forked from vuejs/composition-api
/
watch.ts
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/
watch.ts
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import { ComponentInstance } from '../component'
import { Ref, isRef, isReactive } from '../reactivity'
import { assert, logError, noopFn, warn, isFunction } from '../utils'
import { defineComponentInstance } from '../helper'
import { getCurrentVM, getCurrentVue } from '../runtimeContext'
import { WatcherPreFlushQueueKey, WatcherPostFlushQueueKey } from '../symbols'
import { ComputedRef } from './computed'
export type WatchEffect = (onInvalidate: InvalidateCbRegistrator) => void
export type WatchSource<T = any> = Ref<T> | ComputedRef<T> | (() => T)
export type WatchCallback<V = any, OV = any> = (
value: V,
oldValue: OV,
onInvalidate: InvalidateCbRegistrator
) => any
type MapSources<T> = {
[K in keyof T]: T[K] extends WatchSource<infer V> ? V : never
}
type MapOldSources<T, Immediate> = {
[K in keyof T]: T[K] extends WatchSource<infer V>
? Immediate extends true
? V | undefined
: V
: never
}
export interface WatchOptionsBase {
flush?: FlushMode
// onTrack?: ReactiveEffectOptions['onTrack'];
// onTrigger?: ReactiveEffectOptions['onTrigger'];
}
type InvalidateCbRegistrator = (cb: () => void) => void
export type FlushMode = 'pre' | 'post' | 'sync'
export interface WatchOptions<Immediate = boolean> extends WatchOptionsBase {
immediate?: Immediate
deep?: boolean
}
export interface VueWatcher {
lazy: boolean
get(): any
teardown(): void
}
export type WatchStopHandle = () => void
let fallbackVM: ComponentInstance
function flushPreQueue(this: any) {
flushQueue(this, WatcherPreFlushQueueKey)
}
function flushPostQueue(this: any) {
flushQueue(this, WatcherPostFlushQueueKey)
}
function hasWatchEnv(vm: any) {
return vm[WatcherPreFlushQueueKey] !== undefined
}
function installWatchEnv(vm: any) {
vm[WatcherPreFlushQueueKey] = []
vm[WatcherPostFlushQueueKey] = []
vm.$on('hook:beforeUpdate', flushPreQueue)
vm.$on('hook:updated', flushPostQueue)
}
function getWatcherOption(options?: Partial<WatchOptions>): WatchOptions {
return {
...{
immediate: false,
deep: false,
flush: 'post',
},
...options,
}
}
function getWatchEffectOption(options?: Partial<WatchOptions>): WatchOptions {
return {
...{
immediate: true,
deep: false,
flush: 'post',
},
...options,
}
}
function getWatcherVM() {
let vm = getCurrentVM()
if (!vm) {
if (!fallbackVM) {
fallbackVM = defineComponentInstance(getCurrentVue())
}
vm = fallbackVM
} else if (!hasWatchEnv(vm)) {
installWatchEnv(vm)
}
return vm
}
function flushQueue(vm: any, key: any) {
const queue = vm[key]
for (let index = 0; index < queue.length; index++) {
queue[index]()
}
queue.length = 0
}
function queueFlushJob(
vm: any,
fn: () => void,
mode: Exclude<FlushMode, 'sync'>
) {
// flush all when beforeUpdate and updated are not fired
const fallbackFlush = () => {
vm.$nextTick(() => {
if (vm[WatcherPreFlushQueueKey].length) {
flushQueue(vm, WatcherPreFlushQueueKey)
}
if (vm[WatcherPostFlushQueueKey].length) {
flushQueue(vm, WatcherPostFlushQueueKey)
}
})
}
switch (mode) {
case 'pre':
fallbackFlush()
vm[WatcherPreFlushQueueKey].push(fn)
break
case 'post':
fallbackFlush()
vm[WatcherPostFlushQueueKey].push(fn)
break
default:
assert(
false,
`flush must be one of ["post", "pre", "sync"], but got ${mode}`
)
break
}
}
function createVueWatcher(
vm: ComponentInstance,
getter: () => any,
callback: (n: any, o: any) => any,
options: {
deep: boolean
sync: boolean
immediateInvokeCallback?: boolean
noRun?: boolean
before?: () => void
}
): VueWatcher {
const index = vm._watchers.length
// @ts-ignore: use undocumented options
vm.$watch(getter, callback, {
immediate: options.immediateInvokeCallback,
deep: options.deep,
lazy: options.noRun,
sync: options.sync,
before: options.before,
})
return vm._watchers[index]
}
// We have to monkeypatch the teardown function so Vue will run
// runCleanup() when it tears down the watcher on unmmount.
function patchWatcherTeardown(watcher: VueWatcher, runCleanup: () => void) {
const _teardown = watcher.teardown
watcher.teardown = function (...args) {
_teardown.apply(watcher, args)
runCleanup()
}
}
function createWatcher(
vm: ComponentInstance,
source: WatchSource<unknown> | WatchSource<unknown>[] | WatchEffect,
cb: WatchCallback<any> | null,
options: WatchOptions
): () => void {
const flushMode = options.flush
const isSync = flushMode === 'sync'
let cleanup: (() => void) | null
const registerCleanup: InvalidateCbRegistrator = (fn: () => void) => {
cleanup = () => {
try {
fn()
} catch (error) {
logError(error, vm, 'onCleanup()')
}
}
}
// cleanup before running getter again
const runCleanup = () => {
if (cleanup) {
cleanup()
cleanup = null
}
}
const createScheduler = <T extends Function>(fn: T): T => {
if (
isSync ||
/* without a current active instance, ignore pre|post mode */ vm ===
fallbackVM
) {
return fn
}
return (((...args: any[]) =>
queueFlushJob(
vm,
() => {
fn(...args)
},
flushMode as 'pre' | 'post'
)) as any) as T
}
// effect watch
if (cb === null) {
let running = false
const getter = () => {
// preventing the watch callback being call in the same execution
if (running) {
return
}
try {
running = true
;(source as WatchEffect)(registerCleanup)
} finally {
running = false
}
}
const watcher = createVueWatcher(vm, getter, noopFn, {
deep: options.deep || false,
sync: isSync,
before: runCleanup,
})
patchWatcherTeardown(watcher, runCleanup)
// enable the watcher update
watcher.lazy = false
const originGet = watcher.get.bind(watcher)
// always run watchEffect
watcher.get = createScheduler(originGet)
return () => {
watcher.teardown()
}
}
let deep = options.deep
let getter: () => any
if (Array.isArray(source)) {
getter = () => source.map((s) => (isRef(s) ? s.value : s()))
} else if (isRef(source)) {
getter = () => source.value
} else if (isReactive(source)) {
getter = () => source
deep = true
} else if (isFunction(source)) {
getter = source as () => any
} else {
getter = noopFn
warn(
`Invalid watch source: ${JSON.stringify(source)}.
A watch source can only be a getter/effect function, a ref, a reactive object, or an array of these types.`,
vm
)
}
const applyCb = (n: any, o: any) => {
// cleanup before running cb again
runCleanup()
cb(n, o, registerCleanup)
}
let callback = createScheduler(applyCb)
if (options.immediate) {
const originalCallbck = callback
// `shiftCallback` is used to handle the first sync effect run.
// The subsequent callbacks will redirect to `callback`.
let shiftCallback = (n: any, o: any) => {
shiftCallback = originalCallbck
applyCb(n, o)
}
callback = (n: any, o: any) => {
shiftCallback(n, o)
}
}
// @ts-ignore: use undocumented option "sync"
const stop = vm.$watch(getter, callback, {
immediate: options.immediate,
deep: deep,
sync: isSync,
})
// Once again, we have to hack the watcher for proper teardown
const watcher = vm._watchers[vm._watchers.length - 1]
patchWatcherTeardown(watcher, runCleanup)
return () => {
stop()
}
}
export function watchEffect(
effect: WatchEffect,
options?: WatchOptionsBase
): WatchStopHandle {
const opts = getWatchEffectOption(options)
const vm = getWatcherVM()
return createWatcher(vm, effect, null, opts)
}
// overload #1: array of multiple sources + cb
// Readonly constraint helps the callback to correctly infer value types based
// on position in the source array. Otherwise the values will get a union type
// of all possible value types.
export function watch<
T extends Readonly<WatchSource<unknown>[]>,
Immediate extends Readonly<boolean> = false
>(
sources: T,
cb: WatchCallback<MapSources<T>, MapOldSources<T, Immediate>>,
options?: WatchOptions<Immediate>
): WatchStopHandle
// overload #2: single source + cb
export function watch<T, Immediate extends Readonly<boolean> = false>(
source: WatchSource<T>,
cb: WatchCallback<T, Immediate extends true ? T | undefined : T>,
options?: WatchOptions<Immediate>
): WatchStopHandle
// overload #3: watching reactive object w/ cb
export function watch<
T extends object,
Immediate extends Readonly<boolean> = false
>(
source: T,
cb: WatchCallback<T, Immediate extends true ? T | undefined : T>,
options?: WatchOptions<Immediate>
): WatchStopHandle
// implementation
export function watch<T = any>(
source: WatchSource<T> | WatchSource<T>[],
cb: WatchCallback<T>,
options?: WatchOptions
): WatchStopHandle {
let callback: WatchCallback<unknown> | null = null
if (typeof cb === 'function') {
// source watch
callback = cb as WatchCallback<unknown>
} else {
// effect watch
if (__DEV__) {
warn(
`\`watch(fn, options?)\` signature has been moved to a separate API. ` +
`Use \`watchEffect(fn, options?)\` instead. \`watch\` now only ` +
`supports \`watch(source, cb, options?) signature.`
)
}
options = cb as Partial<WatchOptions>
callback = null
}
const opts = getWatcherOption(options)
const vm = getWatcherVM()
return createWatcher(vm, source, callback, opts)
}