HostInner trait and backend-specific host structs

src/format/clap/host.rs

@@ -0,0 +1,5 @@
+use crate::plugin::HostInner;
+
+pub struct ClapHost {}
+
+impl HostInner for ClapHost {}

src/format/clap/instance.rs

@@ -9,6 +9,7 @@ use std::{io, ptr, slice};
 use clap_sys::ext::{audio_ports::*, audio_ports_config::*, gui::*, params::*, state::*};
 use clap_sys::{events::*, host::*, id::*, plugin::*, process::*, stream::*};
 
+use super::host::ClapHost;
 use crate::buffers::{BufferData, BufferType, Buffers};
 use crate::bus::{BusDir, Format};
 use crate::editor::Editor;
@@ -122,7 +123,7 @@ impl<P: Plugin> Instance<P> {
             processor_params: ParamValues::new(&info.params),
             main_thread_state: UnsafeCell::new(MainThreadState {
                 layout_index: 0,
-                plugin: P::new(Host {}),
+                plugin: P::new(Host::from_inner(Arc::new(ClapHost {}))),
                 editor: None,
             }),
             process_state: UnsafeCell::new(ProcessState {

src/format/clap/mod.rs

@@ -4,6 +4,7 @@ use clap_sys::{entry::*, version::*};
 
 mod factory;
 mod gui;
+mod host;
 mod instance;
 
 #[doc(hidden)]

src/format/vst3/component.rs

@@ -7,6 +7,7 @@ use std::sync::Arc;
 use vst3::{Class, ComRef, ComWrapper, Steinberg::Vst::*, Steinberg::*};
 
 use super::buffers::ScratchBuffers;
+use super::host::Vst3Host;
 use super::util::{copy_wstring, utf16_from_ptr};
 use super::view::View;
 use crate::bus::{BusDir, Format, Layout};
@@ -104,7 +105,7 @@ impl<P: Plugin> Component<P> {
             processor_params: ParamValues::new(&info.params),
             main_thread_state: Arc::new(UnsafeCell::new(MainThreadState {
                 config: config.clone(),
-                plugin: P::new(Host {}),
+                plugin: P::new(Host::from_inner(Arc::new(Vst3Host {}))),
                 editor_params,
                 editor: None,
             })),

src/format/vst3/host.rs

@@ -0,0 +1,5 @@
+use crate::plugin::HostInner;
+
+pub struct Vst3Host {}
+
+impl HostInner for Vst3Host {}

src/format/vst3/mod.rs

@@ -7,6 +7,7 @@ use vst3::{ComWrapper, Steinberg::IPluginFactory};
 mod buffers;
 mod component;
 mod factory;
+mod host;
 mod util;
 mod view;
 

src/plugin.rs

@@ -1,4 +1,5 @@
 use std::io::{self, Read, Write};
+use std::sync::Arc;
 
 use crate::bus::{BusInfo, Layout};
 use crate::editor::{Editor, Parent};
@@ -33,7 +34,18 @@ impl Default for PluginInfo {
     }
 }
 
-pub struct Host {}
+pub trait HostInner {}
+
+#[derive(Clone)]
+pub struct Host {
+    _inner: Arc<dyn HostInner>,
+}
+
+impl Host {
+    pub fn from_inner(inner: Arc<dyn HostInner>) -> Host {
+        Host { _inner: inner }
+    }
+}
 
 pub trait Plugin: Send + Sized + 'static {
     type Processor: Processor;