Adding base indentation for script block formatting and smart indent

src/harness/fourslash.ts

@@ -310,6 +310,7 @@ namespace FourSlash {
             }
 
             this.formatCodeOptions = {
+                BaseIndentSize: 0,
                 IndentSize: 4,
                 TabSize: 4,
                 NewLineCharacter: Harness.IO.newLine(),

src/server/editorServices.ts

@@ -1389,6 +1389,7 @@ namespace ts.server {
 
         static getDefaultFormatCodeOptions(host: ServerHost): ts.FormatCodeOptions {
             return ts.clone({
+                BaseIndentSize: 0,
                 IndentSize: 4,
                 TabSize: 4,
                 NewLineCharacter: host.newLine || "\n",

src/server/protocol.d.ts

@@ -434,6 +434,9 @@ declare namespace ts.server.protocol {
         /** Number of spaces to indent during formatting. Default value is 4. */
         indentSize?: number;
 
+        /** Number of additional spaces to indent during formatting to preserve base indentation (ex. script block indentation). Default value is 0. */
+        baseIndentSize?: number;
+
         /** The new line character to be used. Default value is the OS line delimiter. */
         newLineCharacter?: string;
 
@@ -474,7 +477,7 @@ declare namespace ts.server.protocol {
         placeOpenBraceOnNewLineForControlBlocks?: boolean;
 
         /** Index operator */
-        [key: string]: string | number | boolean;
+        [key: string]: string | number | boolean | undefined;
     }
 
     /**

src/server/session.ts

@@ -674,6 +674,7 @@ namespace ts.server {
                         if (lineText.search("\\S") < 0) {
                             // TODO: get these options from host
                             const editorOptions: ts.EditorOptions = {
+                                BaseIndentSize: formatOptions.BaseIndentSize,
                                 IndentSize: formatOptions.IndentSize,
                                 TabSize: formatOptions.TabSize,
                                 NewLineCharacter: formatOptions.NewLineCharacter,

src/services/formatting/smartIndenter.ts

@@ -10,24 +10,24 @@ namespace ts.formatting {
 
         export function getIndentation(position: number, sourceFile: SourceFile, options: EditorOptions): number {
             if (position > sourceFile.text.length) {
-                return 0; // past EOF
+                return getBaseIndentation(options); // past EOF
             }
 
             // no indentation when the indent style is set to none,
             // so we can return fast
             if (options.IndentStyle === IndentStyle.None) {
-                return 0;
+                return getBaseIndentation(options);
             }
 
             const precedingToken = findPrecedingToken(position, sourceFile);
             if (!precedingToken) {
-                return 0;
+                return getBaseIndentation(options);
             }
 
             // no indentation in string \regex\template literals
             const precedingTokenIsLiteral = isStringOrRegularExpressionOrTemplateLiteral(precedingToken.kind);
             if (precedingTokenIsLiteral && precedingToken.getStart(sourceFile) <= position && precedingToken.end > position) {
-                return 0;
+                return getBaseIndentation(options);
             }
 
             const lineAtPosition = sourceFile.getLineAndCharacterOfPosition(position).line;
@@ -96,13 +96,17 @@ namespace ts.formatting {
             }
 
             if (!current) {
-                // no parent was found - return 0 to be indented on the level of SourceFile
-                return 0;
+                // no parent was found - return the base indentation of the SourceFile
+                return getBaseIndentation(options);
             }
 
             return getIndentationForNodeWorker(current, currentStart, /*ignoreActualIndentationRange*/ undefined, indentationDelta, sourceFile, options);
         }
 
+        function getBaseIndentation(options: EditorOptions) {
+            return options.BaseIndentSize || 0;
+        }
+
         export function getIndentationForNode(n: Node, ignoreActualIndentationRange: TextRange, sourceFile: SourceFile, options: FormatCodeOptions): number {
             const start = sourceFile.getLineAndCharacterOfPosition(n.getStart(sourceFile));
             return getIndentationForNodeWorker(n, start, ignoreActualIndentationRange, /*indentationDelta*/ 0, sourceFile, options);
@@ -162,7 +166,7 @@ namespace ts.formatting {
                 parent = current.parent;
             }
 
-            return indentationDelta;
+            return indentationDelta + getBaseIndentation(options);
         }
 
 

src/services/services.ts

@@ -1244,6 +1244,7 @@ namespace ts {
     }
 
     export interface EditorOptions {
+        BaseIndentSize?: number;
         IndentSize: number;
         TabSize: number;
         NewLineCharacter: string;
@@ -1268,7 +1269,7 @@ namespace ts {
         InsertSpaceAfterOpeningAndBeforeClosingTemplateStringBraces: boolean;
         PlaceOpenBraceOnNewLineForFunctions: boolean;
         PlaceOpenBraceOnNewLineForControlBlocks: boolean;
-        [s: string]: boolean | number | string;
+        [s: string]: boolean | number | string | undefined;
     }
 
     export interface DefinitionInfo {