tinycom 0.1.0

Tiny COM implements the tiny subset necessary to consume IUnknown interfaces.
Documentation 
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// Copyright (c) 2016 com-rs developers
//
// 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.

#![allow(non_upper_case_globals)]
#![allow(missing_docs)]

use std::os::raw::c_void;

use super::{AsComPtr, ComInterface, HResult, IID};

/// Base interface for all COM types.
///
/// None of the methods on this struct should be called directly,
/// use [`ComPtr`](struct.ComPtr.html) instead.

#[derive(Debug)]
#[repr(C)]
pub struct IUnknown {
    vtable: *const IUnknownVtbl,
}

#[allow(missing_debug_implementations)]
#[repr(C)]
#[doc(hidden)]
pub struct IUnknownVtbl {
    query_interface: extern "stdcall" fn(*const IUnknown, &IID, *mut *mut c_void) -> HResult,
    add_ref: extern "stdcall" fn(*const IUnknown) -> u32,
    release: extern "stdcall" fn(*const IUnknown) -> u32,
}

// This doesn't exist on linux "{00000000-0000-0000-C000-000000000046}"
iid!(pub IID_IUnknown = 0x0000_0000, 0x0000, 0x0000, 0xC0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x46);

impl IUnknown {
    /// Retrieves pointers to the supported interfaces on an object.
    /// Use [`ComPtr::from`](struct.ComPtr.html#method.from) instead.
    /// # Safety
    ///
    pub unsafe fn query_interface(&self, iid: &IID, object: *mut *mut c_void) -> HResult {
        ((*self.vtable).query_interface)(self, iid, object)
    }

    /// Increments the reference count for an interface on an object.
    /// Should never need to call this directly.
    /// # Safety
    ///
    pub unsafe fn add_ref(&self) -> u32 {
        ((*self.vtable).add_ref)(self)
    }

    /// Decrements the reference count for an interface on an object.
    /// Should never need to call this directly.
    /// # Safety
    ///
    pub unsafe fn release(&self) -> u32 {
        ((*self.vtable).release)(self)
    }
}

unsafe impl AsComPtr<Self> for IUnknown {}

unsafe impl ComInterface for IUnknown {
    #[doc(hidden)]
    type Vtable = IUnknownVtbl;
    fn iid() -> crate::IID {
        IID_IUnknown
    }
}