cpp-common: add `bt2s::optional`, alias of `nonstd::optional`

[babeltrace.git] / src / cpp-common / bt2 / message.hpp

diff --git a/src/cpp-common/bt2/message.hpp b/src/cpp-common/bt2/message.hpp
index 4e57572286a3ffe29e31ed591f9e973a8784235e..afc751c5df1b50275363b9c655ecbe7e92d81519 100644 (file)
--- a/src/cpp-common/bt2/message.hpp
+++ b/src/cpp-common/bt2/message.hpp
@@ -7,41 +7,41 @@
 #ifndef BABELTRACE_CPP_COMMON_BT2_MESSAGE_HPP
 #define BABELTRACE_CPP_COMMON_BT2_MESSAGE_HPP
 
-#include <type_traits>
 #include <cstdint>
-#include <functional>
+#include <type_traits>
+
 #include <babeltrace2/babeltrace.h>
 
 #include "common/assert.h"
-#include "common/common.h"
-#include "internal/borrowed-obj.hpp"
-#include "internal/shared-obj.hpp"
+#include "cpp-common/bt2/clock-snapshot.hpp"
+#include "cpp-common/bt2/trace-ir.hpp"
+#include "cpp-common/bt2s/optional.hpp"
+
+#include "borrowed-object.hpp"
 #include "internal/utils.hpp"
-#include "cpp-common/optional.hpp"
-#include "cpp-common/string_view.hpp"
-#include "lib-error.hpp"
+#include "shared-object.hpp"
 
 namespace bt2 {
 namespace internal {
 
 struct MessageRefFuncs final
 {
-    static void get(const bt_message * const libObjPtr)
+    static void get(const bt_message * const libObjPtr) noexcept
     {
         bt_message_get_ref(libObjPtr);
     }
 
-    static void put(const bt_message * const libObjPtr)
+    static void put(const bt_message * const libObjPtr) noexcept
     {
         bt_message_put_ref(libObjPtr);
     }
 };
 
-template <typename ObjT, typename LibObjT>
-using SharedMessage = internal::SharedObj<ObjT, LibObjT, internal::MessageRefFuncs>;
-
 } /* namespace internal */
 
+template <typename ObjT, typename LibObjT>
+using SharedMessage = SharedObject<ObjT, LibObjT, internal::MessageRefFuncs>;
+
 template <typename LibObjT>
 class CommonStreamBeginningMessage;
 
@@ -79,34 +79,39 @@ enum class MessageType
 };
 
 template <typename LibObjT>
-class CommonMessage : public internal::BorrowedObj<LibObjT>
+class CommonMessage : public BorrowedObject<LibObjT>
 {
 private:
-    using typename internal::BorrowedObj<LibObjT>::_ThisBorrowedObj;
+    using typename BorrowedObject<LibObjT>::_ThisBorrowedObject;
 
 protected:
-    using typename internal::BorrowedObj<LibObjT>::_LibObjPtr;
+    using typename BorrowedObject<LibObjT>::_LibObjPtr;
     using _ThisCommonMessage = CommonMessage<LibObjT>;
 
 public:
-    using Shared = internal::SharedMessage<CommonMessage<LibObjT>, LibObjT>;
+    using Shared = SharedMessage<CommonMessage<LibObjT>, LibObjT>;
 
-    explicit CommonMessage(const _LibObjPtr libObjPtr) noexcept : _ThisBorrowedObj {libObjPtr}
+    explicit CommonMessage(const _LibObjPtr libObjPtr) noexcept : _ThisBorrowedObject {libObjPtr}
     {
     }
 
     template <typename OtherLibObjT>
-    CommonMessage(const CommonMessage<OtherLibObjT>& val) noexcept : _ThisBorrowedObj {val}
+    CommonMessage(const CommonMessage<OtherLibObjT> val) noexcept : _ThisBorrowedObject {val}
     {
     }
 
     template <typename OtherLibObjT>
-    _ThisCommonMessage& operator=(const CommonMessage<OtherLibObjT>& val) noexcept
+    _ThisCommonMessage operator=(const CommonMessage<OtherLibObjT> val) noexcept
     {
-        _ThisBorrowedObj::operator=(val);
+        _ThisBorrowedObject::operator=(val);
         return *this;
     }
 
+    CommonMessage<const bt_message> asConst() const noexcept
+    {
+        return CommonMessage<const bt_message> {*this};
+    }
+
     MessageType type() const noexcept
     {
         return static_cast<MessageType>(bt_message_get_type(this->libObjPtr()));
@@ -154,7 +159,13 @@ public:
 
     Shared shared() const noexcept
     {
-        return Shared {*this};
+        return Shared::createWithRef(*this);
+    }
+
+    template <typename MessageT>
+    MessageT as() const noexcept
+    {
+        return MessageT {this->libObjPtr()};
     }
 
     CommonStreamBeginningMessage<LibObjT> asStreamBeginning() const noexcept;
@@ -219,13 +230,10 @@ class CommonStreamBeginningMessage final : public CommonMessage<LibObjT>
 private:
     using typename CommonMessage<LibObjT>::_LibObjPtr;
     using typename CommonMessage<LibObjT>::_ThisCommonMessage;
-
-    using _Stream =
-        typename std::conditional<std::is_const<LibObjT>::value, CommonStream<const bt_stream>,
-                                  CommonStream<bt_stream>>::type;
+    using _Stream = internal::DepStream<LibObjT>;
 
 public:
-    using Shared = internal::SharedMessage<CommonStreamBeginningMessage<LibObjT>, LibObjT>;
+    using Shared = SharedMessage<CommonStreamBeginningMessage<LibObjT>, LibObjT>;
 
     explicit CommonStreamBeginningMessage(const _LibObjPtr libObjPtr) noexcept :
         _ThisCommonMessage {libObjPtr}
@@ -234,39 +242,39 @@ public:
     }
 
     template <typename OtherLibObjT>
-    CommonStreamBeginningMessage(const CommonStreamBeginningMessage<OtherLibObjT>& val) noexcept :
+    CommonStreamBeginningMessage(const CommonStreamBeginningMessage<OtherLibObjT> val) noexcept :
         _ThisCommonMessage {val}
     {
     }
 
     template <typename OtherLibObjT>
-    CommonStreamBeginningMessage<LibObjT>&
-    operator=(const CommonStreamBeginningMessage<OtherLibObjT>& val) noexcept
+    CommonStreamBeginningMessage<LibObjT>
+    operator=(const CommonStreamBeginningMessage<OtherLibObjT> val) noexcept
     {
         _ThisCommonMessage::operator=(val);
         return *this;
     }
 
-    ConstStream stream() const noexcept
+    CommonStreamBeginningMessage<const bt_message> asConst() const noexcept
     {
-        return ConstStream {internal::CommonStreamBeginningMessageSpec<const bt_message>::stream(
-            this->libObjPtr())};
+        return CommonStreamBeginningMessage<const bt_message> {*this};
     }
 
-    _Stream stream() noexcept
+    _Stream stream() const noexcept
     {
         return _Stream {
             internal::CommonStreamBeginningMessageSpec<LibObjT>::stream(this->libObjPtr())};
     }
 
-    void defaultClockSnapshot(const std::uint64_t val) noexcept
+    void defaultClockSnapshot(const std::uint64_t val) const noexcept
     {
-        static_assert(!std::is_const<LibObjT>::value, "`LibObjT` must NOT be `const`.");
+        static_assert(!std::is_const<LibObjT>::value,
+                      "Not available with `bt2::ConstStreamBeginningMessage`.");
 
         bt_message_stream_beginning_set_default_clock_snapshot(this->libObjPtr(), val);
     }
 
-    nonstd::optional<ConstClockSnapshot> defaultClockSnapshot() const noexcept
+    bt2s::optional<ConstClockSnapshot> defaultClockSnapshot() const noexcept
     {
         const bt_clock_snapshot *libObjPtr;
         const auto state = bt_message_stream_beginning_borrow_default_clock_snapshot_const(
@@ -276,12 +284,12 @@ public:
             return ConstClockSnapshot {libObjPtr};
         }
 
-        return nonstd::nullopt;
+        return bt2s::nullopt;
     }
 
     Shared shared() const noexcept
     {
-        return Shared {*this};
+        return Shared::createWithRef(*this);
     }
 };
 
@@ -337,13 +345,10 @@ class CommonStreamEndMessage final : public CommonMessage<LibObjT>
 private:
     using typename CommonMessage<LibObjT>::_LibObjPtr;
     using typename CommonMessage<LibObjT>::_ThisCommonMessage;
-
-    using _Stream =
-        typename std::conditional<std::is_const<LibObjT>::value, CommonStream<const bt_stream>,
-                                  CommonStream<bt_stream>>::type;
+    using _Stream = internal::DepStream<LibObjT>;
 
 public:
-    using Shared = internal::SharedMessage<CommonStreamEndMessage<LibObjT>, LibObjT>;
+    using Shared = SharedMessage<CommonStreamEndMessage<LibObjT>, LibObjT>;
 
     explicit CommonStreamEndMessage(const _LibObjPtr libObjPtr) noexcept :
         _ThisCommonMessage {libObjPtr}
@@ -352,38 +357,38 @@ public:
     }
 
     template <typename OtherLibObjT>
-    CommonStreamEndMessage(const CommonStreamEndMessage<OtherLibObjT>& val) noexcept :
+    CommonStreamEndMessage(const CommonStreamEndMessage<OtherLibObjT> val) noexcept :
         _ThisCommonMessage {val}
     {
     }
 
     template <typename OtherLibObjT>
-    CommonStreamEndMessage<LibObjT>&
-    operator=(const CommonStreamEndMessage<OtherLibObjT>& val) noexcept
+    CommonStreamEndMessage<LibObjT>
+    operator=(const CommonStreamEndMessage<OtherLibObjT> val) noexcept
     {
         _ThisCommonMessage::operator=(val);
         return *this;
     }
 
-    ConstStream stream() const noexcept
+    CommonStreamEndMessage<const bt_message> asConst() const noexcept
     {
-        return ConstStream {
-            internal::CommonStreamEndMessageSpec<const bt_message>::stream(this->libObjPtr())};
+        return CommonStreamEndMessage<const bt_message> {*this};
     }
 
-    _Stream stream() noexcept
+    _Stream stream() const noexcept
     {
         return _Stream {internal::CommonStreamEndMessageSpec<LibObjT>::stream(this->libObjPtr())};
     }
 
-    void defaultClockSnapshot(const std::uint64_t val) noexcept
+    void defaultClockSnapshot(const std::uint64_t val) const noexcept
     {
-        static_assert(!std::is_const<LibObjT>::value, "`LibObjT` must NOT be `const`.");
+        static_assert(!std::is_const<LibObjT>::value,
+                      "Not available with `bt2::ConstStreamEndMessage`.");
 
         bt_message_stream_end_set_default_clock_snapshot(this->libObjPtr(), val);
     }
 
-    nonstd::optional<ConstClockSnapshot> defaultClockSnapshot() const noexcept
+    bt2s::optional<ConstClockSnapshot> defaultClockSnapshot() const noexcept
     {
         const bt_clock_snapshot *libObjPtr;
         const auto state = bt_message_stream_end_borrow_default_clock_snapshot_const(
@@ -393,12 +398,12 @@ public:
             return ConstClockSnapshot {libObjPtr};
         }
 
-        return nonstd::nullopt;
+        return bt2s::nullopt;
     }
 
     Shared shared() const noexcept
     {
-        return Shared {*this};
+        return Shared::createWithRef(*this);
     }
 };
 
@@ -454,13 +459,10 @@ class CommonPacketBeginningMessage final : public CommonMessage<LibObjT>
 private:
     using typename CommonMessage<LibObjT>::_LibObjPtr;
     using typename CommonMessage<LibObjT>::_ThisCommonMessage;
-
-    using _Packet =
-        typename std::conditional<std::is_const<LibObjT>::value, CommonPacket<const bt_packet>,
-                                  CommonPacket<bt_packet>>::type;
+    using _Packet = internal::DepPacket<LibObjT>;
 
 public:
-    using Shared = internal::SharedMessage<CommonPacketBeginningMessage<LibObjT>, LibObjT>;
+    using Shared = SharedMessage<CommonPacketBeginningMessage<LibObjT>, LibObjT>;
 
     explicit CommonPacketBeginningMessage(const _LibObjPtr libObjPtr) noexcept :
         _ThisCommonMessage {libObjPtr}
@@ -469,34 +471,34 @@ public:
     }
 
     template <typename OtherLibObjT>
-    CommonPacketBeginningMessage(const CommonPacketBeginningMessage<OtherLibObjT>& val) noexcept :
+    CommonPacketBeginningMessage(const CommonPacketBeginningMessage<OtherLibObjT> val) noexcept :
         _ThisCommonMessage {val}
     {
     }
 
     template <typename OtherLibObjT>
-    CommonPacketBeginningMessage<LibObjT>&
-    operator=(const CommonPacketBeginningMessage<OtherLibObjT>& val) noexcept
+    CommonPacketBeginningMessage<LibObjT>
+    operator=(const CommonPacketBeginningMessage<OtherLibObjT> val) noexcept
     {
         _ThisCommonMessage::operator=(val);
         return *this;
     }
 
-    ConstPacket packet() const noexcept
+    CommonPacketBeginningMessage<const bt_message> asConst() const noexcept
     {
-        return ConstPacket {internal::CommonPacketBeginningMessageSpec<const bt_message>::packet(
-            this->libObjPtr())};
+        return CommonPacketBeginningMessage<const bt_message> {*this};
     }
 
-    _Packet packet() noexcept
+    _Packet packet() const noexcept
     {
         return _Packet {
             internal::CommonPacketBeginningMessageSpec<LibObjT>::packet(this->libObjPtr())};
     }
 
-    void defaultClockSnapshot(const std::uint64_t val) noexcept
+    void defaultClockSnapshot(const std::uint64_t val) const noexcept
     {
-        static_assert(!std::is_const<LibObjT>::value, "`LibObjT` must NOT be `const`.");
+        static_assert(!std::is_const<LibObjT>::value,
+                      "Not available with `bt2::ConstPacketBeginningMessage`.");
 
         bt_message_packet_beginning_set_default_clock_snapshot(this->libObjPtr(), val);
     }
@@ -511,7 +513,7 @@ public:
 
     Shared shared() const noexcept
     {
-        return Shared {*this};
+        return Shared::createWithRef(*this);
     }
 };
 
@@ -567,13 +569,10 @@ class CommonPacketEndMessage final : public CommonMessage<LibObjT>
 private:
     using typename CommonMessage<LibObjT>::_LibObjPtr;
     using typename CommonMessage<LibObjT>::_ThisCommonMessage;
-
-    using _Packet =
-        typename std::conditional<std::is_const<LibObjT>::value, CommonPacket<const bt_packet>,
-                                  CommonPacket<bt_packet>>::type;
+    using _Packet = internal::DepPacket<LibObjT>;
 
 public:
-    using Shared = internal::SharedMessage<CommonPacketEndMessage<LibObjT>, LibObjT>;
+    using Shared = SharedMessage<CommonPacketEndMessage<LibObjT>, LibObjT>;
 
     explicit CommonPacketEndMessage(const _LibObjPtr libObjPtr) noexcept :
         _ThisCommonMessage {libObjPtr}
@@ -582,33 +581,33 @@ public:
     }
 
     template <typename OtherLibObjT>
-    CommonPacketEndMessage(const CommonPacketEndMessage<OtherLibObjT>& val) noexcept :
+    CommonPacketEndMessage(const CommonPacketEndMessage<OtherLibObjT> val) noexcept :
         _ThisCommonMessage {val}
     {
     }
 
     template <typename OtherLibObjT>
-    CommonPacketEndMessage<LibObjT>&
-    operator=(const CommonPacketEndMessage<OtherLibObjT>& val) noexcept
+    CommonPacketEndMessage<LibObjT>
+    operator=(const CommonPacketEndMessage<OtherLibObjT> val) noexcept
     {
         _ThisCommonMessage::operator=(val);
         return *this;
     }
 
-    ConstPacket packet() const noexcept
+    CommonPacketEndMessage<const bt_message> asConst() const noexcept
     {
-        return ConstPacket {
-            internal::CommonPacketEndMessageSpec<const bt_message>::packet(this->libObjPtr())};
+        return CommonPacketEndMessage<const bt_message> {*this};
     }
 
-    _Packet packet() noexcept
+    _Packet packet() const noexcept
     {
         return _Packet {internal::CommonPacketEndMessageSpec<LibObjT>::packet(this->libObjPtr())};
     }
 
-    void defaultClockSnapshot(const std::uint64_t val) noexcept
+    void defaultClockSnapshot(const std::uint64_t val) const noexcept
     {
-        static_assert(!std::is_const<LibObjT>::value, "`LibObjT` must NOT be `const`.");
+        static_assert(!std::is_const<LibObjT>::value,
+                      "Not available with `bt2::ConstPacketEndMessage`.");
 
         bt_message_packet_end_set_default_clock_snapshot(this->libObjPtr(), val);
     }
@@ -623,7 +622,7 @@ public:
 
     Shared shared() const noexcept
     {
-        return Shared {*this};
+        return Shared::createWithRef(*this);
     }
 };
 
@@ -679,13 +678,10 @@ class CommonEventMessage final : public CommonMessage<LibObjT>
 private:
     using typename CommonMessage<LibObjT>::_LibObjPtr;
     using typename CommonMessage<LibObjT>::_ThisCommonMessage;
-
-    using _Event =
-        typename std::conditional<std::is_const<LibObjT>::value, CommonEvent<const bt_event>,
-                                  CommonEvent<bt_event>>::type;
+    using _Event = internal::DepType<LibObjT, CommonEvent<bt_event>, CommonEvent<const bt_event>>;
 
 public:
-    using Shared = internal::SharedMessage<CommonEventMessage<LibObjT>, LibObjT>;
+    using Shared = SharedMessage<CommonEventMessage<LibObjT>, LibObjT>;
 
     explicit CommonEventMessage(const _LibObjPtr libObjPtr) noexcept :
         _ThisCommonMessage {libObjPtr}
@@ -694,25 +690,24 @@ public:
     }
 
     template <typename OtherLibObjT>
-    CommonEventMessage(const CommonEventMessage<OtherLibObjT>& val) noexcept :
+    CommonEventMessage(const CommonEventMessage<OtherLibObjT> val) noexcept :
         _ThisCommonMessage {val}
     {
     }
 
     template <typename OtherLibObjT>
-    CommonEventMessage<LibObjT>& operator=(const CommonEventMessage<OtherLibObjT>& val) noexcept
+    CommonEventMessage<LibObjT> operator=(const CommonEventMessage<OtherLibObjT> val) noexcept
     {
         _ThisCommonMessage::operator=(val);
         return *this;
     }
 
-    ConstEvent event() const noexcept
+    CommonEventMessage<const bt_message> asConst() const noexcept
     {
-        return ConstEvent {
-            internal::CommonEventMessageSpec<const bt_message>::event(this->libObjPtr())};
+        return CommonEventMessage<const bt_message> {*this};
     }
 
-    _Event event() noexcept
+    _Event event() const noexcept
     {
         return _Event {internal::CommonEventMessageSpec<LibObjT>::event(this->libObjPtr())};
     }
@@ -727,7 +722,7 @@ public:
 
     Shared shared() const noexcept
     {
-        return Shared {*this};
+        return Shared::createWithRef(*this);
     }
 };
 
@@ -783,13 +778,10 @@ class CommonDiscardedEventsMessage final : public CommonMessage<LibObjT>
 private:
     using typename CommonMessage<LibObjT>::_LibObjPtr;
     using typename CommonMessage<LibObjT>::_ThisCommonMessage;
-
-    using _Stream =
-        typename std::conditional<std::is_const<LibObjT>::value, CommonStream<const bt_stream>,
-                                  CommonStream<bt_stream>>::type;
+    using _Stream = internal::DepStream<LibObjT>;
 
 public:
-    using Shared = internal::SharedMessage<CommonDiscardedEventsMessage<LibObjT>, LibObjT>;
+    using Shared = SharedMessage<CommonDiscardedEventsMessage<LibObjT>, LibObjT>;
 
     explicit CommonDiscardedEventsMessage(const _LibObjPtr libObjPtr) noexcept :
         _ThisCommonMessage {libObjPtr}
@@ -798,26 +790,25 @@ public:
     }
 
     template <typename OtherLibObjT>
-    CommonDiscardedEventsMessage(const CommonDiscardedEventsMessage<OtherLibObjT>& val) noexcept :
+    CommonDiscardedEventsMessage(const CommonDiscardedEventsMessage<OtherLibObjT> val) noexcept :
         _ThisCommonMessage {val}
     {
     }
 
     template <typename OtherLibObjT>
-    CommonDiscardedEventsMessage<LibObjT>&
-    operator=(const CommonDiscardedEventsMessage<OtherLibObjT>& val) noexcept
+    CommonDiscardedEventsMessage<LibObjT>
+    operator=(const CommonDiscardedEventsMessage<OtherLibObjT> val) noexcept
     {
         _ThisCommonMessage::operator=(val);
         return *this;
     }
 
-    ConstStream stream() const noexcept
+    CommonDiscardedEventsMessage<const bt_message> asConst() const noexcept
     {
-        return ConstStream {internal::CommonDiscardedEventsMessageSpec<const bt_message>::stream(
-            this->libObjPtr())};
+        return CommonDiscardedEventsMessage<const bt_message> {*this};
     }
 
-    _Stream stream() noexcept
+    _Stream stream() const noexcept
     {
         return _Stream {
             internal::CommonDiscardedEventsMessageSpec<LibObjT>::stream(this->libObjPtr())};
@@ -840,14 +831,15 @@ public:
         return ConstClockSnapshot {libObjPtr};
     }
 
-    void count(const std::uint64_t count) noexcept
+    void count(const std::uint64_t count) const noexcept
     {
-        static_assert(!std::is_const<LibObjT>::value, "`LibObjT` must NOT be `const`.");
+        static_assert(!std::is_const<LibObjT>::value,
+                      "Not available with `bt2::ConstDiscardedEventsMessage`.");
 
         bt_message_discarded_events_set_count(this->libObjPtr(), count);
     }
 
-    nonstd::optional<std::uint64_t> count() const noexcept
+    bt2s::optional<std::uint64_t> count() const noexcept
     {
         std::uint64_t count;
         const auto avail = bt_message_discarded_events_get_count(this->libObjPtr(), &count);
@@ -856,12 +848,12 @@ public:
             return count;
         }
 
-        return nonstd::nullopt;
+        return bt2s::nullopt;
     }
 
     Shared shared() const noexcept
     {
-        return Shared {*this};
+        return Shared::createWithRef(*this);
     }
 };
 
@@ -917,13 +909,10 @@ class CommonDiscardedPacketsMessage final : public CommonMessage<LibObjT>
 private:
     using typename CommonMessage<LibObjT>::_LibObjPtr;
     using typename CommonMessage<LibObjT>::_ThisCommonMessage;
-
-    using _Stream =
-        typename std::conditional<std::is_const<LibObjT>::value, CommonStream<const bt_stream>,
-                                  CommonStream<bt_stream>>::type;
+    using _Stream = internal::DepStream<LibObjT>;
 
 public:
-    using Shared = internal::SharedMessage<CommonDiscardedPacketsMessage<LibObjT>, LibObjT>;
+    using Shared = SharedMessage<CommonDiscardedPacketsMessage<LibObjT>, LibObjT>;
 
     explicit CommonDiscardedPacketsMessage(const _LibObjPtr libObjPtr) noexcept :
         _ThisCommonMessage {libObjPtr}
@@ -932,26 +921,25 @@ public:
     }
 
     template <typename OtherLibObjT>
-    CommonDiscardedPacketsMessage(const CommonDiscardedPacketsMessage<OtherLibObjT>& val) noexcept :
+    CommonDiscardedPacketsMessage(const CommonDiscardedPacketsMessage<OtherLibObjT> val) noexcept :
         _ThisCommonMessage {val}
     {
     }
 
     template <typename OtherLibObjT>
-    CommonDiscardedPacketsMessage<LibObjT>&
-    operator=(const CommonDiscardedPacketsMessage<OtherLibObjT>& val) noexcept
+    CommonDiscardedPacketsMessage<LibObjT>
+    operator=(const CommonDiscardedPacketsMessage<OtherLibObjT> val) noexcept
     {
         _ThisCommonMessage::operator=(val);
         return *this;
     }
 
-    ConstStream stream() const noexcept
+    CommonDiscardedPacketsMessage<const bt_message> asConst() const noexcept
     {
-        return ConstStream {internal::CommonDiscardedPacketsMessageSpec<const bt_message>::stream(
-            this->libObjPtr())};
+        return CommonDiscardedPacketsMessage<const bt_message> {*this};
     }
 
-    _Stream stream() noexcept
+    _Stream stream() const noexcept
     {
         return _Stream {
             internal::CommonDiscardedPacketsMessageSpec<LibObjT>::stream(this->libObjPtr())};
@@ -974,14 +962,15 @@ public:
         return ConstClockSnapshot {libObjPtr};
     }
 
-    void count(const std::uint64_t count) noexcept
+    void count(const std::uint64_t count) const noexcept
     {
-        static_assert(!std::is_const<LibObjT>::value, "`LibObjT` must NOT be `const`.");
+        static_assert(!std::is_const<LibObjT>::value,
+                      "Not available with `bt2::ConstDiscardedPacketsMessage`.");
 
         bt_message_discarded_packets_set_count(this->libObjPtr(), count);
     }
 
-    nonstd::optional<std::uint64_t> count() const noexcept
+    bt2s::optional<std::uint64_t> count() const noexcept
     {
         std::uint64_t count;
         const auto avail = bt_message_discarded_packets_get_count(this->libObjPtr(), &count);
@@ -990,12 +979,12 @@ public:
             return count;
         }
 
-        return nonstd::nullopt;
+        return bt2s::nullopt;
     }
 
     Shared shared() const noexcept
     {
-        return Shared {*this};
+        return Shared::createWithRef(*this);
     }
 };
 
@@ -1030,8 +1019,7 @@ private:
     using typename CommonMessage<LibObjT>::_ThisCommonMessage;
 
 public:
-    using Shared =
-        internal::SharedMessage<CommonMessageIteratorInactivityMessage<LibObjT>, LibObjT>;
+    using Shared = SharedMessage<CommonMessageIteratorInactivityMessage<LibObjT>, LibObjT>;
 
     explicit CommonMessageIteratorInactivityMessage(const _LibObjPtr libObjPtr) noexcept :
         _ThisCommonMessage {libObjPtr}
@@ -1041,19 +1029,24 @@ public:
 
     template <typename OtherLibObjT>
     CommonMessageIteratorInactivityMessage(
-        const CommonMessageIteratorInactivityMessage<OtherLibObjT>& val) noexcept :
+        const CommonMessageIteratorInactivityMessage<OtherLibObjT> val) noexcept :
         _ThisCommonMessage {val}
     {
     }
 
     template <typename OtherLibObjT>
-    CommonMessageIteratorInactivityMessage<LibObjT>&
-    operator=(const CommonMessageIteratorInactivityMessage<OtherLibObjT>& val) noexcept
+    CommonMessageIteratorInactivityMessage<LibObjT>
+    operator=(const CommonMessageIteratorInactivityMessage<OtherLibObjT> val) noexcept
     {
         _ThisCommonMessage::operator=(val);
         return *this;
     }
 
+    CommonMessageIteratorInactivityMessage<const bt_message> asConst() const noexcept
+    {
+        return CommonMessageIteratorInactivityMessage<const bt_message> {*this};
+    }
+
     ConstClockSnapshot clockSnapshot() const noexcept
     {
         const auto libObjPtr =
@@ -1064,7 +1057,7 @@ public:
 
     Shared shared() const noexcept
     {
-        return Shared {*this};
+        return Shared::createWithRef(*this);
     }
 };
 
@@ -1136,6 +1129,13 @@ CommonDiscardedEventsMessage<LibObjT> CommonMessage<LibObjT>::asDiscardedEvents(
     return CommonDiscardedEventsMessage<LibObjT> {this->libObjPtr()};
 }
 
+template <typename LibObjT>
+CommonDiscardedPacketsMessage<LibObjT> CommonMessage<LibObjT>::asDiscardedPackets() const noexcept
+{
+    BT_ASSERT_DBG(this->isDiscardedPackets());
+    return CommonDiscardedPacketsMessage<LibObjT> {this->libObjPtr()};
+}
+
 template <typename LibObjT>
 CommonMessageIteratorInactivityMessage<LibObjT>
 CommonMessage<LibObjT>::asMessageIteratorInactivity() const noexcept