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Implement LWG-4016 container-insertable checks do not match what container-inserter does #4539

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Merged
Stephan T. Lavavej (StephanTLavavej) merged 1 commit into from
Apr 9, 2024
Merged

Implement LWG-4016 container-insertable checks do not match what container-inserter does #4539

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37 changes: 24 additions & 13 deletions stl/inc/ranges
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Original file line number Diff line number Diff line change
Expand Up @@ -10328,27 +10328,26 @@ namespace ranges {
&& derived_from<typename iterator_traits<iterator_t<_Rng>>::iterator_category, input_iterator_tag>
&& constructible_from<_Container, iterator_t<_Rng>, iterator_t<_Rng>, _Types...>;

template <class _Container, class _Reference>
concept _Can_emplace_back = requires(_Container& _Cont) { _Cont.emplace_back(_STD declval<_Reference>()); };

template <class _Container, class _Reference>
concept _Can_push_back = requires(_Container& _Cont) { _Cont.push_back(_STD declval<_Reference>()); };

template <class _Container, class _Reference>
concept _Can_emplace_end = requires(_Container& _Cont) { _Cont.emplace(_Cont.end(), _STD declval<_Reference>()); };

template <class _Container, class _Reference>
concept _Can_insert_end = requires(_Container& _Cont) { _Cont.insert(_Cont.end(), _STD declval<_Reference>()); };

template <class _Rng, class _Container, class... _Types>
concept _Converts_constructible_insertable =
concept _Converts_constructible_appendable =
_Ref_converts<_Rng, _Container> && constructible_from<_Container, _Types...>
&& (_Can_push_back<_Container, range_reference_t<_Rng>>
&& (_Can_emplace_back<_Container, range_reference_t<_Rng>>
|| _Can_push_back<_Container, range_reference_t<_Rng>>
|| _Can_emplace_end<_Container, range_reference_t<_Rng>>
|| _Can_insert_end<_Container, range_reference_t<_Rng>>);

template <class _Reference, class _Container>
_NODISCARD constexpr auto _Container_inserter(_Container& _Cont) {
if constexpr (_Can_push_back<_Container, _Reference>) {
return back_insert_iterator{_Cont};
} else {
return insert_iterator{_Cont, _Cont.end()};
}
}

_EXPORT_STD template <class _Container, input_range _Rng, class... _Types>
requires (!view<_Container>)
_NODISCARD constexpr _Container to(_Rng&& _Range, _Types&&... _Args) {
Expand All @@ -10361,12 +10360,24 @@ namespace ranges {
return _Container(from_range, _STD forward<_Rng>(_Range), _STD forward<_Types>(_Args)...);
} else if constexpr (_Converts_and_common_constructible<_Rng, _Container, _Types...>) {
return _Container(_RANGES begin(_Range), _RANGES end(_Range), _STD forward<_Types>(_Args)...);
} else if constexpr (_Converts_constructible_insertable<_Rng, _Container, _Types...>) {
} else if constexpr (_Converts_constructible_appendable<_Rng, _Container, _Types...>) {
_Container _Cont(_STD forward<_Types>(_Args)...);
if constexpr (_Sized_and_reservable<_Rng, _Container>) {
_Cont.reserve(static_cast<range_size_t<_Container>>(_RANGES size(_Range)));
}
_RANGES copy(_Range, _Container_inserter<range_reference_t<_Rng>>(_Cont));
for (auto&& _Elem : _Range) {
using _ElemTy = decltype(_Elem);
if constexpr (_Can_emplace_back<_Container, _ElemTy>) {
_Cont.emplace_back(_STD forward<_ElemTy>(_Elem));
} else if constexpr (_Can_push_back<_Container, _ElemTy>) {
_Cont.push_back(_STD forward<_ElemTy>(_Elem));
} else if constexpr (_Can_emplace_end<_Container, _ElemTy>) {
_Cont.emplace(_Cont.end(), _STD forward<_ElemTy>(_Elem));
} else {
_STL_INTERNAL_STATIC_ASSERT(_Can_insert_end<_Container, _ElemTy>);
_Cont.insert(_Cont.end(), _STD forward<_ElemTy>(_Elem));
}
}
return _Cont;
} else if constexpr (!_Ref_converts<_Rng, _Container> && input_range<range_reference_t<_Rng>>) {
const auto _Xform = [](auto&& _Elem) _STATIC_CALL_OPERATOR {
Expand Down
139 changes: 139 additions & 0 deletions tests/std/tests/P1206R7_ranges_to_misc/test.cpp
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Original file line number Diff line number Diff line change
@@ -1,10 +1,13 @@
// Copyright (c) Microsoft Corporation.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

#include <algorithm>
#include <cassert>
#include <cstddef>
#include <memory>
#include <optional>
#include <ranges>
#include <utility>
#include <vector>

namespace ranges = std::ranges;
Expand Down Expand Up @@ -200,6 +203,139 @@ constexpr bool test_lwg3785() {
return true;
}

enum class restriction_kind {
emplace_back,
push_back,
emplace,
insert,
};

template <restriction_kind K, class T, class A = std::allocator<T>>
class restricted_vector : private std::vector<T, A> {
private:
using base_type = std::vector<T, A>;

public:
using typename base_type::allocator_type;
using typename base_type::const_iterator;
using typename base_type::const_reverse_iterator;
using typename base_type::difference_type;
using typename base_type::iterator;
using typename base_type::pointer;
using typename base_type::reference;
using typename base_type::reverse_iterator;
using typename base_type::size_type;
using typename base_type::value_type;

restricted_vector() = default;
constexpr explicit restricted_vector(const A& alloc) noexcept : base_type(alloc) {}
constexpr explicit restricted_vector(const size_type n, const A& alloc = A()) : base_type(n, alloc) {}
constexpr restricted_vector(const size_type n, const T& val, const A& alloc = A()) : base_type(n, val, alloc) {}
constexpr restricted_vector(const std::initializer_list<T> il, const A& alloc = A()) : base_type(il, alloc) {}
constexpr restricted_vector(const restricted_vector& other, const A& alloc) : base_type(other, alloc) {}
constexpr restricted_vector(restricted_vector&& other, const A& alloc) noexcept(
std::allocator_traits<A>::is_always_equal::value)
: base_type(std::move(other), alloc) {}

using base_type::begin;
using base_type::cbegin;
using base_type::cend;
using base_type::crbegin;
using base_type::crend;
using base_type::end;
using base_type::rbegin;
using base_type::rend;

using base_type::back;
using base_type::front;
using base_type::operator[];
using base_type::at;
using base_type::data;

template <class... Args>
constexpr T& emplace_back(Args&&... args)
requires (K == restriction_kind::emplace_back)
{
return base_type::emplace_back(std::forward<Args>(args)...);
}

constexpr void push_back(const T& t)
requires (K == restriction_kind::push_back)
{
base_type::emplace_back(t);
}
constexpr void push_back(T&& t)
requires (K == restriction_kind::push_back)
{
base_type::emplace_back(std::move(t));
}

template <class... Args>
constexpr iterator emplace(const const_iterator it, Args&&... args)
requires (K == restriction_kind::emplace)
{
return base_type::emplace(it, std::forward<Args>(args)...);
}

constexpr iterator insert(const const_iterator it, const T& t)
requires (K == restriction_kind::insert)
{
return base_type::emplace(it, t);
}
constexpr iterator insert(const const_iterator it, T&& t)
requires (K == restriction_kind::insert)
{
return base_type::emplace(it, std::move(t));
}
};

template <restriction_kind K>
constexpr void test_lwg4016_per_kind() {
using V = restricted_vector<K, int>;
{
std::same_as<V> auto vec = std::views::iota(0, 42) | ranges::to<V>();
assert(ranges::equal(vec, std::views::iota(0, 42)));
}
{
std::same_as<V> auto vec = std::views::iota(0, 42) | ranges::to<V>(std::allocator<int>{});
assert(ranges::equal(vec, std::views::iota(0, 42)));
}
{
std::same_as<V> auto vec = std::views::empty<int> | ranges::to<V>(std::size_t{42});
assert(ranges::equal(vec, std::views::repeat(0, 42)));
}
{
std::same_as<V> auto vec = std::views::empty<int> | ranges::to<V>(std::size_t{42}, std::allocator<int>{});
assert(ranges::equal(vec, std::views::repeat(0, 42)));
}
{
std::same_as<V> auto vec = ranges::to<V>(std::views::iota(0, 42), std::initializer_list<int>{-3, -2, -1});
assert(ranges::equal(vec, std::views::iota(-3, 42)));
}
{
std::same_as<V> auto vec =
ranges::to<V>(std::views::iota(0, 42), std::initializer_list<int>{-3, -2, -1}, std::allocator<int>{});
assert(ranges::equal(vec, std::views::iota(-3, 42)));
}
{
std::same_as<V> auto vec = ranges::to<V>(std::views::iota(0, 42), V{-3, -2, -1}, std::allocator<int>{});
assert(ranges::equal(vec, std::views::iota(-3, 42)));
}
{
V vec0{1, 2, 3};
std::same_as<V> auto vec = ranges::to<V>(std::views::iota(4, 7), vec0, std::allocator<int>{});
assert(ranges::equal(vec, std::views::iota(1, 7)));
}
}

constexpr bool test_lwg4016() {
test_lwg4016_per_kind<restriction_kind::emplace_back>();
test_lwg4016_per_kind<restriction_kind::push_back>();
test_lwg4016_per_kind<restriction_kind::emplace>();
test_lwg4016_per_kind<restriction_kind::insert>();
return true;
}

int main() {
test_reservable();
static_assert(test_reservable());
Expand All @@ -217,4 +353,7 @@ int main() {

test_lwg3785();
static_assert(test_lwg3785());

test_lwg4016();
static_assert(test_lwg4016());
}