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// Copyright (C) 2021-2022 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING3. If not see
// <http://www.gnu.org/licenses/>.
// { dg-options "-std=gnu++23" }
// { dg-do run { target c++23 } }
#include <string_view>
#include <testsuite_hooks.h>
void
test01()
{
struct R
{
const char* begin() const
{ return str; }
const char* end() const
{ return str + std::char_traits<char>::length(str); }
const char* str = "Home on the range";
};
R r;
std::string_view s{r};
VERIFY( s == r.str );
VERIFY( s.data() == std::ranges::data(r) );
VERIFY( s.size() == std::ranges::size(r) );
struct R2 : R
{
using R::begin;
using R::end;
operator std::string_view() const { return "Out of range"; }
};
static_assert( std::ranges::contiguous_range<R2> );
static_assert( std::ranges::sized_range<R2> );
R2 r2;
std::string_view s2(r2); // uses conversion to string_view
VERIFY( s2 == "Out of range" );
VERIFY( std::string_view(const_cast<const R2&>(r2)) == s2 );
// And again using copy-initialization instead of direct-initialization.
std::string_view s2_implicit = r2; // uses conversion to string_view
VERIFY( s2_implicit == "Out of range" );
VERIFY( std::string_view(const_cast<const R2&>(r2)) == s2_implicit );
struct R3 : R
{
using R::begin;
using R::end;
operator const char*() { return "Orange"; }
};
static_assert( std::ranges::contiguous_range<R3> );
static_assert( std::ranges::sized_range<R3> );
R3 r3;
std::string_view s3(r3); // uses conversion to const char*
VERIFY( s3 == "Orange" );
s3 = std::string_view(const_cast<const R3&>(r3)); // uses range constructor
VERIFY( s3 == "Home on the range" );
struct R4 : R
{
using R::begin;
using R::end;
operator std::string_view() { return "Strange"; }
};
static_assert( std::ranges::contiguous_range<R4> );
static_assert( std::ranges::sized_range<R4> );
R4 r4;
std::string_view s4 = r4; // Uses conversion to string_view
VERIFY( s4 == "Strange" );
// Cannot construct from const R4 because of non-const conversion op:
static_assert( ! std::is_constructible_v<std::string_view, const R4&> );
struct R5 : R
{
using R::begin;
using R::end;
operator std::string_view() && { return "Stranger"; }
};
static_assert( std::ranges::contiguous_range<R5> );
static_assert( std::ranges::sized_range<R5> );
R5 r5;
std::string_view s5(r5); // Uses range constructor
VERIFY( s5 == r5.str );
s5 = std::string_view(std::move(r5)); // In C++20 this used conversion op.
VERIFY( s5 == r5.str ); // In C++23 it uses range constructor.
char arr[] = "arrangement\0with\0nulls";
std::string_view sa = arr; // Does not use range constructor
VERIFY( sa.data() == arr );
VERIFY( sa == "arrangement" );
VERIFY( std::end(sa) != std::end(arr) );
}
void
test02()
{
using V1 = std::basic_string_view<signed char>;
// range_value_t<V1> is not the right type
static_assert( ! std::is_constructible_v<std::string_view, V1> );
using V2 = std::basic_string_view<char, __gnu_cxx::char_traits<char>>;
// V2::traits_type is not the right type
static_assert( ! std::is_constructible_v<std::string_view, V2> );
struct V3 : V2
{
private:
using V2::traits_type;
};
// V3::traits_type is not a valid (accessible) type
static_assert( std::is_constructible_v<std::string_view, V3> );
struct V4 : V2
{
using traits_type = std::string_view::traits_type;
};
// V4::traits_type is the right type
static_assert( std::is_constructible_v<std::string_view, V4> );
}
void
test03()
{
struct R
{
char* begin() { return nullptr; }
const char* begin() const noexcept { return nullptr; }
char* end() { return nullptr; }
const char* end() const noexcept { return nullptr; }
};
static_assert( ! noexcept(std::string_view(std::declval<R&>())) );
static_assert( noexcept(std::string_view(std::declval<const R&>())) );
}
void
test04()
{
struct R
{
const char* begin() const { return nullptr; }
const char* end() const { return nullptr; }
};
R r;
std::basic_string_view s(r); // Use deduction guide.
static_assert( std::is_same_v<decltype(s), std::string_view> );
}
void
test05()
{
struct R
{
const char* begin() const { return nullptr; }
const char* end() const { return nullptr; }
};
// P2499R0 string_view range constructor should be explicit
// P2516R0 string_view is implicitly convertible from what?
static_assert( ! std::is_convertible_v<R, std::string_view> );
}
int main()
{
test01();
test02();
test03();
test04();
test05();
}
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