);
+ EXPECT_FALSE(opt.has_value());
+ opt.emplace();
+ EXPECT_TRUE(opt);
+ EXPECT_TRUE(opt.has_value());
+ opt.reset();
+ EXPECT_FALSE(opt);
+ EXPECT_FALSE(opt.has_value());
+ EXPECT_EQ(1, listener.destruct);
+ opt.reset();
+ EXPECT_FALSE(opt);
+ EXPECT_FALSE(opt.has_value());
+
+ constexpr absl::optional<int> empty;
+ static_assert(!empty.has_value(), "");
+ constexpr absl::optional<int> nonempty(1);
+ static_assert(nonempty.has_value(), "");
+}
+
+TEST(optionalTest, Emplace) {
+ StructorListener listener;
+ Listenable::listener = &listener;
+ absl::optional<Listenable> opt;
+ EXPECT_FALSE(opt);
+ opt.emplace(1);
+ EXPECT_TRUE(opt);
+ opt.emplace(1, 2);
+ EXPECT_EQ(1, listener.construct1);
+ EXPECT_EQ(1, listener.construct2);
+ EXPECT_EQ(1, listener.destruct);
+
+ absl::optional<std::string> o;
+ EXPECT_TRUE((std::is_same<std::string&, decltype(o.emplace("abc"))>::value));
+ std::string& ref = o.emplace("abc");
+ EXPECT_EQ(&ref, &o.value());
+}
+
+TEST(optionalTest, ListEmplace) {
+ StructorListener listener;
+ Listenable::listener = &listener;
+ absl::optional<Listenable> opt;
+ EXPECT_FALSE(opt);
+ opt.emplace({1});
+ EXPECT_TRUE(opt);
+ opt.emplace({1, 2});
+ EXPECT_EQ(2, listener.listinit);
+ EXPECT_EQ(1, listener.destruct);
+
+ absl::optional<Listenable> o;
+ EXPECT_TRUE((std::is_same<Listenable&, decltype(o.emplace({1}))>::value));
+ Listenable& ref = o.emplace({1});
+ EXPECT_EQ(&ref, &o.value());
+}
+
+TEST(optionalTest, Swap) {
+ absl::optional<int> opt_empty, opt1 = 1, opt2 = 2;
+ EXPECT_FALSE(opt_empty);
+ EXPECT_TRUE(opt1);
+ EXPECT_EQ(1, opt1.value());
+ EXPECT_TRUE(opt2);
+ EXPECT_EQ(2, opt2.value());
+ swap(opt_empty, opt1);
+ EXPECT_FALSE(opt1);
+ EXPECT_TRUE(opt_empty);
+ EXPECT_EQ(1, opt_empty.value());
+ EXPECT_TRUE(opt2);
+ EXPECT_EQ(2, opt2.value());
+ swap(opt_empty, opt1);
+ EXPECT_FALSE(opt_empty);
+ EXPECT_TRUE(opt1);
+ EXPECT_EQ(1, opt1.value());
+ EXPECT_TRUE(opt2);
+ EXPECT_EQ(2, opt2.value());
+ swap(opt1, opt2);
+ EXPECT_FALSE(opt_empty);
+ EXPECT_TRUE(opt1);
+ EXPECT_EQ(2, opt1.value());
+ EXPECT_TRUE(opt2);
+ EXPECT_EQ(1, opt2.value());
+
+ EXPECT_TRUE(noexcept(opt1.swap(opt2)));
+ EXPECT_TRUE(noexcept(swap(opt1, opt2)));
+}
+
+template <int v>
+struct DeletedOpAddr {
+ constexpr static const int value = v;
+ constexpr DeletedOpAddr() = default;
+ constexpr const DeletedOpAddr<v>* operator&() const = delete; // NOLINT
+ DeletedOpAddr<v>* operator&() = delete; // NOLINT
+};
+
+// The static_assert featuring a constexpr call to operator->() is commented out
+// to document the fact that the current implementation of absl::optional<T>
+// expects such usecases to be malformed and not compile.
+TEST(optionalTest, OperatorAddr) {
+ constexpr const int v = -1;
+ { // constexpr
+ constexpr const absl::optional<DeletedOpAddr<v>> opt(absl::in_place_t{});
+ static_assert(opt.has_value(), "");
+ // static_assert(opt->value == v, "");
+ static_assert((*opt).value == v, "");
+ }
+ { // non-constexpr
+ const absl::optional<DeletedOpAddr<v>> opt(absl::in_place_t{});
+ EXPECT_TRUE(opt.has_value());
+ EXPECT_TRUE(opt->value == v);
+ EXPECT_TRUE((*opt).value == v);
+ }
+}
+
+TEST(optionalTest, PointerStuff) {
+ absl::optional<std::string> opt(absl::in_place, "foo");
+ EXPECT_EQ("foo", *opt);
+ const auto& opt_const = opt;
+ EXPECT_EQ("foo", *opt_const);
+ EXPECT_EQ(opt->size(), 3);
+ EXPECT_EQ(opt_const->size(), 3);
+
+ constexpr absl::optional<ConstexprType> opt1(1);
+ static_assert((*opt1).x == ConstexprType::kCtorInt, "");
+}
+
+// gcc has a bug pre 4.9.1 where it doesn't do correct overload resolution
+// when overloads are const-qualified and *this is an raluve.
+// Skip that test to make the build green again when using the old compiler.
+// https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59296 is fixed in 4.9.1.
+#if defined(__GNUC__) && !defined(__clang__)
+#define GCC_VERSION (__GNUC__ * 10000 \
+ + __GNUC_MINOR__ * 100 \
+ + __GNUC_PATCHLEVEL__)
+#if GCC_VERSION < 40901
+#define ABSL_SKIP_OVERLOAD_TEST_DUE_TO_GCC_BUG
+#endif
+#endif
+
+// MSVC has a bug with "cv-qualifiers in class construction", fixed in 2017. See
+// https://docs.microsoft.com/en-us/cpp/cpp-conformance-improvements-2017#bug-fixes
+// The compiler some incorrectly ingores the cv-qualifier when generating a
+// class object via a constructor call. For example:
+//
+// class optional {
+// constexpr T&& value() &&;
+// constexpr const T&& value() const &&;
+// }
+//
+// using COI = const absl::optional<int>;
+// static_assert(2 == COI(2).value(), ""); // const &&
+//
+// This should invoke the "const &&" overload but since it ignores the const
+// qualifier it finds the "&&" overload the best candidate.
+#if defined(_MSC_VER) && _MSC_VER < 1910
+#define ABSL_SKIP_OVERLOAD_TEST_DUE_TO_MSVC_BUG
+#endif
+
+TEST(optionalTest, Value) {
+ using O = absl::optional<std::string>;
+ using CO = const absl::optional<std::string>;
+ using OC = absl::optional<const std::string>;
+ O lvalue(absl::in_place, "lvalue");
+ CO clvalue(absl::in_place, "clvalue");
+ OC lvalue_c(absl::in_place, "lvalue_c");
+ EXPECT_EQ("lvalue", lvalue.value());
+ EXPECT_EQ("clvalue", clvalue.value());
+ EXPECT_EQ("lvalue_c", lvalue_c.value());
+ EXPECT_EQ("xvalue", O(absl::in_place, "xvalue").value());
+ EXPECT_EQ("xvalue_c", OC(absl::in_place, "xvalue_c").value());
+#ifndef ABSL_SKIP_OVERLOAD_TEST_DUE_TO_GCC_BUG
+ EXPECT_EQ("cxvalue", CO(absl::in_place, "cxvalue").value());
+#endif
+ EXPECT_EQ("&", TypeQuals(lvalue.value()));
+ EXPECT_EQ("c&", TypeQuals(clvalue.value()));
+ EXPECT_EQ("c&", TypeQuals(lvalue_c.value()));
+ EXPECT_EQ("&&", TypeQuals(O(absl::in_place, "xvalue").value()));
+#if !defined(ABSL_SKIP_OVERLOAD_TEST_DUE_TO_MSVC_BUG) && \
+ !defined(ABSL_SKIP_OVERLOAD_TEST_DUE_TO_GCC_BUG)
+ EXPECT_EQ("c&&", TypeQuals(CO(absl::in_place, "cxvalue").value()));
+#endif
+ EXPECT_EQ("c&&", TypeQuals(OC(absl::in_place, "xvalue_c").value()));
+
+ // test on volatile type
+ using OV = absl::optional<volatile int>;
+ OV lvalue_v(absl::in_place, 42);
+ EXPECT_EQ(42, lvalue_v.value());
+ EXPECT_EQ(42, OV(42).value());
+ EXPECT_TRUE((std::is_same<volatile int&, decltype(lvalue_v.value())>::value));
+ EXPECT_TRUE((std::is_same<volatile int&&, decltype(OV(42).value())>::value));
+
+ // test exception throw on value()
+ absl::optional<int> empty;
+#ifdef ABSL_HAVE_EXCEPTIONS
+ EXPECT_THROW(empty.value(), absl::bad_optional_access);
+#else
+ EXPECT_DEATH(empty.value(), "Bad optional access");
+#endif
+
+ // test constexpr value()
+ constexpr absl::optional<int> o1(1);
+ static_assert(1 == o1.value(), ""); // const &
+#if !defined(ABSL_SKIP_OVERLOAD_TEST_DUE_TO_MSVC_BUG) && \
+ !defined(ABSL_SKIP_OVERLOAD_TEST_DUE_TO_GCC_BUG)
+ using COI = const absl::optional<int>;
+ static_assert(2 == COI(2).value(), ""); // const &&
+#endif
+}
+
+TEST(optionalTest, DerefOperator) {
+ using O = absl::optional<std::string>;
+ using CO = const absl::optional<std::string>;
+ using OC = absl::optional<const std::string>;
+ O lvalue(absl::in_place, "lvalue");
+ CO clvalue(absl::in_place, "clvalue");
+ OC lvalue_c(absl::in_place, "lvalue_c");
+ EXPECT_EQ("lvalue", *lvalue);
+ EXPECT_EQ("clvalue", *clvalue);
+ EXPECT_EQ("lvalue_c", *lvalue_c);
+ EXPECT_EQ("xvalue", *O(absl::in_place, "xvalue"));
+ EXPECT_EQ("xvalue_c", *OC(absl::in_place, "xvalue_c"));
+#ifndef ABSL_SKIP_OVERLOAD_TEST_DUE_TO_GCC_BUG
+ EXPECT_EQ("cxvalue", *CO(absl::in_place, "cxvalue"));
+#endif
+ EXPECT_EQ("&", TypeQuals(*lvalue));
+ EXPECT_EQ("c&", TypeQuals(*clvalue));
+ EXPECT_EQ("&&", TypeQuals(*O(absl::in_place, "xvalue")));
+#if !defined(ABSL_SKIP_OVERLOAD_TEST_DUE_TO_MSVC_BUG) && \
+ !defined(ABSL_SKIP_OVERLOAD_TEST_DUE_TO_GCC_BUG)
+ EXPECT_EQ("c&&", TypeQuals(*CO(absl::in_place, "cxvalue")));
+#endif
+ EXPECT_EQ("c&&", TypeQuals(*OC(absl::in_place, "xvalue_c")));
+
+ // test on volatile type
+ using OV = absl::optional<volatile int>;
+ OV lvalue_v(absl::in_place, 42);
+ EXPECT_EQ(42, *lvalue_v);
+ EXPECT_EQ(42, *OV(42));
+ EXPECT_TRUE((std::is_same<volatile int&, decltype(*lvalue_v)>::value));
+ EXPECT_TRUE((std::is_same<volatile int&&, decltype(*OV(42))>::value));
+
+ constexpr absl::optional<int> opt1(1);
+ static_assert(*opt1 == 1, "");
+#if !defined(ABSL_SKIP_OVERLOAD_TEST_DUE_TO_MSVC_BUG) && \
+ !defined(ABSL_SKIP_OVERLOAD_TEST_DUE_TO_GCC_BUG)
+ using COI = const absl::optional<int>;
+ static_assert(*COI(2) == 2, "");
+#endif
+}
+
+TEST(optionalTest, ValueOr) {
+ absl::optional<double> opt_empty, opt_set = 1.2;
+ EXPECT_EQ(42.0, opt_empty.value_or(42));
+ EXPECT_EQ(1.2, opt_set.value_or(42));
+ EXPECT_EQ(42.0, absl::optional<double>().value_or(42));
+ EXPECT_EQ(1.2, absl::optional<double>(1.2).value_or(42));
+
+ constexpr absl::optional<double> copt_empty, copt_set = {1.2};
+ static_assert(42.0 == copt_empty.value_or(42), "");
+ static_assert(1.2 == copt_set.value_or(42), "");
+#ifndef ABSL_SKIP_OVERLOAD_TEST_DUE_TO_MSVC_BUG
+ using COD = const absl::optional<double>;
+ static_assert(42.0 == COD().value_or(42), "");
+ static_assert(1.2 == COD(1.2).value_or(42), "");
+#endif
+}
+
+// make_optional cannot be constexpr until C++17
+TEST(optionalTest, make_optional) {
+ auto opt_int = absl::make_optional(42);
+ EXPECT_TRUE((std::is_same<decltype(opt_int), absl::optional<int>>::value));
+ EXPECT_EQ(42, opt_int);
+
+ StructorListener listener;
+ Listenable::listener = &listener;
+
+ absl::optional<Listenable> opt0 = absl::make_optional<Listenable>();
+ EXPECT_EQ(1, listener.construct0);
+ absl::optional<Listenable> opt1 = absl::make_optional<Listenable>(1);
+ EXPECT_EQ(1, listener.construct1);
+ absl::optional<Listenable> opt2 = absl::make_optional<Listenable>(1, 2);
+ EXPECT_EQ(1, listener.construct2);
+ absl::optional<Listenable> opt3 = absl::make_optional<Listenable>({1});
+ absl::optional<Listenable> opt4 = absl::make_optional<Listenable>({1, 2});
+ EXPECT_EQ(2, listener.listinit);
+
+ // Constexpr tests on trivially copyable types
+ // optional<T> has trivial copy/move ctors when T is trivially copyable.
+ // For nontrivial types with constexpr constructors, we need copy elision in
+ // C++17 for make_optional to be constexpr.
+ {
+ constexpr absl::optional<int> c_opt = absl::make_optional(42);
+ static_assert(c_opt.value() == 42, "");
+ }
+ {
+ struct TrivialCopyable {
+ constexpr TrivialCopyable() : x(0) {}
+ constexpr explicit TrivialCopyable(int i) : x(i) {}
+ int x;
+ };
+
+ constexpr TrivialCopyable v;
+ constexpr absl::optional<TrivialCopyable> c_opt0 = absl::make_optional(v);
+ static_assert((*c_opt0).x == 0, "");
+ constexpr absl::optional<TrivialCopyable> c_opt1 =
+ absl::make_optional<TrivialCopyable>();
+ static_assert((*c_opt1).x == 0, "");
+ constexpr absl::optional<TrivialCopyable> c_opt2 =
+ absl::make_optional<TrivialCopyable>(42);
+ static_assert((*c_opt2).x == 42, "");
+ }
+}
+
+template <typename T, typename U>
+void optionalTest_Comparisons_EXPECT_LESS(T x, U y) {
+ EXPECT_FALSE(x == y);
+ EXPECT_TRUE(x != y);
+ EXPECT_TRUE(x < y);
+ EXPECT_FALSE(x > y);
+ EXPECT_TRUE(x <= y);
+ EXPECT_FALSE(x >= y);
+}
+
+template <typename T, typename U>
+void optionalTest_Comparisons_EXPECT_SAME(T x, U y) {
+ EXPECT_TRUE(x == y);
+ EXPECT_FALSE(x != y);
+ EXPECT_FALSE(x < y);
+ EXPECT_FALSE(x > y);
+ EXPECT_TRUE(x <= y);
+ EXPECT_TRUE(x >= y);
+}
+
+template <typename T, typename U>
+void optionalTest_Comparisons_EXPECT_GREATER(T x, U y) {
+ EXPECT_FALSE(x == y);
+ EXPECT_TRUE(x != y);
+ EXPECT_FALSE(x < y);
+ EXPECT_TRUE(x > y);
+ EXPECT_FALSE(x <= y);
+ EXPECT_TRUE(x >= y);
+}
+
+
+template <typename T, typename U, typename V>
+void TestComparisons() {
+ absl::optional<T> ae, a2{2}, a4{4};
+ absl::optional<U> be, b2{2}, b4{4};
+ V v3 = 3;
+
+ // LHS: absl::nullopt, ae, a2, v3, a4
+ // RHS: absl::nullopt, be, b2, v3, b4
+
+ // optionalTest_Comparisons_EXPECT_NOT_TO_WORK(absl::nullopt,absl::nullopt);
+ optionalTest_Comparisons_EXPECT_SAME(absl::nullopt, be);
+ optionalTest_Comparisons_EXPECT_LESS(absl::nullopt, b2);
+ // optionalTest_Comparisons_EXPECT_NOT_TO_WORK(absl::nullopt,v3);
+ optionalTest_Comparisons_EXPECT_LESS(absl::nullopt, b4);
+
+ optionalTest_Comparisons_EXPECT_SAME(ae, absl::nullopt);
+ optionalTest_Comparisons_EXPECT_SAME(ae, be);
+ optionalTest_Comparisons_EXPECT_LESS(ae, b2);
+ optionalTest_Comparisons_EXPECT_LESS(ae, v3);
+ optionalTest_Comparisons_EXPECT_LESS(ae, b4);
+
+ optionalTest_Comparisons_EXPECT_GREATER(a2, absl::nullopt);
+ optionalTest_Comparisons_EXPECT_GREATER(a2, be);
+ optionalTest_Comparisons_EXPECT_SAME(a2, b2);
+ optionalTest_Comparisons_EXPECT_LESS(a2, v3);
+ optionalTest_Comparisons_EXPECT_LESS(a2, b4);
+
+ // optionalTest_Comparisons_EXPECT_NOT_TO_WORK(v3,absl::nullopt);
+ optionalTest_Comparisons_EXPECT_GREATER(v3, be);
+ optionalTest_Comparisons_EXPECT_GREATER(v3, b2);
+ optionalTest_Comparisons_EXPECT_SAME(v3, v3);
+ optionalTest_Comparisons_EXPECT_LESS(v3, b4);
+
+ optionalTest_Comparisons_EXPECT_GREATER(a4, absl::nullopt);
+ optionalTest_Comparisons_EXPECT_GREATER(a4, be);
+ optionalTest_Comparisons_EXPECT_GREATER(a4, b2);
+ optionalTest_Comparisons_EXPECT_GREATER(a4, v3);
+ optionalTest_Comparisons_EXPECT_SAME(a4, b4);
+}
+
+struct Int1 {
+ Int1() = default;
+ Int1(int i) : i(i) {} // NOLINT(runtime/explicit)
+ int i;
+};
+
+struct Int2 {
+ Int2() = default;
+ Int2(int i) : i(i) {} // NOLINT(runtime/explicit)
+ int i;
+};
+
+// comparison between Int1 and Int2
+constexpr bool operator==(const Int1& lhs, const Int2& rhs) {
+ return lhs.i == rhs.i;
+}
+constexpr bool operator!=(const Int1& lhs, const Int2& rhs) {
+ return !(lhs == rhs);
+}
+constexpr bool operator<(const Int1& lhs, const Int2& rhs) {
+ return lhs.i < rhs.i;
+}
+constexpr bool operator<=(const Int1& lhs, const Int2& rhs) {
+ return lhs < rhs || lhs == rhs;
+}
+constexpr bool operator>(const Int1& lhs, const Int2& rhs) {
+ return !(lhs <= rhs);
+}
+constexpr bool operator>=(const Int1& lhs, const Int2& rhs) {
+ return !(lhs < rhs);
+}
+
+TEST(optionalTest, Comparisons) {
+ TestComparisons<int, int, int>();
+ TestComparisons<const int, int, int>();
+ TestComparisons<Int1, int, int>();
+ TestComparisons<int, Int2, int>();
+ TestComparisons<Int1, Int2, int>();
+
+ // compare absl::optional<std::string> with const char*
+ absl::optional<std::string> opt_str = "abc";
+ const char* cstr = "abc";
+ EXPECT_TRUE(opt_str == cstr);
+ // compare absl::optional<std::string> with absl::optional<const char*>
+ absl::optional<const char*> opt_cstr = cstr;
+ EXPECT_TRUE(opt_str == opt_cstr);
+ // compare absl::optional<std::string> with absl::optional<absl::string_view>
+ absl::optional<absl::string_view> e1;
+ absl::optional<std::string> e2;
+ EXPECT_TRUE(e1 == e2);
+}
+
+
+TEST(optionalTest, SwapRegression) {
+ StructorListener listener;
+ Listenable::listener = &listener;
+
+ {
+ absl::optional<Listenable> a;
+ absl::optional<Listenable> b(absl::in_place);
+ a.swap(b);
+ }
+
+ EXPECT_EQ(1, listener.construct0);
+ EXPECT_EQ(1, listener.move);
+ EXPECT_EQ(2, listener.destruct);
+
+ {
+ absl::optional<Listenable> a(absl::in_place);
+ absl::optional<Listenable> b;
+ a.swap(b);
+ }
+
+ EXPECT_EQ(2, listener.construct0);
+ EXPECT_EQ(2, listener.move);
+ EXPECT_EQ(4, listener.destruct);
+}
+
+TEST(optionalTest, BigStringLeakCheck) {
+ constexpr size_t n = 1 << 16;
+
+ using OS = absl::optional<std::string>;
+
+ OS a;
+ OS b = absl::nullopt;
+ OS c = std::string(n, 'c');
+ std::string sd(n, 'd');
+ OS d = sd;
+ OS e(absl::in_place, n, 'e');
+ OS f;
+ f.emplace(n, 'f');
+
+ OS ca(a);
+ OS cb(b);
+ OS cc(c);
+ OS cd(d);
+ OS ce(e);
+
+ OS oa;
+ OS ob = absl::nullopt;
+ OS oc = std::string(n, 'c');
+ std::string sod(n, 'd');
+ OS od = sod;
+ OS oe(absl::in_place, n, 'e');
+ OS of;
+ of.emplace(n, 'f');
+
+ OS ma(std::move(oa));
+ OS mb(std::move(ob));
+ OS mc(std::move(oc));
+ OS md(std::move(od));
+ OS me(std::move(oe));
+ OS mf(std::move(of));
+
+ OS aa1;
+ OS ab1 = absl::nullopt;
+ OS ac1 = std::string(n, 'c');
+ std::string sad1(n, 'd');
+ OS ad1 = sad1;
+ OS ae1(absl::in_place, n, 'e');
+ OS af1;
+ af1.emplace(n, 'f');
+
+ OS aa2;
+ OS ab2 = absl::nullopt;
+ OS ac2 = std::string(n, 'c');
+ std::string sad2(n, 'd');
+ OS ad2 = sad2;
+ OS ae2(absl::in_place, n, 'e');
+ OS af2;
+ af2.emplace(n, 'f');
+
+ aa1 = af2;
+ ab1 = ae2;
+ ac1 = ad2;
+ ad1 = ac2;
+ ae1 = ab2;
+ af1 = aa2;
+
+ OS aa3;
+ OS ab3 = absl::nullopt;
+ OS ac3 = std::string(n, 'c');
+ std::string sad3(n, 'd');
+ OS ad3 = sad3;
+ OS ae3(absl::in_place, n, 'e');
+ OS af3;
+ af3.emplace(n, 'f');
+
+ aa3 = absl::nullopt;
+ ab3 = absl::nullopt;
+ ac3 = absl::nullopt;
+ ad3 = absl::nullopt;
+ ae3 = absl::nullopt;
+ af3 = absl::nullopt;
+
+ OS aa4;
+ OS ab4 = absl::nullopt;
+ OS ac4 = std::string(n, 'c');
+ std::string sad4(n, 'd');
+ OS ad4 = sad4;
+ OS ae4(absl::in_place, n, 'e');
+ OS af4;
+ af4.emplace(n, 'f');
+
+ aa4 = OS(absl::in_place, n, 'a');
+ ab4 = OS(absl::in_place, n, 'b');
+ ac4 = OS(absl::in_place, n, 'c');
+ ad4 = OS(absl::in_place, n, 'd');
+ ae4 = OS(absl::in_place, n, 'e');
+ af4 = OS(absl::in_place, n, 'f');
+
+ OS aa5;
+ OS ab5 = absl::nullopt;
+ OS ac5 = std::string(n, 'c');
+ std::string sad5(n, 'd');
+ OS ad5 = sad5;
+ OS ae5(absl::in_place, n, 'e');
+ OS af5;
+ af5.emplace(n, 'f');
+
+ std::string saa5(n, 'a');
+ std::string sab5(n, 'a');
+ std::string sac5(n, 'a');
+ std::string sad52(n, 'a');
+ std::string sae5(n, 'a');
+ std::string saf5(n, 'a');
+
+ aa5 = saa5;
+ ab5 = sab5;
+ ac5 = sac5;
+ ad5 = sad52;
+ ae5 = sae5;
+ af5 = saf5;
+
+ OS aa6;
+ OS ab6 = absl::nullopt;
+ OS ac6 = std::string(n, 'c');
+ std::string sad6(n, 'd');
+ OS ad6 = sad6;
+ OS ae6(absl::in_place, n, 'e');
+ OS af6;
+ af6.emplace(n, 'f');
+
+ aa6 = std::string(n, 'a');
+ ab6 = std::string(n, 'b');
+ ac6 = std::string(n, 'c');
+ ad6 = std::string(n, 'd');
+ ae6 = std::string(n, 'e');
+ af6 = std::string(n, 'f');
+
+ OS aa7;
+ OS ab7 = absl::nullopt;
+ OS ac7 = std::string(n, 'c');
+ std::string sad7(n, 'd');
+ OS ad7 = sad7;
+ OS ae7(absl::in_place, n, 'e');
+ OS af7;
+ af7.emplace(n, 'f');
+
+ aa7.emplace(n, 'A');
+ ab7.emplace(n, 'B');
+ ac7.emplace(n, 'C');
+ ad7.emplace(n, 'D');
+ ae7.emplace(n, 'E');
+ af7.emplace(n, 'F');
+}
+
+TEST(optionalTest, MoveAssignRegression) {
+ StructorListener listener;
+ Listenable::listener = &listener;
+
+ {
+ absl::optional<Listenable> a;
+ Listenable b;
+ a = std::move(b);
+ }
+
+ EXPECT_EQ(1, listener.construct0);
+ EXPECT_EQ(1, listener.move);
+ EXPECT_EQ(2, listener.destruct);
+}
+
+TEST(optionalTest, ValueType) {
+ EXPECT_TRUE((std::is_same<absl::optional<int>::value_type, int>::value));
+ EXPECT_TRUE(
+ (std::is_same<absl::optional<std::string>::value_type, std::string>::value));
+ EXPECT_FALSE(
+ (std::is_same<absl::optional<int>::value_type, absl::nullopt_t>::value));
+}
+
+template <typename T>
+struct is_hash_enabled_for {
+ template <typename U, typename = decltype(std::hash<U>()(std::declval<U>()))>
+ static std::true_type test(int);
+
+ template <typename U>
+ static std::false_type test(...);
+
+ static constexpr bool value = decltype(test<T>(0))::value;
+};
+
+TEST(optionalTest, Hash) {
+ std::hash<absl::optional<int>> hash;
+ std::set<size_t> hashcodes;
+ hashcodes.insert(hash(absl::nullopt));
+ for (int i = 0; i < 100; ++i) {
+ hashcodes.insert(hash(i));
+ }
+ EXPECT_GT(hashcodes.size(), 90);
+
+ static_assert(is_hash_enabled_for<absl::optional<int>>::value, "");
+ static_assert(is_hash_enabled_for<absl::optional<Hashable>>::value, "");
+
+#if defined(_MSC_VER) || (defined(_LIBCPP_VERSION) && \
+ _LIBCPP_VERSION < 4000 && _LIBCPP_STD_VER > 11)
+ // For MSVC and libc++ (< 4.0 and c++14), std::hash primary template has a
+ // static_assert to catch any user-defined type that doesn't provide a hash
+ // specialization. So instantiating std::hash<absl::optional<T>> will result
+ // in a hard error which is not SFINAE friendly.
+#define ABSL_STD_HASH_NOT_SFINAE_FRIENDLY 1
+#endif
+
+#ifndef ABSL_STD_HASH_NOT_SFINAE_FRIENDLY
+ static_assert(!is_hash_enabled_for<absl::optional<NonHashable>>::value, "");
+#endif
+
+ // libstdc++ std::optional is missing remove_const_t, i.e. it's using
+ // std::hash<T> rather than std::hash<std::remove_const_t<T>>.
+ // Reference: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82262
+#ifndef __GLIBCXX__
+ static_assert(is_hash_enabled_for<absl::optional<const int>>::value, "");
+ static_assert(is_hash_enabled_for<absl::optional<const Hashable>>::value, "");
+ std::hash<absl::optional<const int>> c_hash;
+ for (int i = 0; i < 100; ++i) {
+ EXPECT_EQ(hash(i), c_hash(i));
+ }
+#endif
+}
+
+struct MoveMeNoThrow {
+ MoveMeNoThrow() : x(0) {}
+ [[noreturn]] MoveMeNoThrow(const MoveMeNoThrow& other) : x(other.x) {
+ ABSL_RAW_LOG(FATAL, "Should not be called.");
+ abort();
+ }
+ MoveMeNoThrow(MoveMeNoThrow&& other) noexcept : x(other.x) {}
+ int x;
+};
+
+struct MoveMeThrow {
+ MoveMeThrow() : x(0) {}
+ MoveMeThrow(const MoveMeThrow& other) : x(other.x) {}
+ MoveMeThrow(MoveMeThrow&& other) : x(other.x) {}
+ int x;
+};
+
+TEST(optionalTest, NoExcept) {
+ static_assert(
+ std::is_nothrow_move_constructible<absl::optional<MoveMeNoThrow>>::value,
+ "");
+#ifndef ABSL_HAVE_STD_OPTIONAL
+ static_assert(absl::default_allocator_is_nothrow::value ==
+ std::is_nothrow_move_constructible<
+ absl::optional<MoveMeThrow>>::value,
+ "");
+#endif
+ std::vector<absl::optional<MoveMeNoThrow>> v;
+ for (int i = 0; i < 10; ++i) v.emplace_back();
+}
+
+struct AnyLike {
+ AnyLike(AnyLike&&) = default;
+ AnyLike(const AnyLike&) = default;
+
+ template <typename ValueType,
+ typename T = typename std::decay<ValueType>::type,
+ typename std::enable_if<
+ !absl::disjunction<
+ std::is_same<AnyLike, T>,
+ absl::negation<std::is_copy_constructible<T>>>::value,
+ int>::type = 0>
+ AnyLike(ValueType&&) {} // NOLINT(runtime/explicit)
+
+ AnyLike& operator=(AnyLike&&) = default;
+ AnyLike& operator=(const AnyLike&) = default;
+
+ template <typename ValueType,
+ typename T = typename std::decay<ValueType>::type>
+ typename std::enable_if<
+ absl::conjunction<absl::negation<std::is_same<AnyLike, T>>,
+ std::is_copy_constructible<T>>::value,
+ AnyLike&>::type
+ operator=(ValueType&& /* rhs */) {
+ return *this;
+ }
+};
+
+TEST(optionalTest, ConstructionConstraints) {
+ EXPECT_TRUE((std::is_constructible<AnyLike, absl::optional<AnyLike>>::value));
+
+ EXPECT_TRUE(
+ (std::is_constructible<AnyLike, const absl::optional<AnyLike>&>::value));
+
+ EXPECT_TRUE((std::is_constructible<absl::optional<AnyLike>, AnyLike>::value));
+ EXPECT_TRUE(
+ (std::is_constructible<absl::optional<AnyLike>, const AnyLike&>::value));
+
+ EXPECT_TRUE((std::is_convertible<absl::optional<AnyLike>, AnyLike>::value));
+
+ EXPECT_TRUE(
+ (std::is_convertible<const absl::optional<AnyLike>&, AnyLike>::value));
+
+ EXPECT_TRUE((std::is_convertible<AnyLike, absl::optional<AnyLike>>::value));
+ EXPECT_TRUE(
+ (std::is_convertible<const AnyLike&, absl::optional<AnyLike>>::value));
+
+ EXPECT_TRUE(std::is_move_constructible<absl::optional<AnyLike>>::value);
+ EXPECT_TRUE(std::is_copy_constructible<absl::optional<AnyLike>>::value);
+}
+
+TEST(optionalTest, AssignmentConstraints) {
+ EXPECT_TRUE((std::is_assignable<AnyLike&, absl::optional<AnyLike>>::value));
+ EXPECT_TRUE(
+ (std::is_assignable<AnyLike&, const absl::optional<AnyLike>&>::value));
+ EXPECT_TRUE((std::is_assignable<absl::optional<AnyLike>&, AnyLike>::value));
+ EXPECT_TRUE(
+ (std::is_assignable<absl::optional<AnyLike>&, const AnyLike&>::value));
+ EXPECT_TRUE(std::is_move_assignable<absl::optional<AnyLike>>::value);
+ EXPECT_TRUE(std::is_copy_assignable<absl::optional<AnyLike>>::value);
+}
+
+} // namespace
http://git-wip-us.apache.org/repos/asf/marmotta/blob/0eb556da/libraries/ostrich/backend/3rdparty/abseil/absl/types/span.h
----------------------------------------------------------------------
diff --git a/libraries/ostrich/backend/3rdparty/abseil/absl/types/span.h b/libraries/ostrich/backend/3rdparty/abseil/absl/types/span.h
new file mode 100644
index 0000000..0ca30d1
--- /dev/null
+++ b/libraries/ostrich/backend/3rdparty/abseil/absl/types/span.h
@@ -0,0 +1,748 @@
+//
+// 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.
+//
+// -----------------------------------------------------------------------------
+// span.h
+// -----------------------------------------------------------------------------
+//
+// This header file defines a `Span<T>` type for holding a view of an existing
+// array of data. The `Span` object, much like the `absl::string_view` object,
+// does not own such data itself. A span provides a lightweight way to pass
+// around view of such data.
+//
+// Additionally, this header file defines `MakeSpan()` and `MakeConstSpan()`
+// factory functions, for clearly creating spans of type `Span<T>` or read-only
+// `Span<const T>` when such types may be difficult to identify due to issues
+// with implicit conversion.
+//
+// The C++ standards committee currently has a proposal for a `std::span` type,
+// (http://wg21.link/p0122), which is not yet part of the standard (though may
+// become part of C++20). As of August 2017, the differences between
+// `absl::Span` and this proposal are:
+// * `absl::Span` uses `size_t` for `size_type`
+// * `absl::Span` has no `operator()`
+// * `absl::Span` has no constructors for `std::unique_ptr` or
+// `std::shared_ptr`
+// * `absl::Span` has the factory functions `MakeSpan()` and
+// `MakeConstSpan()`
+// * `absl::Span` has `front()` and `back()` methods
+// * bounds-checked access to `absl::Span` is accomplished with `at()`
+// * `absl::Span` has compiler-provided move and copy constructors and
+// assignment. This is due to them being specified as `constexpr`, but that
+// implies const in C++11.
+// * `absl::Span` has no `element_type` or `index_type` typedefs
+// * A read-only `absl::Span<const T>` can be implicitly constructed from an
+// initializer list.
+// * `absl::Span` has no `bytes()`, `size_bytes()`, `as_bytes()`, or
+// `as_mutable_bytes()` methods
+// * `absl::Span` has no static extent template parameter, nor constructors
+// which exist only because of the static extent parameter.
+// * `absl::Span` has an explicit mutable-reference constructor
+//
+// For more information, see the class comments below.
+#ifndef ABSL_TYPES_SPAN_H_
+#define ABSL_TYPES_SPAN_H_
+
+#include <algorithm>
+#include <cassert>
+#include <cstddef>
+#include <initializer_list>
+#include <iterator>
+#include <string>
+#include <type_traits>
+#include <utility>
+
+#include "absl/algorithm/algorithm.h"
+#include "absl/base/internal/throw_delegate.h"
+#include "absl/base/macros.h"
+#include "absl/base/optimization.h"
+#include "absl/base/port.h"
+#include "absl/meta/type_traits.h"
+
+namespace absl {
+
+template <typename T>
+class Span;
+
+namespace span_internal {
+// A constexpr min function
+constexpr size_t Min(size_t a, size_t b) noexcept { return a < b ? a : b; }
+
+// Wrappers for access to container data pointers.
+template <typename C>
+constexpr auto GetDataImpl(C& c, char) noexcept // NOLINT(runtime/references)
+ -> decltype(c.data()) {
+ return c.data();
+}
+
+// Before C++17, std::string::data returns a const char* in all cases.
+inline char* GetDataImpl(std::string& s, // NOLINT(runtime/references)
+ int) noexcept {
+ return &s[0];
+}
+
+template <typename C>
+constexpr auto GetData(C& c) noexcept // NOLINT(runtime/references)
+ -> decltype(GetDataImpl(c, 0)) {
+ return GetDataImpl(c, 0);
+}
+
+// Detection idioms for size() and data().
+template <typename C>
+using HasSize =
+ std::is_integral<absl::decay_t<decltype(std::declval<C&>().size())>>;
+
+// We want to enable conversion from vector<T*> to Span<const T* const> but
+// disable conversion from vector<Derived> to Span<Base>. Here we use
+// the fact that U** is convertible to Q* const* if and only if Q is the same
+// type or a more cv-qualified version of U. We also decay the result type of
+// data() to avoid problems with classes which have a member function data()
+// which returns a reference.
+template <typename T, typename C>
+using HasData =
+ std::is_convertible<absl::decay_t<decltype(GetData(std::declval<C&>()))>*,
+ T* const*>;
+
+// Extracts value type from a Container
+template <typename C>
+struct ElementType {
+ using type = typename absl::remove_reference_t<C>::value_type;
+};
+
+template <typename T, size_t N>
+struct ElementType<T (&)[N]> {
+ using type = T;
+};
+
+template <typename C>
+using ElementT = typename ElementType<C>::type;
+
+template <typename T>
+using EnableIfMutable =
+ typename std::enable_if<!std::is_const<T>::value, int>::type;
+
+template <typename T>
+bool EqualImpl(Span<T> a, Span<T> b) {
+ static_assert(std::is_const<T>::value, "");
+ return absl::equal(a.begin(), a.end(), b.begin(), b.end());
+}
+
+template <typename T>
+bool LessThanImpl(Span<T> a, Span<T> b) {
+ static_assert(std::is_const<T>::value, "");
+ return std::lexicographical_compare(a.begin(), a.end(), b.begin(), b.end());
+}
+
+// The `IsConvertible` classes here are needed because of the
+// `std::is_convertible` bug in libcxx when compiled with GCC. This build
+// configuration is used by Android NDK toolchain. Reference link:
+// https://bugs.llvm.org/show_bug.cgi?id=27538.
+template <typename From, typename To>
+struct IsConvertibleHelper {
+ private:
+ static std::true_type testval(To);
+ static std::false_type testval(...);
+
+ public:
+ using type = decltype(testval(std::declval<From>()));
+};
+
+template <typename From, typename To>
+struct IsConvertible : IsConvertibleHelper<From, To>::type {};
+
+// TODO(zhangxy): replace `IsConvertible` with `std::is_convertible` once the
+// older version of libcxx is not supported.
+template <typename From, typename To>
+using EnableIfConvertibleToSpanConst =
+ typename std::enable_if<IsConvertible<From, Span<const To>>::value>::type;
+} // namespace span_internal
+
+//------------------------------------------------------------------------------
+// Span
+//------------------------------------------------------------------------------
+//
+// A `Span` is an "array view" type for holding a view of a contiguous data
+// array; the `Span` object does not and cannot own such data itself. A span
+// provides an easy way to provide overloads for anything operating on
+// contiguous sequences without needing to manage pointers and array lengths
+// manually.
+
+// A span is conceptually a pointer (ptr) and a length (size) into an already
+// existing array of contiguous memory; the array it represents references the
+// elements "ptr[0] .. ptr[size-1]". Passing a properly-constructed `Span`
+// instead of raw pointers avoids many issues related to index out of bounds
+// errors.
+//
+// Spans may also be constructed from containers holding contiguous sequences.
+// Such containers must supply `data()` and `size() const` methods (e.g
+// `std::vector<T>`, `absl::InlinedVector<T, N>`). All implicit conversions to
+// `absl::Span` from such containers will create spans of type `const T`;
+// spans which can mutate their values (of type `T`) must use explicit
+// constructors.
+//
+// A `Span<T>` is somewhat analogous to an `absl::string_view`, but for an array
+// of elements of type `T`. A user of `Span` must ensure that the data being
+// pointed to outlives the `Span` itself.
+//
+// You can construct a `Span<T>` in several ways:
+//
+// * Explicitly from a reference to a container type
+// * Explicitly from a pointer and size
+// * Implicitly from a container type (but only for spans of type `const T`)
+// * Using the `MakeSpan()` or `MakeConstSpan()` factory functions.
+//
+// Examples:
+//
+// // Construct a Span explicitly from a container:
+// std::vector<int> v = {1, 2, 3, 4, 5};
+// auto span = absl::Span<const int>(v);
+//
+// // Construct a Span explicitly from a C-style array:
+// int a[5] = {1, 2, 3, 4, 5};
+// auto span = absl::Span<const int>(a);
+//
+// // Construct a Span implicitly from a container
+// void MyRoutine(absl::Span<const int> a) {
+// ...
+// }
+// std::vector v = {1,2,3,4,5};
+// MyRoutine(v) // convert to Span<const T>
+//
+// Note that `Span` objects, in addition to requiring that the memory they
+// point to remains alive, must also ensure that such memory does not get
+// reallocated. Therefore, to avoid undefined behavior, containers with
+// associated span views should not invoke operations that may reallocate memory
+// (such as resizing) or invalidate iterators into the container.
+//
+// One common use for a `Span` is when passing arguments to a routine that can
+// accept a variety of array types (e.g. a `std::vector`, `absl::InlinedVector`,
+// a C-style array, etc.). Instead of creating overloads for each case, you
+// can simply specify a `Span` as the argument to such a routine.
+//
+// Example:
+//
+// void MyRoutine(absl::Span<const int> a) {
+// ...
+// }
+//
+// std::vector v = {1,2,3,4,5};
+// MyRoutine(v);
+//
+// absl::InlinedVector<int, 4> my_inline_vector;
+// MyRoutine(my_inline_vector);
+//
+// // Explicit constructor from pointer,size
+// int* my_array = new int[10];
+// MyRoutine(absl::Span<const int>(my_array, 10));
+template <typename T>
+class Span {
+ private:
+ // Used to determine whether a Span can be constructed from a container of
+ // type C.
+ template <typename C>
+ using EnableIfConvertibleFrom =
+ typename std::enable_if<span_internal::HasData<T, C>::value &&
+ span_internal::HasSize<C>::value>::type;
+
+ // Used to SFINAE-enable a function when the slice elements are const.
+ template <typename U>
+ using EnableIfConstView =
+ typename std::enable_if<std::is_const<T>::value, U>::type;
+
+ // Used to SFINAE-enable a function when the slice elements are mutable.
+ template <typename U>
+ using EnableIfMutableView =
+ typename std::enable_if<!std::is_const<T>::value, U>::type;
+
+ public:
+ using value_type = absl::remove_cv_t<T>;
+ using pointer = T*;
+ using const_pointer = const T*;
+ using reference = T&;
+ using const_reference = const T&;
+ using iterator = pointer;
+ using const_iterator = const_pointer;
+ using reverse_iterator = std::reverse_iterator<iterator>;
+ using const_reverse_iterator = std::reverse_iterator<const_iterator>;
+ using size_type = size_t;
+ using difference_type = ptrdiff_t;
+
+ static const size_type npos = ~size_type{0};
+
+ constexpr Span() noexcept : Span(nullptr, 0) {}
+ constexpr Span(pointer array, size_type length) noexcept
+ : ptr_(array), len_(length) {}
+
+ // Implicit conversion constructors
+ template <size_t N>
+ constexpr Span(T (&a)[N]) noexcept // NOLINT(runtime/explicit)
+ : Span(a, N) {}
+
+ // Explicit reference constructor for a mutable `Span<T>` type
+ template <typename V, typename = EnableIfConvertibleFrom<V>,
+ typename = EnableIfMutableView<V>>
+ explicit Span(V& v) noexcept // NOLINT(runtime/references)
+ : Span(span_internal::GetData(v), v.size()) {}
+
+ // Implicit reference constructor for a read-only `Span<const T>` type
+ template <typename V, typename = EnableIfConvertibleFrom<V>,
+ typename = EnableIfConstView<V>>
+ constexpr Span(const V& v) noexcept // NOLINT(runtime/explicit)
+ : Span(span_internal::GetData(v), v.size()) {}
+
+ // Implicit constructor from an initializer list, making it possible to pass a
+ // brace-enclosed initializer list to a function expecting a `Span`. Such
+ // spans constructed from an initializer list must be of type `Span<const T>`.
+ //
+ // void Process(absl::Span<const int> x);
+ // Process({1, 2, 3});
+ //
+ // Note that as always the array referenced by the span must outlive the span.
+ // Since an initializer list constructor acts as if it is fed a temporary
+ // array (cf. C++ standard [dcl.init.list]/5), it's safe to use this
+ // constructor only when the `std::initializer_list` itself outlives the span.
+ // In order to meet this requirement it's sufficient to ensure that neither
+ // the span nor a copy of it is used outside of the expression in which it's
+ // created:
+ //
+ // // Assume that this function uses the array directly, not retaining any
+ // // copy of the span or pointer to any of its elements.
+ // void Process(absl::Span<const int> ints);
+ //
+ // // Okay: the std::initializer_list<int> will reference a temporary array
+ // // that isn't destroyed until after the call to Process returns.
+ // Process({ 17, 19 });
+ //
+ // // Not okay: the storage used by the std::initializer_list<int> is not
+ // // allowed to be referenced after the first line.
+ // absl::Span<const int> ints = { 17, 19 };
+ // Process(ints);
+ //
+ // // Not okay for the same reason as above: even when the elements of the
+ // // initializer list expression are not temporaries the underlying array
+ // // is, so the initializer list must still outlive the span.
+ // const int foo = 17;
+ // absl::Span<const int> ints = { foo };
+ // Process(ints);
+ //
+ template <typename LazyT = T,
+ typename = EnableIfConstView<LazyT>>
+ Span(
+ std::initializer_list<value_type> v) noexcept // NOLINT(runtime/explicit)
+ : Span(v.begin(), v.size()) {}
+
+ // Accessors
+
+ // Span::data()
+ //
+ // Returns a pointer to the span's underlying array of data (which is held
+ // outside the span).
+ constexpr pointer data() const noexcept { return ptr_; }
+
+ // Span::size()
+ //
+ // Returns the size of this span.
+ constexpr size_type size() const noexcept { return len_; }
+
+ // Span::length()
+ //
+ // Returns the length (size) of this span.
+ constexpr size_type length() const noexcept { return size(); }
+
+ // Span::empty()
+ //
+ // Returns a boolean indicating whether or not this span is considered empty.
+ constexpr bool empty() const noexcept { return size() == 0; }
+
+ // Span::operator[]
+ //
+ // Returns a reference to the i'th element of this span.
+ constexpr reference operator[](size_type i) const noexcept {
+ // MSVC 2015 accepts this as constexpr, but not ptr_[i]
+ return *(data() + i);
+ }
+
+ // Span::at()
+ //
+ // Returns a reference to the i'th element of this span.
+ constexpr reference at(size_type i) const {
+ return ABSL_PREDICT_TRUE(i < size())
+ ? ptr_[i]
+ : (base_internal::ThrowStdOutOfRange(
+ "Span::at failed bounds check"),
+ ptr_[i]);
+ }
+
+ // Span::front()
+ //
+ // Returns a reference to the first element of this span.
+ reference front() const noexcept { return ABSL_ASSERT(size() > 0), ptr_[0]; }
+
+ // Span::back()
+ //
+ // Returns a reference to the last element of this span.
+ reference back() const noexcept {
+ return ABSL_ASSERT(size() > 0), ptr_[size() - 1];
+ }
+
+ // Span::begin()
+ //
+ // Returns an iterator to the first element of this span.
+ constexpr iterator begin() const noexcept { return ptr_; }
+
+ // Span::cbegin()
+ //
+ // Returns a const iterator to the first element of this span.
+ constexpr const_iterator cbegin() const noexcept { return ptr_; }
+
+ // Span::end()
+ //
+ // Returns an iterator to the last element of this span.
+ iterator end() const noexcept { return ptr_ + len_; }
+
+ // Span::cend()
+ //
+ // Returns a const iterator to the last element of this span.
+ const_iterator cend() const noexcept { return end(); }
+
+ // Span::rbegin()
+ //
+ // Returns a reverse iterator starting at the last element of this span.
+ reverse_iterator rbegin() const noexcept { return reverse_iterator(end()); }
+
+ // Span::crbegin()
+ //
+ // Returns a reverse const iterator starting at the last element of this span.
+ const_reverse_iterator crbegin() const noexcept { return rbegin(); }
+
+ // Span::rend()
+ //
+ // Returns a reverse iterator starting at the first element of this span.
+ reverse_iterator rend() const noexcept { return reverse_iterator(begin()); }
+
+ // Span::crend()
+ //
+ // Returns a reverse iterator starting at the first element of this span.
+ const_reverse_iterator crend() const noexcept { return rend(); }
+
+ // Span mutations
+
+ // Span::remove_prefix()
+ //
+ // Removes the first `n` elements from the span.
+ void remove_prefix(size_type n) noexcept {
+ assert(len_ >= n);
+ ptr_ += n;
+ len_ -= n;
+ }
+
+ // Span::remove_suffix()
+ //
+ // Removes the last `n` elements from the span.
+ void remove_suffix(size_type n) noexcept {
+ assert(len_ >= n);
+ len_ -= n;
+ }
+
+ // Span::subspan()
+ //
+ // Returns a `Span` starting at element `pos` and of length `len`. Both `pos`
+ // and `len` are of type `size_type` and thus non-negative. Parameter `pos`
+ // must be <= size(). Any `len` value that points past the end of the span
+ // will be trimmed to at most size() - `pos`. A default `len` value of `npos`
+ // ensures the returned subspan continues until the end of the span.
+ //
+ // Examples:
+ //
+ // std::vector<int> vec = {10, 11, 12, 13};
+ // absl::MakeSpan(vec).subspan(1, 2); // {11, 12}
+ // absl::MakeSpan(vec).subspan(2, 8); // {12, 13}
+ // absl::MakeSpan(vec).subspan(1); // {11, 12, 13}
+ // absl::MakeSpan(vec).subspan(4); // {}
+ // absl::MakeSpan(vec).subspan(5); // throws std::out_of_range
+ constexpr Span subspan(size_type pos = 0, size_type len = npos) const {
+ return (pos <= len_)
+ ? Span(ptr_ + pos, span_internal::Min(len_ - pos, len))
+ : (base_internal::ThrowStdOutOfRange("pos > size()"), Span());
+ }
+
+ private:
+ pointer ptr_;
+ size_type len_;
+};
+
+template <typename T>
+const typename Span<T>::size_type Span<T>::npos;
+
+// Span relationals
+
+// Equality is compared element-by-element, while ordering is lexicographical.
+// We provide three overloads for each operator to cover any combination on the
+// left or right hand side of mutable Span<T>, read-only Span<const T>, and
+// convertible-to-read-only Span<T>.
+// TODO(zhangxy): Due to MSVC overload resolution bug with partial ordering
+// template functions, 5 overloads per operator is needed as a workaround. We
+// should update them to 3 overloads per operator using non-deduced context like
+// string_view, i.e.
+// - (Span<T>, Span<T>)
+// - (Span<T>, non_deduced<Span<const T>>)
+// - (non_deduced<Span<const T>>, Span<T>)
+
+// operator==
+template <typename T>
+bool operator==(Span<T> a, Span<T> b) {
+ return span_internal::EqualImpl<const T>(a, b);
+}
+template <typename T>
+bool operator==(Span<const T> a, Span<T> b) {
+ return span_internal::EqualImpl<const T>(a, b);
+}
+template <typename T>
+bool operator==(Span<T> a, Span<const T> b) {
+ return span_internal::EqualImpl<const T>(a, b);
+}
+template <typename T, typename U,
+ typename = span_internal::EnableIfConvertibleToSpanConst<U, T>>
+bool operator==(const U& a, Span<T> b) {
+ return span_internal::EqualImpl<const T>(a, b);
+}
+template <typename T, typename U,
+ typename = span_internal::EnableIfConvertibleToSpanConst<U, T>>
+bool operator==(Span<T> a, const U& b) {
+ return span_internal::EqualImpl<const T>(a, b);
+}
+
+// operator!=
+template <typename T>
+bool operator!=(Span<T> a, Span<T> b) {
+ return !(a == b);
+}
+template <typename T>
+bool operator!=(Span<const T> a, Span<T> b) {
+ return !(a == b);
+}
+template <typename T>
+bool operator!=(Span<T> a, Span<const T> b) {
+ return !(a == b);
+}
+template <typename T, typename U,
+ typename = span_internal::EnableIfConvertibleToSpanConst<U, T>>
+bool operator!=(const U& a, Span<T> b) {
+ return !(a == b);
+}
+template <typename T, typename U,
+ typename = span_internal::EnableIfConvertibleToSpanConst<U, T>>
+bool operator!=(Span<T> a, const U& b) {
+ return !(a == b);
+}
+
+// operator<
+template <typename T>
+bool operator<(Span<T> a, Span<T> b) {
+ return span_internal::LessThanImpl<const T>(a, b);
+}
+template <typename T>
+bool operator<(Span<const T> a, Span<T> b) {
+ return span_internal::LessThanImpl<const T>(a, b);
+}
+template <typename T>
+bool operator<(Span<T> a, Span<const T> b) {
+ return span_internal::LessThanImpl<const T>(a, b);
+}
+template <typename T, typename U,
+ typename = span_internal::EnableIfConvertibleToSpanConst<U, T>>
+bool operator<(const U& a, Span<T> b) {
+ return span_internal::LessThanImpl<const T>(a, b);
+}
+template <typename T, typename U,
+ typename = span_internal::EnableIfConvertibleToSpanConst<U, T>>
+bool operator<(Span<T> a, const U& b) {
+ return span_internal::LessThanImpl<const T>(a, b);
+}
+
+// operator>
+template <typename T>
+bool operator>(Span<T> a, Span<T> b) {
+ return b < a;
+}
+template <typename T>
+bool operator>(Span<const T> a, Span<T> b) {
+ return b < a;
+}
+template <typename T>
+bool operator>(Span<T> a, Span<const T> b) {
+ return b < a;
+}
+template <typename T, typename U,
+ typename = span_internal::EnableIfConvertibleToSpanConst<U, T>>
+bool operator>(const U& a, Span<T> b) {
+ return b < a;
+}
+template <typename T, typename U,
+ typename = span_internal::EnableIfConvertibleToSpanConst<U, T>>
+bool operator>(Span<T> a, const U& b) {
+ return b < a;
+}
+
+// operator<=
+template <typename T>
+bool operator<=(Span<T> a, Span<T> b) {
+ return !(b < a);
+}
+template <typename T>
+bool operator<=(Span<const T> a, Span<T> b) {
+ return !(b < a);
+}
+template <typename T>
+bool operator<=(Span<T> a, Span<const T> b) {
+ return !(b < a);
+}
+template <typename T, typename U,
+ typename = span_internal::EnableIfConvertibleToSpanConst<U, T>>
+bool operator<=(const U& a, Span<T> b) {
+ return !(b < a);
+}
+template <typename T, typename U,
+ typename = span_internal::EnableIfConvertibleToSpanConst<U, T>>
+bool operator<=(Span<T> a, const U& b) {
+ return !(b < a);
+}
+
+// operator>=
+template <typename T>
+bool operator>=(Span<T> a, Span<T> b) {
+ return !(a < b);
+}
+template <typename T>
+bool operator>=(Span<const T> a, Span<T> b) {
+ return !(a < b);
+}
+template <typename T>
+bool operator>=(Span<T> a, Span<const T> b) {
+ return !(a < b);
+}
+template <typename T, typename U,
+ typename = span_internal::EnableIfConvertibleToSpanConst<U, T>>
+bool operator>=(const U& a, Span<T> b) {
+ return !(a < b);
+}
+template <typename T, typename U,
+ typename = span_internal::EnableIfConvertibleToSpanConst<U, T>>
+bool operator>=(Span<T> a, const U& b) {
+ return !(a < b);
+}
+
+// MakeSpan()
+//
+// Constructs a mutable `Span<T>`, deducing `T` automatically from either a
+// container or pointer+size.
+//
+// Because a read-only `Span<const T>` is implicitly constructed from container
+// types regardless of whether the container itself is a const container,
+// constructing mutable spans of type `Span<T>` from containers requires
+// explicit constructors. The container-accepting version of `MakeSpan()`
+// deduces the type of `T` by the constness of the pointer received from the
+// container's `data()` member. Similarly, the pointer-accepting version returns
+// a `Span<const T>` if `T` is `const`, and a `Span<T>` otherwise.
+//
+// Examples:
+//
+// void MyRoutine(absl::Span<MyComplicatedType> a) {
+// ...
+// };
+// // my_vector is a container of non-const types
+// std::vector<MyComplicatedType> my_vector;
+//
+// // Constructing a Span implicitly attempts to create a Span of type
+// // `Span<const T>`
+// MyRoutine(my_vector); // error, type mismatch
+//
+// // Explicitly constructing the Span is verbose
+// MyRoutine(absl::Span<MyComplicatedType>(my_vector));
+//
+// // Use MakeSpan() to make an absl::Span<T>
+// MyRoutine(absl::MakeSpan(my_vector));
+//
+// // Construct a span from an array ptr+size
+// absl::Span<T> my_span() {
+// return absl::MakeSpan(&array[0], num_elements_);
+// }
+//
+template <int&... ExplicitArgumentBarrier, typename T>
+constexpr Span<T> MakeSpan(T* ptr, size_t size) noexcept {
+ return Span<T>(ptr, size);
+}
+
+template <int&... ExplicitArgumentBarrier, typename T>
+Span<T> MakeSpan(T* begin, T* end) noexcept {
+ return ABSL_ASSERT(begin <= end), Span<T>(begin, end - begin);
+}
+
+template <int&... ExplicitArgumentBarrier, typename C>
+constexpr auto MakeSpan(C& c) noexcept // NOLINT(runtime/references)
+ -> decltype(absl::MakeSpan(span_internal::GetData(c), c.size())) {
+ return MakeSpan(span_internal::GetData(c), c.size());
+}
+
+template <int&... ExplicitArgumentBarrier, typename T, size_t N>
+constexpr Span<T> MakeSpan(T (&array)[N]) noexcept {
+ return Span<T>(array, N);
+}
+
+// MakeConstSpan()
+//
+// Constructs a `Span<const T>` as with `MakeSpan`, deducing `T` automatically,
+// but always returning a `Span<const T>`.
+//
+// Examples:
+//
+// void ProcessInts(absl::Span<const int> some_ints);
+//
+// // Call with a pointer and size.
+// int array[3] = { 0, 0, 0 };
+// ProcessInts(absl::MakeConstSpan(&array[0], 3));
+//
+// // Call with a [begin, end) pair.
+// ProcessInts(absl::MakeConstSpan(&array[0], &array[3]));
+//
+// // Call directly with an array.
+// ProcessInts(absl::MakeConstSpan(array));
+//
+// // Call with a contiguous container.
+// std::vector<int> some_ints = ...;
+// ProcessInts(absl::MakeConstSpan(some_ints));
+// ProcessInts(absl::MakeConstSpan(std::vector<int>{ 0, 0, 0 }));
+//
+template <int&... ExplicitArgumentBarrier, typename T>
+constexpr Span<const T> MakeConstSpan(T* ptr, size_t size) noexcept {
+ return Span<const T>(ptr, size);
+}
+
+template <int&... ExplicitArgumentBarrier, typename T>
+Span<const T> MakeConstSpan(T* begin, T* end) noexcept {
+ return ABSL_ASSERT(begin <= end), Span<const T>(begin, end - begin);
+}
+
+template <int&... ExplicitArgumentBarrier, typename C>
+constexpr auto MakeConstSpan(const C& c) noexcept -> decltype(MakeSpan(c)) {
+ return MakeSpan(c);
+}
+
+template <int&... ExplicitArgumentBarrier, typename T, size_t N>
+constexpr Span<const T> MakeConstSpan(const T (&array)[N]) noexcept {
+ return Span<const T>(array, N);
+}
+} // namespace absl
+#endif // ABSL_TYPES_SPAN_H_