Create Vst3HostContextProxy from YaHostApplication

This is quite a huge refactor, but note everything is consistent (and
we're going to need one or two more of these `Vst3*Proxy` objects).
Right now nothing extends `IHostApplication`, but this way it will be
trivial to add support for more host context interfaces.

meson.build

@@ -84,10 +84,11 @@ vst3_plugin_sources = [
   'src/common/serialization/vst3/plugin/edit-controller-2.cpp',
   'src/common/serialization/vst3/plugin/plugin-base.cpp',
   'src/common/serialization/vst3/component-handler/component-handler.cpp',
+  'src/common/serialization/vst3/host-context/host-application.cpp',
   'src/common/serialization/vst3/base.cpp',
   'src/common/serialization/vst3/component-handler-proxy.cpp',
   'src/common/serialization/vst3/event-list.cpp',
-  'src/common/serialization/vst3/host-application.cpp',
+  'src/common/serialization/vst3/host-context-proxy.cpp',
   'src/common/serialization/vst3/param-value-queue.cpp',
   'src/common/serialization/vst3/parameter-changes.cpp',
   'src/common/serialization/vst3/plugin-proxy.cpp',
@@ -131,17 +132,18 @@ if with_vst3
     'src/common/serialization/vst3/plugin/edit-controller-2.cpp',
     'src/common/serialization/vst3/plugin/plugin-base.cpp',
     'src/common/serialization/vst3/component-handler/component-handler.cpp',
+    'src/common/serialization/vst3/host-context/host-application.cpp',
     'src/common/serialization/vst3/base.cpp',
     'src/common/serialization/vst3/component-handler-proxy.cpp',
     'src/common/serialization/vst3/event-list.cpp',
-    'src/common/serialization/vst3/host-application.cpp',
+    'src/common/serialization/vst3/host-context-proxy.cpp',
     'src/common/serialization/vst3/param-value-queue.cpp',
     'src/common/serialization/vst3/parameter-changes.cpp',
     'src/common/serialization/vst3/plugin-proxy.cpp',
     'src/common/serialization/vst3/plugin-factory.cpp',
     'src/common/serialization/vst3/process-data.cpp',
     'src/wine-host/bridges/vst3-impls/component-handler-proxy.cpp',
-    'src/wine-host/bridges/vst3-impls/host-application.cpp',
+    'src/wine-host/bridges/vst3-impls/host-context-proxy.cpp',
     'src/wine-host/bridges/vst3.cpp',
   ]
 endif

src/common/logging/vst3.cpp

@@ -411,8 +411,8 @@ bool Vst3Logger::log_request(bool is_host_vst,
     return log_request_base(is_host_vst, [&](auto& message) {
         message << request.instance_id
                 << ": IPluginBase::initialize(context = ";
-        if (request.host_application_context_args) {
-            message << "<IHostApplication*>";
+        if (request.host_context_args) {
+            message << "<FUnknown*>";
         } else {
             message << "<nullptr>";
         }
@@ -434,9 +434,15 @@ bool Vst3Logger::log_request(bool is_host_vst,
 }
 
 bool Vst3Logger::log_request(bool is_host_vst,
-                             const YaPluginFactory::SetHostContext&) {
+                             const YaPluginFactory::SetHostContext& request) {
     return log_request_base(is_host_vst, [&](auto& message) {
-        message << "IPluginFactory3::setHostContext(IHostApplication*)";
+        message << "IPluginFactory3::setHostContext(";
+        if (request.host_context_args) {
+            message << "<FUnknown*>";
+        } else {
+            message << "<nullptr>";
+        }
+        message << ")";
     });
 }
 

src/common/serialization/vst3.h

@@ -24,6 +24,7 @@
 #include "../utils.h"
 #include "common.h"
 #include "vst3/component-handler-proxy.h"
+#include "vst3/host-context-proxy.h"
 #include "vst3/plugin-factory.h"
 #include "vst3/plugin-proxy.h"
 

src/common/serialization/vst3/README.md

@@ -22,7 +22,8 @@ VST3 host interfaces are implemented as follows:
 
 | yabridge class              | Included in                 | Interfaces          |
 | --------------------------- | --------------------------- | ------------------- |
-| `YaHostApplication`         |                             | `IHostApplication`  |
+| `Vst3HostContextProxy`      |                             | All of the below:   |
+| `YaHostApplication`         | `Vst3HostContextProxy`      | `IHostApplication`  |
 | `Vst3ComponentHandlerProxy` |                             | All of the below:   |
 | `YaComponentHandler`        | `Vst3ComponentHandlerProxy` | `IComponentHandler` |
 

src/common/serialization/vst3/host-context-proxy.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 "host-context-proxy.h"
+
+Vst3HostContextProxy::ConstructArgs::ConstructArgs() {}
+
+Vst3HostContextProxy::ConstructArgs::ConstructArgs(
+    Steinberg::IPtr<Steinberg::FUnknown> object,
+    std::optional<size_t> owner_instance_id)
+    : owner_instance_id(owner_instance_id), host_application_args(object) {}
+
+Vst3HostContextProxy::Vst3HostContextProxy(const ConstructArgs&& args)
+    : YaHostApplication(std::move(args.host_application_args)),
+      arguments(std::move(args)){FUNKNOWN_CTOR}
+
+      Vst3HostContextProxy::~Vst3HostContextProxy() {
+    FUNKNOWN_DTOR
+}
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdelete-non-virtual-dtor"
+IMPLEMENT_REFCOUNT(Vst3HostContextProxy)
+#pragma GCC diagnostic pop
+
+tresult PLUGIN_API
+Vst3HostContextProxy::queryInterface(Steinberg::FIDString _iid, void** obj) {
+    if (YaHostApplication::supported()) {
+        QUERY_INTERFACE(_iid, obj, Steinberg::FUnknown::iid,
+                        Steinberg::Vst::IHostApplication)
+        QUERY_INTERFACE(_iid, obj, Steinberg::Vst::IHostApplication::iid,
+                        Steinberg::Vst::IHostApplication)
+    }
+
+    *obj = nullptr;
+    return Steinberg::kNoInterface;
+}

src/common/serialization/vst3/host-context-proxy.h

@@ -16,42 +16,36 @@
 
 #pragma once
 
-#include <type_traits>
-
-#include <bitsery/ext/std_optional.h>
-#include <bitsery/traits/string.h>
-#include <pluginterfaces/vst/ivsthostapplication.h>
-
 #include "../common.h"
-#include "base.h"
+#include "host-context/host-application.h"
 
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wnon-virtual-dtor"
 
 /**
- * Wraps around `IHostApplication` for serialization purposes. An instance of
- * this proxy object will be initialized on the Wine plugin host side after the
- * host passes an actual instance to the plugin, and all function calls made to
- * this proxy will be passed through to the actual object. This is used to proxy
- * both the host application context passed during `IPluginBase::intialize()` as
- * well as for the 'global' context in `IPluginFactory3::setHostContext()`.
- *
- * TODO: Create a `Vst3HostContextProxy`, and make this to only interface it
- *       inherits. For uniformity's sake it's a good idea to have every kind of
- *       object we directly instantiate be in the same form.
+ * An abstract class that optionally implements all interfaces a `context`
+ * object passed to `IPluginBase::intialize()` or
+ * `IPluginFactory3::setHostContext()` might implement. This works exactly the
+ * same as `Vst3PluginProxy`, but instead of proxying for an object provided by
+ * the plugin we are proxying for the `FUnknown*` argument passed to plugin by
+ * the host. When we are proxying for a host context object passed to
+ * `IPluginBase::initialize()` we'll keep track of the object instance ID the
+ * actual context object belongs to.
  */
-class YaHostApplication : public Steinberg::Vst::IHostApplication {
+class Vst3HostContextProxy : public YaHostApplication {
    public:
     /**
-     * These are the arguments for constructing a `YaHostApplicationImpl`.
+     * These are the arguments for constructing a
+     * `Vst3HostContextProxyImpl`.
      */
     struct ConstructArgs {
         ConstructArgs();
 
         /**
-         * Read arguments from an existing implementation.
+         * 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<Steinberg::Vst::IHostApplication> context,
+        ConstructArgs(Steinberg::IPtr<FUnknown> object,
                       std::optional<size_t> owner_instance_id);
 
         /**
@@ -61,10 +55,7 @@ class YaHostApplication : public Steinberg::Vst::IHostApplication {
          */
         std::optional<native_size_t> owner_instance_id;
 
-        /**
-         * For `IHostApplication::getName`.
-         */
-        std::optional<std::u16string> name;
+        YaHostApplication::ConstructArgs host_application_args;
 
         template <typename S>
         void serialize(S& s) {
@@ -72,10 +63,7 @@ class YaHostApplication : public Steinberg::Vst::IHostApplication {
                   [](S& s, native_size_t& instance_id) {
                       s.value8b(instance_id);
                   });
-            s.ext(name, bitsery::ext::StdOptional{},
-                  [](S& s, std::u16string& name) {
-                      s.text2b(name, std::extent_v<Steinberg::Vst::String128>);
-                  });
+            s.object(host_application_args);
         }
     };
 
@@ -89,25 +77,27 @@ class YaHostApplication : public Steinberg::Vst::IHostApplication {
      *   objects they are passed to. If those objects get dropped, then the host
      *   contexts should also be dropped.
      */
-    YaHostApplication(const ConstructArgs&& args);
+    Vst3HostContextProxy(const ConstructArgs&& args);
 
     /**
      * The lifetime of this object should be bound to the object we created it
      * for. When for instance the `Vst3PluginProxy` instance with id `n` gets
-     * dropped, the corresponding `YaHostApplicationImpl` then that should also
-     * be dropped.
+     * dropped a corresponding `Vst3HostContextProxyImpl` should also be
+     * dropped.
      */
-    virtual ~YaHostApplication();
+    virtual ~Vst3HostContextProxy() = 0;
 
     DECLARE_FUNKNOWN_METHODS
 
-    // From `IHostApplication`
-    tresult PLUGIN_API getName(Steinberg::Vst::String128 name) override;
-    virtual tresult PLUGIN_API createInstance(Steinberg::TUID cid,
-                                              Steinberg::TUID _iid,
-                                              void** obj) override = 0;
+    /**
+     * Get the instance ID of the owner of this object, if this is not the
+     * global host context passed to the module's plugin factory.
+     */
+    inline std::optional<size_t> owner_instance_id() const {
+        return arguments.owner_instance_id;
+    }
 
-   protected:
+   private:
     ConstructArgs arguments;
 };
 

src/common/serialization/vst3/host-context/host-application.cpp

@@ -19,37 +19,22 @@
 YaHostApplication::ConstructArgs::ConstructArgs() {}
 
 YaHostApplication::ConstructArgs::ConstructArgs(
-    Steinberg::IPtr<Steinberg::Vst::IHostApplication> context,
-    std::optional<size_t> owner_instance_id)
-    : owner_instance_id(owner_instance_id) {
-    Steinberg::Vst::String128 name_array;
-    if (context->getName(name_array) == Steinberg::kResultOk) {
-        name = tchar_pointer_to_u16string(name_array);
+    Steinberg::IPtr<Steinberg::FUnknown> object)
+    : supported(false) {
+    if (auto host_application =
+            Steinberg::FUnknownPtr<Steinberg::Vst::IHostApplication>(object)) {
+        supported = true;
+
+        // `IHostApplication::getName`
+        Steinberg::Vst::String128 name_array;
+        if (host_application->getName(name_array) == Steinberg::kResultOk) {
+            name = tchar_pointer_to_u16string(name_array);
+        }
     }
 }
 
 YaHostApplication::YaHostApplication(const ConstructArgs&& args)
-    : arguments(std::move(args)){FUNKNOWN_CTOR}
-
-      YaHostApplication::~YaHostApplication() {
-    FUNKNOWN_DTOR
-}
-
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wdelete-non-virtual-dtor"
-IMPLEMENT_REFCOUNT(YaHostApplication)
-#pragma GCC diagnostic pop
-
-tresult PLUGIN_API YaHostApplication::queryInterface(Steinberg::FIDString _iid,
-                                                     void** obj) {
-    QUERY_INTERFACE(_iid, obj, Steinberg::FUnknown::iid,
-                    Steinberg::Vst::IHostApplication);
-    QUERY_INTERFACE(_iid, obj, Steinberg::Vst::IHostApplication::iid,
-                    Steinberg::Vst::IHostApplication)
-
-    *obj = nullptr;
-    return Steinberg::kNoInterface;
-}
+    : arguments(std::move(args)) {}
 
 tresult PLUGIN_API YaHostApplication::getName(Steinberg::Vst::String128 name) {
     if (arguments.name) {

src/common/serialization/vst3/host-context/host-application.h

@@ -0,0 +1,86 @@
+// 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 <type_traits>
+
+#include <bitsery/ext/std_optional.h>
+#include <bitsery/traits/string.h>
+#include <pluginterfaces/vst/ivsthostapplication.h>
+
+#include "../../common.h"
+#include "../base.h"
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wnon-virtual-dtor"
+
+/**
+ * Wraps around `IHostApplication` for serialization purposes. This is
+ * instantiated as part of `Vst3HostContextProxy`.
+ */
+class YaHostApplication : public Steinberg::Vst::IHostApplication {
+   public:
+    /**
+     * These are the arguments for creating a `YaHostApplication`.
+     */
+    struct ConstructArgs {
+        ConstructArgs();
+
+        /**
+         * Check whether an existing implementation implements
+         * `IHostApplication` and read arguments from it.
+         */
+        ConstructArgs(Steinberg::IPtr<Steinberg::FUnknown> object);
+
+        /**
+         * Whether the object supported this interface.
+         */
+        bool supported;
+
+        /**
+         * For `IHostApplication::getName`.
+         */
+        std::optional<std::u16string> name;
+
+        template <typename S>
+        void serialize(S& s) {
+            s.value1b(supported);
+            s.ext(name, bitsery::ext::StdOptional{},
+                  [](S& s, std::u16string& name) {
+                      s.text2b(name, std::extent_v<Steinberg::Vst::String128>);
+                  });
+        }
+    };
+
+    /**
+     * Instantiate this instance with arguments read from another interface
+     * implementation.
+     */
+    YaHostApplication(const ConstructArgs&& args);
+
+    inline bool supported() const { return arguments.supported; }
+
+    tresult PLUGIN_API getName(Steinberg::Vst::String128 name) override;
+    virtual tresult PLUGIN_API createInstance(Steinberg::TUID cid,
+                                              Steinberg::TUID _iid,
+                                              void** obj) override = 0;
+
+   protected:
+    ConstructArgs arguments;
+};
+
+#pragma GCC diagnostic pop

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

@@ -41,7 +41,7 @@ YaPluginFactory::ConstructArgs::ConstructArgs(
         }
     }
 
-    auto factory2 = Steinberg::FUnknownPtr<Steinberg::IPluginFactory2>(factory);
+    Steinberg::FUnknownPtr<Steinberg::IPluginFactory2> factory2(factory);
     if (!factory2) {
         return;
     }
@@ -56,7 +56,7 @@ YaPluginFactory::ConstructArgs::ConstructArgs(
         }
     }
 
-    auto factory3 = Steinberg::FUnknownPtr<Steinberg::IPluginFactory3>(factory);
+    Steinberg::FUnknownPtr<Steinberg::IPluginFactory3> factory3(factory);
     if (!factory3) {
         return;
     }

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

@@ -22,7 +22,7 @@
 
 #include "../../bitsery/ext/vst3.h"
 #include "base.h"
-#include "host-application.h"
+#include "host-context-proxy.h"
 
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wnon-virtual-dtor"
@@ -155,20 +155,22 @@ class YaPluginFactory : public Steinberg::IPluginFactory3 {
 
     /**
      * Message to pass through a call to `IPluginFactory3::setHostContext()` to
-     * the Wine plugin host. A proxy `YaHostApplication` should be created on
-     * the Wine plugin host and then passed as an argument to
-     * `IPluginFactory3::setHostContext()`. If the host called
-     * `IPluginFactory3::setHostContext()` with something other than an
-     * `IHostApplication*`, we return an error immediately and log the call.
+     * the Wine plugin host. A `Vst3HostContextProxy` should be created on the
+     * Wine plugin host and then passed as an argument to
+     * `IPluginFactory3::setHostContext()`.
      */
     struct SetHostContext {
         using Response = UniversalTResult;
 
-        YaHostApplication::ConstructArgs host_application_context_args;
+        /**
+         * Arguments for creating a proxy host context object. If we got passed
+         * an null pointer we'll reflect that.
+         */
+        std::optional<Vst3HostContextProxy::ConstructArgs> host_context_args;
 
         template <typename S>
         void serialize(S& s) {
-            s.object(host_application_context_args);
+            s.ext(host_context_args, bitsery::ext::StdOptional{});
         }
     };
 

src/common/serialization/vst3/plugin/audio-processor.h

@@ -21,7 +21,6 @@
 
 #include "../../common.h"
 #include "../base.h"
-#include "../host-application.h"
 #include "../process-data.h"
 
 #pragma GCC diagnostic push

src/common/serialization/vst3/plugin/component.cpp

@@ -19,10 +19,10 @@
 YaComponent::ConstructArgs::ConstructArgs() {}
 
 YaComponent::ConstructArgs::ConstructArgs(
-    Steinberg::IPtr<Steinberg::FUnknown> object) {
-    auto component = Steinberg::FUnknownPtr<Steinberg::Vst::IComponent>(object);
-
-    if (component) {
+    Steinberg::IPtr<Steinberg::FUnknown> object)
+    : supported(false) {
+    if (auto component =
+            Steinberg::FUnknownPtr<Steinberg::Vst::IComponent>(object)) {
         supported = true;
 
         // `IComponent::getControllerClassId`

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

@@ -21,7 +21,7 @@
 
 #include "../../common.h"
 #include "../base.h"
-#include "../host-application.h"
+#include "../host-context-proxy.h"
 
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wnon-virtual-dtor"
@@ -66,23 +66,23 @@ class YaPluginBase : public Steinberg::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.
+     * plugin host. We will read what interfaces the passed context object
+     * implements so we can then create a proxy object on the Wine side that the
+     * plugin can use to make callbacks with. The lifetime of this
+     * `Vst3HostContextProxy` 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;
+
+        std::optional<Vst3HostContextProxy::ConstructArgs> host_context_args;
 
         template <typename S>
         void serialize(S& s) {
             s.value8b(instance_id);
-            s.ext(host_application_context_args, bitsery::ext::StdOptional{});
+            s.ext(host_context_args, bitsery::ext::StdOptional{});
         }
     };
 

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

@@ -100,24 +100,21 @@ YaPluginFactoryImpl::createInstance(Steinberg::FIDString cid,
 
 tresult PLUGIN_API
 YaPluginFactoryImpl::setHostContext(Steinberg::FUnknown* context) {
-    // This `context` will likely be an `IHostApplication`. If it is, we will
-    // store it for future calls, create a proxy object on the Wine side, and
-    // then pass it to the Windows VST3 plugin's plugin factory using the same
-    // function. If we get passed anything else we'll just return instead since
-    // there's nothing we can do with it.
-    host_application_context = context;
+    // We will create a proxy object that that supports all the same interfaces
+    // as `context`, and then we'll store `context` in this object. We can then
+    // use it to handle callbacks made by the Windows VST3 plugin to this
+    // context.
+    host_context = context;
 
-    if (host_application_context) {
-        YaHostApplication::ConstructArgs host_application_context_args(
-            host_application_context, std::nullopt);
-
-        return bridge.send_message(YaPluginFactory::SetHostContext{
-            .host_application_context_args =
-                std::move(host_application_context_args)});
+    std::optional<Vst3HostContextProxy::ConstructArgs> host_context_args{};
+    if (host_context) {
+        host_context_args =
+            Vst3HostContextProxy::ConstructArgs(host_context, std::nullopt);
     } else {
-        bridge.logger.log_unknown_interface(
-            "In IPluginFactory3::setHostContext(), ignoring",
-            context ? std::optional(context->iid) : std::nullopt);
-        return Steinberg::kNotImplemented;
+        bridge.logger.log(
+            "Null pointer passed to 'IPluginFactory3::setHostContext()'");
     }
+
+    return bridge.send_message(YaPluginFactory::SetHostContext{
+        .host_context_args = std::move(host_context_args)});
 }

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

@@ -32,9 +32,8 @@ class YaPluginFactoryImpl : public YaPluginFactory {
     Vst3PluginBridge& bridge;
 
     /**
-     * An `IHostApplication` instance if we get one through
+     * An host context if we get passed one through
      * `IPluginFactory3::setHostContext()`.
      */
-    Steinberg::FUnknownPtr<Steinberg::Vst::IHostApplication>
-        host_application_context;
+    Steinberg::IPtr<Steinberg::FUnknown> host_context;
 };

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

@@ -315,18 +315,18 @@ Vst3PluginProxyImpl::setParamNormalized(Steinberg::Vst::ParamID id,
 
 tresult PLUGIN_API Vst3PluginProxyImpl::setComponentHandler(
     Steinberg::Vst::IComponentHandler* handler) {
+    // We'll store the pointer for when the plugin later makes a callback to
+    // this component handler
+    component_handler = handler;
+
     std::optional<Vst3ComponentHandlerProxy::ConstructArgs>
         component_handler_proxy_args = std::nullopt;
     if (handler) {
-        // We'll store the pointer for when the plugin later makes a callback to
-        // this component handler
-        component_handler = handler;
-
         component_handler_proxy_args = Vst3ComponentHandlerProxy::ConstructArgs(
             component_handler, instance_id());
     } else {
         bridge.logger.log(
-            "Null pointer passed to 'IEditController::setComponentHandler'");
+            "Null pointer passed to 'IEditController::setComponentHandler()'");
     }
 
     return bridge.send_message(YaEditController::SetComponentHandler{
@@ -362,27 +362,23 @@ tresult PLUGIN_API Vst3PluginProxyImpl::openAboutBox(TBool onlyCheck) {
 }
 
 tresult PLUGIN_API Vst3PluginProxyImpl::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;
+    // We will create a proxy object that that supports all the same interfaces
+    // as `context`, and then we'll store `context` in this object. We can then
+    // use it to handle callbacks made by the Windows VST3 plugin to this
+    // context.
+    host_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, instance_id());
+    std::optional<Vst3HostContextProxy::ConstructArgs> host_context_args{};
+    if (host_context) {
+        host_context_args =
+            Vst3HostContextProxy::ConstructArgs(host_context, instance_id());
     } else {
-        bridge.logger.log_unknown_interface(
-            "In IPluginBase::initialize()",
-            context ? std::optional(context->iid) : std::nullopt);
+        bridge.logger.log("Null pointer passed to 'IPluginBase::initialize()'");
     }
 
-    return bridge.send_message(
-        YaPluginBase::Initialize{.instance_id = instance_id(),
-                                 .host_application_context_args =
-                                     std::move(host_application_context_args)});
+    return bridge.send_message(YaPluginBase::Initialize{
+        .instance_id = instance_id(),
+        .host_context_args = std::move(host_context_args)});
 }
 
 tresult PLUGIN_API Vst3PluginProxyImpl::terminate() {

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

@@ -122,15 +122,6 @@ class Vst3PluginProxyImpl : public Vst3PluginProxy {
     tresult PLUGIN_API initialize(FUnknown* context) override;
     tresult PLUGIN_API terminate() override;
 
-    /**
-     * An `IHostApplication` instance if we get one through
-     * `IPluginBase::initialize()`. This should be the same for all plugin
-     * instances so we should not have to store it here separately, but for the
-     * sake of correctness we will.
-     */
-    Steinberg::FUnknownPtr<Steinberg::Vst::IHostApplication>
-        host_application_context;
-
     /**
      * The component handler the host passed to us during
      * `IEditController::setComponentHandler()`. When the plugin makes a
@@ -141,4 +132,13 @@ class Vst3PluginProxyImpl : public Vst3PluginProxy {
 
    private:
     Vst3PluginBridge& bridge;
+
+    /**
+     * An host context if we get passed one through `IPluginBase::initialize()`.
+     * We'll read which interfaces it supports and we'll then create a proxy
+     * object that supports those same interfaces. This should be the same for
+     * all plugin instances so we should not have to store it here separately,
+     * but for the sake of correctness we will.
+     */
+    Steinberg::IPtr<Steinberg::FUnknown> host_context;
 };

src/wine-host/bridges/vst3-impls/host-context-proxy.cpp

@@ -14,24 +14,25 @@
 // 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 "host-application.h"
+#include "host-context-proxy.h"
 
 #include <iostream>
 
-YaHostApplicationImpl::YaHostApplicationImpl(
+Vst3HostContextProxyImpl::Vst3HostContextProxyImpl(
     Vst3Bridge& bridge,
-    YaHostApplication::ConstructArgs&& args)
-    : YaHostApplication(std::move(args)), bridge(bridge) {
+    Vst3HostContextProxy::ConstructArgs&& args)
+    : Vst3HostContextProxy(std::move(args)), bridge(bridge) {
     // The lifecycle is thos object is managed together with that of the plugin
-    // object instance this belongs to
+    // object instance instance this belongs to
 }
 
 tresult PLUGIN_API
-YaHostApplicationImpl::queryInterface(const Steinberg::TUID _iid, void** obj) {
+Vst3HostContextProxyImpl::queryInterface(const Steinberg::TUID _iid,
+                                         void** obj) {
     // I don't think it's expected of a host to implement multiple interfaces on
     // this object, so if we do get a call here it's important that it's logged
     // TODO: Successful queries should also be logged
-    const tresult result = YaHostApplication::queryInterface(_iid, obj);
+    const tresult result = Vst3HostContextProxy::queryInterface(_iid, obj);
     if (result != Steinberg::kResultOk) {
         std::cerr << "TODO: Implement unknown interface logging on Wine side"
                   << std::endl;
@@ -40,9 +41,10 @@ YaHostApplicationImpl::queryInterface(const Steinberg::TUID _iid, void** obj) {
     return result;
 }
 
-tresult PLUGIN_API YaHostApplicationImpl::createInstance(Steinberg::TUID cid,
-                                                         Steinberg::TUID _iid,
-                                                         void** obj) {
+tresult PLUGIN_API
+Vst3HostContextProxyImpl::createInstance(Steinberg::TUID cid,
+                                         Steinberg::TUID _iid,
+                                         void** obj) {
     // TODO: Implement
     std::cerr << "TODO: IHostApplication::createInstance()" << std::endl;
     return Steinberg::kNotImplemented;

src/wine-host/bridges/vst3-impls/host-context-proxy.h

@@ -18,10 +18,10 @@
 
 #include "../vst3.h"
 
-class YaHostApplicationImpl : public YaHostApplication {
+class Vst3HostContextProxyImpl : public Vst3HostContextProxy {
    public:
-    YaHostApplicationImpl(Vst3Bridge& bridge,
-                          YaHostApplication::ConstructArgs&& args);
+    Vst3HostContextProxyImpl(Vst3Bridge& bridge,
+                             Vst3HostContextProxy::ConstructArgs&& args);
 
     /**
      * We'll override the query interface to log queries for interfaces we do
@@ -30,6 +30,7 @@ class YaHostApplicationImpl : public YaHostApplication {
     tresult PLUGIN_API queryInterface(const Steinberg::TUID _iid,
                                       void** obj) override;
 
+    // From `IHostApplication`
     tresult PLUGIN_API createInstance(Steinberg::TUID cid,
                                       Steinberg::TUID _iid,
                                       void** obj) override;

src/wine-host/bridges/vst3.cpp

@@ -24,7 +24,7 @@
 #include <public.sdk/source/vst/hosting/module_win32.cpp>
 
 #include "vst3-impls/component-handler-proxy.h"
-#include "vst3-impls/host-application.h"
+#include "vst3-impls/host-context-proxy.h"
 
 InstanceInterfaces::InstanceInterfaces() {}
 
@@ -371,21 +371,19 @@ void Vst3Bridge::run() {
                 //       `Vst3HostProxy`
                 // TODO: Does this have to be run from the UI thread? Figure out
                 //       if it does
-                if (request.host_application_context_args) {
-                    object_instances[request.instance_id]
-                        .host_application_context =
-                        Steinberg::owned(new YaHostApplicationImpl(
-                            *this,
-                            std::move(*request.host_application_context_args)));
+                if (request.host_context_args) {
+                    object_instances[request.instance_id].host_context_proxy =
+                        Steinberg::owned(new Vst3HostContextProxyImpl(
+                            *this, std::move(*request.host_context_args)));
                 } else {
-                    object_instances[request.instance_id]
-                        .host_application_context = nullptr;
+                    object_instances[request.instance_id].host_context_proxy =
+                        nullptr;
                 }
 
                 return object_instances[request.instance_id]
                     .plugin_base->initialize(
                         object_instances[request.instance_id]
-                            .host_application_context);
+                            .host_context_proxy);
             },
             [&](const YaPluginBase::Terminate& request)
                 -> YaPluginBase::Terminate::Response {
@@ -399,16 +397,19 @@ void Vst3Bridge::run() {
             },
             [&](YaPluginFactory::SetHostContext& request)
                 -> YaPluginFactory::SetHostContext::Response {
-                plugin_factory_host_application_context =
-                    Steinberg::owned(new YaHostApplicationImpl(
-                        *this,
-                        std::move(request.host_application_context_args)));
+                if (request.host_context_args) {
+                    plugin_factory_host_context =
+                        Steinberg::owned(new Vst3HostContextProxyImpl(
+                            *this, std::move(*request.host_context_args)));
+                } else {
+                    plugin_factory_host_context = nullptr;
+                }
 
                 Steinberg::FUnknownPtr<Steinberg::IPluginFactory3> factory_3(
                     module->getFactory().get());
+
                 assert(factory_3);
-                return factory_3->setHostContext(
-                    plugin_factory_host_application_context);
+                return factory_3->setHostContext(plugin_factory_host_context);
             }});
 }
 

src/wine-host/bridges/vst3.h

@@ -38,12 +38,12 @@ struct InstanceInterfaces {
     InstanceInterfaces(Steinberg::IPtr<Steinberg::FUnknown> object);
 
     /**
-     * If the host passes an `IHostApplication` during
+     * If the host passes a host context object during
      * `IPluginBase::initialize()`, we'll store a proxy object here and then
      * pass it to `plugin_base->initialize()`. Will be initialized with a null
      * pointer until used.
      */
-    Steinberg::IPtr<YaHostApplication> host_application_context;
+    Steinberg::IPtr<Vst3HostContextProxy> host_context_proxy;
 
     /**
      * After a call to `IEditController::setComponentHandler()`, we'll create a
@@ -155,11 +155,10 @@ class Vst3Bridge : public HostBridge {
     std::atomic_size_t current_instance_id;
 
     /**
-     * The host application context proxy object if we got passed a host
-     * application context during a call to `IPluginFactory3::setHostContext()`
-     * by the host.
+     * The host context proxy object if we got passed a host context during a
+     * call to `IPluginFactory3::setHostContext()` by the host.
      */
-    Steinberg::IPtr<YaHostApplication> plugin_factory_host_application_context;
+    Steinberg::IPtr<Vst3HostContextProxy> plugin_factory_host_context;
 
     /**
      * These are all the objects we have created through the Windows VST3