将Observable转换为异步生成器 [英] Convert an Observable to an async generator

问题描述

我正在尝试将rxjs与babeljs结合使用以创建一个异步生成器函数，该函数在调用next时产生，在调用error时抛出，并在调用complete时结束.我的问题是我无法从回调中屈服.

I'm trying to use rxjs in conjunction with babeljs to create an async generator function that yields when next is called, throws when error is called, and finishes when complete is called. The problem I have with this is that I can't yield from a callback.

我可以await一个无条件处理退货/扔东西的要求.

I can await a Promise to handle the return/throw requirement.

async function *getData( observable ) {
    await new Promise( ( resolve, reject ) => {
        observable.subscribe( {
            next( data ) {
                yield data; // can't yield here
            },
            error( err ) {
                reject( err );
            },
            complete() {
                resolve();
            }
        } );
    } );
}

( async function example() {
    for await( const data of getData( foo ) ) {
        console.log( 'data received' );
    }
    console.log( 'done' );
}() );

这可能吗?

推荐答案

我问了橡皮鸭，然后我写了下面的代码来完成我想要的事情:

I asked the rubber duck, then I wrote the following code which does what I wanted:

function defer() {
    const properties = {},
        promise = new Promise( ( resolve, reject ) => {
            Object.assign( properties, { resolve, reject } );
        } );
        return Object.assign( promise, properties );
}

async function *getData( observable ) {
    let nextData = defer();
    const sub = observable.subscribe( {
        next( data ) {
            const n = nextData;
            nextData = defer();
            n.resolve( data );
        },
        error( err ) {
            nextData.reject( err );
        },
        complete() {
            const n = nextData;
            nextData = null;
            n.resolve();
        }
    } );
    try {
        for(;;) {
            const value = await nextData;
            if( !nextData ) break;
            yield value;
        }
    } finally {
        sub.unsubscribe();
    }
}

这篇关于将Observable转换为异步生成器的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！