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c8917048e3
Implement `std::bind_back` function from P2387R3 "Pipe support for user-defined range adaptors".
382 lines
12 KiB
C++
382 lines
12 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
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// <functional>
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// template<class F, class... Args>
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// constexpr unspecified bind_back(F&& f, Args&&... args);
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#include <functional>
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#include <cassert>
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#include <concepts>
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#include <tuple>
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#include <utility>
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#include "callable_types.h"
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#include "types.h"
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constexpr void test_basic_bindings() {
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{ // Bind arguments, call without arguments
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{
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auto f = std::bind_back(MakeTuple{});
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assert(f() == std::make_tuple());
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}
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{
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auto f = std::bind_back(MakeTuple{}, Elem<1>{});
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assert(f() == std::make_tuple(Elem<1>{}));
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}
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{
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auto f = std::bind_back(MakeTuple{}, Elem<1>{}, Elem<2>{});
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assert(f() == std::make_tuple(Elem<1>{}, Elem<2>{}));
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}
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{
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auto f = std::bind_back(MakeTuple{}, Elem<1>{}, Elem<2>{}, Elem<3>{});
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assert(f() == std::make_tuple(Elem<1>{}, Elem<2>{}, Elem<3>{}));
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}
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}
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{ // Bind no arguments, call with arguments
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{
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auto f = std::bind_back(MakeTuple{});
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assert(f(Elem<1>{}) == std::make_tuple(Elem<1>{}));
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}
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{
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auto f = std::bind_back(MakeTuple{});
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assert(f(Elem<1>{}, Elem<2>{}) == std::make_tuple(Elem<1>{}, Elem<2>{}));
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}
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{
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auto f = std::bind_back(MakeTuple{});
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assert(f(Elem<1>{}, Elem<2>{}, Elem<3>{}) == std::make_tuple(Elem<1>{}, Elem<2>{}, Elem<3>{}));
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}
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}
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{ // Bind arguments, call with arguments
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{
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auto f = std::bind_back(MakeTuple{}, Elem<1>{});
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assert(f(Elem<10>{}) == std::make_tuple(Elem<10>{}, Elem<1>{}));
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}
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{
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auto f = std::bind_back(MakeTuple{}, Elem<1>{}, Elem<2>{});
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assert(f(Elem<10>{}) == std::make_tuple(Elem<10>{}, Elem<1>{}, Elem<2>{}));
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}
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{
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auto f = std::bind_back(MakeTuple{}, Elem<1>{}, Elem<2>{}, Elem<3>{});
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assert(f(Elem<10>{}) == std::make_tuple(Elem<10>{}, Elem<1>{}, Elem<2>{}, Elem<3>{}));
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}
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{
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auto f = std::bind_back(MakeTuple{}, Elem<1>{});
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assert(f(Elem<10>{}, Elem<11>{}) == std::make_tuple(Elem<10>{}, Elem<11>{}, Elem<1>{}));
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}
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{
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auto f = std::bind_back(MakeTuple{}, Elem<1>{}, Elem<2>{});
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assert(f(Elem<10>{}, Elem<11>{}) == std::make_tuple(Elem<10>{}, Elem<11>{}, Elem<1>{}, Elem<2>{}));
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}
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{
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auto f = std::bind_back(MakeTuple{}, Elem<1>{}, Elem<2>{}, Elem<3>{});
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assert(f(Elem<10>{}, Elem<11>{}) == std::make_tuple(Elem<10>{}, Elem<11>{}, Elem<1>{}, Elem<2>{}, Elem<3>{}));
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}
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{
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auto f = std::bind_back(MakeTuple{}, Elem<1>{}, Elem<2>{}, Elem<3>{});
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assert(f(Elem<10>{}, Elem<11>{}, Elem<12>{}) ==
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std::make_tuple(Elem<10>{}, Elem<11>{}, Elem<12>{}, Elem<1>{}, Elem<2>{}, Elem<3>{}));
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}
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}
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{ // Basic tests with fundamental types
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int n = 2;
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int m = 1;
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int sum = 0;
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auto add = [](int x, int y) { return x + y; };
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auto add_n = [](int a, int b, int c, int d, int e, int f) { return a + b + c + d + e + f; };
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auto add_ref = [&](int x, int y) -> int& { return sum = x + y; };
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auto add_rref = [&](int x, int y) -> int&& { return std::move(sum = x + y); };
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auto a = std::bind_back(add, m, n);
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assert(a() == 3);
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auto b = std::bind_back(add_n, m, n, m, m, m, m);
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assert(b() == 7);
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auto c = std::bind_back(add_n, n, m);
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assert(c(1, 1, 1, 1) == 7);
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auto d = std::bind_back(add_ref, n, m);
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std::same_as<int&> decltype(auto) dresult(d());
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assert(dresult == 3);
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auto e = std::bind_back(add_rref, n, m);
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std::same_as<int&&> decltype(auto) eresult(e());
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assert(eresult == 3);
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auto f = std::bind_back(add, n);
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assert(f(3) == 5);
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auto g = std::bind_back(add, n, 1);
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assert(g() == 3);
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auto h = std::bind_back(add_n, 1, 1, 1);
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assert(h(2, 2, 2) == 9);
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auto i = std::bind_back(add_ref, n);
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std::same_as<int&> decltype(auto) iresult(i(5));
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assert(iresult == 7);
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auto j = std::bind_back(add_rref, m);
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std::same_as<int&&> decltype(auto) jresult(j(4));
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assert(jresult == 5);
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}
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}
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constexpr void test_edge_cases() {
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{ // Make sure we don't treat std::reference_wrapper specially.
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auto sub = [](std::reference_wrapper<int> a, std::reference_wrapper<int> b) { return a.get() - b.get(); };
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int i = 1;
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int j = 2;
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auto f = std::bind_back(sub, std::ref(i));
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assert(f(std::ref(j)) == 1);
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}
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{ // Make sure we can call a function that's a pointer to a member function.
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struct MemberFunction {
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constexpr int foo(int x, int y) { return x * y; }
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};
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MemberFunction value;
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auto fn = std::bind_back(&MemberFunction::foo, 2, 3);
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assert(fn(value) == 6);
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}
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{ // Make sure we can call a function that's a pointer to a member object.
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struct MemberObject {
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int obj;
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};
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MemberObject value{.obj = 3};
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auto fn = std::bind_back(&MemberObject::obj);
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assert(fn(value) == 3);
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}
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}
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constexpr void test_passing_arguments() {
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{ // Make sure that we copy the bound arguments into the unspecified-type.
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auto add = [](int x, int y) { return x + y; };
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int n = 2;
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auto f = std::bind_back(add, n, 1);
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n = 100;
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assert(f() == 3);
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}
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{ // Make sure we pass the bound arguments to the function object
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// with the right value category.
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{
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auto was_copied = [](CopyMoveInfo info) { return info.copy_kind == CopyMoveInfo::copy; };
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CopyMoveInfo info;
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auto f = std::bind_back(was_copied, info);
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assert(f());
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}
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{
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auto was_moved = [](CopyMoveInfo info) { return info.copy_kind == CopyMoveInfo::move; };
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CopyMoveInfo info;
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auto f = std::bind_back(was_moved, info);
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assert(std::move(f)());
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}
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}
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}
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constexpr void test_function_objects() {
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{ // Make sure we call the correctly cv-ref qualified operator()
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// based on the value category of the bind_back unspecified-type.
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struct X {
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constexpr int operator()() & { return 1; }
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constexpr int operator()() const& { return 2; }
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constexpr int operator()() && { return 3; }
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constexpr int operator()() const&& { return 4; }
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};
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auto f = std::bind_back(X{});
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using F = decltype(f);
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assert(static_cast<F&>(f)() == 1);
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assert(static_cast<const F&>(f)() == 2);
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assert(static_cast<F&&>(f)() == 3);
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assert(static_cast<const F&&>(f)() == 4);
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}
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// Make sure the `bind_back` unspecified-type does not model invocable
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// when the call would select a differently-qualified operator().
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//
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// For example, if the call to `operator()() &` is ill-formed, the call to the unspecified-type
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// should be ill-formed and not fall back to the `operator()() const&` overload.
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{ // Make sure we delete the & overload when the underlying call isn't valid.
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{
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struct X {
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void operator()() & = delete;
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void operator()() const&;
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void operator()() &&;
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void operator()() const&&;
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};
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using F = decltype(std::bind_back(X{}));
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static_assert(!std::invocable<F&>);
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static_assert(std::invocable<const F&>);
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static_assert(std::invocable<F>);
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static_assert(std::invocable<const F>);
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}
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// There's no way to make sure we delete the const& overload when the underlying call isn't valid,
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// so we can't check this one.
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{ // Make sure we delete the && overload when the underlying call isn't valid.
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struct X {
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void operator()() &;
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void operator()() const&;
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void operator()() && = delete;
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void operator()() const&&;
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};
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using F = decltype(std::bind_back(X{}));
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static_assert(std::invocable<F&>);
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static_assert(std::invocable<const F&>);
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static_assert(!std::invocable<F>);
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static_assert(std::invocable<const F>);
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}
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{ // Make sure we delete the const&& overload when the underlying call isn't valid.
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struct X {
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void operator()() &;
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void operator()() const&;
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void operator()() &&;
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void operator()() const&& = delete;
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};
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using F = decltype(std::bind_back(X{}));
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static_assert(std::invocable<F&>);
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static_assert(std::invocable<const F&>);
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static_assert(std::invocable<F>);
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static_assert(!std::invocable<const F>);
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}
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}
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{ // Extra value category tests
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struct X {};
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{
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struct Y {
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void operator()(X&&) const&;
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void operator()(X&&) && = delete;
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};
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using F = decltype(std::bind_back(Y{}));
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static_assert(std::invocable<F&, X>);
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static_assert(!std::invocable<F, X>);
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}
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{
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struct Y {
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void operator()(const X&) const;
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void operator()(X&&) const = delete;
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};
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using F = decltype(std::bind_back(Y{}, X{}));
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static_assert(std::invocable<F&>);
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static_assert(!std::invocable<F>);
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}
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}
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}
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constexpr void test_return_type() {
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{ // Test properties of the constructor of the unspecified-type returned by bind_back.
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{ // Test move constructor when function is move only.
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MoveOnlyCallable<bool> value(true);
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auto f = std::bind_back(std::move(value), 1);
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assert(f());
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assert(f(1, 2, 3));
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auto f1 = std::move(f);
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assert(!f());
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assert(f1());
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assert(f1(1, 2, 3));
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using F = decltype(f);
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static_assert(std::is_move_constructible<F>::value);
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static_assert(!std::is_copy_constructible<F>::value);
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static_assert(!std::is_move_assignable<F>::value);
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static_assert(!std::is_copy_assignable<F>::value);
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}
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{ // Test move constructor when function is copyable but not assignable.
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CopyCallable<bool> value(true);
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auto f = std::bind_back(value, 1);
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assert(f());
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assert(f(1, 2, 3));
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auto f1 = std::move(f);
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assert(!f());
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assert(f1());
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assert(f1(1, 2, 3));
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auto f2 = std::bind_back(std::move(value), 1);
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assert(f1());
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assert(f2());
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assert(f2(1, 2, 3));
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using F = decltype(f);
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static_assert(std::is_move_constructible<F>::value);
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static_assert(std::is_copy_constructible<F>::value);
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static_assert(!std::is_move_assignable<F>::value);
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static_assert(!std::is_copy_assignable<F>::value);
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}
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{ // Test constructors when function is copy assignable.
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using F = decltype(std::bind_back(std::declval<CopyAssignableWrapper&>(), 1));
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static_assert(std::is_move_constructible<F>::value);
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static_assert(std::is_copy_constructible<F>::value);
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static_assert(std::is_move_assignable<F>::value);
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static_assert(std::is_copy_assignable<F>::value);
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}
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{ // Test constructors when function is move assignable only.
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using F = decltype(std::bind_back(std::declval<MoveAssignableWrapper>(), 1));
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static_assert(std::is_move_constructible<F>::value);
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static_assert(!std::is_copy_constructible<F>::value);
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static_assert(std::is_move_assignable<F>::value);
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static_assert(!std::is_copy_assignable<F>::value);
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}
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}
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{ // Make sure bind_back's unspecified type's operator() is SFINAE-friendly.
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using F = decltype(std::bind_back(std::declval<int (*)(int, int)>(), 1));
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static_assert(!std::is_invocable<F>::value);
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static_assert(std::is_invocable<F, int>::value);
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static_assert(!std::is_invocable<F, void*>::value);
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static_assert(!std::is_invocable<F, int, int>::value);
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}
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}
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constexpr bool test() {
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test_basic_bindings();
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test_edge_cases();
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test_passing_arguments();
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test_function_objects();
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test_return_type();
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return true;
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}
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int main(int, char**) {
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test();
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static_assert(test());
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return 0;
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}
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