core/packages/runtime-core/src/apiLifecycle.ts

import {
  ComponentInternalInstance,
  LifecycleHooks,
  currentInstance,
  setCurrentInstance
} from './component'
import { ComponentPublicInstance } from './componentProxy'
import { callWithAsyncErrorHandling, ErrorTypeStrings } from './errorHandling'
import { warn } from './warning'
import { capitalize } from '@vue/shared'
import { pauseTracking, resumeTracking, DebuggerEvent } from '@vue/reactivity'
import { registerKeepAliveHook } from './keepAlive'

export function injectHook(
  type: LifecycleHooks,
  hook: Function,
  target: ComponentInternalInstance | null = currentInstance,
  prepend: boolean = false
) {
  if (target) {
    const hooks = target[type] || (target[type] = [])
    const wrappedHook = (...args: unknown[]) => {
      if (target.isUnmounted) {
        return
      }
      // disable tracking inside all lifecycle hooks
      // since they can potentially be called inside effects.
      pauseTracking()
      // Set currentInstance during hook invocation.
      // This assumes the hook does not synchronously trigger other hooks, which
      // can only be false when the user does something really funky.
      setCurrentInstance(target)
      const res = callWithAsyncErrorHandling(hook, target, type, args)
      setCurrentInstance(null)
      resumeTracking()
      return res
    }
    if (prepend) {
      hooks.unshift(wrappedHook)
    } else {
      hooks.push(wrappedHook)
    }
  } else if (__DEV__) {
    const apiName = `on${capitalize(
      ErrorTypeStrings[type].replace(/ hook$/, '')
    )}`
    warn(
      `${apiName} is called when there is no active component instance to be ` +
        `associated with. ` +
        `Lifecycle injection APIs can only be used during execution of setup().` +
        (__FEATURE_SUSPENSE__
          ? ` If you are using async setup(), make sure to register lifecycle ` +
            `hooks before the first await statement.`
          : ``)
    )
  }
}

export const createHook = <T extends Function = () => any>(
  lifecycle: LifecycleHooks
) => (hook: T, target: ComponentInternalInstance | null = currentInstance) =>
  injectHook(lifecycle, hook, target)

export const onBeforeMount = createHook(LifecycleHooks.BEFORE_MOUNT)
export const onMounted = createHook(LifecycleHooks.MOUNTED)
export const onBeforeUpdate = createHook(LifecycleHooks.BEFORE_UPDATE)
export const onUpdated = createHook(LifecycleHooks.UPDATED)
export const onBeforeUnmount = createHook(LifecycleHooks.BEFORE_UNMOUNT)
export const onUnmounted = createHook(LifecycleHooks.UNMOUNTED)

export type DebuggerHook = (e: DebuggerEvent) => void
export const onRenderTriggered = createHook<DebuggerHook>(
  LifecycleHooks.RENDER_TRIGGERED
)
export const onRenderTracked = createHook<DebuggerHook>(
  LifecycleHooks.RENDER_TRACKED
)

export type ErrorCapturedHook = (
  err: Error,
  instance: ComponentPublicInstance | null,
  info: string
) => boolean | void
export const onErrorCaptured = createHook<ErrorCapturedHook>(
  LifecycleHooks.ERROR_CAPTURED
)

export function onActivated(
  hook: Function,
  target?: ComponentInternalInstance | null
) {
  registerKeepAliveHook(hook, LifecycleHooks.ACTIVATED, target)
}

export function onDeactivated(
  hook: Function,
  target?: ComponentInternalInstance | null
) {
  registerKeepAliveHook(hook, LifecycleHooks.DEACTIVATED, target)
}