servo-script-bindings 0.5.0

/* 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 https://mozilla.org/MPL/2.0/. */

//! Generic finalizer implementations for DOM binding implementations.

use std::any::type_name;
use std::ptr;
use std::rc::Rc;

use js::jsapi::JSObject;
use js::rust::GCMethods;

use crate::DomObject;
use crate::codegen::PrototypeList::PROTO_OR_IFACE_LENGTH;
use crate::utils::{ProtoOrIfaceArray, get_proto_or_iface_array};
use crate::weakref::WeakReferenceable;

/// Drop the resources held by reserved slots of a global object
unsafe fn do_finalize_global(obj: *mut JSObject) {
    unsafe {
        let protolist = get_proto_or_iface_array(obj);
        let list = (*protolist).as_mut_ptr();
        for idx in 0..PROTO_OR_IFACE_LENGTH as isize {
            let entry = list.offset(idx);
            let value = *entry;
            <*mut JSObject>::post_barrier(entry, value, ptr::null_mut());
        }
        let _: Box<ProtoOrIfaceArray> = Box::from_raw(protolist);
    }
}

/// # Safety
/// `this` must point to a valid, non-null instance of T.
pub(crate) unsafe fn finalize_common<T: DomObject>(this: *const T) {
    if !this.is_null() {
        // The pointer can be null if the object is the unforgeable holder of that interface.
        let this = unsafe { Box::from_raw(this as *mut T) };
        this.reflector().drop_memory(&*this);
    }
    debug!("{} finalize: {:p}", type_name::<T>(), this);
}

/// # Safety
/// `obj` must point to a valid, non-null JS object.
/// `this` must point to a valid, non-null instance of T.
pub(crate) unsafe fn finalize_global<T: DomObject>(obj: *mut JSObject, this: *const T) {
    unsafe {
        do_finalize_global(obj);
        finalize_common::<T>(this);
    }
}

/// # Safety
/// `this` must point to a Rced valid, non-null instance of T.
pub(crate) unsafe fn finalize_weak_referenceable<T: WeakReferenceable>(this: *const T) {
    if !this.is_null() {
        // The pointer can be null if the object is the unforgeable holder of that interface.
        let this = unsafe { Rc::from_raw(this) };
        this.reflector().drop_memory(&*this);
    }
    debug!("{} finalize: {:p}", type_name::<T>(), this);
}