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use crate::D3DResult;
use std::{
fmt,
hash::{Hash, Hasher},
ops::Deref,
ptr,
};
use winapi::{ctypes::c_void, um::unknwnbase::IUnknown, Interface};
#[repr(transparent)]
pub struct ComPtr<T: Interface>(*mut T);
impl<T: Interface> ComPtr<T> {
pub fn null() -> Self {
ComPtr(ptr::null_mut())
}
pub unsafe fn from_raw(raw: *mut T) -> Self {
if !raw.is_null() {
(*(raw as *mut IUnknown)).AddRef();
}
ComPtr(raw)
}
pub fn is_null(&self) -> bool {
self.0.is_null()
}
pub fn as_ptr(&self) -> *const T {
self.0
}
pub fn as_mut_ptr(&self) -> *mut T {
self.0
}
pub fn mut_void(&mut self) -> *mut *mut c_void {
&mut self.0 as *mut *mut _ as *mut *mut _
}
pub fn mut_self(&mut self) -> *mut *mut T {
&mut self.0 as *mut *mut _
}
}
impl<T: Interface> ComPtr<T> {
pub unsafe fn as_unknown(&self) -> &IUnknown {
debug_assert!(!self.is_null());
&*(self.0 as *mut IUnknown)
}
pub unsafe fn cast<U>(&self) -> D3DResult<ComPtr<U>>
where
U: Interface,
{
debug_assert!(!self.is_null());
let mut obj = ComPtr::<U>::null();
let hr = self
.as_unknown()
.QueryInterface(&U::uuidof(), obj.mut_void());
(obj, hr)
}
}
impl<T: Interface> Clone for ComPtr<T> {
fn clone(&self) -> Self {
debug_assert!(!self.is_null());
unsafe {
self.as_unknown().AddRef();
}
ComPtr(self.0)
}
}
impl<T: Interface> Drop for ComPtr<T> {
fn drop(&mut self) {
if !self.0.is_null() {
unsafe {
self.as_unknown().Release();
}
}
}
}
impl<T: Interface> Deref for ComPtr<T> {
type Target = T;
fn deref(&self) -> &T {
debug_assert!(!self.is_null());
unsafe { &*self.0 }
}
}
impl<T: Interface> fmt::Debug for ComPtr<T> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "ComPtr( ptr: {:?} )", self.0)
}
}
impl<T: Interface> PartialEq<*mut T> for ComPtr<T> {
fn eq(&self, other: &*mut T) -> bool {
self.0 == *other
}
}
impl<T: Interface> PartialEq for ComPtr<T> {
fn eq(&self, other: &Self) -> bool {
self.0 == other.0
}
}
impl<T: Interface> Hash for ComPtr<T> {
fn hash<H: Hasher>(&self, state: &mut H) {
self.0.hash(state);
}
}
/// Macro that allows generation of an easy to use enum for dealing with many different possible versions of a COM object.
///
/// Give the variants so that parents come before children. This often manifests as going up in order (1 -> 2 -> 3). This is vital for safety.
///
/// Three function names need to be attached to each variant. The examples are given for the MyComObject1 variant below:
/// - the from function (`ComPtr<actual::ComObject1> -> Self`)
/// - the as function (`&self -> Option<ComPtr<actual::ComObject1>>`)
/// - the unwrap function (`&self -> ComPtr<actual::ComObject1>` panicking on failure to cast)
///
/// ```rust
/// # pub use d3d12::weak_com_inheritance_chain;
/// # mod actual {
/// # pub struct ComObject; impl winapi::Interface for ComObject { fn uuidof() -> winapi::shared::guiddef::GUID { todo!() } }
/// # pub struct ComObject1; impl winapi::Interface for ComObject1 { fn uuidof() -> winapi::shared::guiddef::GUID { todo!() } }
/// # pub struct ComObject2; impl winapi::Interface for ComObject2 { fn uuidof() -> winapi::shared::guiddef::GUID { todo!() } }
/// # }
/// weak_com_inheritance_chain! {
/// pub enum MyComObject {
/// MyComObject(actual::ComObject), from_my_com_object, as_my_com_object, my_com_object; // First variant doesn't use "unwrap" as it can never fail
/// MyComObject1(actual::ComObject1), from_my_com_object1, as_my_com_object1, unwrap_my_com_object1;
/// MyComObject2(actual::ComObject2), from_my_com_object2, as_my_com_object2, unwrap_my_com_object2;
/// }
/// }
/// ```
#[macro_export]
macro_rules! weak_com_inheritance_chain {
// We first match a human readable enum style, before going into the recursive section.
//
// Internal calls to the macro have either the prefix
// - @recursion_logic for the recursion and termination
// - @render_members for the actual call to fill in the members.
(
$(#[$meta:meta])*
$vis:vis enum $name:ident {
$first_variant:ident($first_type:ty), $first_from_name:ident, $first_as_name:ident, $first_unwrap_name:ident $(;)?
$($variant:ident($type:ty), $from_name:ident, $as_name:ident, $unwrap_name:ident);* $(;)?
}
) => {
$(#[$meta])*
$vis enum $name {
$first_variant($crate::ComPtr<$first_type>),
$(
$variant($crate::ComPtr<$type>)
),+
}
impl $name {
$crate::weak_com_inheritance_chain! {
@recursion_logic,
$vis,
;
$first_variant($first_type), $first_from_name, $first_as_name, $first_unwrap_name;
$($variant($type), $from_name, $as_name, $unwrap_name);*
}
}
impl std::ops::Deref for $name {
type Target = $crate::ComPtr<$first_type>;
fn deref(&self) -> &Self::Target {
self.$first_unwrap_name()
}
}
};
// This is the iteration case of the recursion. We instantiate the member functions for the variant we
// are currently at, recursing on ourself for the next variant. Note we only keep track of the previous
// variant name, not the functions names, as those are not needed.
(
@recursion_logic,
$vis:vis,
$(,)? $($prev_variant:ident),* $(,)?;
$this_variant:ident($this_type:ty), $this_from_name:ident, $this_as_name:ident, $this_unwrap_name:ident $(;)?
$($next_variant:ident($next_type:ty), $next_from_name:ident, $next_as_name:ident, $next_unwrap_name:ident);*
) => {
// Actually generate the members for this variant. Needs the previous and future variant names.
$crate::weak_com_inheritance_chain! {
@render_members,
$vis,
$this_from_name, $this_as_name, $this_unwrap_name;
$($prev_variant),*;
$this_variant($this_type);
$($next_variant),*;
}
// Recurse on ourselves. If there is no future variants left, we'll hit the base case as the final expansion returns no tokens.
$crate::weak_com_inheritance_chain! {
@recursion_logic,
$vis,
$($prev_variant),* , $this_variant;
$($next_variant($next_type), $next_from_name, $next_as_name, $next_unwrap_name);*
}
};
// Base case for recursion. There are no more variants left
(
@recursion_logic,
$vis:vis,
$($prev_variant:ident),*;
) => {};
// This is where we generate the members using the given names.
(
@render_members,
$vis:vis,
$from_name:ident, $as_name:ident, $unwrap_name:ident;
$($prev_variant:ident),*;
$variant:ident($type:ty);
$($next_variant:ident),*;
) => {
// Construct this enum from weak pointer to this interface. For best usability, always use the highest constructor you can. This doesn't try to upcast.
$vis unsafe fn $from_name(value: $crate::ComPtr<$type>) -> Self {
Self::$variant(value)
}
// Returns Some if the value implements the interface otherwise returns None.
$vis fn $as_name(&self) -> Option<&$crate::ComPtr<$type>> {
match *self {
$(
Self::$prev_variant(_) => None,
)*
Self::$variant(ref v) => Some(v),
$(
Self::$next_variant(ref v) => {
// v is &ComPtr<NextType> and se cast to &ComPtr<Type>
Some(unsafe { std::mem::transmute(v) })
}
)*
}
}
// Returns the interface if the value implements it, otherwise panics.
#[track_caller]
$vis fn $unwrap_name(&self) -> &$crate::ComPtr<$type> {
match *self {
$(
Self::$prev_variant(_) => panic!(concat!("Tried to unwrap a ", stringify!($prev_variant), " as a ", stringify!($variant))),
)*
Self::$variant(ref v) => &*v,
$(
Self::$next_variant(ref v) => {
// v is &ComPtr<NextType> and se cast to &ComPtr<Type>
unsafe { std::mem::transmute(v) }
}
)*
}
}
};
}