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+// 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/base/internal/invoke.h"
+
+#include <functional>
+#include <memory>
+#include <string>
+
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+#include "absl/memory/memory.h"
+#include "absl/strings/str_cat.h"
+
+namespace absl {
+namespace base_internal {
+namespace {
+
+int Function(int a, int b) { return a - b; }
+
+int Sink(std::unique_ptr<int> p) {
+ return *p;
+}
+
+std::unique_ptr<int> Factory(int n) {
+ return make_unique<int>(n);
+}
+
+void NoOp() {}
+
+struct ConstFunctor {
+ int operator()(int a, int b) const { return a - b; }
+};
+
+struct MutableFunctor {
+ int operator()(int a, int b) { return a - b; }
+};
+
+struct EphemeralFunctor {
+ int operator()(int a, int b) && { return a - b; }
+};
+
+struct OverloadedFunctor {
+ template <typename... Args>
+ std::string operator()(const Args&... args) & {
+ return StrCat("&", args...);
+ }
+ template <typename... Args>
+ std::string operator()(const Args&... args) const& {
+ return StrCat("const&", args...);
+ }
+ template <typename... Args>
+ std::string operator()(const Args&... args) && {
+ return StrCat("&&", args...);
+ }
+};
+
+struct Class {
+ int Method(int a, int b) { return a - b; }
+ int ConstMethod(int a, int b) const { return a - b; }
+
+ int member;
+};
+
+struct FlipFlop {
+ int ConstMethod() const { return member; }
+ FlipFlop operator*() const { return {-member}; }
+
+ int member;
+};
+
+// CallMaybeWithArg(f) resolves either to Invoke(f) or Invoke(f, 42), depending
+// on which one is valid.
+template <typename F>
+decltype(Invoke(std::declval<const F&>())) CallMaybeWithArg(const F& f) {
+ return Invoke(f);
+}
+
+template <typename F>
+decltype(Invoke(std::declval<const F&>(), 42)) CallMaybeWithArg(const F& f) {
+ return Invoke(f, 42);
+}
+
+TEST(InvokeTest, Function) {
+ EXPECT_EQ(1, Invoke(Function, 3, 2));
+ EXPECT_EQ(1, Invoke(&Function, 3, 2));
+}
+
+TEST(InvokeTest, NonCopyableArgument) {
+ EXPECT_EQ(42, Invoke(Sink, make_unique<int>(42)));
+}
+
+TEST(InvokeTest, NonCopyableResult) {
+ EXPECT_THAT(Invoke(Factory, 42), ::testing::Pointee(42));
+}
+
+TEST(InvokeTest, VoidResult) {
+ Invoke(NoOp);
+}
+
+TEST(InvokeTest, ConstFunctor) {
+ EXPECT_EQ(1, Invoke(ConstFunctor(), 3, 2));
+}
+
+TEST(InvokeTest, MutableFunctor) {
+ MutableFunctor f;
+ EXPECT_EQ(1, Invoke(f, 3, 2));
+ EXPECT_EQ(1, Invoke(MutableFunctor(), 3, 2));
+}
+
+TEST(InvokeTest, EphemeralFunctor) {
+ EphemeralFunctor f;
+ EXPECT_EQ(1, Invoke(std::move(f), 3, 2));
+ EXPECT_EQ(1, Invoke(EphemeralFunctor(), 3, 2));
+}
+
+TEST(InvokeTest, OverloadedFunctor) {
+ OverloadedFunctor f;
+ const OverloadedFunctor& cf = f;
+
+ EXPECT_EQ("&", Invoke(f));
+ EXPECT_EQ("& 42", Invoke(f, " 42"));
+
+ EXPECT_EQ("const&", Invoke(cf));
+ EXPECT_EQ("const& 42", Invoke(cf, " 42"));
+
+ EXPECT_EQ("&&", Invoke(std::move(f)));
+ EXPECT_EQ("&& 42", Invoke(std::move(f), " 42"));
+}
+
+TEST(InvokeTest, ReferenceWrapper) {
+ ConstFunctor cf;
+ MutableFunctor mf;
+ EXPECT_EQ(1, Invoke(std::cref(cf), 3, 2));
+ EXPECT_EQ(1, Invoke(std::ref(cf), 3, 2));
+ EXPECT_EQ(1, Invoke(std::ref(mf), 3, 2));
+}
+
+TEST(InvokeTest, MemberFunction) {
+ std::unique_ptr<Class> p(new Class);
+ std::unique_ptr<const Class> cp(new Class);
+ EXPECT_EQ(1, Invoke(&Class::Method, p, 3, 2));
+ EXPECT_EQ(1, Invoke(&Class::Method, p.get(), 3, 2));
+
+ EXPECT_EQ(1, Invoke(&Class::ConstMethod, p, 3, 2));
+ EXPECT_EQ(1, Invoke(&Class::ConstMethod, p.get(), 3, 2));
+ EXPECT_EQ(1, Invoke(&Class::ConstMethod, *p, 3, 2));
+
+ EXPECT_EQ(1, Invoke(&Class::ConstMethod, cp, 3, 2));
+ EXPECT_EQ(1, Invoke(&Class::ConstMethod, cp.get(), 3, 2));
+ EXPECT_EQ(1, Invoke(&Class::ConstMethod, *cp, 3, 2));
+
+ EXPECT_EQ(1, Invoke(&Class::Method, make_unique<Class>(), 3, 2));
+ EXPECT_EQ(1, Invoke(&Class::ConstMethod, make_unique<Class>(), 3, 2));
+ EXPECT_EQ(1, Invoke(&Class::ConstMethod, make_unique<const Class>(), 3, 2));
+}
+
+TEST(InvokeTest, DataMember) {
+ std::unique_ptr<Class> p(new Class{42});
+ std::unique_ptr<const Class> cp(new Class{42});
+ EXPECT_EQ(42, Invoke(&Class::member, p));
+ EXPECT_EQ(42, Invoke(&Class::member, *p));
+ EXPECT_EQ(42, Invoke(&Class::member, p.get()));
+
+ Invoke(&Class::member, p) = 42;
+ Invoke(&Class::member, p.get()) = 42;
+
+ EXPECT_EQ(42, Invoke(&Class::member, cp));
+ EXPECT_EQ(42, Invoke(&Class::member, *cp));
+ EXPECT_EQ(42, Invoke(&Class::member, cp.get()));
+}
+
+TEST(InvokeTest, FlipFlop) {
+ FlipFlop obj = {42};
+ // This call could resolve to (obj.*&FlipFlop::ConstMethod)() or
+ // ((*obj).*&FlipFlop::ConstMethod)(). We verify that it's the former.
+ EXPECT_EQ(42, Invoke(&FlipFlop::ConstMethod, obj));
+ EXPECT_EQ(42, Invoke(&FlipFlop::member, obj));
+}
+
+TEST(InvokeTest, SfinaeFriendly) {
+ CallMaybeWithArg(NoOp);
+ EXPECT_THAT(CallMaybeWithArg(Factory), ::testing::Pointee(42));
+}
+
+} // namespace
+} // namespace base_internal
+} // namespace absl