clang-format: [JS] handle parenthesized class expressions.

[mprobst]

Summary

In JavaScript, classes are expressions, so they can appear e.g. in
argument lists.

var C = foo(class {
  bar() {
    return 1;
  }
};

[djasper]

Thanks

[mprobst]

• Parse nested classes as child expressions.

[djasper]

Sorry.. Should have caught this in the initial review. Still looks good.

lib/Format/UnwrappedLineParser.h

private:
   void parseLabel();
   void parseCaseLabel();
   void parseSwitch();
   void parseNamespace();
   void parseNew();
   void parseAccessSpecifier();
   bool parseEnum();
   void parseJavaEnumBody();
-  void parseRecord();
+  // Parses a record (aka class) as a top level element. If ParseAsExpr is true,
+  // parses the record as a child block, i.e. if the class declaration is an
+  // expression.
+  void parseRecord(bool ParseAsExpr = false);
   void parseObjCProtocolList();
   void parseObjCUntilAtEnd();
   void parseObjCInterfaceOrImplementation();
   void parseObjCProtocol();
   void parseJavaScriptEs6ImportExport();
   bool tryToParseLambda();
   bool tryToParseLambdaIntroducer();
   void tryToParseJSFunction();
private:
   SmallVectorImpl<UnwrappedLine> *CurrentLines;
 
   // We store for each line whether it must be a declaration depending on
   // whether we are in a compound statement or not.
   std::vector<bool> DeclarationScopeStack;
 
   const FormatStyle &Style;
   const AdditionalKeywords &Keywords;
-  
   llvm::Regex CommentPragmasRegex;
 
   FormatTokenSource *Tokens;
   UnwrappedLineConsumer &Callback;
 
   // FIXME: This is a temporary measure until we have reworked the ownership
   // of the format tokens. The goal is to have the actual tokens created and
   // owned outside of and handed into the UnwrappedLineParser.

lib/Format/UnwrappedLineParser.cpp

case tok::l_brace:
       if (!tryToParseBracedList())
         parseChildBlock();
       break;
     case tok::at:
       nextToken();
       if (FormatTok->Tok.is(tok::l_brace))
         parseBracedList();
       break;
+    case tok::kw_class:
+      if (Style.Language == FormatStyle::LK_JavaScript)
+        parseRecord(/*ParseAsExpr=*/true);
+      else
+        nextToken();
+      break;
     case tok::identifier:
       if (Style.Language == FormatStyle::LK_JavaScript &&
           (FormatTok->is(Keywords.kw_function) ||
            FormatTok->startsSequence(Keywords.kw_async, Keywords.kw_function)))
         tryToParseJSFunction();
       else
         nextToken();
       break;
void UnwrappedLineParser::parseJavaEnumBody() {
 
   // Parse the class body after the enum's ";" if any.
   parseLevel(/*HasOpeningBrace=*/true);
   nextToken();
   --Line->Level;
   addUnwrappedLine();
 }
 
-void UnwrappedLineParser::parseRecord() {
+void UnwrappedLineParser::parseRecord(bool ParseAsExpr) {
   const FormatToken &InitialToken = *FormatTok;
   nextToken();
 
   // The actual identifier can be a nested name specifier, and in macros
   // it is often token-pasted.
   while (FormatTok->isOneOf(tok::identifier, tok::coloncolon, tok::hashhash,
                             tok::kw___attribute, tok::kw___declspec,
                             tok::kw_alignas) ||
while (!eof()) {
           break;
       }
       if (FormatTok->Tok.is(tok::semi))
         return;
       nextToken();
     }
   }
   if (FormatTok->Tok.is(tok::l_brace)) {
+    if (ParseAsExpr) {
+      parseChildBlock();
+    } else {
       if (ShouldBreakBeforeBrace(Style, InitialToken))
         addUnwrappedLine();
 
       parseBlock(/*MustBeDeclaration=*/true, /*AddLevel=*/true,
                  /*MunchSemi=*/false);
     }
+  }
   // There is no addUnwrappedLine() here so that we fall through to parsing a
   // structural element afterwards. Thus, in "class A {} n, m;",
   // "} n, m;" will end up in one unwrapped line.
 }
 
 void UnwrappedLineParser::parseObjCProtocolList() {
   assert(FormatTok->Tok.is(tok::less) && "'<' expected.");
   do

unittests/Format/FormatTestJS.cpp

TEST_F(FormatTestJS, ClassDeclarations) {
   verifyFormat("class C {\n  x: string = 12;\n}");
   verifyFormat("class C {\n  x(): string => 12;\n}");
   verifyFormat("class C {\n  ['x' + 2]: string = 12;\n}");
   verifyFormat("class C {\n  private x: string = 12;\n}");
   verifyFormat("class C {\n  private static x: string = 12;\n}");
   verifyFormat("class C {\n  static x(): string {\n    return 'asd';\n  }\n}");
   verifyFormat("class C extends P implements I {}");
   verifyFormat("class C extends p.P implements i.I {}");
+  verifyFormat(
+      "x(class {\n"
+      "  a(): A {}\n"
+      "});");
   verifyFormat("class Test {\n"
                "  aaaaaaaaaaaaaaaa(aaaaaaaaaaaaaaa: aaaaaaaaaaaaaaaaaaaa):\n"
                "      aaaaaaaaaaaaaaaaaaaaaa {}\n"
                "}");
   verifyFormat("foo = class Name {\n"
                "  constructor() {}\n"
                "};");
   verifyFormat("foo = class {\n"