//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
// <functional>
// template<class F, class... Args>
// constexpr unspecified bind_back(F&& f, Args&&... args);
#include <functional>
#include <cassert>
#include <concepts>
#include <tuple>
#include <utility>
#include "callable_types.h"
#include "types.h"
constexpr void test_basic_bindings() {
{ // Bind arguments, call without arguments
{
auto f = std::bind_back(MakeTuple{});
assert(f() == std::make_tuple());
}
{
auto f = std::bind_back(MakeTuple{}, Elem<1>{});
assert(f() == std::make_tuple(Elem<1>{}));
}
{
auto f = std::bind_back(MakeTuple{}, Elem<1>{}, Elem<2>{});
assert(f() == std::make_tuple(Elem<1>{}, Elem<2>{}));
}
{
auto f = std::bind_back(MakeTuple{}, Elem<1>{}, Elem<2>{}, Elem<3>{});
assert(f() == std::make_tuple(Elem<1>{}, Elem<2>{}, Elem<3>{}));
}
}
{ // Bind no arguments, call with arguments
{
auto f = std::bind_back(MakeTuple{});
assert(f(Elem<1>{}) == std::make_tuple(Elem<1>{}));
}
{
auto f = std::bind_back(MakeTuple{});
assert(f(Elem<1>{}, Elem<2>{}) == std::make_tuple(Elem<1>{}, Elem<2>{}));
}
{
auto f = std::bind_back(MakeTuple{});
assert(f(Elem<1>{}, Elem<2>{}, Elem<3>{}) == std::make_tuple(Elem<1>{}, Elem<2>{}, Elem<3>{}));
}
}
{ // Bind arguments, call with arguments
{
auto f = std::bind_back(MakeTuple{}, Elem<1>{});
assert(f(Elem<10>{}) == std::make_tuple(Elem<10>{}, Elem<1>{}));
}
{
auto f = std::bind_back(MakeTuple{}, Elem<1>{}, Elem<2>{});
assert(f(Elem<10>{}) == std::make_tuple(Elem<10>{}, Elem<1>{}, Elem<2>{}));
}
{
auto f = std::bind_back(MakeTuple{}, Elem<1>{}, Elem<2>{}, Elem<3>{});
assert(f(Elem<10>{}) == std::make_tuple(Elem<10>{}, Elem<1>{}, Elem<2>{}, Elem<3>{}));
}
{
auto f = std::bind_back(MakeTuple{}, Elem<1>{});
assert(f(Elem<10>{}, Elem<11>{}) == std::make_tuple(Elem<10>{}, Elem<11>{}, Elem<1>{}));
}
{
auto f = std::bind_back(MakeTuple{}, Elem<1>{}, Elem<2>{});
assert(f(Elem<10>{}, Elem<11>{}) == std::make_tuple(Elem<10>{}, Elem<11>{}, Elem<1>{}, Elem<2>{}));
}
{
auto f = std::bind_back(MakeTuple{}, Elem<1>{}, Elem<2>{}, Elem<3>{});
assert(f(Elem<10>{}, Elem<11>{}) == std::make_tuple(Elem<10>{}, Elem<11>{}, Elem<1>{}, Elem<2>{}, Elem<3>{}));
}
{
auto f = std::bind_back(MakeTuple{}, Elem<1>{}, Elem<2>{}, Elem<3>{});
assert(f(Elem<10>{}, Elem<11>{}, Elem<12>{}) ==
std::make_tuple(Elem<10>{}, Elem<11>{}, Elem<12>{}, Elem<1>{}, Elem<2>{}, Elem<3>{}));
}
}
{ // Basic tests with fundamental types
int n = 2;
int m = 1;
int sum = 0;
auto add = [](int x, int y) { return x + y; };
auto add_n = [](int a, int b, int c, int d, int e, int f) { return a + b + c + d + e + f; };
auto add_ref = [&](int x, int y) -> int& { return sum = x + y; };
auto add_rref = [&](int x, int y) -> int&& { return std::move(sum = x + y); };
auto a = std::bind_back(add, m, n);
assert(a() == 3);
auto b = std::bind_back(add_n, m, n, m, m, m, m);
assert(b() == 7);
auto c = std::bind_back(add_n, n, m);
assert(c(1, 1, 1, 1) == 7);
auto d = std::bind_back(add_ref, n, m);
std::same_as<int&> decltype(auto) dresult(d());
assert(dresult == 3);
auto e = std::bind_back(add_rref, n, m);
std::same_as<int&&> decltype(auto) eresult(e());
assert(eresult == 3);
auto f = std::bind_back(add, n);
assert(f(3) == 5);
auto g = std::bind_back(add, n, 1);
assert(g() == 3);
auto h = std::bind_back(add_n, 1, 1, 1);
assert(h(2, 2, 2) == 9);
auto i = std::bind_back(add_ref, n);
std::same_as<int&> decltype(auto) iresult(i(5));
assert(iresult == 7);
auto j = std::bind_back(add_rref, m);
std::same_as<int&&> decltype(auto) jresult(j(4));
assert(jresult == 5);
}
}
constexpr void test_edge_cases() {
{ // Make sure we don't treat std::reference_wrapper specially.
auto sub = [](std::reference_wrapper<int> a, std::reference_wrapper<int> b) { return a.get() - b.get(); };
int i = 1;
int j = 2;
auto f = std::bind_back(sub, std::ref(i));
assert(f(std::ref(j)) == 1);
}
{ // Make sure we can call a function that's a pointer to a member function.
struct MemberFunction {
constexpr int foo(int x, int y) { return x * y; }
};
MemberFunction value;
auto fn = std::bind_back(&MemberFunction::foo, 2, 3);
assert(fn(value) == 6);
}
{ // Make sure we can call a function that's a pointer to a member object.
struct MemberObject {
int obj;
};
MemberObject value{.obj = 3};
auto fn = std::bind_back(&MemberObject::obj);
assert(fn(value) == 3);
}
}
constexpr void test_passing_arguments() {
{ // Make sure that we copy the bound arguments into the unspecified-type.
auto add = [](int x, int y) { return x + y; };
int n = 2;
auto f = std::bind_back(add, n, 1);
n = 100;
assert(f() == 3);
}
{ // Make sure we pass the bound arguments to the function object
// with the right value category.
{
auto was_copied = [](CopyMoveInfo info) { return info.copy_kind == CopyMoveInfo::copy; };
CopyMoveInfo info;
auto f = std::bind_back(was_copied, info);
assert(f());
}
{
auto was_moved = [](CopyMoveInfo info) { return info.copy_kind == CopyMoveInfo::move; };
CopyMoveInfo info;
auto f = std::bind_back(was_moved, info);
assert(std::move(f)());
}
}
}
constexpr void test_function_objects() {
{ // Make sure we call the correctly cv-ref qualified operator()
// based on the value category of the bind_back unspecified-type.
struct X {
constexpr int operator()() & { return 1; }
constexpr int operator()() const& { return 2; }
constexpr int operator()() && { return 3; }
constexpr int operator()() const&& { return 4; }
};
auto f = std::bind_back(X{});
using F = decltype(f);
assert(static_cast<F&>(f)() == 1);
assert(static_cast<const F&>(f)() == 2);
assert(static_cast<F&&>(f)() == 3);
assert(static_cast<const F&&>(f)() == 4);
}
// Make sure the `bind_back` unspecified-type does not model invocable
// when the call would select a differently-qualified operator().
//
// For example, if the call to `operator()() &` is ill-formed, the call to the unspecified-type
// should be ill-formed and not fall back to the `operator()() const&` overload.
{ // Make sure we delete the & overload when the underlying call isn't valid.
{
struct X {
void operator()() & = delete;
void operator()() const&;
void operator()() &&;
void operator()() const&&;
};
using F = decltype(std::bind_back(X{}));
static_assert(!std::invocable<F&>);
static_assert(std::invocable<const F&>);
static_assert(std::invocable<F>);
static_assert(std::invocable<const F>);
}
// There's no way to make sure we delete the const& overload when the underlying call isn't valid,
// so we can't check this one.
{ // Make sure we delete the && overload when the underlying call isn't valid.
struct X {
void operator()() &;
void operator()() const&;
void operator()() && = delete;
void operator()() const&&;
};
using F = decltype(std::bind_back(X{}));
static_assert(std::invocable<F&>);
static_assert(std::invocable<const F&>);
static_assert(!std::invocable<F>);
static_assert(std::invocable<const F>);
}
{ // Make sure we delete the const&& overload when the underlying call isn't valid.
struct X {
void operator()() &;
void operator()() const&;
void operator()() &&;
void operator()() const&& = delete;
};
using F = decltype(std::bind_back(X{}));
static_assert(std::invocable<F&>);
static_assert(std::invocable<const F&>);
static_assert(std::invocable<F>);
static_assert(!std::invocable<const F>);
}
}
{ // Extra value category tests
struct X {};
{
struct Y {
void operator()(X&&) const&;
void operator()(X&&) && = delete;
};
using F = decltype(std::bind_back(Y{}));
static_assert(std::invocable<F&, X>);
static_assert(!std::invocable<F, X>);
}
{
struct Y {
void operator()(const X&) const;
void operator()(X&&) const = delete;
};
using F = decltype(std::bind_back(Y{}, X{}));
static_assert(std::invocable<F&>);
static_assert(!std::invocable<F>);
}
}
}
constexpr void test_return_type() {
{ // Test properties of the constructor of the unspecified-type returned by bind_back.
{ // Test move constructor when function is move only.
MoveOnlyCallable<bool> value(true);
auto f = std::bind_back(std::move(value), 1);
assert(f());
assert(f(1, 2, 3));
auto f1 = std::move(f);
assert(!f());
assert(f1());
assert(f1(1, 2, 3));
using F = decltype(f);
static_assert(std::is_move_constructible<F>::value);
static_assert(!std::is_copy_constructible<F>::value);
static_assert(!std::is_move_assignable<F>::value);
static_assert(!std::is_copy_assignable<F>::value);
}
{ // Test move constructor when function is copyable but not assignable.
CopyCallable<bool> value(true);
auto f = std::bind_back(value, 1);
assert(f());
assert(f(1, 2, 3));
auto f1 = std::move(f);
assert(!f());
assert(f1());
assert(f1(1, 2, 3));
auto f2 = std::bind_back(std::move(value), 1);
assert(f1());
assert(f2());
assert(f2(1, 2, 3));
using F = decltype(f);
static_assert(std::is_move_constructible<F>::value);
static_assert(std::is_copy_constructible<F>::value);
static_assert(!std::is_move_assignable<F>::value);
static_assert(!std::is_copy_assignable<F>::value);
}
{ // Test constructors when function is copy assignable.
using F = decltype(std::bind_back(std::declval<CopyAssignableWrapper&>(), 1));
static_assert(std::is_move_constructible<F>::value);
static_assert(std::is_copy_constructible<F>::value);
static_assert(std::is_move_assignable<F>::value);
static_assert(std::is_copy_assignable<F>::value);
}
{ // Test constructors when function is move assignable only.
using F = decltype(std::bind_back(std::declval<MoveAssignableWrapper>(), 1));
static_assert(std::is_move_constructible<F>::value);
static_assert(!std::is_copy_constructible<F>::value);
static_assert(std::is_move_assignable<F>::value);
static_assert(!std::is_copy_assignable<F>::value);
}
}
{ // Make sure bind_back's unspecified type's operator() is SFINAE-friendly.
using F = decltype(std::bind_back(std::declval<int (*)(int, int)>(), 1));
static_assert(!std::is_invocable<F>::value);
static_assert(std::is_invocable<F, int>::value);
static_assert(!std::is_invocable<F, void*>::value);
static_assert(!std::is_invocable<F, int, int>::value);
}
}
constexpr bool test() {
test_basic_bindings();
test_edge_cases();
test_passing_arguments();
test_function_objects();
test_return_type();
return true;
}
int main(int, char**) {
test();
static_assert(test());
return 0;
}
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