import { isFunction, warn } from 'core/util' import { currentInstance } from './currentInstance' import type { Component } from 'types/component' export interface InjectionKey extends Symbol {} export function provide(key: InjectionKey | string | number, value: T) { if (!currentInstance) { if (__DEV__) { warn(`provide() can only be used inside setup().`) } } else { // TS doesn't allow symbol as index type resolveProvided(currentInstance)[key as string] = value } } export function resolveProvided(vm: Component): Record { // 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 existing = vm._provided const parentProvides = vm.$parent && vm.$parent._provided if (parentProvides === existing) { return (vm._provided = Object.create(parentProvides)) } else { return existing } } export function inject(key: InjectionKey | string): T | undefined export function inject( key: InjectionKey | string, defaultValue: T, treatDefaultAsFactory?: false ): T export function inject( key: InjectionKey | string, defaultValue: T | (() => T), treatDefaultAsFactory: true ): T export function inject( key: InjectionKey | string, defaultValue?: unknown, treatDefaultAsFactory = false ) { // fallback to `currentRenderingInstance` so that this can be called in // a functional component const instance = currentInstance if (instance) { // #2400 // to support `app.use` plugins, // fallback to appContext's `provides` if the instance is at root const provides = instance.$parent && instance.$parent._provided if (provides && (key as string | symbol) in provides) { // TS doesn't allow symbol as index type return provides[key as string] } else if (arguments.length > 1) { return treatDefaultAsFactory && isFunction(defaultValue) ? defaultValue.call(instance) : defaultValue } else if (__DEV__) { warn(`injection "${String(key)}" not found.`) } } else if (__DEV__) { warn(`inject() can only be used inside setup() or functional components.`) } }