feat: add support for string_view as D-Bus type

include/sdbus-c++/Message.h

@@ -100,6 +100,7 @@ namespace sdbus {
         Message& operator<<(double item);
         Message& operator<<(const char *item);
         Message& operator<<(const std::string &item);
+        Message& operator<<(std::string_view item);
         Message& operator<<(const Variant &item);
         template <typename ...Elements>
         Message& operator<<(const std::variant<Elements...>& value);

include/sdbus-c++/TypeTraits.h

@@ -41,6 +41,7 @@
 #  endif
 #endif
 #include <string>
+#include <string_view>
 #include <tuple>
 #include <type_traits>
 #include <unordered_map>
@@ -231,6 +232,10 @@ namespace sdbus {
         static constexpr bool is_trivial_dbus_type = false;
     };
 
+    template <>
+    struct signature_of<std::string_view> : signature_of<std::string>
+    {};
+
     template <>
     struct signature_of<char*> : signature_of<std::string>
     {};

src/Message.cpp

@@ -35,6 +35,7 @@
 #include "ScopeGuard.h"
 
 #include <cassert>
+#include <cstring>
 #include SDBUS_HEADER
 
 namespace sdbus {
@@ -197,6 +198,17 @@ Message& Message::operator<<(const std::string& item)
     return *this;
 }
 
+Message& Message::operator<<(std::string_view item)
+{
+    char* destPtr{};
+    auto r = sd_bus_message_append_string_space((sd_bus_message*)msg_, item.length(), &destPtr);
+    SDBUS_THROW_ERROR_IF(r < 0, "Failed to serialize a string_view value", -r);
+
+    std::memcpy(destPtr, item.data(), item.length());
+
+    return *this;
+}
+
 Message& Message::operator<<(const Variant &item)
 {
     item.serializeTo(*this);

tests/unittests/Message_test.cpp

@@ -119,7 +119,7 @@ namespace my {
 
 template <>
 struct sdbus::signature_of<my::Struct>
-        : sdbus::signature_of<sdbus::Struct<int, std::string, std::list<double>>>
+    : sdbus::signature_of<sdbus::Struct<int, std::string, std::list<double>>>
 {};
 
 /*-------------------------------------*/
@@ -204,6 +204,21 @@ TEST(AMessage, CanCarryASimpleInteger)
     ASSERT_THAT(dataRead, Eq(dataWritten));
 }
 
+TEST(AMessage, CanCarryAStringAsAStringView)
+{
+    auto msg = sdbus::createPlainMessage();
+
+    const std::string_view dataWritten = "Hello";
+
+    msg << dataWritten;
+    msg.seal();
+
+    std::string dataRead;
+    msg >> dataRead;
+
+    ASSERT_THAT(dataRead, Eq(dataWritten));
+}
+
 TEST(AMessage, CanCarryAUnixFd)
 {
     auto msg = sdbus::createPlainMessage();

tests/unittests/TypeTraits_test.cpp

@@ -85,6 +85,7 @@ namespace
     TYPE(double)HAS_DBUS_TYPE_SIGNATURE("d")
     TYPE(const char*)HAS_DBUS_TYPE_SIGNATURE("s")
     TYPE(std::string)HAS_DBUS_TYPE_SIGNATURE("s")
+    TYPE(std::string_view)HAS_DBUS_TYPE_SIGNATURE("s")
     TYPE(sdbus::BusName)HAS_DBUS_TYPE_SIGNATURE("s")
     TYPE(sdbus::InterfaceName)HAS_DBUS_TYPE_SIGNATURE("s")
     TYPE(sdbus::MemberName)HAS_DBUS_TYPE_SIGNATURE("s")
@@ -122,10 +123,11 @@ namespace
                                 >,
                                 sdbus::Signature,
                                 sdbus::UnixFd,
-                                const char*
+                                const char*,
+                                std::string_view
                             >
                         >;
-    TYPE(ComplexType)HAS_DBUS_TYPE_SIGNATURE("a{t(a{ya(oanbva{is})}ghs)}")
+    TYPE(ComplexType)HAS_DBUS_TYPE_SIGNATURE("a{t(a{ya(oanbva{is})}ghss)}")
 
     typedef ::testing::Types< bool
                             , uint8_t
@@ -138,6 +140,7 @@ namespace
                             , double
                             , const char*
                             , std::string
+                            , std::string_view
                             , sdbus::BusName
                             , sdbus::InterfaceName
                             , sdbus::MemberName