Add reverse color option to text diff editor (#4826)

* Add reverse color option to text diff editor

src/sql/editor/browser/diffEditorHelper.ts

@@ -0,0 +1,35 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the Source EULA. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import * as editorCommon from 'vs/editor/common/editorCommon';
+
+/**
+ * Swaps the original and modified line changes
+ * @param lineChanges The line changes to be reversed
+ */
+export function reverseLineChanges(lineChanges: editorCommon.ILineChange[]): editorCommon.ILineChange[] {
+		let reversedLineChanges = lineChanges.map(linechange => {
+			return {
+				modifiedStartLineNumber: linechange.originalStartLineNumber,
+				modifiedEndLineNumber: linechange.originalEndLineNumber,
+				originalStartLineNumber: linechange.modifiedStartLineNumber,
+				originalEndLineNumber: linechange.modifiedEndLineNumber,
+				charChanges: (linechange.charChanges) ?
+					linechange.charChanges.map(charchange => {
+						return {
+							originalStartColumn: charchange.modifiedStartColumn,
+							originalEndColumn: charchange.modifiedEndColumn,
+							modifiedStartColumn: charchange.originalStartColumn,
+							modifiedEndColumn: charchange.originalEndColumn,
+							modifiedStartLineNumber: charchange.originalStartLineNumber,
+							modifiedEndLineNumber: charchange.originalEndLineNumber,
+							originalStartLineNumber: charchange.modifiedStartLineNumber,
+							originalEndLineNumber: charchange.modifiedEndLineNumber,
+						};
+					}) : undefined
+			};
+		});
+		return reversedLineChanges;
+	}