Create setting that trims newlines from the end of a file

src/vs/workbench/api/electron-browser/mainThreadSaveParticipant.ts

@@ -127,6 +127,53 @@ export class FinalNewLineParticipant implements INamedSaveParticpant {
 	}
 }
 
+export class TrimFinalNewLinesParticipant implements INamedSaveParticpant {
+
+	readonly name = 'TrimFinalNewLinesParticipant';
+
+	constructor(
+		@IConfigurationService private configurationService: IConfigurationService,
+		@ICodeEditorService private codeEditorService: ICodeEditorService
+	) {
+		// Nothing
+	}
+
+	public participate(model: ITextFileEditorModel, env: { reason: SaveReason }): void {
+		if (this.configurationService.lookup('files.trimFinalNewlines', { overrideIdentifier: model.textEditorModel.getLanguageIdentifier().language, resource: model.getResource() }).value) {
+			this.doTrimFinalNewLines(model.textEditorModel);
+		}
+	}
+
+	private doTrimFinalNewLines(model: IModel): void {
+		const lineCount = model.getLineCount();
+
+		// Do not insert new line if file does not end with new line
+		if (!lineCount) {
+			return;
+		}
+
+		let prevSelection: Selection[] = [new Selection(1, 1, 1, 1)];
+		const editor = findEditor(model, this.codeEditorService);
+		if (editor) {
+			prevSelection = editor.getSelections();
+		}
+
+		let currentLineNumber = model.getLineCount();
+		let currentLine = model.getLineContent(currentLineNumber);
+		let currentLineIsEmptyOrWhitespace = strings.lastNonWhitespaceIndex(currentLine) === -1;
+		while (currentLineIsEmptyOrWhitespace) {
+			currentLineNumber--;
+			currentLine = model.getLineContent(currentLineNumber);
+			currentLineIsEmptyOrWhitespace = strings.lastNonWhitespaceIndex(currentLine) === -1;
+		}
+		model.pushEditOperations(prevSelection, [EditOperation.delete(new Range(currentLineNumber + 1, 1, lineCount + 1, 1))], edits => prevSelection);
+
+		if (editor) {
+			editor.setSelections(prevSelection);
+		}
+	}
+}
+
 class FormatOnSaveParticipant implements INamedSaveParticpant {
 
 	readonly name = 'FormatOnSaveParticipant';
@@ -237,6 +284,7 @@ export class SaveParticipant implements ISaveParticipant {
 			new TrimWhitespaceParticipant(configurationService, codeEditorService),
 			new FormatOnSaveParticipant(codeEditorService, configurationService),
 			new FinalNewLineParticipant(configurationService, codeEditorService),
+			new TrimFinalNewLinesParticipant(configurationService, codeEditorService),
 			new ExtHostSaveParticipant(extHostContext)
 		];
 

src/vs/workbench/parts/files/browser/files.contribution.ts

@@ -236,6 +236,13 @@ configurationRegistry.registerConfiguration({
 			'overridable': true,
 			'scope': ConfigurationScope.RESOURCE
 		},
+		'files.trimFinalNewlines': {
+			'type': 'boolean',
+			'default': false,
+			'description': nls.localize('trimFinalNewlines', "When enabled, will trim all new lines after the final new line at the end of the file when saving it."),
+			'overridable': true,
+			'scope': ConfigurationScope.RESOURCE
+		},
 		'files.autoSave': {
 			'type': 'string',
 			'enum': [AutoSaveConfiguration.OFF, AutoSaveConfiguration.AFTER_DELAY, AutoSaveConfiguration.ON_FOCUS_CHANGE, , AutoSaveConfiguration.ON_WINDOW_CHANGE],

src/vs/workbench/test/electron-browser/api/mainThreadSaveParticipant.test.ts

@@ -7,7 +7,7 @@
 
 import * as assert from 'assert';
 import { IInstantiationService } from 'vs/platform/instantiation/common/instantiation';
-import { FinalNewLineParticipant } from 'vs/workbench/api/electron-browser/mainThreadSaveParticipant';
+import { FinalNewLineParticipant, TrimFinalNewLinesParticipant } from 'vs/workbench/api/electron-browser/mainThreadSaveParticipant';
 import { TestConfigurationService } from 'vs/platform/configuration/test/common/testConfigurationService';
 import { workbenchInstantiationService, TestTextFileService } from 'vs/workbench/test/workbenchTestServices';
 import { toResource } from 'vs/base/test/common/utils';
@@ -72,4 +72,44 @@ suite('MainThreadSaveParticipant', function () {
 			done();
 		});
 	});
+
+	test('trim final new lines', function (done) {
+		const model: TextFileEditorModel = instantiationService.createInstance(TextFileEditorModel, toResource.call(this, '/path/trim_final_new_line.txt'), 'utf8');
+
+		model.load().then(() => {
+			const configService = new TestConfigurationService();
+			configService.setUserConfiguration('files', { 'trimFinalNewlines': true });
+
+			const participant = new TrimFinalNewLinesParticipant(configService, undefined);
+
+			const textContent = 'Trim New Line';
+			const eol = `${model.textEditorModel.getEOL()}`;
+
+			// No new line removal if last line is not new line
+			let lineContent = `${textContent}`;
+			model.textEditorModel.setValue(lineContent);
+			participant.participate(model, { reason: SaveReason.EXPLICIT });
+			assert.equal(model.getValue(), lineContent);
+
+			// No new line removal if last line is single new line
+			lineContent = `${textContent}${eol}`;
+			model.textEditorModel.setValue(lineContent);
+			participant.participate(model, { reason: SaveReason.EXPLICIT });
+			assert.equal(model.getValue(), lineContent);
+
+			// Remove new line (single line with two new lines)
+			lineContent = `${textContent}${eol}${eol}`;
+			model.textEditorModel.setValue(lineContent);
+			participant.participate(model, { reason: SaveReason.EXPLICIT });
+			assert.equal(model.getValue(), `${textContent}${eol}`);
+
+			// Remove new lines (multiple lines with multiple new lines)
+			lineContent = `${textContent}${eol}${textContent}${eol}${eol}${eol}`;
+			model.textEditorModel.setValue(lineContent);
+			participant.participate(model, { reason: SaveReason.EXPLICIT });
+			assert.equal(model.getValue(), `${textContent}${eol}${textContent}${eol}`);
+
+			done();
+		});
+	});
 });