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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 strict";
module.metadata = {
"stability": "experimental"
};
// This module provides `marshal` and `demarshal` functions
// that can be used to send MessagePort's over `nsIFrameMessageManager`
// until Bug 914974 is fixed.
const { add, iterator } = require("../sdk/lang/weak-set");
const { curry } = require("../sdk/lang/functional");
var id = 0;
const ports = new WeakMap();
// Takes `nsIFrameMessageManager` and `MessagePort` instances
// and returns a handle representing given `port`. Messages
// received on given `port` will be forwarded to a message
// manager under `sdk/port/message` and messages like:
// { port: { type: "MessagePort", id: 2}, data: data }
// Where id is an identifier associated with a given `port`
// and `data` is an `event.data` received on port.
const marshal = curry((manager, port) => {
if (!ports.has(port)) {
id = id + 1;
const handle = {type: "MessagePort", id: id};
// Bind id to the given port
ports.set(port, handle);
// Obtain a weak reference to a port.
add(exports, port);
port.onmessage = event => {
manager.sendAsyncMessage("sdk/port/message", {
port: handle,
message: event.data
});
};
return handle;
}
return ports.get(port);
});
exports.marshal = marshal;
// Takes `nsIFrameMessageManager` instance and a handle returned
// `marshal(manager, port)` returning a `port` that was passed
// to it. Note that `port` may be GC-ed in which case returned
// value will be `null`.
const demarshal = curry((manager, {type, id}) => {
if (type === "MessagePort") {
for (let port of iterator(exports)) {
if (id === ports.get(port).id)
return port;
}
}
return null;
});
exports.demarshal = demarshal;
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