vue3-core/packages/runtime-core/src/apiSetupHelpers.ts

import {
  getCurrentInstance,
  SetupContext,
  createSetupContext,
  setCurrentInstance
} from './component'
import { EmitFn, EmitsOptions } from './componentEmits'
import {
  ComponentObjectPropsOptions,
  PropOptions,
  ExtractPropTypes
} from './componentProps'
import { warn } from './warning'

// dev only
const warnRuntimeUsage = (method: string) =>
  warn(
    `${method}() is a compiler-hint helper that is only usable inside ` +
      `<script setup> of a single file component. Its arguments should be ` +
      `compiled away and passing it at runtime has no effect.`
  )

/**
 * Vue `<script setup>` compiler macro for declaring component props. The
 * expected argument is the same as the component `props` option.
 *
 * Example runtime declaration:
 * ```js
 * // using Array syntax
 * const props = defineProps(['foo', 'bar'])
 * // using Object syntax
 * const props = defineProps({
 *   foo: String,
 *   bar: {
 *     type: Number,
 *     required: true
 *   }
 * })
 * ```
 *
 * Equivalent type-based decalration:
 * ```ts
 * // will be compiled into equivalent runtime declarations
 * const props = defineProps<{
 *   foo?: string
 *   bar: number
 * }>()
 * ```
 *
 * This is only usable inside `<script setup>`, is compiled away in the
 * output and should **not** be actually called at runtime.
 */
// overload 1: runtime props w/ array
export function defineProps<PropNames extends string = string>(
  props: PropNames[]
): Readonly<{ [key in PropNames]?: any }>
// overload 2: runtime props w/ object
export function defineProps<
  PP extends ComponentObjectPropsOptions = ComponentObjectPropsOptions
>(props: PP): Readonly<ExtractPropTypes<PP>>
// overload 3: typed-based declaration
export function defineProps<TypeProps>(): Readonly<TypeProps>
// implementation
export function defineProps() {
  if (__DEV__) {
    warnRuntimeUsage(`defineProps`)
  }
  return null as any
}

/**
 * Vue `<script setup>` compiler macro for declaring a component's emitted
 * events. The expected argument is the same as the component `emits` option.
 *
 * Example runtime declaration:
 * ```js
 * const emit = defineEmits(['change', 'update'])
 * ```
 *
 * Example type-based decalration:
 * ```ts
 * const emit = defineEmits<{
 *   (event: 'change'): void
 *   (event: 'update', id: number): void
 * }>()
 *
 * emit('change')
 * emit('update', 1)
 * ```
 *
 * This is only usable inside `<script setup>`, is compiled away in the
 * output and should **not** be actually called at runtime.
 */
// overload 1: runtime emits w/ array
export function defineEmits<EE extends string = string>(
  emitOptions: EE[]
): EmitFn<EE[]>
export function defineEmits<E extends EmitsOptions = EmitsOptions>(
  emitOptions: E
): EmitFn<E>
export function defineEmits<TypeEmit>(): TypeEmit
// implementation
export function defineEmits() {
  if (__DEV__) {
    warnRuntimeUsage(`defineEmits`)
  }
  return null as any
}

/**
 * @deprecated use `defineEmits` instead.
 */
export const defineEmit = defineEmits

/**
 * Vue `<script setup>` compiler macro for declaring a component's exposed
 * instance properties when it is accessed by a parent component via template
 * refs.
 *
 * `<script setup>` components are closed by default - i.e. varaibles inside
 * the `<script setup>` scope is not exposed to parent unless explicitly exposed
 * via `defineExpose`.
 *
 * This is only usable inside `<script setup>`, is compiled away in the
 * output and should **not** be actually called at runtime.
 */
export function defineExpose(exposed?: Record<string, any>) {
  if (__DEV__) {
    warnRuntimeUsage(`defineExpose`)
  }
}

type NotUndefined<T> = T extends undefined ? never : T

type InferDefaults<T> = {
  [K in keyof T]?: NotUndefined<T[K]> extends (
    | number
    | string
    | boolean
    | symbol
    | Function)
    ? NotUndefined<T[K]>
    : (props: T) => NotUndefined<T[K]>
}

type PropsWithDefaults<Base, Defaults> = Base &
  {
    [K in keyof Defaults]: K extends keyof Base ? NotUndefined<Base[K]> : never
  }

/**
 * Vue `<script setup>` compiler macro for providing props default values when
 * using type-based `defineProps` decalration.
 *
 * Example usage:
 * ```ts
 * withDefaults(defineProps<{
 *   size?: number
 *   labels?: string[]
 * }>(), {
 *   size: 3,
 *   labels: () => ['default label']
 * })
 * ```
 *
 * This is only usable inside `<script setup>`, is compiled away in the output
 * and should **not** be actually called at runtime.
 */
export function withDefaults<Props, Defaults extends InferDefaults<Props>>(
  props: Props,
  defaults: Defaults
): PropsWithDefaults<Props, Defaults> {
  if (__DEV__) {
    warnRuntimeUsage(`withDefaults`)
  }
  return null as any
}

/**
 * @deprecated use `useSlots` and `useAttrs` instead.
 */
export function useContext(): SetupContext {
  if (__DEV__) {
    warn(
      `\`useContext()\` has been deprecated and will be removed in the ` +
        `next minor release. Use \`useSlots()\` and \`useAttrs()\` instead.`
    )
  }
  return getContext()
}

export function useSlots(): SetupContext['slots'] {
  return getContext().slots
}

export function useAttrs(): SetupContext['attrs'] {
  return getContext().attrs
}

function getContext(): SetupContext {
  const i = getCurrentInstance()!
  if (__DEV__ && !i) {
    warn(`useContext() called without active instance.`)
  }
  return i.setupContext || (i.setupContext = createSetupContext(i))
}

/**
 * Runtime helper for merging default declarations. Imported by compiled code
 * only.
 * @internal
 */
export function mergeDefaults(
  // the base props is compiler-generated and guaranteed to be in this shape.
  props: Record<string, PropOptions | null>,
  defaults: Record<string, any>
) {
  for (const key in defaults) {
    const val = props[key]
    if (val) {
      val.default = defaults[key]
    } else if (val === null) {
      props[key] = { default: defaults[key] }
    } else if (__DEV__) {
      warn(`props default key "${key}" has no corresponding declaration.`)
    }
  }
  return props
}

/**
 * Runtime helper for storing and resuming current instance context in
 * async setup().
 * @internal
 */
export async function withAsyncContext<T>(
  awaitable: T | Promise<T>
): Promise<T> {
  const ctx = getCurrentInstance()
  const res = await awaitable
  setCurrentInstance(ctx)
  return res
}