vue3-yuanma/packages/runtime-core/src/apiInject.ts
2020-03-30 15:24:55 -04:00

52 lines
1.8 KiB
TypeScript

import { currentInstance } from './component'
import { currentRenderingInstance } from './componentRenderUtils'
import { warn } from './warning'
export interface InjectionKey<T> extends Symbol {}
export function provide<T>(key: InjectionKey<T> | string, value: T) {
if (!currentInstance) {
if (__DEV__) {
warn(`provide() can only be used inside setup().`)
}
} else {
let provides = currentInstance.provides
// by default an instance inherits its parent's provides object
// but when it needs to provide values of its own, it creates its
// own provides object using parent provides object as prototype.
// this way in `inject` we can simply look up injections from direct
// parent and let the prototype chain do the work.
const parentProvides =
currentInstance.parent && currentInstance.parent.provides
if (parentProvides === provides) {
provides = currentInstance.provides = Object.create(parentProvides)
}
// TS doesn't allow symbol as index type
provides[key as string] = value
}
}
export function inject<T>(key: InjectionKey<T> | string): T | undefined
export function inject<T>(key: InjectionKey<T> | string, defaultValue: T): T
export function inject(
key: InjectionKey<any> | string,
defaultValue?: unknown
) {
// fallback to `currentRenderingInstance` so that this can be called in
// a functional component
const instance = currentInstance || currentRenderingInstance
if (instance) {
const provides = instance.provides
if (key in provides) {
// TS doesn't allow symbol as index type
return provides[key as string]
} else if (arguments.length > 1) {
return defaultValue
} else if (__DEV__) {
warn(`injection "${String(key)}" not found.`)
}
} else if (__DEV__) {
warn(`inject() can only be used inside setup() or functional components.`)
}
}