Rename the monolitic class to Vst3PluginProxy

Now it's starting to look promising.

src/common/serialization/vst3/plugin-proxy.h

@@ -0,0 +1,151 @@
+// 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_variant.h>
+#include <pluginterfaces/vst/ivstcomponent.h>
+
+#include "../common.h"
+#include "audio-processor.h"
+#include "base.h"
+#include "component.h"
+#include "host-application.h"
+#include "plugin-base.h"
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wnon-virtual-dtor"
+
+/**
+ * An abstract class that optionally implements all VST3 interfaces a plugin
+ * object could implement. A more in depth explanation can be found in
+ * `docs/vst3.md`, but the way this works is that we begin with an `FUnknown`
+ * pointer from the Windows VST3 plugin obtained by a call to
+ * `IPluginFactory::createInstance()` (with an interface decided by the host).
+ * We then go through all the plugin interfaces and check whether that object
+ * supports them one by one. For each supported interface we remember that the
+ * plugin supports it, and we'll optionally write down some static data (such as
+ * the edit controller cid) that can't change over the lifetime of the
+ * application. On the plugin side we then return a `Vst3PluginProxyImpl` object
+ * that contains all of this information about interfaces the object we're
+ * proxying might support. This way we can allow casts to all of those object
+ * types in `queryInterface()`, essentially perfectly mimicing the original
+ * object.
+ *
+ * This monolith approach is also important when it comes to `IConnectionPoint`.
+ * The host should be able to connect arbitrary objects together, and the plugin
+ * can then use the query interface smart pointer casting system to cast those
+ * objects to the types they want. By having a huge monolithic class that
+ * implements any interface such an object might also implement, we can allow
+ * perfect proxying behaviour for connecting components.
+ */
+class Vst3PluginProxy : public YaAudioProcessor,
+                        public YaComponent,
+                        public YaPluginBase {
+   public:
+    /**
+     * These are the arguments for creating a `Vst3PluginProxyImpl`.
+     */
+    struct ConstructArgs {
+        ConstructArgs();
+
+        /**
+         * Read from an existing object. We will try to mimic this object, so
+         * we'll support any interfaces this object also supports.
+         */
+        ConstructArgs(Steinberg::IPtr<FUnknown> object, size_t instance_id);
+
+        /**
+         * The unique identifier for this specific object instance.
+         */
+        native_size_t instance_id;
+
+        YaAudioProcessor::ConstructArgs audio_processor_args;
+        YaComponent::ConstructArgs component_args;
+        YaPluginBase::ConstructArgs plugin_base_args;
+
+        template <typename S>
+        void serialize(S& s) {
+            s.value8b(instance_id);
+            s.object(audio_processor_args);
+            s.object(component_args);
+            s.object(plugin_base_args);
+        }
+    };
+
+    /**
+     * Message to request the Wine plugin host to instantiate a new IComponent
+     * to pass through a call to `IComponent::createInstance(cid,
+     * IComponent::iid, ...)`.
+     */
+    struct Construct {
+        using Response = std::variant<ConstructArgs, UniversalTResult>;
+
+        ArrayUID cid;
+
+        // TODO: Add an enum class to reify the type of object we want to
+        //       instantiate so we can initialize things other than
+        //       `IComponent`, like `IEditController.`
+
+        template <typename S>
+        void serialize(S& s) {
+            s.container1b(cid);
+        }
+    };
+
+    /**
+     * Instantiate this object instance with arguments read from another
+     * interface implementation.
+     */
+    Vst3PluginProxy(const ConstructArgs&& args);
+
+    /**
+     * Message to request the Wine plugin host to destroy this object instance
+     * with the given instance ID. Sent from the destructor of
+     * `Vst3PluginProxyImpl`. This will cause all smart pointers to the actual
+     * object in the Wine plugin host to be dropped.
+     */
+    struct Destruct {
+        using Response = Ack;
+
+        native_size_t instance_id;
+
+        template <typename S>
+        void serialize(S& s) {
+            s.value8b(instance_id);
+        }
+    };
+
+    /**
+     * @remark The plugin side implementation should send a control message to
+     *   clean up the instance on the Wine side in its destructor.
+     */
+    virtual ~Vst3PluginProxy() = 0;
+
+    DECLARE_FUNKNOWN_METHODS
+
+   protected:
+    ConstructArgs arguments;
+};
+
+#pragma GCC diagnostic pop
+
+template <typename S>
+void serialize(
+    S& s,
+    std::variant<Vst3PluginProxy::ConstructArgs, UniversalTResult>& result) {
+    s.ext(result, bitsery::ext::StdVariant{});
+}