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// Licensed under the Apache License, Version 2.0
// <LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
// All files in the project carrying such notice may not be copied, modified, or distributed
// except according to those terms.
use std::fmt::{Debug, Error as FmtError, Formatter};
use std::mem::forget;
use std::ops::Deref;
use std::ptr::{NonNull, null_mut};
use winapi::Interface;
use winapi::um::unknwnbase::IUnknown;
// ComPtr to wrap COM interfaces sanely
#[repr(transparent)]
pub struct ComPtr<T>(NonNull<T>);
impl<T> ComPtr<T> {
/// Creates a `ComPtr` to wrap a raw pointer.
/// It takes ownership over the pointer which means it does __not__ call `AddRef`.
/// `T` __must__ be a COM interface that inherits from `IUnknown`.
pub unsafe fn from_raw(ptr: *mut T) -> ComPtr<T> where T: Interface {
ComPtr(NonNull::new(ptr).expect("ptr should not be null"))
}
/// Casts up the inheritance chain
pub fn up<U>(self) -> ComPtr<U> where T: Deref<Target=U>, U: Interface {
unsafe { ComPtr::from_raw(self.into_raw() as *mut U) }
}
/// Extracts the raw pointer.
/// You are now responsible for releasing it yourself.
pub fn into_raw(self) -> *mut T {
let p = self.0.as_ptr();
forget(self);
p
}
/// For internal use only.
fn as_unknown(&self) -> &IUnknown {
unsafe { &*(self.as_raw() as *mut IUnknown) }
}
/// Performs QueryInterface fun.
pub fn cast<U>(&self) -> Result<ComPtr<U>, i32> where U: Interface {
let mut obj = null_mut();
let err = unsafe { self.as_unknown().QueryInterface(&U::uuidof(), &mut obj) };
if err < 0 { return Err(err); }
Ok(unsafe { ComPtr::from_raw(obj as *mut U) })
}
/// Obtains the raw pointer without transferring ownership.
/// Do __not__ release this pointer because it is still owned by the `ComPtr`.
pub fn as_raw(&self) -> *mut T {
self.0.as_ptr()
}
}
impl<T> Deref for ComPtr<T> {
type Target = T;
fn deref(&self) -> &T {
unsafe { &*self.as_raw() }
}
}
impl<T> Clone for ComPtr<T> where T: Interface {
fn clone(&self) -> Self {
unsafe {
self.as_unknown().AddRef();
ComPtr::from_raw(self.as_raw())
}
}
}
impl<T> Debug for ComPtr<T> {
fn fmt(&self, f: &mut Formatter) -> Result<(), FmtError> {
write!(f, "{:?}", self.0)
}
}
impl<T> Drop for ComPtr<T> {
fn drop(&mut self) {
unsafe { self.as_unknown().Release(); }
}
}
impl<T> PartialEq<ComPtr<T>> for ComPtr<T> where T: Interface {
fn eq(&self, other: &ComPtr<T>) -> bool {
self.0 == other.0
}
}
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