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// Copyright 2018 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
//
//
// 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/functional/bind_front.h"
#include <stddef.h>
#include <functional>
#include <memory>
#include <string>
#include "gmock/gmock.h"
#include "gtest/gtest.h"
#include "absl/memory/memory.h"
namespace {
char CharAt(const char* s, size_t index) { return s[index]; }
TEST(BindTest, Basics) {
EXPECT_EQ('C', absl::bind_front(CharAt)("ABC", 2));
EXPECT_EQ('C', absl::bind_front(CharAt, "ABC")(2));
EXPECT_EQ('C', absl::bind_front(CharAt, "ABC", 2)());
}
TEST(BindTest, Lambda) {
auto lambda = [](int x, int y, int z) { return x + y + z; };
EXPECT_EQ(6, absl::bind_front(lambda)(1, 2, 3));
EXPECT_EQ(6, absl::bind_front(lambda, 1)(2, 3));
EXPECT_EQ(6, absl::bind_front(lambda, 1, 2)(3));
EXPECT_EQ(6, absl::bind_front(lambda, 1, 2, 3)());
}
struct Functor {
std::string operator()() & { return "&"; }
std::string operator()() const& { return "const&"; }
std::string operator()() && { return "&&"; }
std::string operator()() const&& { return "const&&"; }
};
TEST(BindTest, PerfectForwardingOfBoundArgs) {
auto f = absl::bind_front(Functor());
const auto& cf = f;
EXPECT_EQ("&", f());
EXPECT_EQ("const&", cf());
EXPECT_EQ("&&", std::move(f)());
EXPECT_EQ("const&&", std::move(cf)());
}
struct ArgDescribe {
std::string operator()(int&) const { return "&"; } // NOLINT
std::string operator()(const int&) const { return "const&"; } // NOLINT
std::string operator()(int&&) const { return "&&"; }
std::string operator()(const int&&) const { return "const&&"; }
};
TEST(BindTest, PerfectForwardingOfFreeArgs) {
ArgDescribe f;
int i;
EXPECT_EQ("&", absl::bind_front(f)(static_cast<int&>(i)));
EXPECT_EQ("const&", absl::bind_front(f)(static_cast<const int&>(i)));
EXPECT_EQ("&&", absl::bind_front(f)(static_cast<int&&>(i)));
EXPECT_EQ("const&&", absl::bind_front(f)(static_cast<const int&&>(i)));
}
struct NonCopyableFunctor {
NonCopyableFunctor() = default;
NonCopyableFunctor(const NonCopyableFunctor&) = delete;
NonCopyableFunctor& operator=(const NonCopyableFunctor&) = delete;
const NonCopyableFunctor* operator()() const { return this; }
};
TEST(BindTest, RefToFunctor) {
// It won't copy/move the functor and use the original object.
NonCopyableFunctor ncf;
auto bound_ncf = absl::bind_front(std::ref(ncf));
auto bound_ncf_copy = bound_ncf;
EXPECT_EQ(&ncf, bound_ncf_copy());
}
struct Struct {
std::string value;
};
TEST(BindTest, StoreByCopy) {
Struct s = {"hello"};
auto f = absl::bind_front(&Struct::value, s);
auto g = f;
EXPECT_EQ("hello", f());
EXPECT_EQ("hello", g());
EXPECT_NE(&s.value, &f());
EXPECT_NE(&s.value, &g());
EXPECT_NE(&g(), &f());
}
struct NonCopyable {
explicit NonCopyable(const std::string& s) : value(s) {}
NonCopyable(const NonCopyable&) = delete;
NonCopyable& operator=(const NonCopyable&) = delete;
std::string value;
};
const std::string& GetNonCopyableValue(const NonCopyable& n) { return n.value; }
TEST(BindTest, StoreByRef) {
NonCopyable s("hello");
auto f = absl::bind_front(&GetNonCopyableValue, std::ref(s));
EXPECT_EQ("hello", f());
EXPECT_EQ(&s.value, &f());
auto g = std::move(f); // NOLINT
EXPECT_EQ("hello", g());
EXPECT_EQ(&s.value, &g());
s.value = "goodbye";
EXPECT_EQ("goodbye", g());
}
TEST(BindTest, StoreByCRef) {
NonCopyable s("hello");
auto f = absl::bind_front(&GetNonCopyableValue, std::cref(s));
EXPECT_EQ("hello", f());
EXPECT_EQ(&s.value, &f());
auto g = std::move(f); // NOLINT
EXPECT_EQ("hello", g());
EXPECT_EQ(&s.value, &g());
s.value = "goodbye";
EXPECT_EQ("goodbye", g());
}
const std::string& GetNonCopyableValueByWrapper(
std::reference_wrapper<NonCopyable> n) {
return n.get().value;
}
TEST(BindTest, StoreByRefInvokeByWrapper) {
NonCopyable s("hello");
auto f = absl::bind_front(GetNonCopyableValueByWrapper, std::ref(s));
EXPECT_EQ("hello", f());
EXPECT_EQ(&s.value, &f());
auto g = std::move(f);
EXPECT_EQ("hello", g());
EXPECT_EQ(&s.value, &g());
s.value = "goodbye";
EXPECT_EQ("goodbye", g());
}
TEST(BindTest, StoreByPointer) {
NonCopyable s("hello");
auto f = absl::bind_front(&NonCopyable::value, &s);
EXPECT_EQ("hello", f());
EXPECT_EQ(&s.value, &f());
auto g = std::move(f);
EXPECT_EQ("hello", g());
EXPECT_EQ(&s.value, &g());
}
int Sink(std::unique_ptr<int> p) {
return *p;
}
std::unique_ptr<int> Factory(int n) { return absl::make_unique<int>(n); }
TEST(BindTest, NonCopyableArg) {
EXPECT_EQ(42, absl::bind_front(Sink)(absl::make_unique<int>(42)));
EXPECT_EQ(42, absl::bind_front(Sink, absl::make_unique<int>(42))());
}
TEST(BindTest, NonCopyableResult) {
EXPECT_THAT(absl::bind_front(Factory)(42), ::testing::Pointee(42));
EXPECT_THAT(absl::bind_front(Factory, 42)(), ::testing::Pointee(42));
}
// is_copy_constructible<FalseCopyable<unique_ptr<T>> is true but an attempt to
// instantiate the copy constructor leads to a compile error. This is similar
// to how standard containers behave.
template <class T>
struct FalseCopyable {
FalseCopyable() {}
FalseCopyable(const FalseCopyable& other) : m(other.m) {}
FalseCopyable(FalseCopyable&& other) : m(std::move(other.m)) {}
T m;
};
int GetMember(FalseCopyable<std::unique_ptr<int>> x) { return *x.m; }
TEST(BindTest, WrappedMoveOnly) {
FalseCopyable<std::unique_ptr<int>> x;
x.m = absl::make_unique<int>(42);
auto f = absl::bind_front(&GetMember, std::move(x));
EXPECT_EQ(42, std::move(f)());
}
int Plus(int a, int b) { return a + b; }
TEST(BindTest, ConstExpr) {
constexpr auto f = absl::bind_front(CharAt);
EXPECT_EQ(f("ABC", 1), 'B');
static constexpr int five = 5;
constexpr auto plus5 = absl::bind_front(Plus, five);
EXPECT_EQ(plus5(1), 6);
// There seems to be a bug in MSVC dealing constexpr construction of
// char[]. Notice 'plus5' above; 'int' works just fine.
#if !(defined(_MSC_VER) && _MSC_VER < 1910)
static constexpr char data[] = "DEF";
constexpr auto g = absl::bind_front(CharAt, data);
EXPECT_EQ(g(1), 'E');
#endif
}
struct ManglingCall {
int operator()(int, double, std::string) const { return 0; }
};
TEST(BindTest, Mangling) {
// We just want to generate a particular instantiation to see its mangling.
absl::bind_front(ManglingCall{}, 1, 3.3)("A");
}
} // namespace