blob: e712c4da182dba9447204134d4cccb19ed21a371 (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
|
import { Event } from 'event-target-shim'
/** An event fired by a context requester to signal it desires a named context. */
export class ContextEvent<T = unknown> extends Event<'context-request'> {
constructor(init: ContextEventInit<T>) {
super('context-request', { bubbles: true, composed: true })
init = Object(init) as Required<ContextEventInit<T>>
this.context = init.context
}
context!: Context<T>
multiple!: boolean
callback!: ContextCallback<Context<T>>
}
interface ContextEventInit<T = unknown> {
context: Context<T>
multiple?: boolean
callback: ContextCallback<Context<T>>
}
/** A Context object defines an optional initial value for a Context, as well as a name identifier for debugging purposes. */
export type Context<T = unknown> = {
name: string
initialValue?: T
}
/** A helper type which can extract a Context value type from a Context type. */
export type ContextType<T extends Context> = T extends Context<infer Y>
? Y
: never
/** A function which creates a Context value object */
export function createContext<T>(
name: string,
initialValue?: T
): Readonly<Context<T>> {
return {
name,
initialValue,
}
}
/** A callback which is provided by a context requester and is called with the value satisfying the request. */
export type ContextCallback<ValueType> = (
value: ValueType,
dispose?: () => void
) => void
declare global {
interface HTMLElementEventMap {
/** A 'context-request' event can be emitted by any element which desires a context value to be injected by an external provider. */
'context-request': ContextEvent
}
}
|
