add overwrite[Before|After] to SnippetSession

src/vs/editor/contrib/snippet/browser/editorSnippets.ts

@@ -166,13 +166,34 @@ export class SnippetSession {
 		return templateLines.join(model.getEOL());
 	}
 
+	static adjustRange(model: IModel, range: Range, overwriteBefore: number, overwriteAfter: number): Range {
+		if (overwriteBefore !== 0 || overwriteAfter !== 0) {
+			let { startLineNumber, startColumn, endLineNumber, endColumn } = range;
+			startColumn -= overwriteBefore;
+			endColumn += overwriteAfter;
+
+			range = Range.plusRange(range, {
+				startLineNumber,
+				startColumn,
+				endLineNumber,
+				endColumn,
+			});
+			range = model.validateRange(range);
+		}
+		return range;
+	}
+
 	private readonly _editor: ICommonCodeEditor;
 	private readonly _template: string;
+	private readonly _overwriteBefore: number;
+	private readonly _overwriteAfter: number;
 	private readonly _snippets: OneSnippet[];
 
-	constructor(editor: ICommonCodeEditor, template: string) {
+	constructor(editor: ICommonCodeEditor, template: string, overwriteBefore: number = 0, overwriteAfter: number = 0) {
 		this._editor = editor;
 		this._template = template;
+		this._overwriteBefore = overwriteBefore;
+		this._overwriteAfter = overwriteAfter;
 		this._snippets = [];
 	}
 
@@ -186,16 +207,17 @@ export class SnippetSession {
 		let model = this._editor.getModel();
 
 		for (const selection of this._editor.getSelections()) {
-			const start = selection.getStartPosition();
+			const range = SnippetSession.adjustRange(model, selection, this._overwriteBefore, this._overwriteAfter);
+			const start = range.getStartPosition();
 			const adjustedTemplate = SnippetSession.normalizeWhitespace(model, start, this._template);
 
 			const snippet = SnippetParser.parse(adjustedTemplate);
 			const offset = model.getOffsetAt(start) + delta;
 
-			edits.push(EditOperation.replaceMove(selection, snippet.text));
+			edits.push(EditOperation.replaceMove(range, snippet.text));
 			this._snippets.push(new OneSnippet(this._editor, snippet, offset));
 
-			delta += snippet.text.length - model.getValueLengthInRange(selection);
+			delta += snippet.text.length - model.getValueLengthInRange(range);
 		}
 
 		// make insert edit and start with first selections

src/vs/editor/contrib/snippet/browser/snippetController2.ts

@@ -45,7 +45,7 @@ export class SnippetController2 {
 	}
 
 	insert(template: string, overwriteBefore: number = 0, overwriteAfter: number = 0): void {
-		const session = new SnippetSession(this._editor, template);
+		const session = new SnippetSession(this._editor, template, overwriteBefore, overwriteAfter);
 		const newLen = this._snippetStack.unshift(session);
 		if (newLen === 1) {
 			this._inSnippet.set(true);

src/vs/editor/contrib/snippet/test/browser/editorSnippets.test.ts

@@ -6,6 +6,7 @@
 
 import * as assert from 'assert';
 import { Selection } from 'vs/editor/common/core/selection';
+import { Range } from 'vs/editor/common/core/range';
 import { IPosition, Position } from 'vs/editor/common/core/position';
 import { SnippetSession } from 'vs/editor/contrib/snippet/browser/editorSnippets';
 import { ICommonCodeEditor } from 'vs/editor/common/editorCommon';
@@ -51,6 +52,19 @@ suite('SnippetSession', function () {
 		assertNormalized(new Position(2, 3), 'foo\r\tbar', 'foo\n      bar');
 	});
 
+	test('adjust selection (overwrite[Before|After]', function () {
+
+		let range = SnippetSession.adjustRange(model, new Range(1, 2, 1, 2), 1, 0);
+		assert.ok(range.equalsRange(new Range(1, 1, 1, 2)));
+		range = SnippetSession.adjustRange(model, new Range(1, 2, 1, 2), 1111, 0);
+		assert.ok(range.equalsRange(new Range(1, 1, 1, 2)));
+		range = SnippetSession.adjustRange(model, new Range(1, 2, 1, 2), 0, 10);
+		assert.ok(range.equalsRange(new Range(1, 2, 1, 12)));
+		range = SnippetSession.adjustRange(model, new Range(1, 2, 1, 2), 0, 10111);
+		assert.ok(range.equalsRange(new Range(1, 2, 1, 17)));
+
+	});
+
 	test('text edits & selection', function () {
 		const session = new SnippetSession(editor, 'foo${1:bar}foo$0');
 		session.insert();