From cf44d2c1ae91204501745bb512206974a4c29ba0 Mon Sep 17 00:00:00 2001
From: Martin Probst <martin@probst.io>
Date: Tue, 9 May 2017 20:04:09 +0000
Subject: [PATCH] clang-format: [JS] Don't indent JavaScript IIFEs.

Because IIFEs[1] are often used like an anonymous namespace around large
sections of JavaScript code, it's useful not to indent to them (which
effectively reduces the column limit by the indent amount needlessly).

It's also common for developers to wrap these around entire files or
libraries. When adopting clang-format, changing the indent entire file
can reduce the usefulness of the blame annotations.

Patch by danbeam, thanks!

Differential Revision: https://reviews.llvm.org/D32989

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@302580 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Format/UnwrappedLineParser.cpp | 27 +++++++++++++++++++++++----
 unittests/Format/FormatTestJS.cpp  | 19 +++++++++++++++++++
 2 files changed, 42 insertions(+), 4 deletions(-)

diff --git a/lib/Format/UnwrappedLineParser.cpp b/lib/Format/UnwrappedLineParser.cpp
index 2d788b52df..899da0f989 100644
--- a/lib/Format/UnwrappedLineParser.cpp
+++ b/lib/Format/UnwrappedLineParser.cpp
@@ -476,6 +476,24 @@ static bool isGoogScope(const UnwrappedLine &Line) {
   return I->Tok->is(tok::l_paren);
 }
 
+static bool isIIFE(const UnwrappedLine &Line,
+                   const AdditionalKeywords &Keywords) {
+  // Look for the start of an immediately invoked anonymous function.
+  // https://en.wikipedia.org/wiki/Immediately-invoked_function_expression
+  // This is commonly done in JavaScript to create a new, anonymous scope.
+  // Example: (function() { ... })()
+  if (Line.Tokens.size() < 3)
+    return false;
+  auto I = Line.Tokens.begin();
+  if (I->Tok->isNot(tok::l_paren))
+    return false;
+  ++I;
+  if (I->Tok->isNot(Keywords.kw_function))
+    return false;
+  ++I;
+  return I->Tok->is(tok::l_paren);
+}
+
 static bool ShouldBreakBeforeBrace(const FormatStyle &Style,
                                    const FormatToken &InitialToken) {
   if (InitialToken.is(tok::kw_namespace))
@@ -493,15 +511,16 @@ void UnwrappedLineParser::parseChildBlock() {
   FormatTok->BlockKind = BK_Block;
   nextToken();
   {
-    bool GoogScope =
-        Style.Language == FormatStyle::LK_JavaScript && isGoogScope(*Line);
+    bool SkipIndent =
+        (Style.Language == FormatStyle::LK_JavaScript &&
+         (isGoogScope(*Line) || isIIFE(*Line, Keywords)));
     ScopedLineState LineState(*this);
     ScopedDeclarationState DeclarationState(*Line, DeclarationScopeStack,
                                             /*MustBeDeclaration=*/false);
-    Line->Level += GoogScope ? 0 : 1;
+    Line->Level += SkipIndent ? 0 : 1;
     parseLevel(/*HasOpeningBrace=*/true);
     flushComments(isOnNewLine(*FormatTok));
-    Line->Level -= GoogScope ? 0 : 1;
+    Line->Level -= SkipIndent ? 0 : 1;
   }
   nextToken();
 }
diff --git a/unittests/Format/FormatTestJS.cpp b/unittests/Format/FormatTestJS.cpp
index 288975374d..05aee91a1d 100644
--- a/unittests/Format/FormatTestJS.cpp
+++ b/unittests/Format/FormatTestJS.cpp
@@ -367,6 +367,25 @@ TEST_F(FormatTestJS, GoogScopes) {
                "});");
 }
 
+TEST_F(FormatTestJS, IIFEs) {
+  // Internal calling parens; no semi.
+  verifyFormat("(function() {\n"
+               "var a = 1;\n"
+               "}())");
+  // External calling parens; no semi.
+  verifyFormat("(function() {\n"
+               "var b = 2;\n"
+               "})()");
+  // Internal calling parens; with semi.
+  verifyFormat("(function() {\n"
+               "var c = 3;\n"
+               "}());");
+  // External calling parens; with semi.
+  verifyFormat("(function() {\n"
+               "var d = 4;\n"
+               "})();");
+}
+
 TEST_F(FormatTestJS, GoogModules) {
   verifyFormat("goog.module('this.is.really.absurdly.long');",
                getGoogleJSStyleWithColumns(40));
-- 
2.50.1