speed up getSnippets, getSnippetsSync, and updateSnippets, #36427

src/vs/workbench/parts/snippets/electron-browser/snippetsService.ts

@@ -95,13 +95,15 @@ class SnippetsService implements ISnippetsService {
 	private readonly _extensionSnippets = new Map<LanguageId, Snippet[]>();
 	private readonly _userSnippets = new Map<LanguageId, Snippet[]>();
 	private readonly _userSnippetsFolder: string;
+	private readonly _wait: Promise<any>;
 	private readonly _disposables: IDisposable[] = [];
 
 	constructor(
 		@IModeService readonly _modeService: IModeService,
-		@IExtensionService readonly _extensionService: IExtensionService,
+		@IExtensionService extensionService: IExtensionService,
 		@IEnvironmentService environmentService: IEnvironmentService,
 	) {
+		this._wait = Promise.resolve(extensionService.onReady());
 		this._userSnippetsFolder = join(environmentService.appSettingsHome, 'snippets');
 		this._prepUserSnippetsWatching();
 		this._prepExtensionSnippets();
@@ -115,25 +117,34 @@ class SnippetsService implements ISnippetsService {
 
 	getSnippets(languageId: LanguageId): Promise<Snippet[]> {
 		let result: Snippet[] = [];
-		return Promise.all([
-			this._extensionService.onReady(),
-			this._getOrLoadUserSnippets(languageId, result),
-			this._getOrLoadExtensionSnippets(languageId, result)
-		]).then(() => {
+		return this._wait.then(() => {
+			return this._getOrLoadUserSnippets(languageId, result);
+		}).then(() => {
+			return this._getOrLoadExtensionSnippets(languageId, result);
+		}).then(() => {
 			return result;
 		});
 	}
 
 	getSnippetsSync(languageId: LanguageId): Snippet[] {
 		// just kick off snippet loading for this language such
-		// that subseqent calls to this method return more
+		// that subsequent calls to this method return more
 		// correct results
 		this.getSnippets(languageId).catch(undefined);
 
 		// collect and return what we already have
-		let userSnippets = this._userSnippets.get(languageId);
-		let extensionSnippets = this._extensionSnippets.get(languageId);
-		return (userSnippets || []).concat(extensionSnippets || []);
+		const userSnippets = this._userSnippets.get(languageId);
+		const extensionSnippets = this._extensionSnippets.get(languageId);
+
+		if (userSnippets && extensionSnippets) {
+			return userSnippets.concat(extensionSnippets);
+		} else if (!userSnippets) {
+			return extensionSnippets;
+		} else if (!extensionSnippets) {
+			return userSnippets;
+		} else {
+			return undefined;
+		}
 	}
 
 	// --- extension snippet logic ---

src/vs/workbench/parts/snippets/electron-browser/tabCompletion.ts

@@ -15,6 +15,7 @@ import { Registry } from 'vs/platform/registry/common/platform';
 import { endsWith } from 'vs/base/common/strings';
 import { IDisposable, dispose } from 'vs/base/common/lifecycle';
 import * as editorCommon from 'vs/editor/common/editorCommon';
+import { Range } from 'vs/editor/common/core/range';
 import { CommonEditorRegistry, commonEditorContribution, EditorCommand } from 'vs/editor/common/editorCommonExtensions';
 import { SnippetController2 } from 'vs/editor/contrib/snippet/browser/snippetController2';
 import { showSimpleSuggestions } from 'vs/editor/contrib/suggest/browser/suggest';
@@ -32,9 +33,8 @@ export class TabCompletionController implements editorCommon.IEditorContribution
 		return editor.getContribution<TabCompletionController>(TabCompletionController.ID);
 	}
 
-	private readonly _hasSnippets: IContextKey<boolean>;
-
-	private _snippets: Snippet[] = [];
+	private _hasSnippets: IContextKey<boolean>;
+	private _activeSnippets: Snippet[] = [];
 	private _selectionListener: IDisposable;
 	private _configListener: IDisposable;
 
@@ -68,53 +68,66 @@ export class TabCompletionController implements editorCommon.IEditorContribution
 			dispose(this._selectionListener);
 		} else {
 			this._selectionListener = this._editor.onDidChangeCursorSelection(e => this._updateSnippets());
-			this._updateSnippets();
+			if (this._editor.getModel()) {
+				this._updateSnippets();
+			}
 		}
 	}
 
 	private _updateSnippets(): void {
 
-		let selection = this._editor.getSelection();
-		let model = this._editor.getModel();
-		let selectFn: (snippet: Snippet) => boolean;
+		// reset first
+		this._activeSnippets = [];
 
-		if (!selection || !model) {
-			// too early
+		// lots of dance for getting the
+		const selection = this._editor.getSelection();
+		const model = this._editor.getModel();
+		model.tokenizeIfCheap(selection.positionLineNumber);
+		const id = model.getLanguageIdAtPosition(selection.positionLineNumber, selection.positionColumn);
+		const snippets = this._snippetService.getSnippetsSync(id);
+
+		if (!snippets) {
+			// nothing for this language
 			this._hasSnippets.set(false);
-			this._snippets = undefined;
 			return;
 		}
 
-		if (selection.isEmpty()) {
+		if (Range.isEmpty(selection)) {
 			// empty selection -> real text (no whitespace) left of cursor
-			const prefix = getNonWhitespacePrefix(model, this._editor.getPosition());
-			selectFn = prefix && (snippet => endsWith(prefix, snippet.prefix));
+			const prefix = getNonWhitespacePrefix(model, selection.getPosition());
+			if (prefix) {
+				for (const snippet of snippets) {
+					if (endsWith(prefix, snippet.prefix)) {
+						this._activeSnippets.push(snippet);
+					}
+				}
+			}
 
-		} else if (selection.startLineNumber === selection.endLineNumber && model.getValueLengthInRange(selection) <= 100) {
+		} else if (!Range.spansMultipleLines(selection) && model.getValueLengthInRange(selection) <= 100) {
 			// actual selection -> snippet must be a full match
 			const selected = model.getValueInRange(selection);
-			selectFn = snippet => selected === snippet.prefix;
-		}
-
-		if (selectFn) {
-			model.tokenizeIfCheap(selection.positionLineNumber);
-			const id = model.getLanguageIdAtPosition(selection.positionLineNumber, selection.positionColumn);
-			this._snippets = this._snippetService.getSnippetsSync(id).filter(selectFn);
+			if (selected) {
+				for (const snippet of snippets) {
+					if (selected === snippet.prefix) {
+						this._activeSnippets.push(snippet);
+					}
+				}
+			}
 		}
 
-		this._hasSnippets.set(this._snippets && this._snippets.length > 0);
+		this._hasSnippets.set(this._activeSnippets.length > 0);
 	}
 
 	performSnippetCompletions(): void {
 
-		if (this._snippets.length === 1) {
+		if (this._activeSnippets.length === 1) {
 			// one -> just insert
-			const [snippet] = this._snippets;
+			const [snippet] = this._activeSnippets;
 			SnippetController2.get(this._editor).insert(snippet.codeSnippet, snippet.prefix.length, 0);
 
-		} else if (this._snippets.length > 1) {
+		} else if (this._activeSnippets.length > 1) {
 			// two or more -> show IntelliSense box
-			showSimpleSuggestions(this._editor, this._snippets.map(snippet => new SnippetSuggestion(snippet, snippet.prefix.length)));
+			showSimpleSuggestions(this._editor, this._activeSnippets.map(snippet => new SnippetSuggestion(snippet, snippet.prefix.length)));
 		}
 	}
 }