44 */
55
66/**
7- * A Context object defines an optional initial value for a Context, as well as a name identifier for debugging purposes.
7+ * A context key.
8+ *
9+ * A context key can be any type of object, including strings and symbols. The
10+ * Context type brands the key type with the `__context__` property that
11+ * carries the type of the value the context references.
812 */
9- export type Context < T > = {
10- name : string ;
11- initialValue ?: T ;
13+ export type Context < KeyType , ValueType > = KeyType & {
14+ __context__ : ValueType ;
1215} ;
1316
1417/**
15- * An unknown context typeU
18+ * An unknown context type
1619 */
17- export type UnknownContext = Context < unknown > ;
20+ export type UnknownContext = Context < unknown , unknown > ;
1821
1922/**
2023 * A helper type which can extract a Context value type from a Context type
2124 */
22- export type ContextType < T extends UnknownContext > = T extends Context < infer Y >
23- ? Y
25+ export type ContextType < T extends UnknownContext > = T extends Context < infer _ , infer V >
26+ ? V
2427 : never ;
2528
2629/**
2730 * A function which creates a Context value object
2831 */
29- export function createContext < T > (
30- name : string ,
31- initialValue ?: T
32- ) : Readonly < Context < T > > {
33- return {
34- name,
35- initialValue,
36- } ;
32+ export function createContext < ValueType > (
33+ key : unknown ,
34+ ) : Readonly < Context < typeof key , ValueType > > {
35+ return key as Context < typeof key , ValueType > ;
3736}
3837
3938/**
@@ -42,7 +41,7 @@ export function createContext<T>(
4241 */
4342export type ContextCallback < ValueType > = (
4443 value : ValueType ,
45- dispose ?: ( ) => void
44+ unsubscribe ?: ( ) => void
4645) => void ;
4746
4847/**
@@ -51,15 +50,15 @@ export type ContextCallback<ValueType> = (
5150 * A provider should inspect the `context` property of the event to determine if it has a value that can
5251 * satisfy the request, calling the `callback` with the requested value if so.
5352 *
54- * If the requested context event contains a truthy `multiple ` value, then a provider can call the callback
55- * multiple times if the value is changed, if this is the case the provider should pass a `dispose `
56- * method to the callback which requesters can invoke to indicate they no longer wish to receive these updates.
53+ * If the requested context event contains a truthy `subscribe ` value, then a provider can call the callback
54+ * multiple times if the value is changed, if this is the case the provider should pass an `unsubscribe `
55+ * function to the callback which requesters can invoke to indicate they no longer wish to receive these updates.
5756 */
58- export class ContextEvent < T extends UnknownContext > extends Event {
57+ export class ContextRequestEvent < T extends UnknownContext > extends Event {
5958 public constructor (
6059 public readonly context : T ,
6160 public readonly callback : ContextCallback < ContextType < T > > ,
62- public readonly multiple ?: boolean
61+ public readonly subscribe ?: boolean
6362 ) {
6463 super ( 'context-request' , { bubbles : true , composed : true } ) ;
6564 }
@@ -71,7 +70,6 @@ declare global {
7170 * A 'context-request' event can be emitted by any element which desires
7271 * a context value to be injected by an external provider.
7372 */
74- 'context-request' : ContextEvent < UnknownContext > ;
73+ 'context-request' : ContextRequestEvent < Context < unknown , unknown > > ;
7574 }
7675}
77-
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