Add sv_stream_insert_test

include/boost/core/string_view.hpp

@@ -928,7 +928,38 @@ public:
 
 template<class Ch> std::basic_ostream<Ch>& operator<<( std::basic_ostream<Ch>& os, basic_string_view<Ch> str )
 {
-    os.write( str.data(), str.size() );
+    Ch const* p = str.data();
+    std::size_t n = str.size();
+
+    if( n == 0 )
+    {
+        os << "";
+    }
+    else
+    {
+        std::size_t m = os.width();
+
+        if( n >= m )
+        {
+            os.write( p, n );
+        }
+        else if( ( os.flags() & std::ios_base::adjustfield ) == std::ios_base::left )
+        {
+            os.write( p, n - 1 );
+
+            os.width( m - n + 1 );
+            os << p[ n-1 ];
+        }
+        else
+        {
+            os.width( m - n + 1 );
+            os << p[0];
+
+            os.write( p + 1, n - 1 );
+        }
+    }
+
+    os.width( 0 );
     return os;
 }
 

test/Jamfile.v2

@@ -266,6 +266,7 @@ run sv_find_last_not_of_test.cpp ;
 run sv_contains_test.cpp ;
 run sv_eq_test.cpp ;
 run sv_lt_test.cpp ;
+run sv_stream_insert_test.cpp ;
 
 use-project /boost/core/swap : ./swap ;
 build-project ./swap ;

test/sv_stream_insert_test.cpp

@@ -0,0 +1,111 @@
+// Copyright 2021 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/core/string_view.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <sstream>
+#include <iomanip>
+
+int main()
+{
+    using boost::core::string_view;
+
+    {
+        std::ostringstream os;
+
+        os << string_view( "" );
+
+        BOOST_TEST_EQ( os.str(), std::string( "" ) );
+    }
+
+    {
+        std::ostringstream os;
+
+        os << string_view( "123" );
+
+        BOOST_TEST_EQ( os.str(), std::string( "123" ) );
+    }
+
+    {
+        std::ostringstream os;
+
+        os << std::setw( 5 ) << string_view( "" );
+
+        BOOST_TEST_EQ( os.str(), std::string( "     " ) );
+    }
+
+    {
+        std::ostringstream os;
+
+        os << std::setfill( '-' ) << std::setw( 5 ) << string_view( "" );
+
+        BOOST_TEST_EQ( os.str(), std::string( "-----" ) );
+    }
+
+    {
+        std::ostringstream os;
+
+        os << std::setw( 5 ) << string_view( "123" );
+
+        BOOST_TEST_EQ( os.str(), std::string( "  123" ) );
+    }
+
+    {
+        std::ostringstream os;
+
+        os << std::left << std::setw( 5 ) << string_view( "123" );
+
+        BOOST_TEST_EQ( os.str(), std::string( "123  " ) );
+    }
+
+    {
+        std::ostringstream os;
+
+        os << std::right << std::setw( 5 ) << string_view( "123" );
+
+        BOOST_TEST_EQ( os.str(), std::string( "  123" ) );
+    }
+
+    {
+        std::ostringstream os;
+
+        os << std::setfill( '-' ) << std::setw( 5 ) << string_view( "123" );
+
+        BOOST_TEST_EQ( os.str(), std::string( "--123" ) );
+    }
+
+    {
+        std::ostringstream os;
+
+        os << std::setfill( '-' ) << std::left << std::setw( 5 ) << string_view( "123" );
+
+        BOOST_TEST_EQ( os.str(), std::string( "123--" ) );
+    }
+
+    {
+        std::ostringstream os;
+
+        os << std::setfill( '-' ) << std::right << std::setw( 5 ) << string_view( "123" );
+
+        BOOST_TEST_EQ( os.str(), std::string( "--123" ) );
+    }
+
+    {
+        std::ostringstream os;
+
+        os << std::setw( 5 ) << string_view( "12345" );
+
+        BOOST_TEST_EQ( os.str(), std::string( "12345" ) );
+    }
+
+    {
+        std::ostringstream os;
+
+        os << std::setw( 5 ) << string_view( "1234567" );
+
+        BOOST_TEST_EQ( os.str(), std::string( "1234567" ) );
+    }
+
+    return boost::report_errors();
+}