Wrap generator returns promise. Got by myself

wrapGenerator

const wrapGenerator = function (Generator) {
	const promise = new Promise(function (resolve, reject) {
		const g = Generator()
		let r = g.next()
		const nextYield = function (r) {
			if (r.done == true) {
				resolve(r.value)
				return
			}
			r.value.then(function (x) {
				r = g.next(x)
				nextYield(r)
			}).catch(function (e) {
				g.throw(e)
			})
		}
		nextYield(r)
	});
	return promise
}
// 转换 Generator 为普通函数
const convertGenerator = function (Generator) {
	const handleFunc = function (Generator) {
		const s = Generator.toString()
		const lines = s.split('\n').slice(1, -1)
		const appendBrackets = []
		for (let i = 0; i < lines.length; i++) {
			const line = lines[i]
			const match = line.match(/\s*(?!const|let|var)\s+?([\w0-9_]+?)\s*=\s*yield\s+?(.+)/)
			if (match == null) {
				continue
			}
			const declare = match[1]
			const yieldIn = match[2]
			const yieldFunc = 'yield'
			lines[i] = `${yieldFunc}(${yieldIn}, function (${declare}) {`
			appendBrackets.push('})')
		}
		const newS = lines.concat(appendBrackets).join('\n')
		// const newF = new Function(newS)
		return `(function (){${newS}})`
	}
	return function () {
		// 处理 func，在这里使用 eval 才能使得 g 处于当前作用域
		const g = eval(handleFunc(Generator))
		// yielding 应该是一个随着 try/catch 层级深入而嵌套的数据结构，才能正确使用生成器 throw 方法
		// 此处简单看作没有 try/catch 的情形
		let yielding = {in: undefined, out: g};
		const yield = function (yieldInValue, yieldOutCb) {
			yielding = {
				in: yieldInValue,
				out: yieldOutCb
			}
		}
		g.next = function (value) {
			const yieldOutCb = yielding.out
			yielding = null
			const returnValue = yieldOutCb(value)
			const done = yielding == null
			return {
				value: done ? returnValue : yielding.in,
				done: done
			}
		}
		return g
	}
}

const fetch1 = function (g) {
	return Promise.resolve('fetch1')
}
const fetch2 = function (g) {
	return Promise.resolve('fetch2')
}
const Generator = function *() {
	console.log('before first yield statement')
	const u1 = yield fetch1()
	const u2 = yield fetch2()
	console.log('inner done', 'u1', u1, 'u2', u2)
	return 'outer done'
}

console.log('origin Generator')
wrapGenerator(Generator).then(function (x) {
	console.log(x, '\n')

	console.log('converted ....')
	wrapGenerator(convertGenerator(Generator)).then(function (x) {
		console.log(x)
	})
})

添加将 Generator 转换为普通函数。
这里只考虑简单的单一作用域代码块，因此也不考虑异常捕获。