[PATCH] libstdc++: c++2b, implement WG21 P1679R3

[PATCH] libstdc++: c++2b, implement WG21 P1679R3

[Paul Fee]

Add contains member function to basic_string_view and basic_string.

The new method is enabled for -std=gnu++20, gnu++2b and c++2b.  This allows
users to access the method as a GNU extension to C++20.  The conditional
test may be reduced to "__cplusplus > 202011L" once GCC has a c++2b switch.

libstdc++-v3/

    Add contains member function to basic_string_view.
    Likewise to basic_string_view, both with and without _GLIBCXX_USE_CXX11_ABI.
    Enabled with -std=gnu++20, gnu++2b and c++2b.
    * include/bits/basic_string.h (basic_string::contains): New.
    * libstdc++-v3/include/std/string_view (basic_string_view::contains): New.
    * testsuite/21_strings/basic_string/operations/contains/char/1.cc: New test.
    * testsuite/21_strings/basic_string/operations/contains/wchar_t/1.cc:
New test.
    * testsuite/21_strings/basic_string/operations/starts_with/char/1.cc:
Remove trailing whitespace
    * testsuite/21_strings/basic_string/operations/starts_with/wchar_t/1.cc:
Remove trailing whitespace
    * testsuite/21_strings/basic_string_view/operations/contains/char/1.cc:
New test.
    * testsuite/21_strings/basic_string_view/operations/contains/wchar_t/1.cc:
New test.
---
 libstdc++-v3/include/bits/basic_string.h
               |   30 ++++
 libstdc++-v3/include/std/string_view
               |   16 ++
 libstdc++-v3/testsuite/21_strings/basic_string/operations/contains/char/1.cc
        |   65 ++++++++++
 libstdc++-v3/testsuite/21_strings/basic_string/operations/contains/wchar_t/1.cc
     |   65 ++++++++++
 libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/char/1.cc
     |    2
 libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/wchar_t/1.cc
  |    2
 libstdc++-v3/testsuite/21_strings/basic_string_view/operations/contains/char/1.cc
   |   51 +++++++
 libstdc++-v3/testsuite/21_strings/basic_string_view/operations/contains/wchar_t/1.cc
|   51 +++++++
 8 files changed, 280 insertions(+), 2 deletions(-)


diff --git a/libstdc++-v3/include/bits/basic_string.h
b/libstdc++-v3/include/bits/basic_string.h
index e272d332934..a569ecd8c08 100644
--- a/libstdc++-v3/include/bits/basic_string.h
+++ b/libstdc++-v3/include/bits/basic_string.h
@@ -3073,6 +3073,21 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
       { return __sv_type(this->data(), this->size()).ends_with(__x); }
 #endif // C++20

+#if __cplusplus > 202011L || \
+  (__cplusplus == 202002L && !defined __STRICT_ANSI__)
+      bool
+      contains(basic_string_view<_CharT, _Traits> __x) const noexcept
+      { return __sv_type(this->data(), this->size()).contains(__x); }
+
+      bool
+      contains(_CharT __x) const noexcept
+      { return __sv_type(this->data(), this->size()).contains(__x); }
+
+      bool
+      contains(const _CharT* __x) const noexcept
+      { return __sv_type(this->data(), this->size()).contains(__x); }
+#endif // C++23
+
       // Allow basic_stringbuf::__xfer_bufptrs to call _M_length:
       template<typename, typename, typename> friend class basic_stringbuf;
     };
@@ -5998,6 +6013,21 @@ _GLIBCXX_END_NAMESPACE_CXX11
       { return __sv_type(this->data(), this->size()).ends_with(__x); }
 #endif // C++20

+#if __cplusplus > 202011L || \
+  (__cplusplus == 202002L && !defined __STRICT_ANSI__)
+      bool
+      contains(basic_string_view<_CharT, _Traits> __x) const noexcept
+      { return __sv_type(this->data(), this->size()).contains(__x); }
+
+      bool
+      contains(_CharT __x) const noexcept
+      { return __sv_type(this->data(), this->size()).contains(__x); }
+
+      bool
+      contains(const _CharT* __x) const noexcept
+      { return __sv_type(this->data(), this->size()).contains(__x); }
+#endif // C++23
+
 # ifdef _GLIBCXX_TM_TS_INTERNAL
       friend void
       ::_txnal_cow_string_C1_for_exceptions(void* that, const char* s,
diff --git a/libstdc++-v3/include/std/string_view
b/libstdc++-v3/include/std/string_view
index e33e1bc4b79..2f47ef6ed12 100644
--- a/libstdc++-v3/include/std/string_view
+++ b/libstdc++-v3/include/std/string_view
@@ -352,6 +352,22 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       { return this->ends_with(basic_string_view(__x)); }
 #endif // C++20

+#if __cplusplus > 202011L || \
+  (__cplusplus == 202002L && !defined __STRICT_ANSI__)
+#define __cpp_lib_string_contains 202011L
+      constexpr bool
+      contains(basic_string_view __x) const noexcept
+      { return this->find(__x) != npos; }
+
+      constexpr bool
+      contains(_CharT __x) const noexcept
+      { return this->find(__x) != npos; }
+
+      constexpr bool
+      contains(const _CharT* __x) const noexcept
+      { return this->find(__x) != npos; }
+#endif // C++23
+
       // [string.view.find], searching

       constexpr size_type
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/operations/contains/char/1.cc
b/libstdc++-v3/testsuite/21_strings/basic_string/operations/contains/char/1.cc
new file mode 100644
index 00000000000..5d81dcee0ad
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/operations/contains/char/1.cc
@@ -0,0 +1,65 @@
+// { dg-options "-std=gnu++2b" }
+// { dg-do run { target c++2b } }
+
+// Copyright (C) 2018-2020 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/>.
+
+// basic_string contains
+
+#include <string>
+#include <testsuite_hooks.h>
+
+void
+test01()
+{
+    const std::string haystack("no place for needles");
+
+    VERIFY(haystack.contains(std::string("")));
+    VERIFY(haystack.contains(std::string("no")));
+    VERIFY(haystack.contains(std::string("needles")));
+    VERIFY(haystack.contains(std::string(" for ")));
+    VERIFY(!haystack.contains(std::string("places")));
+
+    VERIFY(haystack.contains(std::string_view("")));
+    VERIFY(haystack.contains(std::string_view("no")));
+    VERIFY(haystack.contains(std::string_view("needles")));
+    VERIFY(haystack.contains(std::string_view(" for ")));
+    VERIFY(!haystack.contains(std::string_view("places")));
+
+    VERIFY(!haystack.contains('\0'));
+    VERIFY(haystack.contains('n'));
+    VERIFY(haystack.contains('e'));
+    VERIFY(haystack.contains('s'));
+    VERIFY(!haystack.contains('x'));
+
+    VERIFY(haystack.contains(""));
+    VERIFY(haystack.contains("no"));
+    VERIFY(haystack.contains("needles"));
+    VERIFY(haystack.contains(" for "));
+    VERIFY(!haystack.contains("places"));
+
+    const std::string nothing;
+    VERIFY(nothing.contains(""));
+    VERIFY(!nothing.contains('\0'));
+}
+
+int
+main()
+{
+  test01();
+  return 0;
+}
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/operations/contains/wchar_t/1.cc
b/libstdc++-v3/testsuite/21_strings/basic_string/operations/contains/wchar_t/1.cc
new file mode 100644
index 00000000000..21196add4dc
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/operations/contains/wchar_t/1.cc
@@ -0,0 +1,65 @@
+// { dg-options "-std=gnu++2b" }
+// { dg-do run { target c++2b } }
+
+// Copyright (C) 2018-2020 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/>.
+
+// basic_string begins_with
+
+#include <string>
+#include <testsuite_hooks.h>
+
+void
+test01()
+{
+    const std::wstring haystack(L"no place for needles");
+
+    VERIFY(haystack.contains(std::wstring(L"")));
+    VERIFY(haystack.contains(std::wstring(L"no")));
+    VERIFY(haystack.contains(std::wstring(L"needles")));
+    VERIFY(haystack.contains(std::wstring(L" for ")));
+    VERIFY(!haystack.contains(std::wstring(L"places")));
+
+    VERIFY(haystack.contains(std::wstring_view(L"")));
+    VERIFY(haystack.contains(std::wstring_view(L"no")));
+    VERIFY(haystack.contains(std::wstring_view(L"needles")));
+    VERIFY(haystack.contains(std::wstring_view(L" for ")));
+    VERIFY(!haystack.contains(std::wstring_view(L"places")));
+
+    VERIFY(!haystack.contains('\0'));
+    VERIFY(haystack.contains('n'));
+    VERIFY(haystack.contains('e'));
+    VERIFY(haystack.contains('s'));
+    VERIFY(!haystack.contains('x'));
+
+    VERIFY(haystack.contains(L""));
+    VERIFY(haystack.contains(L"no"));
+    VERIFY(haystack.contains(L"needles"));
+    VERIFY(haystack.contains(L" for "));
+    VERIFY(!haystack.contains(L"places"));
+
+    const std::wstring nothing;
+    VERIFY(nothing.contains(L""));
+    VERIFY(!nothing.contains('\0'));
+}
+
+int
+main()
+{
+  test01();
+  return 0;
+}
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/char/1.cc
b/libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/char/1.cc
index 7445942679b..4f4a8d2c20c 100644
--- a/libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/char/1.cc
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/char/1.cc
@@ -50,7 +50,7 @@ test01()

 int
 main()
-{
+{
   test01();
   return 0;
 }
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/wchar_t/1.cc
b/libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/wchar_t/1.cc
index 5c4e94aba75..022f128a2a0 100644
--- a/libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/wchar_t/1.cc
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/operations/starts_with/wchar_t/1.cc
@@ -50,7 +50,7 @@ test01()

 int
 main()
-{
+{
   test01();
   return 0;
 }
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string_view/operations/contains/char/1.cc
b/libstdc++-v3/testsuite/21_strings/basic_string_view/operations/contains/char/1.cc
new file mode 100644
index 00000000000..6acc2baf28a
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string_view/operations/contains/char/1.cc
@@ -0,0 +1,51 @@
+// { dg-options "-std=gnu++2b" }
+// { dg-do compile { target c++2b } }
+
+// Copyright (C) 2018-2020 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/>.
+
+// basic_string_view contains
+
+#include <string_view>
+
+void
+test01()
+{
+    constexpr std::string_view haystack("no place for needles");
+
+    static_assert(haystack.contains(std::string_view("")));
+    static_assert(haystack.contains(std::string_view("no")));
+    static_assert(haystack.contains(std::string_view("needles")));
+    static_assert(haystack.contains(std::string_view(" for ")));
+    static_assert(!haystack.contains(std::string_view("places")));
+
+    static_assert(!haystack.contains('\0'));
+    static_assert(haystack.contains('n'));
+    static_assert(haystack.contains('e'));
+    static_assert(haystack.contains('s'));
+    static_assert(!haystack.contains('x'));
+
+    static_assert(haystack.contains(""));
+    static_assert(haystack.contains("no"));
+    static_assert(haystack.contains("needles"));
+    static_assert(haystack.contains(" for "));
+    static_assert(!haystack.contains("places"));
+
+    constexpr std::string_view nothing;
+    static_assert(nothing.contains(""));
+    static_assert(!nothing.contains('\0'));
+}
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string_view/operations/contains/wchar_t/1.cc
b/libstdc++-v3/testsuite/21_strings/basic_string_view/operations/contains/wchar_t/1.cc
new file mode 100644
index 00000000000..ba64f613633
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string_view/operations/contains/wchar_t/1.cc
@@ -0,0 +1,51 @@
+// { dg-options "-std=gnu++2b" }
+// { dg-do compile { target c++2b } }
+
+// Copyright (C) 2018-2020 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/>.
+
+// basic_string_view contains
+
+#include <string_view>
+
+void
+test01()
+{
+    constexpr std::wstring_view haystack = L"no place for needles";
+
+    static_assert(haystack.contains(std::wstring_view(L"")));
+    static_assert(haystack.contains(std::wstring_view(L"no")));
+    static_assert(haystack.contains(std::wstring_view(L"needles")));
+    static_assert(haystack.contains(std::wstring_view(L" for ")));
+    static_assert(!haystack.contains(std::wstring_view(L"places")));
+
+    static_assert(!haystack.contains('\0'));
+    static_assert(haystack.contains('n'));
+    static_assert(haystack.contains('e'));
+    static_assert(haystack.contains('s'));
+    static_assert(!haystack.contains('x'));
+
+    static_assert(haystack.contains(L""));
+    static_assert(haystack.contains(L"no"));
+    static_assert(haystack.contains(L"needles"));
+    static_assert(haystack.contains(L" for "));
+    static_assert(!haystack.contains(L"places"));
+
+    constexpr std::wstring_view nothing;
+    static_assert(nothing.contains(L""));
+    static_assert(!nothing.contains('\0'));
+}

Re: [PATCH] libstdc++: c++2b, implement WG21 P1679R3

[Jonathan Wakely]

On 13/01/21 01:21 +0000, Paul Fee via Libstdc++ wrote:
>Add contains member function to basic_string_view and basic_string.
>
>The new method is enabled for -std=gnu++20, gnu++2b and c++2b.  This allows
>users to access the method as a GNU extension to C++20.  The conditional
>test may be reduced to "__cplusplus > 202011L" once GCC has a c++2b switch.

Thanks for the patch.

A few comments below.

>diff --git a/libstdc++-v3/include/bits/basic_string.h
>b/libstdc++-v3/include/bits/basic_string.h
>index e272d332934..a569ecd8c08 100644
>--- a/libstdc++-v3/include/bits/basic_string.h
>+++ b/libstdc++-v3/include/bits/basic_string.h
>@@ -3073,6 +3073,21 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
>       { return __sv_type(this->data(), this->size()).ends_with(__x); }
> #endif // C++20
>
>+#if __cplusplus > 202011L || \
>+  (__cplusplus == 202002L && !defined __STRICT_ANSI__)

Please put the line break before the binary operator i.e.

#if __cplusplus > 202011L \
   || (__cplusplus == 202002L && !defined __STRICT_ANSI__)

This has the advantage that the operator is at a predictable place,
so it's easier to see at a glance whether this is an && or ||
condition.

>+      bool
>+      contains(basic_string_view<_CharT, _Traits> __x) const noexcept
>+      { return __sv_type(this->data(), this->size()).contains(__x); }
>+
>+      bool
>+      contains(_CharT __x) const noexcept
>+      { return __sv_type(this->data(), this->size()).contains(__x); }
>+
>+      bool
>+      contains(const _CharT* __x) const noexcept
>+      { return __sv_type(this->data(), this->size()).contains(__x); }
>+#endif // C++23
>+
>       // Allow basic_stringbuf::__xfer_bufptrs to call _M_length:
>       template<typename, typename, typename> friend class basic_stringbuf;
>     };
>@@ -5998,6 +6013,21 @@ _GLIBCXX_END_NAMESPACE_CXX11
>       { return __sv_type(this->data(), this->size()).ends_with(__x); }
> #endif // C++20
>
>+#if __cplusplus > 202011L || \
>+  (__cplusplus == 202002L && !defined __STRICT_ANSI__)
>+      bool
>+      contains(basic_string_view<_CharT, _Traits> __x) const noexcept
>+      { return __sv_type(this->data(), this->size()).contains(__x); }
>+
>+      bool
>+      contains(_CharT __x) const noexcept
>+      { return __sv_type(this->data(), this->size()).contains(__x); }
>+
>+      bool
>+      contains(const _CharT* __x) const noexcept
>+      { return __sv_type(this->data(), this->size()).contains(__x); }
>+#endif // C++23
>+
> # ifdef _GLIBCXX_TM_TS_INTERNAL
>       friend void
>       ::_txnal_cow_string_C1_for_exceptions(void* that, const char* s,
>diff --git a/libstdc++-v3/include/std/string_view
>b/libstdc++-v3/include/std/string_view
>index e33e1bc4b79..2f47ef6ed12 100644
>--- a/libstdc++-v3/include/std/string_view
>+++ b/libstdc++-v3/include/std/string_view
>@@ -352,6 +352,22 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>       { return this->ends_with(basic_string_view(__x)); }
> #endif // C++20
>
>+#if __cplusplus > 202011L || \
>+  (__cplusplus == 202002L && !defined __STRICT_ANSI__)
>+#define __cpp_lib_string_contains 202011L

This macro should also be defined in <version>, and should depend on
the same conditions.

There should also be tests that the macro is defined by <string_view>
and by <version>.

You can add this to the top of any one of the new tests for
string_view::contains:

#ifndef __cpp_lib_string_contains
# error "Feature-test macro for contains missing in <string_view>"
#elif __cpp_lib_string_contains != 202011L
# error "Feature-test macro for contains has wrong value in <string_view>"
#endif

And then add a new version.cc test adjacent to that file, which
includes <version> (and nothing else) and tests the same conditions:

#include <version>

#ifndef __cpp_lib_string_contains
# error "Feature-test macro for contains missing in <version>"
#elif __cpp_lib_string_contains != 202011L
# error "Feature-test macro for contains has wrong value in <version>"
#endif



>+      constexpr bool
>+      contains(basic_string_view __x) const noexcept
>+      { return this->find(__x) != npos; }
>+
>+      constexpr bool
>+      contains(_CharT __x) const noexcept
>+      { return this->find(__x) != npos; }
>+
>+      constexpr bool
>+      contains(const _CharT* __x) const noexcept
>+      { return this->find(__x) != npos; }
>+#endif // C++23
>+
>       // [string.view.find], searching
>
>       constexpr size_type
>diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/operations/contains/char/1.cc
>b/libstdc++-v3/testsuite/21_strings/basic_string/operations/contains/char/1.cc
>new file mode 100644
>index 00000000000..5d81dcee0ad
>--- /dev/null
>+++ b/libstdc++-v3/testsuite/21_strings/basic_string/operations/contains/char/1.cc
>@@ -0,0 +1,65 @@
>+// { dg-options "-std=gnu++2b" }
>+// { dg-do run { target c++2b } }
>+
>+// Copyright (C) 2018-2020 Free Software Foundation, Inc.

These dates should be 2021 only.


>diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/operations/contains/wchar_t/1.cc
>b/libstdc++-v3/testsuite/21_strings/basic_string/operations/contains/wchar_t/1.cc
>new file mode 100644
>index 00000000000..21196add4dc
>--- /dev/null
>+++ b/libstdc++-v3/testsuite/21_strings/basic_string/operations/contains/wchar_t/1.cc
>@@ -0,0 +1,65 @@
>+// { dg-options "-std=gnu++2b" }
>+// { dg-do run { target c++2b } }
>+
>+// Copyright (C) 2018-2020 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/>.
>+
>+// basic_string begins_with

Comment not adjusted after copying the begins_with test.

Re: [PATCH] libstdc++: c++2b, implement WG21 P1679R3

[Paul Fee]

On Thu, Jan 14, 2021 at 5:06 PM Jonathan Wakely <jwakely@redhat.com> wrote:
>
> On 13/01/21 01:21 +0000, Paul Fee via Libstdc++ wrote:
> >Add contains member function to basic_string_view and basic_string.
> >
> >The new method is enabled for -std=gnu++20, gnu++2b and c++2b.  This allows
> >users to access the method as a GNU extension to C++20.  The conditional
> >test may be reduced to "__cplusplus > 202011L" once GCC has a c++2b switch.
>
> Thanks for the patch.
>
> A few comments below.
>

Thanks for the feedback, see "[PATCH v2] libstdc++: C++23, implement
WG21 P1679R3" for fixes.