Support doc comment template at function expression (microsoft#25050)

Author: Andy

src/services/jsDoc.ts

@@ -263,11 +263,7 @@ namespace ts.JsDoc {
             return { newText: singleLineResult, caretOffset: 3 };
         }
 
-        const posLineAndChar = sourceFile.getLineAndCharacterOfPosition(position);
-        const lineStart = sourceFile.getLineStarts()[posLineAndChar.line];
-
-        // replace non-whitespace characters in prefix with spaces.
-        const indentationStr = sourceFile.text.substr(lineStart, posLineAndChar.character).replace(/\S/i, () => " ");
+        const indentationStr = getIndentationStringAtPosition(sourceFile, position);
 
         // A doc comment consists of the following
         // * The opening comment line
@@ -276,8 +272,7 @@ namespace ts.JsDoc {
         // * TODO: other tags.
         // * the closing comment line
         // * if the caret was directly in front of the object, then we add an extra line and indentation.
-        const preamble = "/**" + newLine +
-            indentationStr + " * ";
+        const preamble = "/**" + newLine + indentationStr + " * ";
         const result =
             preamble + newLine +
             parameterDocComments(parameters, hasJavaScriptFileExtension(sourceFile.fileName), indentationStr, newLine) +
@@ -287,6 +282,14 @@ namespace ts.JsDoc {
         return { newText: result, caretOffset: preamble.length };
     }
 
+    function getIndentationStringAtPosition(sourceFile: SourceFile, position: number): string {
+        const { text } = sourceFile;
+        const lineStart = getLineStartPositionForPosition(position, sourceFile);
+        let pos = lineStart;
+        for (; pos <= position && isWhiteSpaceSingleLine(text.charCodeAt(pos)); pos++);
+        return text.slice(lineStart, pos);
+    }
+
     function parameterDocComments(parameters: ReadonlyArray<ParameterDeclaration>, isJavaScriptFile: boolean, indentationStr: string, newLine: string): string {
         return parameters.map(({ name, dotDotDotToken }, i) => {
             const paramName = name.kind === SyntaxKind.Identifier ? name.text : "param" + i;
@@ -303,6 +306,7 @@ namespace ts.JsDoc {
         for (let commentOwner = tokenAtPos; commentOwner; commentOwner = commentOwner.parent) {
             switch (commentOwner.kind) {
                 case SyntaxKind.FunctionDeclaration:
+                case SyntaxKind.FunctionExpression:
                 case SyntaxKind.MethodDeclaration:
                 case SyntaxKind.Constructor:
                 case SyntaxKind.MethodSignature:

tests/cases/fourslash/docCommentTemplateClassDeclMethods01.ts

@@ -9,7 +9,7 @@ const multiLineOffset = 12;
 ////    foo();
 ////    /*2*/foo(a);
 ////    /*3*/foo(a, b);
-////    /*4*/ foo(a, {x: string}, [c]);
+////    /*4*/foo(a, {x: string}, [c]);
 ////    /*5*/foo(a?, b?, ...args) {
 ////    }
 ////}
@@ -43,7 +43,8 @@ verify.docCommentTemplateAt("4", multiLineOffset,
      * @param a
      * @param param1
      * @param param2
-     */`);
+     */
+    `);
 
 verify.docCommentTemplateAt("5", multiLineOffset,
     `/**

tests/cases/fourslash/docCommentTemplateFunctionExpression.ts

@@ -0,0 +1,12 @@
+/// <reference path='fourslash.ts' />
+
+/////*above*/
+////const x = /*next*/ function f(p) {}
+
+for (const marker of test.markerNames()) {
+    verify.docCommentTemplateAt(marker, 8,
+`/**
+ * 
+ * @param p
+ */`);
+}

tests/cases/fourslash/docCommentTemplateObjectLiteralMethods01.ts

@@ -12,13 +12,12 @@ const multiLineOffset = 12;
 ////    [1 + 2 + 3 + Math.rand()](x: number, y: string, z = true) { }
 ////}
 
-verify.docCommentTemplateAt("0", singleLineOffset,
-  "/** */");
+verify.docCommentTemplateAt("0", singleLineOffset, "/** */");
 
 verify.docCommentTemplateAt("1", multiLineOffset,
    `/**
      * 
      * @param x
      * @param y
      * @param z
-     */`);
+     */`);

tests/cases/fourslash/docCommentTemplateRegex.ts

@@ -1,6 +1,5 @@
 /// <reference path='fourslash.ts' />
 
-// @Filename: regex.ts
 ////var regex = /*0*///*1*/asdf/*2*/ /*3*///*4*/;
 
 for (const marker of test.markers()) {