Split IPluginBase from IComponent

We're also going to need this for `IEditController`. Separating all of
these classes will also keep everything much more maintainable with all
of these associated structs.

docs/vst3.md

@@ -2,6 +2,8 @@
 
 TODO: Flesh this out further
 
+TODO: Link to `src/common/serialization/vst3/README.md`
+
 The VST3 SDK uses an architecture where every concrete object inherits from an
 interface, and every interface inherits from `FUnknown`. `FUnkonwn` offers a
 dynamic casting interface through `queryInterface()` and a reference counting

meson.build

@@ -83,6 +83,7 @@ vst3_plugin_sources = [
   'src/common/serialization/vst3/host-application.cpp',
   'src/common/serialization/vst3/param-value-queue.cpp',
   'src/common/serialization/vst3/parameter-changes.cpp',
+  'src/common/serialization/vst3/plugin-base.cpp',
   'src/common/serialization/vst3/plugin-factory.cpp',
   'src/common/serialization/vst3/process-data.cpp',
   'src/common/configuration.cpp',
@@ -122,6 +123,7 @@ if with_vst3
     'src/common/serialization/vst3/host-application.cpp',
     'src/common/serialization/vst3/param-value-queue.cpp',
     'src/common/serialization/vst3/parameter-changes.cpp',
+    'src/common/serialization/vst3/plugin-base.cpp',
     'src/common/serialization/vst3/plugin-factory.cpp',
     'src/common/serialization/vst3/process-data.cpp',
     'src/wine-host/bridges/vst3-impls/host-application.cpp',

src/common/logging/vst3.cpp

@@ -54,27 +54,6 @@ void Vst3Logger::log_request(bool is_host_vst,
     });
 }
 
-void Vst3Logger::log_request(bool is_host_vst,
-                             const YaComponent::Initialize& request) {
-    log_request_base(is_host_vst, [&](auto& message) {
-        message << "<IComponent* #" << request.instance_id
-                << ">::initialize(context = ";
-        if (request.host_application_context_args) {
-            message << "<IHostApplication*>";
-        } else {
-            message << "<nullptr>";
-        }
-        message << ")";
-    });
-}
-
-void Vst3Logger::log_request(bool is_host_vst,
-                             const YaComponent::Terminate& request) {
-    log_request_base(is_host_vst, [&](auto& message) {
-        message << "<IComponent* #" << request.instance_id << ">::terminate()";
-    });
-}
-
 void Vst3Logger::log_request(bool is_host_vst,
                              const YaComponent::SetIoMode& request) {
     log_request_base(is_host_vst, [&](auto& message) {
@@ -227,6 +206,27 @@ void Vst3Logger::log_request(bool is_host_vst,
     });
 }
 
+void Vst3Logger::log_request(bool is_host_vst,
+                             const YaPluginBase::Initialize& request) {
+    log_request_base(is_host_vst, [&](auto& message) {
+        message << "<IPluginBase* #" << request.instance_id
+                << ">::initialize(context = ";
+        if (request.host_application_context_args) {
+            message << "<IHostApplication*>";
+        } else {
+            message << "<nullptr>";
+        }
+        message << ")";
+    });
+}
+
+void Vst3Logger::log_request(bool is_host_vst,
+                             const YaPluginBase::Terminate& request) {
+    log_request_base(is_host_vst, [&](auto& message) {
+        message << "<IPluginBase* #" << request.instance_id << ">::terminate()";
+    });
+}
+
 void Vst3Logger::log_request(bool is_host_vst,
                              const YaPluginFactory::Construct&) {
     log_request_base(is_host_vst,

src/common/logging/vst3.h

@@ -58,8 +58,6 @@ class Vst3Logger {
 
     void log_request(bool is_host_vst, const YaComponent::Construct&);
     void log_request(bool is_host_vst, const YaComponent::Destruct&);
-    void log_request(bool is_host_vst, const YaComponent::Initialize&);
-    void log_request(bool is_host_vst, const YaComponent::Terminate&);
     void log_request(bool is_host_vst, const YaComponent::SetIoMode&);
     void log_request(bool is_host_vst, const YaComponent::GetBusCount&);
     void log_request(bool is_host_vst, const YaComponent::GetBusInfo&);
@@ -77,6 +75,8 @@ class Vst3Logger {
     void log_request(bool is_host_vst, const YaComponent::SetProcessing&);
     void log_request(bool is_host_vst, const YaComponent::Process&);
     void log_request(bool is_host_vst, const YaComponent::GetTailSamples&);
+    void log_request(bool is_host_vst, const YaPluginBase::Initialize&);
+    void log_request(bool is_host_vst, const YaPluginBase::Terminate&);
     void log_request(bool is_host_vst, const YaPluginFactory::Construct&);
     void log_request(bool is_host_vst, const YaPluginFactory::SetHostContext&);
     void log_request(bool is_host_vst, const WantsConfiguration&);

src/common/serialization/vst3.h

@@ -59,8 +59,6 @@ struct WantsConfiguration {
  */
 using ControlRequest = std::variant<YaComponent::Construct,
                                     YaComponent::Destruct,
-                                    YaComponent::Initialize,
-                                    YaComponent::Terminate,
                                     YaComponent::SetIoMode,
                                     YaComponent::GetBusCount,
                                     YaComponent::GetBusInfo,
@@ -77,6 +75,8 @@ using ControlRequest = std::variant<YaComponent::Construct,
                                     YaComponent::SetProcessing,
                                     YaComponent::Process,
                                     YaComponent::GetTailSamples,
+                                    YaPluginBase::Initialize,
+                                    YaPluginBase::Terminate,
                                     YaPluginFactory::Construct,
                                     YaPluginFactory::SetHostContext>;
 

src/common/serialization/vst3/README.md

@@ -7,11 +7,12 @@ serialization works.
 
 VST3 interfaces are implemented as follows:
 
-| Yabridge class      | Interfaces                                             | Notes                                                      |
-| ------------------- | ------------------------------------------------------ | ---------------------------------------------------------- |
-| `YaComponent`       | `IComponent`, `IPluginBase`, `IAudioProcessor`         |                                                            |
-| `YaHostApplication` | `iHostAPplication`                                     | Used as a 'context' to allow the plugin to maek callbacks. |
-| `YaPluginFactory`   | `IPluginFactory`, `IPluginFactory2`, `IPluginFactory3` |                                                            |
+| Yabridge class      | Included in   | Interfaces                                             |
+| ------------------- | ------------- | ------------------------------------------------------ |
+| `YaComponent`       |               | `IComponent`, `IAudioProcessor`                        |
+| `YaHostApplication` |               | `iHostAPplication`                                     |
+| `YaPluginBase`      | `YaComponent` | `IPluginBase`                                          |
+| `YaPluginFactory`   |               | `IPluginFactory`, `IPluginFactory2`, `IPluginFactory3` |
 
 The following interfaces are implemented purely fur serialization purposes:
 

src/common/serialization/vst3/component.cpp

@@ -21,30 +21,21 @@ YaComponent::ConstructArgs::ConstructArgs() {}
 YaComponent::ConstructArgs::ConstructArgs(
     Steinberg::IPtr<Steinberg::Vst::IComponent> component,
     size_t instance_id)
-    : instance_id(instance_id) {
-    known_iids.insert(component->iid);
+    : instance_id(instance_id),
+      audio_processor_supported(
+          Steinberg::FUnknownPtr<Steinberg::Vst::IAudioProcessor>(component)) {
     // `IComponent::getControllerClassId`
     Steinberg::TUID cid;
     if (component->getControllerClassId(cid) == Steinberg::kResultOk) {
         edit_controller_cid = std::to_array(cid);
     }
-
-    // There's no static data we can copy from the audio processor
-    if (auto audio_processor =
-            Steinberg::FUnknownPtr<Steinberg::Vst::IAudioProcessor>(
-                component)) {
-        known_iids.insert(Steinberg::Vst::IAudioProcessor::iid);
-    }
 }
 
-YaComponent::YaComponent(const ConstructArgs&& args) : arguments(std::move(args)) {
-    FUNKNOWN_CTOR
+YaComponent::YaComponent(const ConstructArgs&& args)
+    : YaPluginBase(std::move(args.plugin_base_args)),
+      arguments(std::move(args)){FUNKNOWN_CTOR}
 
-    // Everything else is handled directly through callbacks to minimize the
-    // potential for errors
-}
-
-YaComponent::~YaComponent() {
+      YaComponent::~YaComponent() {
     FUNKNOWN_DTOR
 }
 
@@ -55,14 +46,22 @@ IMPLEMENT_REFCOUNT(YaComponent)
 
 tresult PLUGIN_API YaComponent::queryInterface(Steinberg::FIDString _iid,
                                                void** obj) {
-    QUERY_INTERFACE(_iid, obj, Steinberg::FUnknown::iid, Steinberg::IPluginBase)
-    if (arguments.known_iids.contains(Steinberg::Vst::IComponent::iid)) {
-        QUERY_INTERFACE(_iid, obj, Steinberg::IPluginBase::iid,
-                        Steinberg::IPluginBase)
-        QUERY_INTERFACE(_iid, obj, Steinberg::Vst::IComponent::iid,
-                        Steinberg::Vst::IComponent)
+    QUERY_INTERFACE(_iid, obj, Steinberg::FUnknown::iid,
+                    Steinberg::Vst::IComponent)
+    if (YaPluginBase::supported()) {
+        // We had to expand the macro here because we need to cast through
+        // `YaPluginBase`, since `IpluginBase` is also a base of `IComponent`
+        if (Steinberg::FUnknownPrivate ::iidEqual(
+                _iid, Steinberg::IPluginBase::iid)) {
+            addRef();
+            *obj = static_cast<Steinberg ::IPluginBase*>(
+                static_cast<YaPluginBase*>(this));
+            return ::Steinberg ::kResultOk;
+        }
     }
-    if (arguments.known_iids.contains(Steinberg::Vst::IAudioProcessor::iid)) {
+    QUERY_INTERFACE(_iid, obj, Steinberg::Vst::IComponent::iid,
+                    Steinberg::Vst::IComponent)
+    if (arguments.audio_processor_supported) {
         QUERY_INTERFACE(_iid, obj, Steinberg::Vst::IAudioProcessor::iid,
                         Steinberg::Vst::IAudioProcessor)
     }

src/common/serialization/vst3/component.h

@@ -32,6 +32,7 @@
 #include "../common.h"
 #include "base.h"
 #include "host-application.h"
+#include "plugin-base.h"
 #include "process-data.h"
 
 #pragma GCC diagnostic push
@@ -43,18 +44,18 @@
  * used for serialization, and on the plugin side have an implementation that
  * can send control messages.
  *
+ * This implements all interfaces that an `IComponent` might also implement.
+ *
  * We might be able to do some caching here with the buss infos, but since that
  * sounds like a huge potential source of errors we'll just do pure callbacks
  * for everything other than the edit controller's class ID.
  *
- * TODO: Amplement IConnectionPoint
- * TODO: How should we support IComponents without a seperate edit controller?
- *       Can we just use a separate `YaEditController` that just points to the
- *       same implementation (with the same CID)? Check the reference
- *       implementation in the framework to see how this is initialized, make
- *       sure we support the reference w workflow.
+ * TODO: Rework this into `YaPluginMonolith`
+ * TODO: Eventually this should (optionally) implement everything supported by
+ *       the SDK's `AudioEffect` component.
  */
 class YaComponent : public Steinberg::Vst::IComponent,
+                    public YaPluginBase,
                     public Steinberg::Vst::IAudioProcessor {
    public:
     /**
@@ -76,10 +77,10 @@ class YaComponent : public Steinberg::Vst::IComponent,
          */
         native_size_t instance_id;
 
-        /**
-         * The IIDs that the interface we serialized supports.
-         */
-        std::set<Steinberg::FUID> known_iids;
+        YaPluginBase::ConstructArgs plugin_base_args;
+
+        // TODO: Remove, transitional
+        bool audio_processor_supported;
 
         /**
          * The class ID of this component's corresponding editor controller. You
@@ -90,10 +91,8 @@ class YaComponent : public Steinberg::Vst::IComponent,
         template <typename S>
         void serialize(S& s) {
             s.value8b(instance_id);
-            s.ext(known_iids, bitsery::ext::StdSet{32},
-                  [](S& s, Steinberg::FUID& iid) {
-                      s.ext(iid, bitsery::ext::FUID{});
-                  });
+            s.object(plugin_base_args);
+            s.value1b(audio_processor_supported);
             s.ext(edit_controller_cid, bitsery::ext::StdOptional{},
                   [](S& s, auto& cid) { s.container1b(cid); });
         }
@@ -146,49 +145,6 @@ class YaComponent : public Steinberg::Vst::IComponent,
 
     DECLARE_FUNKNOWN_METHODS
 
-    // From `IPluginBase`
-
-    /**
-     * Message to pass through a call to `IPluginBase::initialize()` to the Wine
-     * plugin host. if we pass an `IHostApplication` instance, then a proxy
-     * `YaHostApplication` should be created and passed as an argument to
-     * `IPluginBase::initialize()`. If this is absent a null pointer should be
-     * passed. The lifetime of this `YaHostApplication` object should be bound
-     * to the `IComponent` we are proxying.
-     */
-    struct Initialize {
-        using Response = UniversalTResult;
-
-        native_size_t instance_id;
-        std::optional<YaHostApplication::ConstructArgs>
-            host_application_context_args;
-
-        template <typename S>
-        void serialize(S& s) {
-            s.value8b(instance_id);
-            s.ext(host_application_context_args, bitsery::ext::StdOptional{});
-        }
-    };
-
-    virtual tresult PLUGIN_API initialize(FUnknown* context) override = 0;
-
-    /**
-     * Message to pass through a call to `IPluginBase::terminate()` to the Wine
-     * plugin host.
-     */
-    struct Terminate {
-        using Response = UniversalTResult;
-
-        native_size_t instance_id;
-
-        template <typename S>
-        void serialize(S& s) {
-            s.value8b(instance_id);
-        }
-    };
-
-    virtual tresult PLUGIN_API terminate() override = 0;
-
     // From `IComponent`
     tresult PLUGIN_API getControllerClassId(Steinberg::TUID classId) override;
 

src/common/serialization/vst3/plugin-base.cpp

@@ -0,0 +1,26 @@
+// 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 "plugin-base.h"
+
+YaPluginBase::ConstructArgs::ConstructArgs() {}
+
+YaPluginBase::ConstructArgs::ConstructArgs(
+    Steinberg::IPtr<Steinberg::FUnknown> component)
+    : supported(Steinberg::FUnknownPtr<Steinberg::IPluginBase>(component)) {}
+
+YaPluginBase::YaPluginBase(const ConstructArgs&& args)
+    : arguments(std::move(args)) {}

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

@@ -0,0 +1,113 @@
+// 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/base/ipluginbase.h>
+
+#include "../common.h"
+#include "base.h"
+#include "host-application.h"
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wnon-virtual-dtor"
+
+/**
+ * Wraps around `IPluginBase` for serialization purposes. Both components and
+ * edit controllers inherit from this. This is instantiated as part of
+ * `YaComponent` or `YaEditController`.
+ */
+class YaPluginBase : public Steinberg::IPluginBase {
+   public:
+    /**
+     * These are the arguments for creating a `YaPluginBase`.
+     */
+    struct ConstructArgs {
+        ConstructArgs();
+
+        /**
+         * Read arguments from an existing implementation. Depending on the
+         * supported interface function more or less of this struct will be left
+         * empty, and `known_iids` will be set accordingly.
+         */
+        ConstructArgs(Steinberg::IPtr<Steinberg::FUnknown> object);
+
+        /**
+         * Whether the object supported this interface.
+         */
+        bool supported;
+
+        template <typename S>
+        void serialize(S& s) {
+            s.value1b(supported);
+        }
+    };
+
+    /**
+     * Instantiate this instance with arguments read from another interface
+     * implementation.
+     */
+    YaPluginBase(const ConstructArgs&& args);
+
+    inline bool supported() { return arguments.supported; }
+
+    /**
+     * Message to pass through a call to `IPluginBase::initialize()` to the Wine
+     * plugin host. if we pass an `IHostApplication` instance, then a proxy
+     * `YaHostApplication` should be created and passed as an argument to
+     * `IPluginBase::initialize()`. If this is absent a null pointer should be
+     * passed. The lifetime of this `YaHostApplication` object should be bound
+     * to the `IComponent` we are proxying.
+     */
+    struct Initialize {
+        using Response = UniversalTResult;
+
+        native_size_t instance_id;
+        std::optional<YaHostApplication::ConstructArgs>
+            host_application_context_args;
+
+        template <typename S>
+        void serialize(S& s) {
+            s.value8b(instance_id);
+            s.ext(host_application_context_args, bitsery::ext::StdOptional{});
+        }
+    };
+
+    virtual tresult PLUGIN_API initialize(FUnknown* context) override = 0;
+
+    /**
+     * Message to pass through a call to `IPluginBase::terminate()` to the Wine
+     * plugin host.
+     */
+    struct Terminate {
+        using Response = UniversalTResult;
+
+        native_size_t instance_id;
+
+        template <typename S>
+        void serialize(S& s) {
+            s.value8b(instance_id);
+        }
+    };
+
+    virtual tresult PLUGIN_API terminate() override = 0;
+
+   protected:
+    ConstructArgs arguments;
+};
+
+#pragma GCC diagnostic pop

src/plugin/bridges/vst3-impls/component.cpp

@@ -40,35 +40,6 @@ YaComponentPluginImpl::queryInterface(const Steinberg::TUID _iid, void** obj) {
     return result;
 }
 
-tresult PLUGIN_API YaComponentPluginImpl::initialize(FUnknown* context) {
-    // This `context` will likely be an `IHostApplication`. If it is, we will
-    // store it here, and we'll proxy through all calls to it made from the Wine
-    // side. Otherwise we'll still call `IPluginBase::initialize()` but with a
-    // null pointer instead.
-    host_application_context = context;
-
-    std::optional<YaHostApplication::ConstructArgs>
-        host_application_context_args = std::nullopt;
-    if (host_application_context) {
-        host_application_context_args = YaHostApplication::ConstructArgs(
-            host_application_context, arguments.instance_id);
-    } else {
-        bridge.logger.log_unknown_interface(
-            "In IPluginBase::initialize()",
-            context ? std::optional(context->iid) : std::nullopt);
-    }
-
-    return bridge.send_message(
-        YaComponent::Initialize{.instance_id = arguments.instance_id,
-                                .host_application_context_args =
-                                    std::move(host_application_context_args)});
-}
-
-tresult PLUGIN_API YaComponentPluginImpl::terminate() {
-    return bridge.send_message(
-        YaComponent::Terminate{.instance_id = arguments.instance_id});
-}
-
 tresult PLUGIN_API
 YaComponentPluginImpl::setIoMode(Steinberg::Vst::IoMode mode) {
     return bridge.send_message(YaComponent::SetIoMode{
@@ -143,6 +114,35 @@ tresult PLUGIN_API YaComponentPluginImpl::getState(Steinberg::IBStream* state) {
     return response.result;
 }
 
+tresult PLUGIN_API YaComponentPluginImpl::initialize(FUnknown* context) {
+    // This `context` will likely be an `IHostApplication`. If it is, we will
+    // store it here, and we'll proxy through all calls to it made from the Wine
+    // side. Otherwise we'll still call `IPluginBase::initialize()` but with a
+    // null pointer instead.
+    host_application_context = context;
+
+    std::optional<YaHostApplication::ConstructArgs>
+        host_application_context_args = std::nullopt;
+    if (host_application_context) {
+        host_application_context_args = YaHostApplication::ConstructArgs(
+            host_application_context, arguments.instance_id);
+    } else {
+        bridge.logger.log_unknown_interface(
+            "In IPluginBase::initialize()",
+            context ? std::optional(context->iid) : std::nullopt);
+    }
+
+    return bridge.send_message(
+        YaPluginBase::Initialize{.instance_id = arguments.instance_id,
+                                 .host_application_context_args =
+                                     std::move(host_application_context_args)});
+}
+
+tresult PLUGIN_API YaComponentPluginImpl::terminate() {
+    return bridge.send_message(
+        YaPluginBase::Terminate{.instance_id = arguments.instance_id});
+}
+
 tresult PLUGIN_API YaComponentPluginImpl::setBusArrangements(
     Steinberg::Vst::SpeakerArrangement* inputs,
     int32 numIns,

src/plugin/bridges/vst3-impls/component.h

@@ -39,9 +39,7 @@ class YaComponentPluginImpl : public YaComponent {
     tresult PLUGIN_API queryInterface(const Steinberg::TUID _iid,
                                       void** obj) override;
 
-    tresult PLUGIN_API initialize(FUnknown* context) override;
-    tresult PLUGIN_API terminate() override;
-
+    // From `IComponent`
     tresult PLUGIN_API setIoMode(Steinberg::Vst::IoMode mode) override;
     int32 PLUGIN_API getBusCount(Steinberg::Vst::MediaType type,
                                  Steinberg::Vst::BusDirection dir) override;
@@ -61,6 +59,10 @@ class YaComponentPluginImpl : public YaComponent {
     tresult PLUGIN_API setState(Steinberg::IBStream* state) override;
     tresult PLUGIN_API getState(Steinberg::IBStream* state) override;
 
+    // From `IPluginBase`
+    tresult PLUGIN_API initialize(FUnknown* context) override;
+    tresult PLUGIN_API terminate() override;
+
     tresult PLUGIN_API
     setBusArrangements(Steinberg::Vst::SpeakerArrangement* inputs,
                        int32 numIns,

src/wine-host/bridges/vst3.cpp

@@ -26,7 +26,9 @@ ComponentInstance::ComponentInstance() {}
 
 ComponentInstance::ComponentInstance(
     Steinberg::IPtr<Steinberg::Vst::IComponent> component)
-    : component(component), audio_processor(component) {}
+    : component(component),
+      plugin_base(component),
+      audio_processor(component) {}
 
 Vst3Bridge::Vst3Bridge(MainContext& main_context,
                        std::string plugin_dll_path,
@@ -86,8 +88,8 @@ void Vst3Bridge::run() {
 
                 return Ack{};
             },
-            [&](YaComponent::Initialize& request)
-                -> YaComponent::Initialize::Response {
+            [&](YaPluginBase::Initialize& request)
+                -> YaPluginBase::Initialize::Response {
                 // If we got passed a host context, we'll create a proxy object
                 // and pass that to the initialize function. This object should
                 // be cleaned up again during `YaComponent::Destruct`.
@@ -103,12 +105,12 @@ void Vst3Bridge::run() {
                 }
 
                 return component_instances[request.instance_id]
-                    .component->initialize(context);
+                    .plugin_base->initialize(context);
             },
-            [&](const YaComponent::Terminate& request)
-                -> YaComponent::Terminate::Response {
+            [&](const YaPluginBase::Terminate& request)
+                -> YaPluginBase::Terminate::Response {
                 return component_instances[request.instance_id]
-                    .component->terminate();
+                    .plugin_base->terminate();
             },
             [&](const YaComponent::SetIoMode& request)
                 -> YaComponent::SetIoMode::Response {

src/wine-host/bridges/vst3.h

@@ -28,6 +28,9 @@
  * A holder for an `IComponent` instance created from the factory along with any
  * host context proxy objects belonging to it, and several predefined
  * `FUnknownPtrs` so we don't have to do these dynamic casts all the times..
+ *
+ * TODO: When implementing `IEditController`, change this to use `IPluginBase`
+ *       as the base interface.
  */
 struct ComponentInstance {
     ComponentInstance();
@@ -37,7 +40,7 @@ struct ComponentInstance {
     /**
      * If the host passes an `IHostApplication` during
      * `IPluginBase::initialize()`, we'll store a proxy object here and then
-     * pass it to `component->initialize()`.
+     * pass it to `plugin_base->initialize()`.
      */
     Steinberg::IPtr<YaHostApplication> hsot_application_context;
 
@@ -49,6 +52,7 @@ struct ComponentInstance {
     // All smart pointers below are created from `component`. They will be null
     // pointers if `component` did not implement the interface.
 
+    Steinberg::FUnknownPtr<Steinberg::IPluginBase> plugin_base;
     Steinberg::FUnknownPtr<Steinberg::Vst::IAudioProcessor> audio_processor;
 };