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import { FSWatcher } from "chokidar";
import { Project, ProjectOptions } from "ts-morph";
import invariant from "invariant";
interface TsMorphWatcherFsEvent {
type: "add" | "unlink" | "change";
path: string;
}
type TsMorphWatcherEvent = TsMorphWatcherFsEvent | { type: "ready" };
class PromiseSignal<T> {
private promise: Promise<T>;
private resolve?: (value: T) => void;
private resolved = false;
constructor() {
this.promise = new Promise(resolve => {
this.resolve = resolve;
});
}
getPromise() {
return this.promise;
}
notify(value: T) {
invariant(!this.resolved, "already resolved");
this.resolved = true;
this.resolve!(value);
}
}
export class TsMorphWatcher {
private project: Project;
private started = false;
private ready = false;
private eventQueue: TsMorphWatcherEvent[] = [];
private signal = new PromiseSignal<void>();
private lastError: Error | null = null;
constructor(
private watcher: FSWatcher,
private projectOptions: ProjectOptions
) {
this.project = new Project(this.projectOptions);
}
async stop() {
this.started = false;
}
async getNext(): Promise<Project> {
if (this.lastError) {
const lastError = this.lastError;
this.lastError = null;
throw lastError;
}
if (!this.started) {
await this.start();
}
if (this.eventQueue.length === 0) {
await this.signal.getPromise();
}
const eventQueue = this.eventQueue;
this.eventQueue = [];
this.signal = new PromiseSignal();
for (let event of eventQueue) {
if (event.type === "add") {
this.project!.addSourceFileAtPath(event.path);
} else if (event.type === "change") {
const path = event.path.toLowerCase();
if (path.indexOf("tsconfig") > -1 && path.endsWith(".json")) {
// create a fresh project when the tsconfig changes
this.project = new Project(this.projectOptions);
} else {
const sourceFile = this.project!.getSourceFile(event.path);
if (sourceFile) {
await sourceFile.refreshFromFileSystem();
}
}
} else if (event.type === "unlink") {
const sourceFile = this.project!.getSourceFile(event.path);
if (sourceFile) {
this.project!.removeSourceFile(sourceFile);
}
} else {
// on ready, do nothing.
}
}
return this.project;
}
private pushEvent(event: TsMorphWatcherEvent) {
this.eventQueue.push(event);
if (this.eventQueue.length === 1) {
this.signal.notify();
}
}
private async start() {
invariant(!this.started, "already started");
this.started = true;
this.ready = false;
this.project = new Project(this.projectOptions);
this.watcher.on("ready", () => {
this.ready = true;
this.pushEvent({ type: "ready" });
});
this.watcher.on("add", path => {
if (!this.ready) {
return;
}
this.pushEvent({ type: "add", path });
});
this.watcher.on("change", async path => {
this.pushEvent({ type: "change", path });
});
this.watcher.on("unlink", path => {
this.pushEvent({ type: "unlink", path });
});
this.watcher.on("error", err => {
this.lastError = err;
});
}
}
// example usage:
const watcher = new TsMorphWatcher({
tsConfigFilePath: require.resolve("../tsconfig.json")
});
while (true) {
// getNext() waits until there is a change and returns a ts-morph Project instance.
// during getNext() it will update the project with any changes from the filesystem.
// getNext() will return a fresh Project instance if any file named tsconfig.json
// changes.
const project = await watcher.getNext();
// do something with project
}
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