feat(editor): add option to insert newline when folding last line

Introduce a new editor option `foldingAddNewlineAtEnd` that controls whether a newline character is added when folding the last line of a file. This option defaults to true, ensuring that a newline is inserted to maintain a clean separation at the end of the file when the last line is folded.

The implementation includes updates to the folding model to check for this option and conditionally insert a newline. Additionally, tests have been added to verify the behavior of this new feature under various scenarios, including when the option is disabled or when the last line is already empty.

Author: akyTheDev

src/vs/editor/common/config/editorOptions.ts

@@ -692,6 +692,11 @@ export interface IEditorOptions {
 	 * Defaults to 5000.
 	 */
 	foldingMaximumRegions?: number;
+	/**
+	 * Controls whether to add a new line character when folding the last line of a file.
+	 * Defaults to true.
+	 */
+	foldingAddNewlineAtEnd?: boolean;
 	/**
 	 * Controls whether the fold actions in the gutter stay always visible or hide unless the mouse is over the gutter.
 	 * Defaults to 'mouseover'.
@@ -5780,6 +5785,7 @@ export const enum EditorOption {
 	foldingHighlight,
 	foldingImportsByDefault,
 	foldingMaximumRegions,
+	foldingAddNewlineAtEnd,
 	unfoldOnClickAfterEndOfLine,
 	fontFamily,
 	fontInfo,
@@ -6276,6 +6282,10 @@ export const EditorOptions = {
 		5000, 10, 65000, // limit must be less than foldingRanges MAX_FOLDING_REGIONS
 		{ description: nls.localize('foldingMaximumRegions', "The maximum number of foldable regions. Increasing this value may result in the editor becoming less responsive when the current source has a large number of foldable regions.") }
 	)),
+	foldingAddNewlineAtEnd: register(new EditorBooleanOption(
+		EditorOption.foldingAddNewlineAtEnd, 'foldingAddNewlineAtEnd', true,
+		{ description: nls.localize('foldingAddNewlineAtEnd', "Controls whether a new line character is added when folding the last line of a file.") }
+	)),
 	unfoldOnClickAfterEndOfLine: register(new EditorBooleanOption(
 		EditorOption.unfoldOnClickAfterEndOfLine, 'unfoldOnClickAfterEndOfLine', false,
 		{ description: nls.localize('unfoldOnClickAfterEndOfLine', "Controls whether clicking on the empty content after a folded line will unfold the line.") }

src/vs/editor/common/standalone/standaloneEnums.ts

@@ -231,122 +231,123 @@ export enum EditorOption {
 	foldingHighlight = 54,
 	foldingImportsByDefault = 55,
 	foldingMaximumRegions = 56,
-	unfoldOnClickAfterEndOfLine = 57,
-	fontFamily = 58,
-	fontInfo = 59,
-	fontLigatures = 60,
-	fontSize = 61,
-	fontWeight = 62,
-	fontVariations = 63,
-	formatOnPaste = 64,
-	formatOnType = 65,
-	glyphMargin = 66,
-	gotoLocation = 67,
-	hideCursorInOverviewRuler = 68,
-	hover = 69,
-	inDiffEditor = 70,
-	inlineSuggest = 71,
-	letterSpacing = 72,
-	lightbulb = 73,
-	lineDecorationsWidth = 74,
-	lineHeight = 75,
-	lineNumbers = 76,
-	lineNumbersMinChars = 77,
-	linkedEditing = 78,
-	links = 79,
-	matchBrackets = 80,
-	minimap = 81,
-	mouseStyle = 82,
-	mouseWheelScrollSensitivity = 83,
-	mouseWheelZoom = 84,
-	multiCursorMergeOverlapping = 85,
-	multiCursorModifier = 86,
-	mouseMiddleClickAction = 87,
-	multiCursorPaste = 88,
-	multiCursorLimit = 89,
-	occurrencesHighlight = 90,
-	occurrencesHighlightDelay = 91,
-	overtypeCursorStyle = 92,
-	overtypeOnPaste = 93,
-	overviewRulerBorder = 94,
-	overviewRulerLanes = 95,
-	padding = 96,
-	pasteAs = 97,
-	parameterHints = 98,
-	peekWidgetDefaultFocus = 99,
-	placeholder = 100,
-	definitionLinkOpensInPeek = 101,
-	quickSuggestions = 102,
-	quickSuggestionsDelay = 103,
-	readOnly = 104,
-	readOnlyMessage = 105,
-	renameOnType = 106,
-	renderRichScreenReaderContent = 107,
-	renderControlCharacters = 108,
-	renderFinalNewline = 109,
-	renderLineHighlight = 110,
-	renderLineHighlightOnlyWhenFocus = 111,
-	renderValidationDecorations = 112,
-	renderWhitespace = 113,
-	revealHorizontalRightPadding = 114,
-	roundedSelection = 115,
-	rulers = 116,
-	scrollbar = 117,
-	scrollBeyondLastColumn = 118,
-	scrollBeyondLastLine = 119,
-	scrollPredominantAxis = 120,
-	selectionClipboard = 121,
-	selectionHighlight = 122,
-	selectionHighlightMaxLength = 123,
-	selectionHighlightMultiline = 124,
-	selectOnLineNumbers = 125,
-	showFoldingControls = 126,
-	showUnused = 127,
-	snippetSuggestions = 128,
-	smartSelect = 129,
-	smoothScrolling = 130,
-	stickyScroll = 131,
-	stickyTabStops = 132,
-	stopRenderingLineAfter = 133,
-	suggest = 134,
-	suggestFontSize = 135,
-	suggestLineHeight = 136,
-	suggestOnTriggerCharacters = 137,
-	suggestSelection = 138,
-	tabCompletion = 139,
-	tabIndex = 140,
-	trimWhitespaceOnDelete = 141,
-	unicodeHighlighting = 142,
-	unusualLineTerminators = 143,
-	useShadowDOM = 144,
-	useTabStops = 145,
-	wordBreak = 146,
-	wordSegmenterLocales = 147,
-	wordSeparators = 148,
-	wordWrap = 149,
-	wordWrapBreakAfterCharacters = 150,
-	wordWrapBreakBeforeCharacters = 151,
-	wordWrapColumn = 152,
-	wordWrapOverride1 = 153,
-	wordWrapOverride2 = 154,
-	wrappingIndent = 155,
-	wrappingStrategy = 156,
-	showDeprecated = 157,
-	inertialScroll = 158,
-	inlayHints = 159,
-	wrapOnEscapedLineFeeds = 160,
-	effectiveCursorStyle = 161,
-	editorClassName = 162,
-	pixelRatio = 163,
-	tabFocusMode = 164,
-	layoutInfo = 165,
-	wrappingInfo = 166,
-	defaultColorDecorators = 167,
-	colorDecoratorsActivatedOn = 168,
-	inlineCompletionsAccessibilityVerbose = 169,
-	effectiveEditContext = 170,
-	scrollOnMiddleClick = 171,
-	effectiveAllowVariableFonts = 172
+	foldingAddNewlineAtEnd = 57,
+	unfoldOnClickAfterEndOfLine = 58,
+	fontFamily = 59,
+	fontInfo = 60,
+	fontLigatures = 61,
+	fontSize = 62,
+	fontWeight = 63,
+	fontVariations = 64,
+	formatOnPaste = 65,
+	formatOnType = 66,
+	glyphMargin = 67,
+	gotoLocation = 68,
+	hideCursorInOverviewRuler = 69,
+	hover = 70,
+	inDiffEditor = 71,
+	inlineSuggest = 72,
+	letterSpacing = 73,
+	lightbulb = 74,
+	lineDecorationsWidth = 75,
+	lineHeight = 76,
+	lineNumbers = 77,
+	lineNumbersMinChars = 78,
+	linkedEditing = 79,
+	links = 80,
+	matchBrackets = 81,
+	minimap = 82,
+	mouseStyle = 83,
+	mouseWheelScrollSensitivity = 84,
+	mouseWheelZoom = 85,
+	multiCursorMergeOverlapping = 86,
+	multiCursorModifier = 87,
+	mouseMiddleClickAction = 88,
+	multiCursorPaste = 89,
+	multiCursorLimit = 90,
+	occurrencesHighlight = 91,
+	occurrencesHighlightDelay = 92,
+	overtypeCursorStyle = 93,
+	overtypeOnPaste = 94,
+	overviewRulerBorder = 95,
+	overviewRulerLanes = 96,
+	padding = 97,
+	pasteAs = 98,
+	parameterHints = 99,
+	peekWidgetDefaultFocus = 100,
+	placeholder = 101,
+	definitionLinkOpensInPeek = 102,
+	quickSuggestions = 103,
+	quickSuggestionsDelay = 104,
+	readOnly = 105,
+	readOnlyMessage = 106,
+	renameOnType = 107,
+	renderRichScreenReaderContent = 108,
+	renderControlCharacters = 109,
+	renderFinalNewline = 110,
+	renderLineHighlight = 111,
+	renderLineHighlightOnlyWhenFocus = 112,
+	renderValidationDecorations = 113,
+	renderWhitespace = 114,
+	revealHorizontalRightPadding = 115,
+	roundedSelection = 116,
+	rulers = 117,
+	scrollbar = 118,
+	scrollBeyondLastColumn = 119,
+	scrollBeyondLastLine = 120,
+	scrollPredominantAxis = 121,
+	selectionClipboard = 122,
+	selectionHighlight = 123,
+	selectionHighlightMaxLength = 124,
+	selectionHighlightMultiline = 125,
+	selectOnLineNumbers = 126,
+	showFoldingControls = 127,
+	showUnused = 128,
+	snippetSuggestions = 129,
+	smartSelect = 130,
+	smoothScrolling = 131,
+	stickyScroll = 132,
+	stickyTabStops = 133,
+	stopRenderingLineAfter = 134,
+	suggest = 135,
+	suggestFontSize = 136,
+	suggestLineHeight = 137,
+	suggestOnTriggerCharacters = 138,
+	suggestSelection = 139,
+	tabCompletion = 140,
+	tabIndex = 141,
+	trimWhitespaceOnDelete = 142,
+	unicodeHighlighting = 143,
+	unusualLineTerminators = 144,
+	useShadowDOM = 145,
+	useTabStops = 146,
+	wordBreak = 147,
+	wordSegmenterLocales = 148,
+	wordSeparators = 149,
+	wordWrap = 150,
+	wordWrapBreakAfterCharacters = 151,
+	wordWrapBreakBeforeCharacters = 152,
+	wordWrapColumn = 153,
+	wordWrapOverride1 = 154,
+	wordWrapOverride2 = 155,
+	wrappingIndent = 156,
+	wrappingStrategy = 157,
+	showDeprecated = 158,
+	inertialScroll = 159,
+	inlayHints = 160,
+	wrapOnEscapedLineFeeds = 161,
+	effectiveCursorStyle = 162,
+	editorClassName = 163,
+	pixelRatio = 164,
+	tabFocusMode = 165,
+	layoutInfo = 166,
+	wrappingInfo = 167,
+	defaultColorDecorators = 168,
+	colorDecoratorsActivatedOn = 169,
+	inlineCompletionsAccessibilityVerbose = 170,
+	effectiveEditContext = 171,
+	scrollOnMiddleClick = 172,
+	effectiveAllowVariableFonts = 173
 }
 
 /**

src/vs/editor/contrib/folding/browser/folding.ts

@@ -234,7 +234,7 @@ export class FoldingController extends Disposable implements IEditorContribution
 		}
 
 		this._currentModelHasFoldedImports = false;
-		this.foldingModel = new FoldingModel(model, this.foldingDecorationProvider);
+		this.foldingModel = new FoldingModel(model, this.foldingDecorationProvider, this.editor);
 		this.localToDispose.add(this.foldingModel);
 
 		this.hiddenRangeModel = new HiddenRangeModel(this.foldingModel);

src/vs/editor/contrib/folding/browser/foldingModel.ts

@@ -5,9 +5,11 @@
 
 import { Emitter, Event } from '../../../../base/common/event.js';
 import { IModelDecorationOptions, IModelDecorationsChangeAccessor, IModelDeltaDecoration, ITextModel } from '../../../common/model.js';
+import { ICodeEditor } from '../../../browser/editorBrowser.js';
 import { FoldingRegion, FoldingRegions, ILineRange, FoldRange, FoldSource } from './foldingRanges.js';
 import { hash } from '../../../../base/common/hash.js';
 import { SelectedLines } from './folding.js';
+import { EditorOption } from '../../../common/config/editorOptions.js';
 
 export interface IDecorationProvider {
 	getDecorationOption(isCollapsed: boolean, isHidden: boolean, isManual: boolean): IModelDecorationOptions;
@@ -31,6 +33,7 @@ export type CollapseMemento = ILineMemento[];
 export class FoldingModel {
 	private readonly _textModel: ITextModel;
 	private readonly _decorationProvider: IDecorationProvider;
+	private readonly editor: ICodeEditor;
 
 	private _regions: FoldingRegions;
 	private _editorDecorationIds: string[];
@@ -42,11 +45,12 @@ export class FoldingModel {
 	public get textModel() { return this._textModel; }
 	public get decorationProvider() { return this._decorationProvider; }
 
-	constructor(textModel: ITextModel, decorationProvider: IDecorationProvider) {
+	constructor(textModel: ITextModel, decorationProvider: IDecorationProvider, editor: ICodeEditor) {
 		this._textModel = textModel;
 		this._decorationProvider = decorationProvider;
 		this._regions = new FoldingRegions(new Uint32Array(0), new Uint32Array(0));
 		this._editorDecorationIds = [];
+		this.editor = editor;
 	}
 
 	public toggleCollapseState(toggledRegions: FoldingRegion[]) {
@@ -60,6 +64,7 @@ export class FoldingModel {
 			let k = 0; // index from [0 ... this.regions.length]
 			let dirtyRegionEndLine = -1; // end of the range where decorations need to be updated
 			let lastHiddenLine = -1; // the end of the last hidden lines
+			let isNewlineNeededAtEnd: boolean = false;
 			const updateDecorationsUntil = (index: number) => {
 				while (k < index) {
 					const endLineNumber = this._regions.getEndLineNumber(k);
@@ -86,8 +91,33 @@ export class FoldingModel {
 					this._regions.setCollapsed(index, newCollapseState);
 
 					dirtyRegionEndLine = Math.max(dirtyRegionEndLine, this._regions.getEndLineNumber(index));
+
+					// If isNewlineNeededAtEnd is already true, we can skip this check
+					if (!isNewlineNeededAtEnd && this.editor.getOption(EditorOption.foldingAddNewlineAtEnd) && newCollapseState && dirtyRegionEndLine === this._textModel.getLineCount()) {
+						const lastLineContent = this._textModel.getLineContent(dirtyRegionEndLine);
+						// Only insert a newline if the last line is not already empty
+						if (lastLineContent.trim().length > 0) {
+							this._textModel.pushEditOperations(
+								null,
+								[{
+									range: {
+										startLineNumber: dirtyRegionEndLine,
+										startColumn: lastLineContent.length + 1,
+										endLineNumber: dirtyRegionEndLine,
+										endColumn: lastLineContent.length + 1,
+									},
+									text: this._textModel.getEOL(),
+									forceMoveMarkers: true
+								}],
+								() => null
+							);
+						}
+					}
+					isNewlineNeededAtEnd = true;
 				}
 			}
+
+
 			updateDecorationsUntil(this._regions.length);
 		});
 		this._updateEventEmitter.fire({ model: this, collapseStateChanged: toggledRegions });