Implement IMessage

meson.build

@@ -92,6 +92,7 @@ vst3_plugin_sources = [
   'src/common/serialization/vst3/component-handler-proxy.cpp',
   'src/common/serialization/vst3/event-list.cpp',
   'src/common/serialization/vst3/host-context-proxy.cpp',
+  'src/common/serialization/vst3/message.cpp',
   'src/common/serialization/vst3/param-value-queue.cpp',
   'src/common/serialization/vst3/parameter-changes.cpp',
   'src/common/serialization/vst3/plug-frame-proxy.cpp',
@@ -146,6 +147,7 @@ if with_vst3
     'src/common/serialization/vst3/component-handler-proxy.cpp',
     'src/common/serialization/vst3/event-list.cpp',
     'src/common/serialization/vst3/host-context-proxy.cpp',
+    'src/common/serialization/vst3/message.cpp',
     'src/common/serialization/vst3/param-value-queue.cpp',
     'src/common/serialization/vst3/parameter-changes.cpp',
     'src/common/serialization/vst3/plug-frame-proxy.cpp',

src/common/serialization/vst3/README.md

@@ -38,6 +38,7 @@ implemented for serialization purposes:
 | -------------------- | ------------------- | ---------------------------------------------------------------------- |
 | `YaAttributeList`    | `IAttributeList`    |                                                                        |
 | `YaEventList`        | `IEventList`        | Comes with a lot of serialization wrappers around the related structs. |
+| `YaMessage`          | `IMessage`          |                                                                        |
 | `YaParameterChanges` | `IParameterChanges` |                                                                        |
 | `YaParamValueQueue`  | `IParamValueQueue`  |                                                                        |
 | `VectorStream`       | `IBStream`          | Used for serializing data streams.                                     |

src/common/serialization/vst3/message.cpp

@@ -0,0 +1,50 @@
+// yabridge: a Wine VST bridge
+// Copyright (C) 2020  Robbert van der Helm
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+#include "message.h"
+
+YaMessage::YaMessage(){FUNKNOWN_CTOR}
+
+YaMessage::~YaMessage() {
+    FUNKNOWN_DTOR
+}
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdelete-non-virtual-dtor"
+IMPLEMENT_FUNKNOWN_METHODS(YaMessage,
+                           Steinberg::Vst::IMessage,
+                           Steinberg::Vst::IMessage::iid)
+#pragma GCC diagnostic pop
+
+Steinberg::FIDString PLUGIN_API YaMessage::getMessageID() {
+    if (message_id) {
+        return message_id->c_str();
+    } else {
+        return nullptr;
+    }
+}
+
+void PLUGIN_API YaMessage::setMessageID(Steinberg::FIDString id /*in*/) {
+    if (id) {
+        message_id = id;
+    } else {
+        message_id.reset();
+    }
+}
+
+Steinberg::Vst::IAttributeList* PLUGIN_API YaMessage::getAttributes() {
+    return &attribute_list;
+}

src/common/serialization/vst3/message.h

@@ -0,0 +1,71 @@
+// yabridge: a Wine VST bridge
+// Copyright (C) 2020  Robbert van der Helm
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+#pragma once
+
+#include <bitsery/ext/std_optional.h>
+#include <pluginterfaces/vst/ivstmessage.h>
+
+#include "attribute-list.h"
+#include "base.h"
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wnon-virtual-dtor"
+
+/**
+ * Wraps around `IMessage` for serialization purposes. We create instances of
+ * these in `IHostApplication::createInstance()` so the Windows VST3 plugin can
+ * send messages between objects. There is one huge caveat here: it is
+ * impossible to work with arbitrary `IMessage` objects, since there's no way to
+ * retrieve all of the keys in the attribute list. With this approach we support
+ * hosts that indirectly connect the processor and the controller through a
+ * proxy (like Ardour), but we still require a dynamic cast from the `IMessage*`
+ * passed to `YaConnectionPoint::notify()` to a `YaMessage*` for this to work
+ * for the above mentioned reason.
+ */
+class YaMessage : public Steinberg::Vst::IMessage {
+   public:
+    /**
+     * Default constructor with an empty message. The plugin can use this to
+     * write a message.
+     */
+    YaMessage();
+
+    ~YaMessage();
+
+    DECLARE_FUNKNOWN_METHODS
+
+    virtual Steinberg::FIDString PLUGIN_API getMessageID() override;
+    virtual void PLUGIN_API
+    setMessageID(Steinberg::FIDString id /*in*/) override;
+    virtual Steinberg::Vst::IAttributeList* PLUGIN_API getAttributes() override;
+
+    template <typename S>
+    void serialize(S& s) {
+        s.ext(message_id, bitsery::ext::StdOptional{},
+              [](S& s, std::string& id) { s.text1b(id, 1024); });
+        s.object(attribute_list);
+    }
+
+   private:
+    /**
+     * The implementation that comes with the SDK returns a null pointer when
+     * the ID has not yet been set, so we'll do the same thing.
+     */
+    std::optional<std::string> message_id;
+
+    YaAttributeList attribute_list;
+};