mirror of
git://gcc.gnu.org/git/gcc.git
synced 2025-04-13 21:01:29 +08:00
libstdc++: Implement string_view range constructor for C++20
This implements the new string_view constructor proposed by P1989R2. This hasn't been voted into the C++23 draft yet, but it's been reviewed by LWG and is expected to be approved at the next WG21 meeting. libstdc++-v3/ChangeLog: * include/std/string_view (basic_string_view(Range&&)): Define new constructor and deduction guide. * testsuite/21_strings/basic_string_view/cons/char/range_c++20.cc: New test. * testsuite/21_strings/basic_string_view/cons/wchar_t/range_c++20.cc: New test.
This commit is contained in:
Jonathan Wakely
parent
2bfd081f1b
commit
7c1006135d
@ -45,6 +45,10 @@
|
||||
#include <bits/ostream_insert.h>
|
||||
#include <ext/numeric_traits.h>
|
||||
|
||||
#if __cplusplus > 202002L
|
||||
# include <bits/ranges_base.h>
|
||||
#endif
|
||||
|
||||
namespace std _GLIBCXX_VISIBILITY(default)
|
||||
{
|
||||
_GLIBCXX_BEGIN_NAMESPACE_VERSION
|
||||
@ -135,7 +139,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
|
||||
: _M_len{__len}, _M_str{__str}
|
||||
{ }
|
||||
|
||||
#if __cplusplus > 201703L && __cpp_lib_concepts
|
||||
#if __cplusplus >= 202002L && __cpp_lib_concepts
|
||||
template<contiguous_iterator _It, sized_sentinel_for<_It> _End>
|
||||
requires same_as<iter_value_t<_It>, _CharT>
|
||||
&& (!convertible_to<_End, size_type>)
|
||||
@ -143,7 +147,26 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
|
||||
basic_string_view(_It __first, _End __last)
|
||||
: _M_len(__last - __first), _M_str(std::to_address(__first))
|
||||
{ }
|
||||
#endif
|
||||
|
||||
#if __cplusplus > 202002L
|
||||
template<typename _Range, typename _DRange = remove_cvref_t<_Range>>
|
||||
requires (!is_same_v<_DRange, basic_string_view>)
|
||||
&& ranges::contiguous_range<_Range>
|
||||
&& ranges::sized_range<_Range>
|
||||
&& is_same_v<ranges::range_value_t<_Range>, _CharT>
|
||||
&& (!is_convertible_v<_Range, const _CharT*>)
|
||||
&& (!requires (_DRange& __d) {
|
||||
__d.operator ::std::basic_string_view<_CharT, _Traits>();
|
||||
})
|
||||
&& (!requires { typename _DRange::traits_type; }
|
||||
|| is_same_v<typename _DRange::traits_type, _Traits>)
|
||||
constexpr
|
||||
basic_string_view(_Range&& __r)
|
||||
noexcept(noexcept(ranges::size(__r)) && noexcept(ranges::data(__r)))
|
||||
: _M_len(ranges::size(__r)), _M_str(ranges::data(__r))
|
||||
{ }
|
||||
#endif // C++23
|
||||
#endif // C++20
|
||||
|
||||
constexpr basic_string_view&
|
||||
operator=(const basic_string_view&) noexcept = default;
|
||||
@ -490,6 +513,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
|
||||
#if __cplusplus > 201703L && __cpp_lib_concepts && __cpp_deduction_guides
|
||||
template<contiguous_iterator _It, sized_sentinel_for<_It> _End>
|
||||
basic_string_view(_It, _End) -> basic_string_view<iter_value_t<_It>>;
|
||||
|
||||
#if __cplusplus > 202002L
|
||||
template<ranges::contiguous_range _Range>
|
||||
basic_string_view(_Range&&)
|
||||
-> basic_string_view<ranges::range_value_t<_Range>>;
|
||||
#endif
|
||||
#endif
|
||||
|
||||
// [string.view.comparison], non-member basic_string_view comparison function
|
||||
|
||||
@ -0,0 +1,170 @@
|
||||
// Copyright (C) 2021 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 );
|
||||
|
||||
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> );
|
||||
}
|
||||
|
||||
int main()
|
||||
{
|
||||
test01();
|
||||
test02();
|
||||
test03();
|
||||
test04();
|
||||
}
|
||||
@ -0,0 +1,170 @@
|
||||
// Copyright (C) 2021 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 wchar_t* begin() const
|
||||
{ return str; }
|
||||
|
||||
const wchar_t* end() const
|
||||
{ return str + std::char_traits<wchar_t>::length(str); }
|
||||
|
||||
const wchar_t* str = L"Home on the range";
|
||||
};
|
||||
|
||||
R r;
|
||||
std::wstring_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::wstring_view() const { return L"Out of range"; }
|
||||
};
|
||||
static_assert( std::ranges::contiguous_range<R2> );
|
||||
static_assert( std::ranges::sized_range<R2> );
|
||||
R2 r2;
|
||||
std::wstring_view s2 = r2; // uses conversion to wstring_view
|
||||
VERIFY( s2 == L"Out of range" );
|
||||
VERIFY( std::wstring_view(const_cast<const R2&>(r2)) == s2 );
|
||||
|
||||
struct R3 : R
|
||||
{
|
||||
using R::begin;
|
||||
using R::end;
|
||||
operator const wchar_t*() { return L"Orange"; }
|
||||
};
|
||||
static_assert( std::ranges::contiguous_range<R3> );
|
||||
static_assert( std::ranges::sized_range<R3> );
|
||||
R3 r3;
|
||||
std::wstring_view s3(r3); // uses conversion to const wchar_t*
|
||||
VERIFY( s3 == L"Orange" );
|
||||
s3 = std::wstring_view(const_cast<const R3&>(r3)); // uses range constructor
|
||||
VERIFY( s3 == L"Home on the range" );
|
||||
|
||||
struct R4 : R
|
||||
{
|
||||
using R::begin;
|
||||
using R::end;
|
||||
operator std::wstring_view() { return L"Strange"; }
|
||||
};
|
||||
static_assert( std::ranges::contiguous_range<R4> );
|
||||
static_assert( std::ranges::sized_range<R4> );
|
||||
R4 r4;
|
||||
std::wstring_view s4 = r4; // Uses conversion to wstring_view
|
||||
VERIFY( s4 == L"Strange" );
|
||||
// Cannot construct from const R4 because of non-const conversion op:
|
||||
static_assert( ! std::is_constructible_v<std::wstring_view, const R4&> );
|
||||
|
||||
struct R5 : R
|
||||
{
|
||||
using R::begin;
|
||||
using R::end;
|
||||
operator std::wstring_view() && { return L"Stranger"; }
|
||||
};
|
||||
static_assert( std::ranges::contiguous_range<R5> );
|
||||
static_assert( std::ranges::sized_range<R5> );
|
||||
R5 r5;
|
||||
std::wstring_view s5 = r5; // Uses range constructor
|
||||
VERIFY( s5 == r5.str );
|
||||
s5 = std::wstring_view(std::move(r5)); // In C++20 this used conversion op.
|
||||
VERIFY( s5 == r5.str ); // In C++23 it uses range constructor.
|
||||
|
||||
wchar_t arr[] = L"arrangement\0with\0nulls";
|
||||
std::wstring_view sa = arr; // Does not use range constructor
|
||||
VERIFY( sa.data() == arr );
|
||||
VERIFY( sa == L"arrangement" );
|
||||
VERIFY( std::end(sa) != std::end(arr) );
|
||||
}
|
||||
|
||||
void
|
||||
test02()
|
||||
{
|
||||
using V1 = std::basic_string_view<char>;
|
||||
// range_value_t<V1> is not the right type
|
||||
static_assert( ! std::is_constructible_v<std::wstring_view, V1> );
|
||||
|
||||
using V2 = std::basic_string_view<wchar_t, __gnu_cxx::char_traits<wchar_t>>;
|
||||
// V2::traits_type is not the right type
|
||||
static_assert( ! std::is_constructible_v<std::wstring_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::wstring_view, V3> );
|
||||
|
||||
struct V4 : V2
|
||||
{
|
||||
using traits_type = std::wstring_view::traits_type;
|
||||
};
|
||||
// V4::traits_type is the right type
|
||||
static_assert( std::is_constructible_v<std::wstring_view, V4> );
|
||||
}
|
||||
|
||||
void
|
||||
test03()
|
||||
{
|
||||
struct R
|
||||
{
|
||||
wchar_t* begin() { return nullptr; }
|
||||
const wchar_t* begin() const noexcept { return nullptr; }
|
||||
|
||||
wchar_t* end() { return nullptr; }
|
||||
const wchar_t* end() const noexcept { return nullptr; }
|
||||
};
|
||||
|
||||
static_assert( ! noexcept(std::wstring_view(std::declval<R&>())) );
|
||||
static_assert( noexcept(std::wstring_view(std::declval<const R&>())) );
|
||||
}
|
||||
|
||||
void
|
||||
test04()
|
||||
{
|
||||
struct R
|
||||
{
|
||||
const wchar_t* begin() const { return nullptr; }
|
||||
const wchar_t* end() const { return nullptr; }
|
||||
};
|
||||
|
||||
R r;
|
||||
std::basic_string_view s = r; // Use deduction guide.
|
||||
|
||||
static_assert( std::is_same_v<decltype(s), std::wstring_view> );
|
||||
}
|
||||
|
||||
int main()
|
||||
{
|
||||
test01();
|
||||
test02();
|
||||
test03();
|
||||
test04();
|
||||
}
|
||||
Loading…
x
Reference in New Issue
Block a user