Provide a public method to get StringRef's underlying pointer

This allows reducing the amount of friends needed for its interface
and some extra tricks later.

The bad part is that the pointer can become invalidated via
calls to other StringRef's public methods, but c'est la vie.

include/internal/catch_stringref.cpp

@@ -43,7 +43,7 @@ namespace Catch {
            const_cast<StringRef*>( this )->takeOwnership();
         return m_start;
     }
-    auto StringRef::data() const noexcept -> char const* {
+    auto StringRef::currentData() const noexcept -> char const* {
         return m_start;
     }
 
@@ -112,11 +112,11 @@ namespace Catch {
     }
 
     auto operator << ( std::ostream& os, StringRef const& str ) -> std::ostream& {
-        return os.write(str.m_start, str.m_size);
+        return os.write(str.currentData(), str.size());
     }
 
     auto operator+=( std::string& lhs, StringRef const& rhs ) -> std::string& {
-        lhs.append(rhs.m_start, rhs.m_size);
+        lhs.append(rhs.currentData(), rhs.size());
         return lhs;
     }
 

include/internal/catch_stringref.h

@@ -84,16 +84,12 @@ namespace Catch {
 
         void swap( StringRef& other ) noexcept;
 
-        friend auto operator << (std::ostream& os, StringRef const& sr)->std::ostream&;
-
     public: // operators
         auto operator == ( StringRef const& other ) const noexcept -> bool;
         auto operator != ( StringRef const& other ) const noexcept -> bool;
 
         auto operator[] ( size_type index ) const noexcept -> char;
 
-        friend auto operator += ( std::string& lhs, StringRef const& rhs ) -> std::string&;
-
     public: // named queries
         auto empty() const noexcept -> bool {
             return m_size == 0;
@@ -108,16 +104,22 @@ namespace Catch {
     public: // substrings and searches
         auto substr( size_type start, size_type size ) const noexcept -> StringRef;
 
+        // Returns the current start pointer.
+        // Note that the pointer can change when if the StringRef is a substring
+        auto currentData() const noexcept -> char const*;
+
     private: // ownership queries - may not be consistent between calls
         auto isOwned() const noexcept -> bool;
         auto isSubstring() const noexcept -> bool;
-        auto data() const noexcept -> char const*;
     };
 
     auto operator + ( StringRef const& lhs, StringRef const& rhs ) -> std::string;
     auto operator + ( StringRef const& lhs, char const* rhs ) -> std::string;
     auto operator + ( char const* lhs, StringRef const& rhs ) -> std::string;
 
+    auto operator += ( std::string& lhs, StringRef const& sr ) -> std::string&;
+    auto operator << ( std::ostream& os, StringRef const& sr ) -> std::ostream&;
+
 
     inline auto operator "" _sr( char const* rawChars, std::size_t size ) noexcept -> StringRef {
         return StringRef( rawChars, size );

projects/SelfTest/Baselines/compact.sw.approved.txt

@@ -637,11 +637,11 @@ String.tests.cpp:<line number>: passed: std::strcmp( ss.c_str(), "hello" ) == 0
 String.tests.cpp:<line number>: passed: ss == "hello" for: hello == "hello"
 String.tests.cpp:<line number>: passed: isSubstring( ss ) for: true
 String.tests.cpp:<line number>: passed: isOwned( ss ) == false for: false == false
-String.tests.cpp:<line number>: passed: rawChars == data( s ) for: "hello world!" == "hello world!"
+String.tests.cpp:<line number>: passed: rawChars == s.currentData() for: "hello world!" == "hello world!"
 String.tests.cpp:<line number>: passed: ss.c_str() != rawChars for: "hello" != "hello world!"
 String.tests.cpp:<line number>: passed: isSubstring( ss ) == false for: false == false
 String.tests.cpp:<line number>: passed: isOwned( ss ) for: true
-String.tests.cpp:<line number>: passed: data( ss ) != data( s ) for: "hello" != "hello world!"
+String.tests.cpp:<line number>: passed: ss.currentData() != s.currentData() for: "hello" != "hello world!"
 String.tests.cpp:<line number>: passed: ss.size() == 6 for: 6 == 6
 String.tests.cpp:<line number>: passed: std::strcmp( ss.c_str(), "world!" ) == 0 for: 0 == 0
 String.tests.cpp:<line number>: passed: s.c_str() == s2.c_str() for: "hello world!" == "hello world!"

projects/SelfTest/Baselines/console.sw.approved.txt

@@ -5076,7 +5076,7 @@ with expansion:
 
 String.tests.cpp:<line number>:
 PASSED:
-  REQUIRE( rawChars == data( s ) )
+  REQUIRE( rawChars == s.currentData() )
 with expansion:
   "hello world!" == "hello world!"
 
@@ -5100,7 +5100,7 @@ with expansion:
 
 String.tests.cpp:<line number>:
 PASSED:
-  REQUIRE( data( ss ) != data( s ) )
+  REQUIRE( ss.currentData() != s.currentData() )
 with expansion:
   "hello" != "hello world!"
 

projects/SelfTest/Baselines/xml.sw.approved.txt

@@ -5808,7 +5808,7 @@ Message from section two
           </Expression>
           <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/IntrospectiveTests/String.tests.cpp" >
             <Original>
-              rawChars == data( s )
+              rawChars == s.currentData()
             </Original>
             <Expanded>
               "hello world!" == "hello world!"
@@ -5840,7 +5840,7 @@ Message from section two
           </Expression>
           <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/IntrospectiveTests/String.tests.cpp" >
             <Original>
-              data( ss ) != data( s )
+              ss.currentData() != s.currentData()
             </Original>
             <Expanded>
               "hello" != "hello world!"

projects/SelfTest/IntrospectiveTests/String.tests.cpp

@@ -14,9 +14,6 @@ namespace Catch {
         static auto isSubstring( StringRef const& stringRef ) -> bool {
             return stringRef.isSubstring();
         }
-        static auto data( StringRef const& stringRef ) -> char const* {
-            return stringRef.data();
-        }
     };
 
     auto isOwned( StringRef const& stringRef ) -> bool {
@@ -25,14 +22,11 @@ namespace Catch {
     auto isSubstring( StringRef const& stringRef ) -> bool {
         return StringRefTestAccess::isSubstring( stringRef );
     }
-    auto data( StringRef const& stringRef ) -> char const* {
-        return StringRefTestAccess::data( stringRef );
-    }
 } // namespace Catch2
 
 namespace Catch {
     inline auto toString( Catch::StringRef const& stringRef ) -> std::string {
-        return std::string( data( stringRef ), stringRef.size() );
+        return std::string( stringRef.currentData(), stringRef.size() );
     }
 } // namespace Catch
 
@@ -53,7 +47,7 @@ TEST_CASE( "StringRef", "[Strings][StringRef]" ) {
         REQUIRE( s.size() == 5 );
         REQUIRE( isSubstring( s ) == false );
 
-        auto rawChars = data( s );
+        auto rawChars = s.currentData();
         REQUIRE( std::strcmp( rawChars, "hello" ) == 0 );
 
         SECTION( "c_str() does not cause copy" ) {
@@ -74,7 +68,6 @@ TEST_CASE( "StringRef", "[Strings][StringRef]" ) {
 
         REQUIRE( isSubstring( original ) == false );
         REQUIRE( isOwned( original ) );
-
     }
 
 
@@ -92,14 +85,14 @@ TEST_CASE( "StringRef", "[Strings][StringRef]" ) {
             REQUIRE( isSubstring( ss ) );
             REQUIRE( isOwned( ss ) == false );
 
-            auto rawChars = data( ss );
+            auto rawChars = ss.currentData();
-            REQUIRE( rawChars == data( s ) ); // same pointer value
+            REQUIRE( rawChars == s.currentData() ); // same pointer value
             REQUIRE( ss.c_str() != rawChars );
 
             REQUIRE( isSubstring( ss ) == false );
             REQUIRE( isOwned( ss ) );
 
-            REQUIRE( data( ss ) != data( s ) ); // different pointer value
+            REQUIRE( ss.currentData() != s.currentData() ); // different pointer value
         }
 
         SECTION( "non-zero-based substring") {