feat(environment): support extended Extension types for addl props

Author: sqs

src/environment/controller.ts

@@ -55,8 +55,8 @@ type ConfigurationUpdate = ConfigurationUpdateParams & MessageSource & PromiseCa
 /**
  * The controller for the environment.
  */
-export class Controller implements Unsubscribable {
-    private _environment = new BehaviorSubject<Environment>(EMPTY_ENVIRONMENT)
+export class Controller<X extends Extension = Extension> implements Unsubscribable {
+    private _environment = new BehaviorSubject<Environment<X>>(EMPTY_ENVIRONMENT)
 
     private clients: ClientEntry[] = []
 
@@ -95,7 +95,7 @@ export class Controller implements Unsubscribable {
         })
     }
 
-    public setEnvironment(nextEnvironment: Environment): void {
+    public setEnvironment(nextEnvironment: Environment<X>): void {
         if (isEqual(this._environment.value, nextEnvironment)) {
             return // no change
         }
@@ -137,7 +137,7 @@ export class Controller implements Unsubscribable {
             })
             const settings = this._environment.pipe(
                 map(({ extensions }) => (extensions ? extensions.find(x => x.id === key.id) : null)),
-                filter((x): x is Extension => !!x),
+                filter((x): x is X => !!x),
                 map(x => x.settings),
                 distinctUntilChanged((a, b) => isEqual(a, b))
             )
@@ -189,7 +189,7 @@ export class Controller implements Unsubscribable {
         )
     }
 
-    public readonly environment: ObservableEnvironment = createObservableEnvironment(this._environment)
+    public readonly environment: ObservableEnvironment<X> = createObservableEnvironment<X>(this._environment)
 
     public set trace(value: Trace) {
         for (const client of this.clients) {

src/environment/environment.ts

@@ -10,8 +10,10 @@ import { Extension } from './extension'
  *
  * This models the state of editor-like tools that display documents, allow selections and scrolling in documents,
  * and support extension configuration.
+ *
+ * @template X extension type, to support storing additional properties on extensions
  */
-export interface Environment {
+export interface Environment<X extends Extension = Extension> {
     /**
      * The root URI of the environment, or null if there is none (which means the extension is unable to access any
      * documents in the environment).
@@ -26,11 +28,11 @@ export interface Environment {
     readonly component: Component | null
 
     /** The active extensions, or null if there are none. */
-    readonly extensions: Extension[] | null
+    readonly extensions: X[] | null
 }
 
 /** An empty CXP environment. */
-export const EMPTY_ENVIRONMENT: Environment = { root: null, component: null, extensions: null }
+export const EMPTY_ENVIRONMENT: Environment<any> = { root: null, component: null, extensions: null }
 
 /** An application component that displays a [TextDocument](#TextDocument). */
 export interface Component {
@@ -52,9 +54,9 @@ export interface Component {
  *
  * Includes derived observables for convenience.
  */
-export interface ObservableEnvironment {
+export interface ObservableEnvironment<X extends Extension = Extension> {
     /** The environment (and changes to it). */
-    readonly environment: Observable<Environment> & { readonly value: Environment }
+    readonly environment: Observable<Environment<X>> & { readonly value: Environment<X> }
 
     /** The environment's root URI (and changes to it). */
     readonly root: Observable<URI | null>
@@ -67,16 +69,16 @@ export interface ObservableEnvironment {
 }
 
 /** An ObservableEnvironment that always represents the empty environment and never emits changes. */
-export const EMPTY_OBSERVABLE_ENVIRONMENT: ObservableEnvironment = {
+export const EMPTY_OBSERVABLE_ENVIRONMENT: ObservableEnvironment<any> = {
     environment: { ...of(EMPTY_ENVIRONMENT), value: EMPTY_ENVIRONMENT } as ObservableEnvironment['environment'],
     root: of(null),
     component: of(null),
     textDocument: of(null),
 }
 
-export function createObservableEnvironment(
-    environment: Observable<Environment> & { readonly value: Environment }
-): ObservableEnvironment {
+export function createObservableEnvironment<X extends Extension>(
+    environment: Observable<Environment<X>> & { readonly value: Environment<X> }
+): ObservableEnvironment<X> {
     const component = environment.pipe(
         map(({ component }) => component),
         distinctUntilChanged((a, b) => isEqual(a, b))