wip

src/cxx_util.rs

@@ -0,0 +1,42 @@
+use std::marker::PhantomData;
+use std::mem::size_of;
+
+pub type Opaque = [usize; 0];
+
+#[derive(Copy, Clone, Debug)]
+pub struct RustVTable<DynT>(pub *const Opaque, pub PhantomData<DynT>);
+
+#[derive(Debug)]
+pub struct FieldOffset<F>(usize, PhantomData<F>);
+
+unsafe impl<F> Send for FieldOffset<F> where F: Send {}
+unsafe impl<F> Sync for FieldOffset<F> where F: Sync {}
+impl<F> Copy for FieldOffset<F> {}
+
+impl<F> Clone for FieldOffset<F> {
+  fn clone(&self) -> Self {
+    Self(self.0, self.1)
+  }
+}
+
+impl<F> FieldOffset<F> {
+  pub fn from_ptrs<E>(embedder_ptr: *const E, field_ptr: *const F) -> Self {
+    let embedder_addr = embedder_ptr as usize;
+    let field_addr = field_ptr as usize;
+    assert!(field_addr >= embedder_addr);
+    assert!((field_addr + size_of::<F>()) <= (embedder_addr + size_of::<E>()));
+    Self(embedder_addr - field_addr, PhantomData)
+  }
+
+  pub unsafe fn to_embedder<E>(self, field: &F) -> &E {
+    (((field as *const _ as usize) - self.0) as *const E)
+      .as_ref()
+      .unwrap()
+  }
+
+  pub unsafe fn to_embedder_mut<E>(self, field: &mut F) -> &mut E {
+    (((field as *mut _ as usize) - self.0) as *mut E)
+      .as_mut()
+      .unwrap()
+  }
+}

src/lib.cpp

@@ -21,8 +21,8 @@ class Channel {
 }  // namespace v8
 
 extern "C" {
-void v8__Channel__EXTENDER__method1(v8::Channel& self, int32_t arg);
-int32_t v8__Channel__EXTENDER__method2(const v8::Channel& self);
+void v8_inspector__Channel__EXTENDER__method1(v8::Channel& self, int32_t arg);
+int32_t v8_inspector__Channel__EXTENDER__method2(const v8::Channel& self);
 }
 
 namespace extender {
@@ -34,30 +34,30 @@ struct Channel : public ::v8::Channel {
   using ::v8::Channel::Channel;
 
   void method1(int32_t arg) override {
-    v8__Channel__EXTENDER__method1(*this, arg);
+    v8_inspector__Channel__EXTENDER__method1(*this, arg);
   }
 
   int32_t method2() const override {
-    return v8__Channel__EXTENDER__method2(*this);
+    return v8_inspector__Channel__EXTENDER__method2(*this);
   }
 };
 }  // namespace v8
 }  // namespace extender
 
 extern "C" {
-void v8__Channel__DTOR(v8::Channel& self) {
+void v8_inspector__Channel__DTOR(v8::Channel& self) {
   self.~Channel();
 }
-void v8__Channel__method1(v8::Channel& self, int32_t arg) {
+void v8_inspector__Channel__method1(v8::Channel& self, int32_t arg) {
   self.method1(arg);
 }
-void v8__Channel__Channel__method1(v8::Channel& self, int32_t arg) {
+void v8_inspector__Channel__Channel__method1(v8::Channel& self, int32_t arg) {
   self.::v8::Channel::method1(arg);
 }
-int32_t v8__Channel__method2(const v8::Channel& self) {
+int32_t v8_inspector__Channel__method2(const v8::Channel& self) {
   return self.method2();
 }
-void v8__Channel__EXTENDER__CTOR(
+void v8_inspector__Channel__EXTENDER__CTOR(
     extender::uninit_t<extender::v8::Channel>& buf) {
   new (std::launder(&buf)) extender::v8::Channel();
 }

src/main.rs

@@ -1,226 +1,8 @@
-mod channel {
-  use super::util;
-
-  extern "C" {
-    // Call a method/destructor; virtual methods use C++ dynamic dispatch.
-    fn v8__Channel__DTOR(this: &mut Channel) -> ();
-    fn v8__Channel__method1(this: &mut Channel, arg: i32) -> ();
-    fn v8__Channel__method2(this: &Channel) -> i32;
-
-    // Call a method of a specific class implementation, bypassing dynamic
-    // dispatch. C++ equivalent: `my_channel.Channel::a()`.
-    fn v8__Channel__Channel__method1(this: &mut Channel, arg: i32) -> ();
-
-    // Constructs a special class derived from Channel that forwards all
-    // virtual method invocations to rust. It is assumed that this subclass
-    // has the same size and memory layout as the class it's deriving from.
-    fn v8__Channel__EXTENDER__CTOR(
-      buf: &mut std::mem::MaybeUninit<Channel>,
-    ) -> ();
-  }
-
-    #[allow(non_snake_case)]
-    #[no_mangle]
-    pub unsafe extern "C"  fn v8__Channel__EXTENDER__method1(
-      this: &mut Channel,
-      arg: i32,
-    ) {
-      ChannelExtender::dispatch_mut(this).method1(arg)
-    }
-
-    #[allow(non_snake_case)]
-    #[no_mangle]
-    pub unsafe extern "C" fn v8__Channel__EXTENDER__method2(
-      this: &Channel,
-    ) -> i32 {
-      ChannelExtender::dispatch(this).method2()
-    }
-
-  #[repr(C)]
-  pub struct Channel {
-    _cxx_vtable: *const util::Opaque,
-  }
-
-  impl Channel {
-    pub fn method1(&mut self, arg: i32) {
-      unsafe { v8__Channel__method1(self, arg) }
-    }
-    pub fn method2(&self) -> i32 {
-      unsafe { v8__Channel__method2(self) }
-    }
-  }
-
-  impl Drop for Channel {
-    fn drop(&mut self) {
-      unsafe { v8__Channel__DTOR(self) }
-    }
-  }
-
-  pub trait AsChannel {
-    fn as_channel(&self) -> &Channel;
-    fn as_channel_mut(&mut self) -> &mut Channel;
-  }
-
-  impl AsChannel for Channel {
-    fn as_channel(&self) -> &Channel {
-      self
-    }
-    fn as_channel_mut(&mut self) -> &mut Channel {
-      self
-    }
-  }
-
-  impl<T> AsChannel for T
-  where
-    T: ChannelOverrides,
-  {
-    fn as_channel(&self) -> &Channel {
-      &self.extender().cxx_channel
-    }
-    fn as_channel_mut(&mut self) -> &mut Channel {
-      &mut self.extender_mut().cxx_channel
-    }
-  }
-
-  pub struct ChannelDefaults;
-  impl ChannelDefaults {
-    pub fn method1(channel: &mut Channel, arg: i32) {
-      unsafe { v8__Channel__Channel__method1(channel, arg) }
-    }
-  }
-
-  pub trait ChannelOverrides: AsChannel {
-    fn extender(&self) -> &ChannelExtender;
-    fn extender_mut(&mut self) -> &mut ChannelExtender;
-
-    fn method1(&mut self, arg: i32) {
-      ChannelDefaults::method1(self.as_channel_mut(), arg)
-    }
-    fn method2(&self) -> i32;
-  }
-
-  pub struct ChannelExtender {
-    cxx_channel: Channel,
-    extender_offset: util::FieldOffset<Self>,
-    rust_vtable: util::RustVTable<&'static dyn ChannelOverrides>,
-  }
-
-  impl ChannelExtender {
-    fn construct_cxx_channel() -> Channel {
-      unsafe {
-        let mut buf = std::mem::MaybeUninit::<Channel>::uninit();
-        v8__Channel__EXTENDER__CTOR(&mut buf);
-        buf.assume_init()
-      }
-    }
-
-    fn get_extender_offset<T>() -> util::FieldOffset<Self>
-    where
-      T: ChannelOverrides,
-    {
-      let buf = std::mem::MaybeUninit::<T>::uninit();
-      let embedder_ptr: *const T = buf.as_ptr();
-      let self_ptr: *const Self = unsafe { (*embedder_ptr).extender() };
-      util::FieldOffset::from_ptrs(embedder_ptr, self_ptr)
-    }
-
-    fn get_rust_vtable<T>() -> util::RustVTable<&'static dyn ChannelOverrides>
-    where
-      T: ChannelOverrides,
-    {
-      let buf = std::mem::MaybeUninit::<T>::uninit();
-      let embedder_ptr = buf.as_ptr();
-      let trait_object: *const dyn ChannelOverrides = embedder_ptr;
-      let (data_ptr, vtable): (*const T, util::RustVTable<_>) =
-        unsafe { std::mem::transmute(trait_object) };
-      assert_eq!(data_ptr, embedder_ptr);
-      vtable
-    }
-
-    pub fn new<T>() -> Self
-    where
-      T: ChannelOverrides,
-    {
-      Self {
-        cxx_channel: Self::construct_cxx_channel(),
-        extender_offset: Self::get_extender_offset::<T>(),
-        rust_vtable: Self::get_rust_vtable::<T>(),
-      }
-    }
-
-    fn get_channel_offset() -> util::FieldOffset<Channel> {
-      let buf = std::mem::MaybeUninit::<Self>::uninit();
-      util::FieldOffset::from_ptrs(buf.as_ptr(), unsafe {
-        &(*buf.as_ptr()).cxx_channel
-      })
-    }
-
-    pub unsafe fn dispatch(channel: &Channel) -> &dyn ChannelOverrides {
-      let this = Self::get_channel_offset().to_embedder::<Self>(channel);
-      let embedder = this.extender_offset.to_embedder::<util::Opaque>(this);
-      std::mem::transmute((embedder, this.rust_vtable))
-    }
-
-    pub unsafe fn dispatch_mut(channel: &mut Channel) -> &mut dyn ChannelOverrides {
-      let this = Self::get_channel_offset().to_embedder_mut::<Self>(channel);
-      let vtable = this.rust_vtable;
-      let embedder = this.extender_offset.to_embedder_mut::<util::Opaque>(this);
-      std::mem::transmute((embedder, vtable))
-    }
-  }
-}
-
-mod util {
-  use std::marker::PhantomData;
-  use std::mem::size_of;
-
-  pub type Opaque = [usize; 0];
-
-  #[repr(transparent)]
-  #[derive(Copy, Clone, Debug)]
-  pub struct RustVTable<DynT>(pub *const Opaque, pub PhantomData<DynT>);
-
-  #[repr(transparent)]
-  #[derive(Debug)]
-  pub struct FieldOffset<F>(usize, PhantomData<F>);
-
-  unsafe impl<F> Send for FieldOffset<F> where F: Send {}
-  unsafe impl<F> Sync for FieldOffset<F> where F: Sync {}
-  impl<F> Copy for FieldOffset<F> {}
-
-  impl<F> Clone for FieldOffset<F> {
-    fn clone(&self) -> Self {
-      Self(self.0, self.1)
-    }
-  }
-
-  impl<F> FieldOffset<F> {
-    pub fn from_ptrs<E>(embedder_ptr: *const E, field_ptr: *const F) -> Self {
-      let embedder_addr = embedder_ptr as usize;
-      let field_addr = field_ptr as usize;
-      assert!(field_addr >= embedder_addr);
-      assert!(
-        (field_addr + size_of::<F>()) <= (embedder_addr + size_of::<E>())
-      );
-      Self(embedder_addr - field_addr, PhantomData)
-    }
-
-    pub unsafe fn to_embedder<E>(self, field: &F) -> &E {
-      (((field as *const _ as usize) - self.0) as *const E)
-        .as_ref()
-        .unwrap()
-    }
-
-    pub unsafe fn to_embedder_mut<E>(self, field: &mut F) -> &mut E {
-      (((field as *mut _ as usize) - self.0) as *mut E)
-        .as_mut()
-        .unwrap()
-    }
-  }
-}
+mod cxx_util;
+mod v8_inspector;
 
 mod example {
-  use super::channel::*;
+  use crate::v8_inspector::channel::*;
 
   pub struct Example {
     a: i32,
@@ -259,7 +41,7 @@ mod example {
 }
 
 fn main() {
-  use channel::*;
+  use crate::v8_inspector::channel::*;
   use example::*;
   let mut ex = Example::new();
   let chan = ex.as_channel_mut();

src/v8_inspector/channel.rs

@@ -0,0 +1,176 @@
+use crate::cxx_util::FieldOffset;
+use crate::cxx_util::Opaque;
+use crate::cxx_util::RustVTable;
+
+extern "C" {
+  // Call a method/destructor; virtual methods use C++ dynamic dispatch.
+  fn v8_inspector__Channel__DTOR(this: &mut Channel) -> ();
+  fn v8_inspector__Channel__method1(this: &mut Channel, arg: i32) -> ();
+  fn v8_inspector__Channel__method2(this: &Channel) -> i32;
+
+  // Call a method of a specific class implementation, bypassing dynamic
+  // dispatch. C++ equivalent: `my_channel.Channel::a()`.
+  fn v8_inspector__Channel__Channel__method1(
+    this: &mut Channel,
+    arg: i32,
+  ) -> ();
+
+  // Constructs a special class derived from Channel that forwards all
+  // virtual method invocations to rust. It is assumed that this subclass
+  // has the same size and memory layout as the class it's deriving from.
+  fn v8_inspector__Channel__EXTENDER__CTOR(
+    buf: &mut std::mem::MaybeUninit<Channel>,
+  ) -> ();
+}
+
+#[allow(non_snake_case)]
+#[no_mangle]
+pub unsafe extern "C" fn v8_inspector__Channel__EXTENDER__method1(
+  this: &mut Channel,
+  arg: i32,
+) {
+  ChannelExtender::dispatch_mut(this).method1(arg)
+}
+
+#[allow(non_snake_case)]
+#[no_mangle]
+pub unsafe extern "C" fn v8_inspector__Channel__EXTENDER__method2(
+  this: &Channel,
+) -> i32 {
+  ChannelExtender::dispatch(this).method2()
+}
+
+#[repr(C)]
+pub struct Channel {
+  _cxx_vtable: *const Opaque,
+}
+
+impl Channel {
+  pub fn method1(&mut self, arg: i32) {
+    unsafe { v8_inspector__Channel__method1(self, arg) }
+  }
+  pub fn method2(&self) -> i32 {
+    unsafe { v8_inspector__Channel__method2(self) }
+  }
+}
+
+impl Drop for Channel {
+  fn drop(&mut self) {
+    unsafe { v8_inspector__Channel__DTOR(self) }
+  }
+}
+
+pub trait AsChannel {
+  fn as_channel(&self) -> &Channel;
+  fn as_channel_mut(&mut self) -> &mut Channel;
+}
+
+impl AsChannel for Channel {
+  fn as_channel(&self) -> &Channel {
+    self
+  }
+  fn as_channel_mut(&mut self) -> &mut Channel {
+    self
+  }
+}
+
+impl<T> AsChannel for T
+where
+  T: ChannelOverrides,
+{
+  fn as_channel(&self) -> &Channel {
+    &self.extender().cxx_channel
+  }
+  fn as_channel_mut(&mut self) -> &mut Channel {
+    &mut self.extender_mut().cxx_channel
+  }
+}
+
+pub struct ChannelDefaults;
+impl ChannelDefaults {
+  pub fn method1(channel: &mut Channel, arg: i32) {
+    unsafe { v8_inspector__Channel__Channel__method1(channel, arg) }
+  }
+}
+
+pub trait ChannelOverrides: AsChannel {
+  fn extender(&self) -> &ChannelExtender;
+  fn extender_mut(&mut self) -> &mut ChannelExtender;
+
+  fn method1(&mut self, arg: i32) {
+    ChannelDefaults::method1(self.as_channel_mut(), arg)
+  }
+  fn method2(&self) -> i32;
+}
+
+pub struct ChannelExtender {
+  cxx_channel: Channel,
+  extender_offset: FieldOffset<Self>,
+  rust_vtable: RustVTable<&'static dyn ChannelOverrides>,
+}
+
+impl ChannelExtender {
+  fn construct_cxx_channel() -> Channel {
+    unsafe {
+      let mut buf = std::mem::MaybeUninit::<Channel>::uninit();
+      v8_inspector__Channel__EXTENDER__CTOR(&mut buf);
+      buf.assume_init()
+    }
+  }
+
+  fn get_extender_offset<T>() -> FieldOffset<Self>
+  where
+    T: ChannelOverrides,
+  {
+    let buf = std::mem::MaybeUninit::<T>::uninit();
+    let embedder_ptr: *const T = buf.as_ptr();
+    let self_ptr: *const Self = unsafe { (*embedder_ptr).extender() };
+    FieldOffset::from_ptrs(embedder_ptr, self_ptr)
+  }
+
+  fn get_rust_vtable<T>() -> RustVTable<&'static dyn ChannelOverrides>
+  where
+    T: ChannelOverrides,
+  {
+    let buf = std::mem::MaybeUninit::<T>::uninit();
+    let embedder_ptr = buf.as_ptr();
+    let trait_object: *const dyn ChannelOverrides = embedder_ptr;
+    let (data_ptr, vtable): (*const T, RustVTable<_>) =
+      unsafe { std::mem::transmute(trait_object) };
+    assert_eq!(data_ptr, embedder_ptr);
+    vtable
+  }
+
+  pub fn new<T>() -> Self
+  where
+    T: ChannelOverrides,
+  {
+    Self {
+      cxx_channel: Self::construct_cxx_channel(),
+      extender_offset: Self::get_extender_offset::<T>(),
+      rust_vtable: Self::get_rust_vtable::<T>(),
+    }
+  }
+
+  fn get_channel_offset() -> FieldOffset<Channel> {
+    let buf = std::mem::MaybeUninit::<Self>::uninit();
+    FieldOffset::from_ptrs(buf.as_ptr(), unsafe {
+      &(*buf.as_ptr()).cxx_channel
+    })
+  }
+
+  pub unsafe fn dispatch(channel: &Channel) -> &dyn ChannelOverrides {
+    let this = Self::get_channel_offset().to_embedder::<Self>(channel);
+    let embedder = this.extender_offset.to_embedder::<Opaque>(this);
+    std::mem::transmute((embedder, this.rust_vtable))
+  }
+
+  pub unsafe fn dispatch_mut(
+    channel: &mut Channel,
+  ) -> &mut dyn ChannelOverrides {
+    let this = Self::get_channel_offset().to_embedder_mut::<Self>(channel);
+    let vtable = this.rust_vtable;
+    let embedder = this.extender_offset.to_embedder_mut::<Opaque>(this);
+    std::mem::transmute((embedder, vtable))
+  }
+}

src/v8_inspector/mod.rs

@@ -0,0 +1 @@
+pub mod channel;