clang-format: [js] Support type annotations

[mprobst]

Summary

This patch adds support for type annotations that follow TypeScript's, Flow's, and AtScript's syntax style.

[mprobst]

Add test for function types.

[mprobst]

One more test.

[djasper]

I'd use ternary expressions, what do you think? Otherwise looks good, I can submit this for you.

lib/Format/TokenAnnotator.cpp

424–429

Maybe

Tok->Type = Style.Language == FormatStyle::LK_JavaScript
    ? TT_JsTypeColon
    : TT_RangeBasedForLoopColon;

?

435–438

Here, too?

445–450

Here, too?

[mprobst]

Use ternaries.

lib/Format/TokenAnnotator.cpp

424–429

Done.

435–438

I don't think a double nested ternary is very readable here (note this is three cases).

445–450

Done.

[djasper]

Submitted as r229700.

lib/Format/FormatToken.h

enum TokenType {
   TT_DictLiteral,
   TT_FunctionDeclarationName,
   TT_FunctionLBrace,
   TT_FunctionTypeLParen,
   TT_ImplicitStringLiteral,
   TT_InheritanceColon,
   TT_InlineASMColon,
   TT_JavaAnnotation,
+  TT_JsTypeColon,
   TT_LambdaArrow,
   TT_LambdaLSquare,
   TT_LeadingJavaAnnotation,
   TT_LineComment,
   TT_ObjCBlockLBrace,
   TT_ObjCBlockLParen,
   TT_ObjCDecl,
   TT_ObjCForIn,

lib/Format/TokenAnnotator.cpp

bool consumeToken() {
     case tok::minus:
       if (!Tok->Previous && Line.MustBeDeclaration)
         Tok->Type = TT_ObjCMethodSpecifier;
       break;
     case tok::colon:
       if (!Tok->Previous)
         return false;
       // Colons from ?: are handled in parseConditional().
-      if (Tok->Previous->is(tok::r_paren) && Contexts.size() == 1 &&
-          Line.First->isNot(tok::kw_case)) {
-        Tok->Type = TT_CtorInitializerColon;
-      } else if (Contexts.back().ColonIsDictLiteral) {
+      if (Contexts.back().ColonIsDictLiteral) {
         Tok->Type = TT_DictLiteral;
       } else if (Contexts.back().ColonIsObjCMethodExpr ||
                  Line.First->is(TT_ObjCMethodSpecifier)) {
         Tok->Type = TT_ObjCMethodExpr;
         Tok->Previous->Type = TT_SelectorName;
         if (Tok->Previous->ColumnWidth >
             Contexts.back().LongestObjCSelectorName) {
           Contexts.back().LongestObjCSelectorName = Tok->Previous->ColumnWidth;
         }
         if (!Contexts.back().FirstObjCSelectorName)
           Contexts.back().FirstObjCSelectorName = Tok->Previous;
       } else if (Contexts.back().ColonIsForRangeExpr) {
+        if (Style.Language == FormatStyle::LK_JavaScript) {
+          Tok->Type = TT_JsTypeColon;
+        } else {
           Tok->Type = TT_RangeBasedForLoopColon;
+        }
       } else if (CurrentToken && CurrentToken->is(tok::numeric_constant)) {
         Tok->Type = TT_BitFieldColon;
       } else if (Contexts.size() == 1 &&
                  !Line.First->isOneOf(tok::kw_enum, tok::kw_case)) {
+        if (Style.Language == FormatStyle::LK_JavaScript)
+          Tok->Type = TT_JsTypeColon;
+        else if (Tok->Previous->is(tok::r_paren))
+          Tok->Type = TT_CtorInitializerColon;
+        else
           Tok->Type = TT_InheritanceColon;
       } else if (Tok->Previous->is(tok::identifier) && Tok->Next &&
                  Tok->Next->isOneOf(tok::r_paren, tok::comma)) {
         // This handles a special macro in ObjC code where selectors including
         // the colon are passed as macro arguments.
         Tok->Type = TT_ObjCMethodExpr;
       } else if (Contexts.back().ContextKind == tok::l_paren) {
+        if (Style.Language == FormatStyle::LK_JavaScript) {
+          Tok->Type = TT_JsTypeColon;
+        } else {
           Tok->Type = TT_InlineASMColon;
         }
+      }
       break;
     case tok::kw_if:
     case tok::kw_while:
       if (CurrentToken && CurrentToken->is(tok::l_paren)) {
         next();
         if (!parseParens(/*LookForDecls=*/true))
           return false;
       }
if (Right.is(tok::period) &&
                      Keywords.kw_repeated))
       return true;
     if (Right.is(tok::l_paren) &&
         Left.isOneOf(Keywords.kw_returns, Keywords.kw_option))
       return true;
   } else if (Style.Language == FormatStyle::LK_JavaScript) {
     if (Left.is(Keywords.kw_var))
       return true;
+    if (Right.is(TT_JsTypeColon))
+      return false;
   } else if (Style.Language == FormatStyle::LK_Java) {
     if (Left.is(tok::r_square) && Right.is(tok::l_brace))
       return true;
     if (Left.is(TT_LambdaArrow) || Right.is(TT_LambdaArrow))
       return true;
     if (Left.is(Keywords.kw_synchronized) && Right.is(tok::l_paren))
       return Style.SpaceBeforeParens != FormatStyle::SBPO_Never;
     if ((Left.isOneOf(tok::kw_static, tok::kw_public, tok::kw_private,

unittests/Format/FormatTestJS.cpp

TEST_F(FormatTestJS, RegexLiteralLength) {
   verifyFormat("var regex = /\\xaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa/;",
                getGoogleJSStyleWithColumns(50));
 }
 
 TEST_F(FormatTestJS, RegexLiteralExamples) {
   verifyFormat("var regex = search.match(/(?:\?|&)times=([^?&]+)/i);");
 }
 
+TEST_F(FormatTestJS, TypeAnnotations) {
+  verifyFormat("var x: string;");
+  verifyFormat("function x(): string {\n  return 'x';\n}");
+  verifyFormat("function x(y: string): string {\n  return 'x';\n}");
+  verifyFormat("for (var y: string in x) {\n  x();\n}");
+  verifyFormat("((a: string, b: number): string => a + b);");
+  verifyFormat("var x: (y: number) => string;");
+}
+
 } // end namespace tooling
 } // end namespace clang