异步串行 —— AsyncSeriesHook

串行one by one

6.use.js

let {AsyncSeriesHook} = require('tapable')   // 解构同步勾子


class Lesson {
    constructor() {
        this.index = 0
        this.hooks = {
            // 订阅勾子
            arch: new AsyncSeriesHook(['name']),

        }
    }

    start() {
        // 发布
        // this.hooks.arch.callAsync('may', function () {
        //     console.log('end');
        // })
        // 另一种发布
        this.hooks.arch.promise('may').then(function () {
                console.log('end');
            }
        )
    }

    tap() {   //  注册监听函数,订阅
        // this.hooks.arch.tapAsync('node',  (name, callback) => {
        //     setTimeout(() => {
        //         console.log('node', name)
        //         callback()
        //     }, 1000)
        // })
        // this.hooks.arch.tapAsync('react',  (name, callback) => {
        //     setTimeout(() => {
        //         console.log('react', name)
        //         callback()
        //     }, 1000)
        // })
        // 另一种订阅
        this.hooks.arch.tapPromise('node', (name) => {
            return new Promise((resolve, reject) => {
                setTimeout(() => {
                    console.log('node', name)
                    resolve()
                }, 1000)
            })
        })
        this.hooks.arch.tapPromise('react', (name) => {
            return new Promise((resolve, reject) => {
                setTimeout(() => {
                    console.log('react', name)
                    resolve()
                }, 1000)
            })
        })
    }
}


let l = new Lesson()

l.tap();  //注册两个函数
l.start(); // 启动勾子

6.theory.js

class AsyncSeriesHook {  //
    constructor(args) {  // args => ['name']
        this.tasks = []
    }

    tapAsync(name, task) {
        this.tasks.push(task)
    }

    tapPromise(name, task) {
        this.tasks.push(task)
    }

    callAsync(...args) {
        let finalCallback = args.pop()
        let index = 0;
        let next = () => {
            if (this.tasks.length === index) return finalCallback();
            let task = this.tasks[index++];
            task(...args, next);
        }
        next();
    }

    promise(...args) {
        // 将promise串联起来
        let [first, ...other] = this.tasks
        return other.reduce((p, n) => {
             return p.then(() => n (...args))
        }, first(...args))
    }
}

let hook = new AsyncSeriesHook(['name'])


// hook.tapAsync('react', function (name, callback) {
//     setTimeout(() => {
//         console.log('react', name);
//         callback()
//     }, 1000)
// })
//
// hook.tapAsync('node', function (name, callback) {
//     setTimeout(() => {
//         console.log('node', name);
//         callback()
//     }, 1000)
// })
//
// hook.tapAsync('webpack', function (name, callback) {
//     setTimeout(() => {
//         console.log('webpack', name);
//         callback()
//     }, 1000)
// })


hook.tapPromise('react', function (name, callback) {
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            console.log('react', name);
            resolve()
        }, 1000)
    })
})

hook.tapPromise('node', function (name, callback) {
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            console.log('node', name);
            resolve()
        }, 1000)
    })
})




// hook.callAsync('jw', function () {
//     console.log('end');
// })


hook.promise('jw').then(function () {
    console.log('end');
})