Add conversions from and to boost::string_view

.github/workflows/ci.yml

@@ -386,6 +386,9 @@ jobs:
             git submodule init libs/static_assert
             git submodule init libs/throw_exception
             git submodule init libs/type_traits
+            git submodule init libs/utility
+            git submodule init libs/io
+            git submodule init libs/preprocessor
             git submodule update $GIT_ARGS
             if [ -z "${{matrix.cmake_tests}}" ]
             then
@@ -517,6 +520,8 @@ jobs:
             git submodule init libs/static_assert
             git submodule init libs/throw_exception
             git submodule init libs/type_traits
+            git submodule init libs/utility
+            git submodule init libs/io
             git submodule update --jobs %GIT_FETCH_JOBS%
             cmd /c bootstrap
             b2 -d0 headers

appveyor.yml

@@ -1,4 +1,4 @@
-# Copyright 2016-2019 Peter Dimov
+# Copyright 2016-2021 Peter Dimov
 # Distributed under the Boost Software License, Version 1.0.
 # (See accompanying file LICENSE_1_0.txt or copy at http://boost.org/LICENSE_1_0.txt)
 
@@ -77,6 +77,8 @@ install:
   - git submodule init libs/static_assert
   - git submodule init libs/throw_exception
   - git submodule init libs/type_traits
+  - git submodule init libs/utility
+  - git submodule init libs/io
   - git submodule init tools/build
   - git submodule init tools/boost_install
   - git submodule update --jobs 4

include/boost/core/detail/string_view.hpp

@@ -34,6 +34,9 @@
 
 namespace boost
 {
+
+template<class Ch, class Tr> class basic_string_view;
+
 namespace core
 {
 namespace detail
@@ -388,6 +391,11 @@ public:
 
 #endif
 
+    template<class Ch2> basic_string_view( boost::basic_string_view<Ch2, std::char_traits<Ch2> > const& str,
+        typename boost::enable_if<is_same<Ch, Ch2> >::type* = 0 ) BOOST_NOEXCEPT: p_( str.data() ), n_( str.size() )
+    {
+    }
+
     // BOOST_CONSTEXPR basic_string_view& operator=( basic_string_view const& ) BOOST_NOEXCEPT & = default;
 
     // conversions
@@ -407,6 +415,12 @@ public:
 
 #endif
 
+    template<class Ch2> operator boost::basic_string_view<Ch2,
+        typename boost::enable_if<boost::core::is_same<Ch2, Ch>, std::char_traits<Ch> >::type> () const BOOST_NOEXCEPT
+    {
+        return boost::basic_string_view< Ch, std::char_traits<Ch> >( data(), size() );
+    }
+
     // iterator support
 
     BOOST_CONSTEXPR const_iterator begin() const BOOST_NOEXCEPT

test/CMakeLists.txt

@@ -1,4 +1,4 @@
-# Copyright 2018, 2019, 2021 Peter Dimov
+# Copyright 2018-2021 Peter Dimov
 # Distributed under the Boost Software License, Version 1.0.
 # See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt
 
@@ -23,6 +23,10 @@ set(BOOST_TEST_LINK_LIBRARIES Boost::core Boost::throw_exception)
 
 boost_test(TYPE run SOURCES no_exceptions_support_test.cpp)
 
+set(BOOST_TEST_LINK_LIBRARIES Boost::core Boost::utility)
+
+boost_test(TYPE run SOURCES sv_conversion_test2.cpp)
+
 endif()
 
 add_subdirectory(swap)

test/Jamfile.v2

@@ -305,6 +305,7 @@ run sv_eq_test.cpp ;
 run sv_lt_test.cpp ;
 run sv_stream_insert_test.cpp ;
 run sv_conversion_test.cpp ;
+run sv_conversion_test2.cpp : ;
 
 run span_test.cpp ;
 run span_types_test.cpp ;

test/sv_conversion_test2.cpp

@@ -0,0 +1,32 @@
+// Copyright 2021 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/core/detail/string_view.hpp>
+#include <boost/utility/string_view.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <string>
+
+boost::core::string_view f( boost::core::string_view const& str )
+{
+    return str;
+}
+
+int main()
+{
+    {
+        std::string s1( "123" );
+        std::string s2 = f( s1 );
+
+        BOOST_TEST_EQ( s1, s2 );
+    }
+
+    {
+        boost::string_view s1( "123" );
+        boost::string_view s2 = f( s1 );
+
+        BOOST_TEST_EQ( s1, s2 );
+    }
+
+    return boost::report_errors();
+}