[libc++][sstream] P2495R3: Interfacing stringstreams with string_view

libcxx/docs/FeatureTestMacroTable.rst

@@ -442,7 +442,7 @@ Status
     --------------------------------------------------- -----------------
     ``__cpp_lib_span_initializer_list``                 ``202311L``
     --------------------------------------------------- -----------------
-    ``__cpp_lib_sstream_from_string_view``              *unimplemented*
+    ``__cpp_lib_sstream_from_string_view``              ``202306L``
     --------------------------------------------------- -----------------
     ``__cpp_lib_submdspan``                             *unimplemented*
     --------------------------------------------------- -----------------

libcxx/docs/ReleaseNotes/19.rst

@@ -41,6 +41,7 @@ Implemented Papers
 - P2637R3 - Member ``visit``
 - P2652R2 - Disallow User Specialization of ``allocator_traits``
 - P2819R2 - Add ``tuple`` protocol to ``complex``
+- P2495R3 - Interfacing ``stringstream``s with ``string_view``
 - P2302R4 - ``std::ranges::contains``
 - P1659R3 - ``std::ranges::starts_with`` and ``std::ranges::ends_with``
 

libcxx/docs/Status/Cxx2cPapers.csv

@@ -6,7 +6,7 @@
 "`P2545R4 <https://wg21.link/P2545R4>`__","LWG","Read-Copy Update (RCU)","Varna June 2023","","",""
 "`P2530R3 <https://wg21.link/P2530R3>`__","LWG","Hazard Pointers for C++26","Varna June 2023","","",""
 "`P2538R1 <https://wg21.link/P2538R1>`__","LWG","ADL-proof ``std::projected``","Varna June 2023","|Complete|","18.0","|ranges|"
-"`P2495R3 <https://wg21.link/P2495R3>`__","LWG","Interfacing ``stringstreams`` with ``string_view``","Varna June 2023","","",""
+"`P2495R3 <https://wg21.link/P2495R3>`__","LWG","Interfacing ``stringstream``s with ``string_view``","Varna June 2023","|Complete|","19.0",""
 "`P2510R3 <https://wg21.link/P2510R3>`__","LWG","Formatting pointers","Varna June 2023","|Complete| [#note-P2510R3]_","17.0","|format|"
 "`P2198R7 <https://wg21.link/P2198R7>`__","LWG","Freestanding Feature-Test Macros and Implementation-Defined Extensions","Varna June 2023","","",""
 "`P2338R4 <https://wg21.link/P2338R4>`__","LWG","Freestanding Library: Character primitives and the C library","Varna June 2023","","",""

libcxx/include/sstream

@@ -48,6 +48,13 @@ public:
     template <class SAlloc>
     explicit basic_stringbuf(const basic_string<char_type, traits_type, SAlloc>& s,
                              ios_base::openmode which = ios_base::in | ios_base::out); // C++20
+    template<class T>
+      explicit basic_stringbuf(const T& t,
+                               ios_base::openmode which = ios_base::in | ios_base::out); // Since C++26
+    template<class T>
+      basic_stringbuf(const T& t, const Allocator& a);                                   // Since C++26
+    template<class T>
+      basic_stringbuf(const T& t, ios_base::openmode which, const Allocator& a);         // Since C++26
     basic_stringbuf(const basic_stringbuf&) = delete;
     basic_stringbuf(basic_stringbuf&& rhs);
     basic_stringbuf(basic_stringbuf&& rhs, const allocator_type& a);                   // C++20
@@ -69,6 +76,8 @@ public:
     template <class SAlloc>
     void str(const basic_string<char_type, traits_type, SAlloc>& s);                   // C++20
     void str(basic_string<char_type, traits_type, allocator_type>&& s);                // C++20
+    template<class T>
+      void str(const T& t);                                                            // Since C++26
 
 protected:
     // [stringbuf.virtuals] Overridden virtual functions:
@@ -121,6 +130,12 @@ public:
     template <class SAlloc>
     explicit basic_istringstream(const basic_string<char_type, traits_type, SAlloc>& s,
                                  ios_base::openmode which = ios_base::in);             // C++20
+    template<class T>
+      explicit basic_istringstream(const T& t, ios_base::openmode which = ios_base::in); // Since C++26
+    template<class T>
+      basic_istringstream(const T& t, const Allocator& a);                               // Since C++26
+    template<class T>
+      basic_istringstream(const T& t, ios_base::openmode which, const Allocator& a);     // Since C++26
     basic_istringstream(const basic_istringstream&) = delete;
     basic_istringstream(basic_istringstream&& rhs);
 
@@ -141,6 +156,8 @@ public:
     template <class SAlloc>
     void str(const basic_string<char_type, traits_type, SAlloc>& s);                   // C++20
     void str(basic_string<char_type, traits_type, allocator_type>&& s);                // C++20
+    template<class T>
+      void str(const T& t);                                                            // Since C++26
 };
 
 template <class charT, class traits, class Allocator>
@@ -182,6 +199,12 @@ public:
     template <class SAlloc>
     explicit basic_ostringstream(const basic_string<char_type, traits_type, SAlloc>& s,
                                  ios_base::openmode which = ios_base::out);            // C++20
+    template<class T>
+      explicit basic_ostringstream(const T& t, ios_base::openmode which = ios_base::out); // Since C++26
+    template<class T>
+      basic_ostringstream(const T& t, const Allocator& a);                                // Since C++26
+    template<class T>
+      basic_ostringstream(const T& t, ios_base::openmode which, const Allocator& a);      // Since C++26
     basic_ostringstream(const basic_ostringstream&) = delete;                             
     basic_ostringstream(basic_ostringstream&& rhs);
 
@@ -202,6 +225,8 @@ public:
     template <class SAlloc>
     void str(const basic_string<char_type, traits_type, SAlloc>& s);                   // C++20
     void str(basic_string<char_type, traits_type, allocator_type>&& s);                // C++20
+    template<class T>
+      void str(const T& t);                                                            // Since C++26
 };
 
 template <class charT, class traits, class Allocator>
@@ -243,6 +268,13 @@ public:
     template <class SAlloc>
     explicit basic_stringstream(const basic_string<char_type, traits_type, SAlloc>& s,
                                 ios_base::openmode which = ios_base::out | ios_base::in); // C++20
+    template<class T>
+      explicit basic_stringstream(const T& t,
+                                  ios_base::openmode which = ios_base::out | ios_base::in); // Since C++26
+    template<class T>
+      basic_stringstream(const T& t, const Allocator& a);                                   // Since C++26
+    template<class T>
+      basic_stringstream(const T& t, ios_base::openmode which, const Allocator& a);         // Since C++26
     basic_stringstream(const basic_stringstream&) = delete;
     basic_stringstream(basic_stringstream&& rhs);
 
@@ -263,6 +295,8 @@ public:
     template <class SAlloc>
     void str(const basic_string<char_type, traits_type, SAlloc>& s);                      // C++20
     void str(basic_string<char_type, traits_type, allocator_type>&& s);                   // C++20
+    template<class T>
+      void str(const T& t);                                                               // Since C++26
 };
 
 template <class charT, class traits, class Allocator>
@@ -281,10 +315,12 @@ typedef basic_stringstream<wchar_t> wstringstream;
 #include <__availability>
 #include <__config>
 #include <__fwd/sstream.h>
+#include <__type_traits/is_convertible.h>
 #include <__utility/swap.h>
 #include <istream>
 #include <ostream>
 #include <string>
+#include <string_view>
 #include <version>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
@@ -371,6 +407,30 @@ public:
   }
 #endif // _LIBCPP_STD_VER >= 20
 
+#if _LIBCPP_STD_VER >= 26
+
+  template <class _Tp>
+    requires is_convertible_v<const _Tp&, basic_string_view<_CharT, _Traits>>
+  _LIBCPP_HIDE_FROM_ABI explicit basic_stringbuf(const _Tp& __t,
+                                                 ios_base::openmode __which = ios_base::in | ios_base::out)
+      : basic_stringbuf(__t, __which, _Allocator()) {}
+
+  template <class _Tp>
+    requires is_convertible_v<const _Tp&, basic_string_view<_CharT, _Traits>>
+  _LIBCPP_HIDE_FROM_ABI basic_stringbuf(const _Tp& __t, const _Allocator& __a)
+      : basic_stringbuf(__t, ios_base::in | ios_base::out, __a) {}
+
+  template <class _Tp>
+    requires is_convertible_v<const _Tp&, basic_string_view<_CharT, _Traits>>
+  _LIBCPP_HIDE_FROM_ABI basic_stringbuf(const _Tp& __t, ios_base::openmode __which, const _Allocator& __a)
+      : __hm_(nullptr), __mode_(__which) {
+    basic_string_view<_CharT, _Traits> __sv = __t;
+    __str_                                  = string_type(__sv, __a);
+    __init_buf_ptrs();
+  }
+
+#endif //  _LIBCPP_STD_VER >= 26
+
   basic_stringbuf(const basic_stringbuf&) = delete;
   basic_stringbuf(basic_stringbuf&& __rhs) : __mode_(__rhs.__mode_) { __move_init(std::move(__rhs)); }
 
@@ -444,6 +504,18 @@ public:
   }
 #endif // _LIBCPP_STD_VER >= 20
 
+#if _LIBCPP_STD_VER >= 26
+
+  template <class _Tp>
+    requires is_convertible_v<const _Tp&, basic_string_view<_CharT, _Traits>>
+  _LIBCPP_HIDE_FROM_ABI void str(const _Tp& __t) {
+    basic_string_view<_CharT, _Traits> __sv = __t;
+    __str_                                  = __sv;
+    __init_buf_ptrs();
+  }
+
+#endif //  _LIBCPP_STD_VER >= 26
+
 protected:
   // [stringbuf.virtuals] Overridden virtual functions:
   int_type underflow() override;
@@ -831,6 +903,25 @@ public:
       : basic_istream<_CharT, _Traits>(std::addressof(__sb_)), __sb_(__s, __wch | ios_base::in) {}
 #endif // _LIBCPP_STD_VER >= 20
 
+#if _LIBCPP_STD_VER >= 26
+
+  template <class _Tp>
+    requires is_convertible_v<const _Tp&, basic_string_view<_CharT, _Traits>>
+  _LIBCPP_HIDE_FROM_ABI explicit basic_istringstream(const _Tp& __t, ios_base::openmode __which = ios_base::in)
+      : basic_istringstream(__t, __which, _Allocator()) {}
+
+  template <class _Tp>
+    requires is_convertible_v<const _Tp&, basic_string_view<_CharT, _Traits>>
+  _LIBCPP_HIDE_FROM_ABI basic_istringstream(const _Tp& __t, const _Allocator& __a)
+      : basic_istringstream(__t, ios_base::in, __a) {}
+
+  template <class _Tp>
+    requires is_convertible_v<const _Tp&, basic_string_view<_CharT, _Traits>>
+  _LIBCPP_HIDE_FROM_ABI basic_istringstream(const _Tp& __t, ios_base::openmode __which, const _Allocator& __a)
+      : basic_istream<_CharT, _Traits>(std::addressof(__sb_)), __sb_(__t, __which | ios_base::in, __a) {}
+
+#endif //  _LIBCPP_STD_VER >= 26
+
   basic_istringstream(const basic_istringstream&) = delete;
   _LIBCPP_HIDE_FROM_ABI basic_istringstream(basic_istringstream&& __rhs)
       : basic_istream<_CharT, _Traits>(std::move(__rhs)), __sb_(std::move(__rhs.__sb_)) {
@@ -882,6 +973,14 @@ public:
 
   _LIBCPP_HIDE_FROM_ABI void str(string_type&& __s) { __sb_.str(std::move(__s)); }
 #endif // _LIBCPP_STD_VER >= 20
+
+#if _LIBCPP_STD_VER >= 26
+  template <class _Tp>
+    requires is_convertible_v<const _Tp&, basic_string_view<_CharT, _Traits>>
+  _LIBCPP_HIDE_FROM_ABI void str(const _Tp& __t) {
+    rdbuf()->str(__t);
+  }
+#endif //  _LIBCPP_STD_VER >= 26
 };
 
 template <class _CharT, class _Traits, class _Allocator>
@@ -940,6 +1039,25 @@ public:
       : basic_ostream<_CharT, _Traits>(std::addressof(__sb_)), __sb_(__s, __wch | ios_base::out) {}
 #endif // _LIBCPP_STD_VER >= 20
 
+#if _LIBCPP_STD_VER >= 26
+
+  template <class _Tp>
+    requires is_convertible_v<const _Tp&, basic_string_view<_CharT, _Traits>>
+  _LIBCPP_HIDE_FROM_ABI explicit basic_ostringstream(const _Tp& __t, ios_base::openmode __which = ios_base::out)
+      : basic_ostringstream(__t, __which | ios_base::out, _Allocator()) {}
+
+  template <class _Tp>
+    requires is_convertible_v<const _Tp&, basic_string_view<_CharT, _Traits>>
+  _LIBCPP_HIDE_FROM_ABI basic_ostringstream(const _Tp& __t, const _Allocator& __a)
+      : basic_ostringstream(__t, ios_base::out, __a) {}
+
+  template <class _Tp>
+    requires is_convertible_v<const _Tp&, basic_string_view<_CharT, _Traits>>
+  _LIBCPP_HIDE_FROM_ABI basic_ostringstream(const _Tp& __t, ios_base::openmode __which, const _Allocator& __a)
+      : basic_ostream<_CharT, _Traits>(std::addressof(__sb_)), __sb_(__t, __which | ios_base::out, __a) {}
+
+#endif //  _LIBCPP_STD_VER >= 26
+
   basic_ostringstream(const basic_ostringstream&) = delete;
   _LIBCPP_HIDE_FROM_ABI basic_ostringstream(basic_ostringstream&& __rhs)
       : basic_ostream<_CharT, _Traits>(std::move(__rhs)), __sb_(std::move(__rhs.__sb_)) {
@@ -992,6 +1110,14 @@ public:
 
   _LIBCPP_HIDE_FROM_ABI void str(string_type&& __s) { __sb_.str(std::move(__s)); }
 #endif // _LIBCPP_STD_VER >= 20
+
+#if _LIBCPP_STD_VER >= 26
+  template <class _Tp>
+    requires is_convertible_v<const _Tp&, basic_string_view<_CharT, _Traits>>
+  _LIBCPP_HIDE_FROM_ABI void str(const _Tp& __t) {
+    rdbuf()->str(__t);
+  }
+#endif //  _LIBCPP_STD_VER >= 26
 };
 
 template <class _CharT, class _Traits, class _Allocator>
@@ -1053,6 +1179,26 @@ public:
       : basic_iostream<_CharT, _Traits>(std::addressof(__sb_)), __sb_(__s, __wch) {}
 #endif // _LIBCPP_STD_VER >= 20
 
+#if _LIBCPP_STD_VER >= 26
+
+  template <class _Tp>
+    requires is_convertible_v<const _Tp&, basic_string_view<_CharT, _Traits>>
+  _LIBCPP_HIDE_FROM_ABI explicit basic_stringstream(const _Tp& __t,
+                                                    ios_base::openmode __which = ios_base::out | ios_base::in)
+      : basic_stringstream(__t, __which, _Allocator()) {}
+
+  template <class _Tp>
+    requires is_convertible_v<const _Tp&, basic_string_view<_CharT, _Traits>>
+  _LIBCPP_HIDE_FROM_ABI basic_stringstream(const _Tp& __t, const _Allocator& __a)
+      : basic_stringstream(__t, ios_base::out | ios_base::in, __a) {}
+
+  template <class _Tp>
+    requires is_convertible_v<const _Tp&, basic_string_view<_CharT, _Traits>>
+  _LIBCPP_HIDE_FROM_ABI basic_stringstream(const _Tp& __t, ios_base::openmode __which, const _Allocator& __a)
+      : basic_iostream<_CharT, _Traits>(std::addressof(__sb_)), __sb_(__t, __which, __a) {}
+
+#endif //  _LIBCPP_STD_VER >= 26
+
   basic_stringstream(const basic_stringstream&) = delete;
   _LIBCPP_HIDE_FROM_ABI basic_stringstream(basic_stringstream&& __rhs)
       : basic_iostream<_CharT, _Traits>(std::move(__rhs)), __sb_(std::move(__rhs.__sb_)) {
@@ -1104,6 +1250,14 @@ public:
 
   _LIBCPP_HIDE_FROM_ABI void str(string_type&& __s) { __sb_.str(std::move(__s)); }
 #endif // _LIBCPP_STD_VER >= 20
+
+#if _LIBCPP_STD_VER >= 26
+  template <class _Tp>
+    requires is_convertible_v<const _Tp&, basic_string_view<_CharT, _Traits>>
+  _LIBCPP_HIDE_FROM_ABI void str(const _Tp& __t) {
+    rdbuf()->str(__t);
+  }
+#endif //  _LIBCPP_STD_VER >= 26
 };
 
 template <class _CharT, class _Traits, class _Allocator>

libcxx/include/version

@@ -515,7 +515,7 @@ __cpp_lib_within_lifetime                               202306L <type_traits>
 // # define __cpp_lib_smart_ptr_owner_equality             202306L
 # define __cpp_lib_span_at                              202311L
 # define __cpp_lib_span_initializer_list                202311L
-// # define __cpp_lib_sstream_from_string_view             202306L
+# define __cpp_lib_sstream_from_string_view             202306L
 // # define __cpp_lib_submdspan                            202306L
 // # define __cpp_lib_text_encoding                        202306L
 # undef  __cpp_lib_to_chars

libcxx/test/libcxx/transitive_includes/cxx03.csv

@@ -745,6 +745,7 @@ sstream cstddef
 sstream istream
 sstream ostream
 sstream string
+sstream string_view
 sstream type_traits
 sstream version
 stack compare

libcxx/test/libcxx/transitive_includes/cxx11.csv

@@ -751,6 +751,7 @@ sstream cstddef
 sstream istream
 sstream ostream
 sstream string
+sstream string_view
 sstream type_traits
 sstream version
 stack compare

libcxx/test/libcxx/transitive_includes/cxx14.csv

@@ -753,6 +753,7 @@ sstream cstddef
 sstream istream
 sstream ostream
 sstream string
+sstream string_view
 sstream type_traits
 sstream version
 stack compare

libcxx/test/libcxx/transitive_includes/cxx17.csv

@@ -753,6 +753,7 @@ sstream cstddef
 sstream istream
 sstream ostream
 sstream string
+sstream string_view
 sstream type_traits
 sstream version
 stack compare

libcxx/test/libcxx/transitive_includes/cxx20.csv

@@ -758,6 +758,7 @@ sstream cstddef
 sstream istream
 sstream ostream
 sstream string
+sstream string_view
 sstream type_traits
 sstream version
 stack compare

libcxx/test/libcxx/transitive_includes/cxx23.csv

@@ -520,6 +520,7 @@ sstream cstddef
 sstream istream
 sstream ostream
 sstream string
+sstream string_view
 sstream version
 stack compare
 stack cstddef

libcxx/test/libcxx/transitive_includes/cxx26.csv

@@ -520,6 +520,7 @@ sstream cstddef
 sstream istream
 sstream ostream
 sstream string
+sstream string_view
 sstream version
 stack compare
 stack cstddef

libcxx/test/std/input.output/string.streams/helper_concepts.h

@@ -0,0 +1,17 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef TEST_STD_INPUTOUTPUT_STRINGSTREAMS_HELPER_CONCEPTS_H
+#define TEST_STD_INPUTOUTPUT_STRINGSTREAMS_HELPER_CONCEPTS_H
+
+template <typename S, typename T>
+concept is_valid_argument_for_str_member = requires(S s, const T& sv) {
+  { s.str(sv) };
+};
+
+#endif // TEST_STD_INPUTOUTPUT_STRINGSTREAMS_HELPER_CONCEPTS_H