//===----------------------------------------------------------------------===//
//
// 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
// functional
// template <class F, class... Args>
// constexpr unspecified __bind_back(F&&, Args&&...);
// This isn't part of the standard, however we use it internally and there is a
// chance that it will be added to the standard, so we implement those tests
// as-if it were part of the spec.
#include <functional>
#include <cassert>
#include <tuple>
#include <utility>
#include "callable_types.h"
#include "test_macros.h"
struct CopyMoveInfo {
enum { none, copy, move } copy_kind;
constexpr CopyMoveInfo() : copy_kind(none) {}
constexpr CopyMoveInfo(CopyMoveInfo const&) : copy_kind(copy) {}
constexpr CopyMoveInfo(CopyMoveInfo&&) : copy_kind(move) {}
};
template <class ...Args>
struct is_bind_backable {
template <class ...LocalArgs>
static auto test(int)
-> decltype((void)std::__bind_back(std::declval<LocalArgs>()...), std::true_type());
template <class...>
static std::false_type test(...);
static constexpr bool value = decltype(test<Args...>(0))::value;
};
struct NotCopyMove {
NotCopyMove() = delete;
NotCopyMove(const NotCopyMove&) = delete;
NotCopyMove(NotCopyMove&&) = delete;
template <class ...Args>
void operator()(Args&& ...) const { }
};
struct NonConstCopyConstructible {
explicit NonConstCopyConstructible() {}
NonConstCopyConstructible(NonConstCopyConstructible&) {}
};
struct MoveConstructible {
explicit MoveConstructible() {}
MoveConstructible(MoveConstructible&&) {}
};
struct MakeTuple {
template <class ...Args>
constexpr auto operator()(Args&& ...args) const {
return std::make_tuple(std::forward<Args>(args)...);
}
};
template <int X>
struct Elem {
template <int Y>
constexpr bool operator==(Elem<Y> const&) const
{ return X == Y; }
};
constexpr bool test() {
// 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>{}));
}
}
// Basic tests with fundamental types
{
int n = 2;
int m = 1;
auto add = [](int x, int y) { return x + y; };
auto addN = [](int a, int b, int c, int d, int e, int f) {
return a + b + c + d + e + f;
};
auto a = std::__bind_back(add, m, n);
assert(a() == 3);
auto b = std::__bind_back(addN, m, n, m, m, m, m);
assert(b() == 7);
auto c = std::__bind_back(addN, n, m);
assert(c(1, 1, 1, 1) == 7);
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(addN, 1, 1, 1);
assert(h(2, 2, 2) == 9);
}
// 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, j = 2;
auto f = std::__bind_back(sub, std::ref(i));
assert(f(std::ref(j)) == 2 - 1);
}
// Make sure we can call a function that's a pointer to a member function.
{
struct MemberFunction {
constexpr bool foo(int, int) { return true; }
};
MemberFunction value;
auto fn = std::__bind_back(&MemberFunction::foo, 0, 0);
assert(fn(value));
}
// 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 i = std::__bind_back(add, n, 1);
n = 100;
assert(i() == 3);
}
// Make sure we pass the bound arguments to the function object
// with the right value category.
{
{
auto wasCopied = [](CopyMoveInfo info) {
return info.copy_kind == CopyMoveInfo::copy;
};
CopyMoveInfo info;
auto copied = std::__bind_back(wasCopied, info);
assert(copied());
}
{
auto wasMoved = [](CopyMoveInfo info) {
return info.copy_kind == CopyMoveInfo::move;
};
CopyMoveInfo info;
auto moved = std::__bind_back(wasMoved, info);
assert(std::move(moved)());
}
}
// Make sure we call the correctly cv-ref qualified operator() based on the
// value category of the __bind_back unspecified-type.
{
struct F {
constexpr int operator()() & { return 1; }
constexpr int operator()() const& { return 2; }
constexpr int operator()() && { return 3; }
constexpr int operator()() const&& { return 4; }
};
auto x = std::__bind_back(F{});
using X = decltype(x);
assert(static_cast<X&>(x)() == 1);
assert(static_cast<X const&>(x)() == 2);
assert(static_cast<X&&>(x)() == 3);
assert(static_cast<X const&&>(x)() == 4);
}
// Make sure the __bind_back unspecified-type is NOT 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 F {
void operator()() & = delete;
void operator()() const&;
void operator()() &&;
void operator()() const&&;
};
using X = decltype(std::__bind_back(F{}));
static_assert(!std::is_invocable_v<X&>);
static_assert( std::is_invocable_v<X const&>);
static_assert( std::is_invocable_v<X>);
static_assert( std::is_invocable_v<X const>);
}
// 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 F {
void operator()() &;
void operator()() const&;
void operator()() && = delete;
void operator()() const&&;
};
using X = decltype(std::__bind_back(F{}));
static_assert( std::is_invocable_v<X&>);
static_assert( std::is_invocable_v<X const&>);
static_assert(!std::is_invocable_v<X>);
static_assert( std::is_invocable_v<X const>);
}
// Make sure we delete the const&& overload when the underlying call isn't valid
{
struct F {
void operator()() &;
void operator()() const&;
void operator()() &&;
void operator()() const&& = delete;
};
using X = decltype(std::__bind_back(F{}));
static_assert( std::is_invocable_v<X&>);
static_assert( std::is_invocable_v<X const&>);
static_assert( std::is_invocable_v<X>);
static_assert(!std::is_invocable_v<X const>);
}
}
// Some examples by Tim Song
{
{
struct T { };
struct F {
void operator()(T&&) const &;
void operator()(T&&) && = delete;
};
using X = decltype(std::__bind_back(F{}));
static_assert(!std::is_invocable_v<X, T>);
}
{
struct T { };
struct F {
void operator()(T const&) const;
void operator()(T&&) const = delete;
};
using X = decltype(std::__bind_back(F{}, T{}));
static_assert(!std::is_invocable_v<X>);
}
}
// Test properties of the constructor of the unspecified-type returned by __bind_back.
{
{
MoveOnlyCallable<bool> value(true);
auto ret = std::__bind_back(std::move(value), 1);
assert(ret());
assert(ret(1, 2, 3));
auto ret1 = std::move(ret);
assert(!ret());
assert(ret1());
assert(ret1(1, 2, 3));
using RetT = decltype(ret);
static_assert( std::is_move_constructible<RetT>::value);
static_assert(!std::is_copy_constructible<RetT>::value);
static_assert(!std::is_move_assignable<RetT>::value);
static_assert(!std::is_copy_assignable<RetT>::value);
}
{
CopyCallable<bool> value(true);
auto ret = std::__bind_back(value, 1);
assert(ret());
assert(ret(1, 2, 3));
auto ret1 = std::move(ret);
assert(ret1());
assert(ret1(1, 2, 3));
auto ret2 = std::__bind_back(std::move(value), 1);
assert(!ret());
assert(ret2());
assert(ret2(1, 2, 3));
using RetT = decltype(ret);
static_assert( std::is_move_constructible<RetT>::value);
static_assert( std::is_copy_constructible<RetT>::value);
static_assert(!std::is_move_assignable<RetT>::value);
static_assert(!std::is_copy_assignable<RetT>::value);
}
{
CopyAssignableWrapper value(true);
using RetT = decltype(std::__bind_back(value, 1));
static_assert(std::is_move_constructible<RetT>::value);
static_assert(std::is_copy_constructible<RetT>::value);
static_assert(std::is_move_assignable<RetT>::value);
static_assert(std::is_copy_assignable<RetT>::value);
}
{
MoveAssignableWrapper value(true);
using RetT = decltype(std::__bind_back(std::move(value), 1));
static_assert( std::is_move_constructible<RetT>::value);
static_assert(!std::is_copy_constructible<RetT>::value);
static_assert( std::is_move_assignable<RetT>::value);
static_assert(!std::is_copy_assignable<RetT>::value);
}
}
// Make sure __bind_back is SFINAE friendly
{
static_assert(!std::is_constructible_v<NotCopyMove, NotCopyMove&>);
static_assert(!std::is_move_constructible_v<NotCopyMove>);
static_assert(!is_bind_backable<NotCopyMove>::value);
static_assert(!is_bind_backable<NotCopyMove&>::value);
auto takeAnything = [](auto&& ...) { };
static_assert(!std::is_constructible_v<MoveConstructible, MoveConstructible&>);
static_assert( std::is_move_constructible_v<MoveConstructible>);
static_assert( is_bind_backable<decltype(takeAnything), MoveConstructible>::value);
static_assert(!is_bind_backable<decltype(takeAnything), MoveConstructible&>::value);
static_assert( std::is_constructible_v<NonConstCopyConstructible, NonConstCopyConstructible&>);
static_assert(!std::is_move_constructible_v<NonConstCopyConstructible>);
static_assert(!is_bind_backable<decltype(takeAnything), NonConstCopyConstructible&>::value);
static_assert(!is_bind_backable<decltype(takeAnything), NonConstCopyConstructible>::value);
}
// Make sure bind_back's unspecified type's operator() is SFINAE-friendly
{
using T = decltype(std::__bind_back(std::declval<int(*)(int, int)>(), 1));
static_assert(!std::is_invocable<T>::value);
static_assert( std::is_invocable<T, int>::value);
static_assert(!std::is_invocable<T, void*>::value);
static_assert(!std::is_invocable<T, int, int>::value);
}
return true;
}
int main(int, char**) {
test();
static_assert(test());
return 0;
}
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