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//===----------------------------------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
// REQUIRES: std-at-least-c++23
// <ranges>
// constexpr decltype(auto) operator*() const;
#include <ranges>
#include <array>
#include <cassert>
#include <cstddef>
#include <string>
#include <string_view>
#include <type_traits>
#include <utility>
#include <vector>
#include "../types.h"
struct ProxyRef {
int& val;
};
class CommonProxyRef {
public:
constexpr CommonProxyRef(ProxyRef i) : val(i.val) {}
constexpr CommonProxyRef(int i) : val(i) {}
constexpr int get() const { return val; }
private:
int val;
};
template <template <class> class TQual, template <class> class UQual>
struct std::basic_common_reference<ProxyRef, int, TQual, UQual> {
using type = CommonProxyRef;
};
template <template <class> class TQual, template <class> class UQual>
struct std::basic_common_reference<int, ProxyRef, TQual, UQual> {
using type = CommonProxyRef;
};
static_assert(std::common_reference_with<int&, ProxyRef>);
static_assert(std::common_reference_with<int&, CommonProxyRef>);
class ProxyIter {
public:
using value_type = int;
using difference_type = std::ptrdiff_t;
constexpr ProxyIter() : ptr_(nullptr) {}
constexpr explicit ProxyIter(int* p) : ptr_(p) {}
constexpr ProxyRef operator*() const { return ProxyRef{*ptr_}; }
constexpr ProxyIter& operator++() {
++ptr_;
return *this;
}
constexpr ProxyIter operator++(int) {
ProxyIter tmp = *this;
++ptr_;
return tmp;
}
constexpr bool operator==(const ProxyIter& other) const { return ptr_ == other.ptr_; }
private:
int* ptr_;
};
static_assert(std::forward_iterator<ProxyIter>);
constexpr bool test() {
{ // Result of `operator*` is (maybe const) lvalue reference
using V = std::ranges::owning_view<std::vector<std::string>>;
using Pattern = std::ranges::owning_view<std::string>;
using JWV = std::ranges::join_with_view<V, Pattern>;
JWV jwv(V{{"ab", "cd", "ef"}}, Pattern{"><"});
{
auto it = jwv.begin();
std::same_as<char&> decltype(auto) v_ref = *std::as_const(it);
assert(v_ref == 'a');
std::ranges::advance(it, 2);
std::same_as<char&> decltype(auto) pattern_ref = *it;
assert(pattern_ref == '>');
}
{
auto cit = std::as_const(jwv).begin();
std::same_as<const char&> decltype(auto) cv_ref = *cit;
assert(cv_ref == 'a');
std::ranges::advance(cit, 3);
std::same_as<const char&> decltype(auto) cpattern_ref = *std::as_const(cit);
assert(cpattern_ref == '<');
}
}
{ // Result of `operator*` is const lvalue reference
using V = std::ranges::owning_view<std::vector<std::string_view>>;
using Pattern = std::string_view;
using JWV = std::ranges::join_with_view<V, Pattern>;
JWV jwv(V{{"123", "456", "789"}}, Pattern{"._."});
{
auto it = jwv.begin();
std::same_as<const char&> decltype(auto) v_ref = *it;
assert(v_ref == '1');
std::ranges::advance(it, 3);
std::same_as<const char&> decltype(auto) pattern_ref = *std::as_const(it);
assert(pattern_ref == '.');
}
{
auto cit = std::as_const(jwv).begin();
std::same_as<const char&> decltype(auto) cv_ref = *std::as_const(cit);
assert(cv_ref == '1');
std::ranges::advance(cit, 4);
std::same_as<const char&> decltype(auto) cpattern_ref = *cit;
assert(cpattern_ref == '_');
}
}
{ // Result of `operator*` is prvalue
using V = std::vector<std::string_view>;
using Pattern = RvalueVector<char>;
using JWV = std::ranges::join_with_view<std::ranges::owning_view<V>, std::ranges::owning_view<Pattern>>;
JWV jwv(V{"x^2", "y^2", "z^2"}, Pattern{{' ', '+', ' '}});
{
auto it = jwv.begin();
std::same_as<char> decltype(auto) v_ref = *std::as_const(it);
assert(v_ref == 'x');
std::ranges::advance(it, 3);
std::same_as<char> decltype(auto) pattern_ref = *it;
assert(pattern_ref == ' ');
}
{
auto cit = std::as_const(jwv).begin();
std::same_as<char> decltype(auto) cv_ref = *cit;
assert(cv_ref == 'x');
std::ranges::advance(cit, 4);
std::same_as<char> decltype(auto) cpattern_ref = *std::as_const(cit);
assert(cpattern_ref == '+');
}
}
{ // Result of `operator*` is (maybe const) rvalue reference
using Inner = std::ranges::as_rvalue_view<std::ranges::owning_view<std::string>>;
using V = std::ranges::owning_view<std::vector<Inner>>;
using Pattern = std::ranges::as_rvalue_view<std::ranges::owning_view<std::array<char, 2>>>;
using JWV = std::ranges::join_with_view<V, Pattern>;
std::vector<Inner> vec;
vec.emplace_back(Inner{{"x*y"}});
vec.emplace_back(Inner{{"y*z"}});
vec.emplace_back(Inner{{"z*x"}});
JWV jwv(V(std::move(vec)), Pattern(std::array{',', ' '}));
{
auto it = jwv.begin();
std::same_as<char&&> decltype(auto) v_ref = *it;
assert(v_ref == 'x');
std::ranges::advance(it, 3);
std::same_as<char&&> decltype(auto) pattern_ref = *std::as_const(it);
assert(pattern_ref == ',');
}
{
auto cit = std::as_const(jwv).begin();
std::same_as<const char&&> decltype(auto) cv_ref = *std::as_const(cit);
assert(cv_ref == 'x');
std::ranges::advance(cit, 4);
std::same_as<const char&&> decltype(auto) cpattern_ref = *cit;
assert(cpattern_ref == ' ');
}
}
{ // Result of `operator*` is type different from range_reference_t<InnerRng> and range_reference_t<Pattern>
using Inner = std::vector<int>;
using V = std::vector<Inner>;
using Pattern = std::ranges::subrange<ProxyIter, ProxyIter>;
using JWV = std::ranges::join_with_view<std::ranges::owning_view<V>, Pattern>;
static_assert(!std::same_as<std::ranges::range_reference_t<V>, std::ranges::range_reference_t<JWV>>);
static_assert(!std::same_as<std::ranges::range_reference_t<Pattern>, std::ranges::range_reference_t<JWV>>);
std::array<int, 2> pattern = {-1, -1};
Pattern pattern_as_subrange(ProxyIter{pattern.data()}, ProxyIter{pattern.data() + pattern.size()});
JWV jwv(V{Inner{1, 1}, Inner{2, 2}, Inner{3, 3}}, pattern_as_subrange);
auto it = jwv.begin();
std::same_as<CommonProxyRef> decltype(auto) v_ref = *it;
assert(v_ref.get() == 1);
std::ranges::advance(it, 7);
std::same_as<CommonProxyRef> decltype(auto) pattern_ref = *std::as_const(it);
assert(pattern_ref.get() == -1);
}
return true;
}
int main(int, char**) {
test();
static_assert(test());
return 0;
}
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