piral-cli/lib/common/watcher.js

The standard CLI for creating and building a Piral instance or a Pilet.

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.watcherTask = watcherTask;
const fs_1 = require("fs");
function watcherTask(cb) {
    let running = Promise.resolve();
    let pending = false;
    let notify = () => { };
    const disposers = [];
    const triggers = [];
    const end = new Promise((resolve) => {
        notify = resolve;
    });
    const ref = {
        data: undefined,
        on(cb) {
            triggers.push(cb);
        },
        off(cb) {
            const idx = triggers.indexOf(cb);
            idx >= 0 && triggers.splice(idx, 1);
        },
        end,
    };
    const reRun = async () => {
        if (!pending) {
            pending = true;
            await running;
            await Promise.all(disposers.splice(0, disposers.length).map((dispose) => dispose()));
            pending = false;
            context.status = 'reoccuring';
            await run();
            triggers.splice(0, triggers.length).forEach((trigger) => trigger());
        }
    };
    const context = {
        onClean(dispose) {
            disposers.push(dispose);
        },
        watch(file) {
            if ((0, fs_1.existsSync)(file)) {
                const watcher = (0, fs_1.watch)(file, {
                    persistent: false,
                }, reRun);
                disposers.push(() => watcher.close());
            }
        },
        dependOn(anotherRef) {
            anotherRef.on(reRun);
        },
        close() {
            cb = () => Promise.resolve(undefined);
            reRun().then(notify);
        },
        status: 'initial',
    };
    const run = async () => {
        running = cb(context).then((data) => {
            ref.data = data;
        });
        await running;
        return ref;
    };
    return new Promise((resolve, reject) => {
        run().then(resolve, reject);
    });
}
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