feat: support scoped component when computing contributions

This allows multiple contribution points, such as multiple editor/title menus when multiple editors are shown on the screen at once. Each contribution point will be scoped to the document it is actually showing, which lets contributions use those scoped values when determining visibility, labels, etc.

Author: sqs

src/environment/context/context.ts

@@ -1,5 +1,5 @@
 import { basename, dirname, extname } from 'path'
-import { Environment } from '../environment'
+import { Component, Environment } from '../environment'
 
 /**
  * Returns a new context created by applying the update context to the base context. It is equivalent to `{...base,
@@ -29,11 +29,12 @@ export const EMPTY_CONTEXT: Context = {}
 
 /**
  * Looks up a key in the computed context, which consists of special context properties (with higher precedence)
- * and the environment's context properties (with lower precedence). environment.
+ * and the environment's context properties (with lower precedence).
  *
  * @param key the context property key to look up
+ * @param scope the user interface component in whose scope this computation should occur
  */
-export function getComputedContextProperty(environment: Environment, key: string): any {
+export function getComputedContextProperty(environment: Environment, key: string, scope?: Component): any {
     if (key.startsWith('config.')) {
         const prop = key.slice('config.'.length)
         const value = environment.configuration.merged[prop]
@@ -42,11 +43,12 @@ export function getComputedContextProperty(environment: Environment, key: string
         // which a falsey null default is useful).
         return value === undefined ? null : value
     }
+    const component = scope || environment.component
     if (key === 'resource' || key === 'component') {
-        return !!environment.component
+        return !!component
     }
     if (key.startsWith('resource.')) {
-        if (!environment.component) {
+        if (!component) {
             return undefined
         }
         // TODO(sqs): Define these precisely. If the resource is in a repository, what is the "path"? Is it the
@@ -55,23 +57,23 @@ export function getComputedContextProperty(environment: Environment, key: string
         const prop = key.slice('resource.'.length)
         switch (prop) {
             case 'uri':
-                return environment.component.document.uri
+                return component.document.uri
             case 'basename':
-                return basename(environment.component.document.uri)
+                return basename(component.document.uri)
             case 'dirname':
-                return dirname(environment.component.document.uri)
+                return dirname(component.document.uri)
             case 'extname':
-                return extname(environment.component.document.uri)
+                return extname(component.document.uri)
             case 'language':
-                return environment.component.document.languageId
+                return component.document.languageId
             case 'textContent':
-                return environment.component.document.text
+                return component.document.text
             case 'type':
                 return 'textDocument'
         }
     }
     if (key.startsWith('component.')) {
-        if (!environment.component) {
+        if (!component) {
             return undefined
         }
         const prop = key.slice('component.'.length)

src/environment/providers/contribution.test.ts

@@ -98,13 +98,15 @@ describe('ContributionRegistry', () => {
     describe('contributions observable', () => {
         it('emits stream of results of registrations', () => {
             const registry = new class extends ContributionRegistry {
-                public getContributions(entries: Observable<ContributionsEntry[]>): Observable<Contributions> {
-                    return super.getContributions(entries)
+                public getContributionsFromEntries(
+                    entries: Observable<ContributionsEntry[]>
+                ): Observable<Contributions> {
+                    return super.getContributionsFromEntries(entries)
                 }
             }(EMPTY_OBSERVABLE_ENVIRONMENT.environment)
             scheduler().run(({ cold, expectObservable }) =>
                 expectObservable(
-                    registry.getContributions(
+                    registry.getContributionsFromEntries(
                         cold<ContributionsEntry[]>('-a-b-c-|', {
                             a: [{ contributions: FIXTURE_CONTRIBUTIONS_1 }],
                             b: [{ contributions: FIXTURE_CONTRIBUTIONS_1 }, { contributions: {} }],
@@ -120,13 +122,15 @@ describe('ContributionRegistry', () => {
 
         it('supports registration of an observable', () => {
             const registry = new class extends ContributionRegistry {
-                public getContributions(entries: Observable<ContributionsEntry[]>): Observable<Contributions> {
-                    return super.getContributions(entries)
+                public getContributionsFromEntries(
+                    entries: Observable<ContributionsEntry[]>
+                ): Observable<Contributions> {
+                    return super.getContributionsFromEntries(entries)
                 }
             }(EMPTY_OBSERVABLE_ENVIRONMENT.environment)
             scheduler().run(({ cold, expectObservable }) =>
                 expectObservable(
-                    registry.getContributions(
+                    registry.getContributionsFromEntries(
                         cold<ContributionsEntry[]>('-a-----|', {
                             a: [
                                 {
@@ -157,12 +161,14 @@ describe('ContributionRegistry', () => {
                         )
                     }
 
-                    public getContributions(entries: Observable<ContributionsEntry[]>): Observable<Contributions> {
-                        return super.getContributions(entries)
+                    public getContributionsFromEntries(
+                        entries: Observable<ContributionsEntry[]>
+                    ): Observable<Contributions> {
+                        return super.getContributionsFromEntries(entries)
                     }
                 }()
                 expectObservable(
-                    registry.getContributions(
+                    registry.getContributionsFromEntries(
                         of([
                             {
                                 contributions: { menus: { commandPalette: [{ action: 'a', when: 'x == y' }] } },
@@ -183,12 +189,14 @@ describe('ContributionRegistry', () => {
                         super(cold<Environment>('a', { a: EMPTY_ENVIRONMENT }))
                     }
 
-                    public getContributions(entries: Observable<ContributionsEntry[]>): Observable<Contributions> {
-                        return super.getContributions(entries)
+                    public getContributionsFromEntries(
+                        entries: Observable<ContributionsEntry[]>
+                    ): Observable<Contributions> {
+                        return super.getContributionsFromEntries(entries)
                     }
                 }()
                 expectObservable(
-                    registry.getContributions(
+                    registry.getContributionsFromEntries(
                         of([
                             {
                                 // Expression "!" will cause an error to be thrown.

src/environment/providers/contribution.ts

@@ -12,7 +12,7 @@ import { flatten, isEqual } from '../../util'
 import { getComputedContextProperty } from '../context/context'
 import { ComputedContext, evaluate, evaluateTemplate } from '../context/expr/evaluator'
 import { TEMPLATE_BEGIN } from '../context/expr/lexer'
-import { Environment } from '../environment'
+import { Component, Environment } from '../environment'
 
 /** A registered set of contributions from an extension in the registry. */
 export interface ContributionsEntry {
@@ -71,11 +71,17 @@ export class ContributionRegistry {
     }
 
     /**
-     * All contributions (merged) that are enabled for the current context, emitted whenever the set changes.
+     * Returns an observable that emits all contributions (merged) evaluated in the current
+     * environment (with the optional scope). It emits whenever there is any change.
      */
-    public readonly contributions: Observable<Contributions> = this.getContributions(this._entries)
+    public getContributions(scope?: Component): Observable<Contributions> {
+        return this.getContributionsFromEntries(this._entries, scope)
+    }
 
-    protected getContributions(entries: Observable<ContributionsEntry[]>): Observable<Contributions> {
+    protected getContributionsFromEntries(
+        entries: Observable<ContributionsEntry[]>,
+        scope?: Component
+    ): Observable<Contributions> {
         return combineLatest(
             entries.pipe(
                 switchMap(entries =>
@@ -89,7 +95,7 @@ export class ContributionRegistry {
             this.environment
         ).pipe(
             map(([multiContributions, environment]) => {
-                const computedContext = { get: (key: string) => getComputedContextProperty(environment, key) }
+                const computedContext = { get: (key: string) => getComputedContextProperty(environment, key, scope) }
                 return flatten(multiContributions).map(contributions => {
                     try {
                         return evaluateContributions(
@@ -115,17 +121,18 @@ export class ContributionRegistry {
     /**
      * All contribution entries, emitted whenever the set of registered contributions changes.
      *
-     * Most callers should use ContributionsRegistry#contributions. Only use #entries if the caller needs
-     * information that is discarded when the contributions are merged (such as the extension that registered each
-     * set of contributions).
+     * Most callers should use ContributionsRegistry#getContributions. Only use #entries if the
+     * caller needs information that is discarded when the contributions are merged (such as the
+     * extension that registered each set of contributions).
      */
     public readonly entries: Observable<ContributionsEntry[]> & { value: ContributionsEntry[] } = this._entries
 }
 
 /**
  * Merges the contributions.
  *
- * Most callers should use ContributionRegistry's contributions field, which merges all registered contributions.
+ * Most callers should use ContributionRegistry#getContributions, which merges all registered
+ * contributions.
  */
 export function mergeContributions(contributions: Contributions[]): Contributions {
     if (contributions.length === 0) {