co原理实现

function co(it: Generator): Promise<any> {
    return new Promise((resolve, reject) => {
        next();
        function next(val?: any) {
            const { value, done } = it.next(val);
            if (done) return resolve(value);
            Promise.resolve(value).then(data => {
                next(data);
            }, reject);
        }
    });
}

function * read() {
    const r: string = yield fs.readFile(_path('name.txt'), 'utf8');
    const age: string = yield fs.readFile(_path(r), 'utf8');
    const result: string[] = yield [1 + age];
    return result
}
co(read()).then((data: string) => {
    console.log(data);
}).catch((err: any) => {
    console.log('error: ', err);
});