clang-format: [JS] Support shebang lines on the very first line.

Summary:
Shebang lines (`#!/bin/blah`) can be used in JavaScript scripts to indicate
they should be run using e.g. node. This change treats # lines on the first line
as line comments.

Reviewers: djasper

Subscribers: klimek, cfe-commits

Differential Revision: http://reviews.llvm.org/D20632

llvm-svn: 271185

clang/lib/Format/FormatToken.h

@@ -145,7 +145,7 @@ struct FormatToken {
   /// \brief Whether the token text contains newlines (escaped or not).
   bool IsMultiline = false;
 
-  /// \brief Indicates that this is the first token.
+  /// \brief Indicates that this is the first token of the file.
   bool IsFirst = false;
 
   /// \brief Whether there must be a line break before this token.

clang/lib/Format/TokenAnnotator.cpp

@@ -690,10 +690,24 @@ private:
   }
 
   LineType parsePreprocessorDirective() {
+    bool IsFirstToken = CurrentToken->IsFirst;
     LineType Type = LT_PreprocessorDirective;
     next();
     if (!CurrentToken)
       return Type;
+
+    if (Style.Language == FormatStyle::LK_JavaScript && IsFirstToken) {
+      // JavaScript files can contain shebang lines of the form:
+      // #!/usr/bin/env node
+      // Treat these like C++ #include directives.
+      while (CurrentToken) {
+        // Tokens cannot be comments here.
+        CurrentToken->Type = TT_ImplicitStringLiteral;
+        next();
+      }
+      return LT_ImportStatement;
+    }
+
     if (CurrentToken->Tok.is(tok::numeric_constant)) {
       CurrentToken->SpacesRequiredBefore = 1;
       return Type;

clang/unittests/Format/FormatTestJS.cpp

@@ -1276,5 +1276,12 @@ TEST_F(FormatTestJS, RequoteStringsLeave) {
   verifyFormat("var x = 'foo';", LeaveQuotes);
 }
 
+TEST_F(FormatTestJS, SupportShebangLines) {
+  verifyFormat("#!/usr/bin/env node\n"
+               "var x = hello();",
+               "#!/usr/bin/env node\n"
+               "var x   =  hello();");
+}
+
 } // end namespace tooling
 } // end namespace clang