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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
use crate::interfaces::{nsIInterfaceRequestor, nsISupports};
use crate::{GetterAddrefs, RefCounted, RefPtr};
#[repr(C)]
#[derive(Copy, Clone, Eq, PartialEq)]
/// A "unique identifier". This is modeled after OSF DCE UUIDs.
pub struct nsID(pub u32, pub u16, pub u16, pub [u8; 8]);
/// Interface IDs
pub type nsIID = nsID;
/// Class IDs
pub type nsCID = nsID;
/// A type which implements XpCom must follow the following rules:
///
/// * It must be a legal XPCOM interface.
/// * The result of a QueryInterface or similar call, passing IID, must return a
/// valid reference to an object of the given type.
/// * It must be valid to cast a &self reference to a &nsISupports reference.
pub unsafe trait XpCom: RefCounted {
const IID: nsIID;
/// Perform a QueryInterface call on this object, attempting to dynamically
/// cast it to the requested interface type. Returns Some(RefPtr<T>) if the
/// cast succeeded, and None otherwise.
fn query_interface<T: XpCom>(&self) -> Option<RefPtr<T>> {
let mut ga = GetterAddrefs::<T>::new();
unsafe {
if (*(self as *const Self as *const nsISupports))
.QueryInterface(&T::IID, ga.void_ptr())
.succeeded()
{
ga.refptr()
} else {
None
}
}
}
/// Perform a `GetInterface` call on this object, returning `None` if the
/// object doesn't implement `nsIInterfaceRequestor`, or can't access the
/// interface `T`.
fn get_interface<T: XpCom>(&self) -> Option<RefPtr<T>> {
let ireq = self.query_interface::<nsIInterfaceRequestor>()?;
let mut ga = GetterAddrefs::<T>::new();
unsafe {
if ireq.GetInterface(&T::IID, ga.void_ptr()).succeeded() {
ga.refptr()
} else {
None
}
}
}
}
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