44 lines
1.6 KiB
TypeScript
44 lines
1.6 KiB
TypeScript
import { currentInstance } from './component'
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import { warn } from './warning'
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export interface InjectionKey<T> extends Symbol {}
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export function provide<T>(key: InjectionKey<T> | string, value: T) {
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if (!currentInstance) {
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if (__DEV__) {
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warn(`provide() is used without an active component instance.`)
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}
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} else {
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let provides = currentInstance.provides
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// by default an instance inherits its parent's provides object
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// but when it needs to provide values of its own, it creates its
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// own provides object using parent provides object as prototype.
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// this way in `inject` we can simply look up injections from direct
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// parent and let the prototype chain do the work.
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const parentProvides =
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currentInstance.parent && currentInstance.parent.provides
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if (parentProvides === provides) {
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provides = currentInstance.provides = Object.create(parentProvides)
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}
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provides[key as any] = value
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}
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}
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export function inject<T>(key: InjectionKey<T> | string): T | undefined
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export function inject<T>(key: InjectionKey<T> | string, defaultValue: T): T
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export function inject(key: InjectionKey<any> | string, defaultValue?: any) {
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if (!currentInstance) {
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// TODO warn
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} else {
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// TODO should also check for app-level provides
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const provides = currentInstance.parent && currentInstance.provides
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if (provides && key in provides) {
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return provides[key as any] as any
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} else if (defaultValue !== undefined) {
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return defaultValue
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} else if (__DEV__) {
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warn(`injection "${key}" not found.`)
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}
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}
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}
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