Initial commit

node_modules/execa/lib/ipc/forward.js

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+import {EventEmitter} from 'node:events';
+import {onMessage, onDisconnect} from './incoming.js';
+import {undoAddedReferences} from './reference.js';
+
+// Forward the `message` and `disconnect` events from the process and subprocess to a proxy emitter.
+// This prevents the `error` event from stopping IPC.
+// This also allows debouncing the `message` event.
+export const getIpcEmitter = (anyProcess, channel, isSubprocess) => {
+	if (IPC_EMITTERS.has(anyProcess)) {
+		return IPC_EMITTERS.get(anyProcess);
+	}
+
+	// Use an `EventEmitter`, like the `process` that is being proxied
+	// eslint-disable-next-line unicorn/prefer-event-target
+	const ipcEmitter = new EventEmitter();
+	ipcEmitter.connected = true;
+	IPC_EMITTERS.set(anyProcess, ipcEmitter);
+	forwardEvents({
+		ipcEmitter,
+		anyProcess,
+		channel,
+		isSubprocess,
+	});
+	return ipcEmitter;
+};
+
+const IPC_EMITTERS = new WeakMap();
+
+// The `message` and `disconnect` events are buffered in the subprocess until the first listener is setup.
+// However, unbuffering happens after one tick, so this give enough time for the caller to setup the listener on the proxy emitter first.
+// See https://github.com/nodejs/node/blob/2aaeaa863c35befa2ebaa98fb7737ec84df4d8e9/lib/internal/child_process.js#L721
+const forwardEvents = ({ipcEmitter, anyProcess, channel, isSubprocess}) => {
+	const boundOnMessage = onMessage.bind(undefined, {
+		anyProcess,
+		channel,
+		isSubprocess,
+		ipcEmitter,
+	});
+	anyProcess.on('message', boundOnMessage);
+	anyProcess.once('disconnect', onDisconnect.bind(undefined, {
+		anyProcess,
+		channel,
+		isSubprocess,
+		ipcEmitter,
+		boundOnMessage,
+	}));
+	undoAddedReferences(channel, isSubprocess);
+};
+
+// Check whether there might still be some `message` events to receive
+export const isConnected = anyProcess => {
+	const ipcEmitter = IPC_EMITTERS.get(anyProcess);
+	return ipcEmitter === undefined
+		? anyProcess.channel !== null
+		: ipcEmitter.connected;
+};