servo/components/script/dom/bindings/transferable.rs

/* 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/. */

//! Trait representing the concept of [transferable objects]
//! (<https://html.spec.whatwg.org/multipage/#transferable-objects>).

use std::collections::HashMap;
use std::num::NonZeroU32;

use base::id::PipelineNamespaceId;

use crate::dom::bindings::reflector::DomObject;
use crate::dom::bindings::root::DomRoot;
use crate::dom::bindings::structuredclone::{StructuredData, StructuredDataReader};
use crate::dom::globalscope::GlobalScope;

pub(crate) trait IdFromComponents
where
    Self: Sized,
{
    fn from(namespace_id: PipelineNamespaceId, index: NonZeroU32) -> Self;
}

pub(crate) trait ExtractComponents {
    fn components(&self) -> (PipelineNamespaceId, NonZeroU32);
}

pub(crate) trait Transferable: DomObject
where
    Self: Sized,
{
    type Id: Eq + std::hash::Hash + Copy + IdFromComponents + ExtractComponents;
    type Data;

    fn can_transfer(&self) -> bool {
        true
    }

    fn transfer(&self) -> Result<(Self::Id, Self::Data), ()>;
    fn transfer_receive(
        owner: &GlobalScope,
        id: Self::Id,
        serialized: Self::Data,
    ) -> Result<DomRoot<Self>, ()>;

    fn serialized_storage(data: StructuredData<'_>) -> &mut Option<HashMap<Self::Id, Self::Data>>;
    fn deserialized_storage(reader: &mut StructuredDataReader) -> &mut Option<Vec<DomRoot<Self>>>;
}