when the 'query' string is getting longer it's save to score afore sc…

…ored/filtered items only, #15419

src/vs/editor/contrib/suggest/completionModel.ts

@@ -37,20 +37,28 @@ export class LineContext {
 	characterCountDelta: number;
 }
 
+const enum Refilter {
+	Nothing = 0,
+	All = 1,
+	Incr = 2
+}
+
 export class CompletionModel {
 
 	private readonly _column: number;
-	private readonly _items: ISuggestionItem[];
+	private readonly _items: ICompletionItem[];
 	private readonly _snippetCompareFn = CompletionModel._compareCompletionItems;
 
 	private _lineContext: LineContext;
+	private _refilterKind: Refilter;
 	private _filteredItems: ICompletionItem[];
 	private _isIncomplete: boolean;
 	private _stats: ICompletionStats;
 
 	constructor(items: ISuggestionItem[], column: number, lineContext: LineContext, snippetConfig?: SnippetConfig) {
 		this._items = items;
 		this._column = column;
+		this._refilterKind = Refilter.All;
 		this._lineContext = lineContext;
 
 		if (snippetConfig === 'top') {
@@ -78,10 +86,10 @@ export class CompletionModel {
 
 	set lineContext(value: LineContext) {
 		if (this._lineContext.leadingLineContent !== value.leadingLineContent
-			|| this._lineContext.characterCountDelta !== value.characterCountDelta) {
-
+			|| this._lineContext.characterCountDelta !== value.characterCountDelta
+		) {
+			this._refilterKind = this._lineContext.characterCountDelta < value.characterCountDelta ? Refilter.Incr : Refilter.All;
 			this._lineContext = value;
-			this._filteredItems = undefined;
 		}
 	}
 
@@ -116,22 +124,26 @@ export class CompletionModel {
 	}
 
 	private _ensureCachedState(): void {
-		if (!this._filteredItems) {
+		if (this._refilterKind !== Refilter.Nothing) {
 			this._createCachedState();
 		}
 	}
 
 	private _createCachedState(): void {
-		this._filteredItems = [];
+
 		this._isIncomplete = false;
 		this._stats = { suggestionCount: 0, snippetCount: 0, textCount: 0 };
 
 		const { leadingLineContent, characterCountDelta } = this._lineContext;
 		let word = '';
 
-		for (let i = 0; i < this._items.length; i++) {
+		// incrementally filter less
+		const source = this._refilterKind === Refilter.All ? this._items : this._filteredItems;
+		const target: typeof source = [];
+
+		for (let i = 0; i < source.length; i++) {
 
-			const item = <ICompletionItem>this._items[i];
+			const item = source[i];
 			const { suggestion, container } = item;
 
 			// collect those supports that signaled having
@@ -182,7 +194,7 @@ export class CompletionModel {
 
 			item.idx = i;
 
-			this._filteredItems.push(item);
+			target.push(item);
 
 			// update stats
 			this._stats.suggestionCount++;
@@ -192,7 +204,8 @@ export class CompletionModel {
 			}
 		}
 
-		this._filteredItems.sort(this._snippetCompareFn);
+		this._filteredItems = target.sort(this._snippetCompareFn);
+		this._refilterKind = Refilter.Nothing;
 	}
 
 	private static _compareCompletionItems(a: ICompletionItem, b: ICompletionItem): number {

src/vs/editor/contrib/suggest/test/completionModel.test.ts

@@ -225,7 +225,32 @@ suite('CompletionModel', function () {
 		const [first, second] = model.items;
 		assert.equal(first.suggestion.label, 'source');
 		assert.equal(second.suggestion.label, '<- groups');
-
 	});
 
+	test('Score only filtered items when typing more, score all when typing less', function () {
+		model = new CompletionModel([
+			createSuggestItem('console', 0, 'property'),
+			createSuggestItem('co_new', 0, 'property'),
+			createSuggestItem('bar', 0, 'property'),
+			createSuggestItem('car', 0, 'property'),
+			createSuggestItem('foo', 0, 'property'),
+		], 1, {
+				leadingLineContent: '',
+				characterCountDelta: 0
+			}, 'inline');
+
+		assert.equal(model.items.length, 5);
+
+		// narrow down once
+		model.lineContext = { leadingLineContent: 'c', characterCountDelta: 1 };
+		assert.equal(model.items.length, 3);
+
+		// query gets longer, narrow down the narrow-down'ed-set from before
+		model.lineContext = { leadingLineContent: 'cn', characterCountDelta: 2 };
+		assert.equal(model.items.length, 2);
+
+		// query gets shorter, refilter everything
+		model.lineContext = { leadingLineContent: '', characterCountDelta: 0 };
+		assert.equal(model.items.length, 5);
+	});
 });