clang-format: [JS] do not format MPEG transport streams.

Summary:
The MPEG transport stream file format also uses ".ts" as its file extension.
This change detects its specific framing format (0x47 every 189 bytes) and
simply ignores MPEG TS files.

Reviewers: djasper, sammccall

Subscribers: klimek, cfe-commits

Differential Revision: https://reviews.llvm.org/D29186

llvm-svn: 293270

clang/lib/Format/Format.cpp

@@ -1462,12 +1462,22 @@ tooling::Replacements sortCppIncludes(const FormatStyle &Style, StringRef Code,
   return Replaces;
 }
 
+bool isMpegTS(StringRef Code) {
+  // MPEG transport streams use the ".ts" file extension. clang-format should
+  // not attempt to format those. MPEG TS' frame format starts with 0x47 every
+  // 189 bytes - detect that and return.
+  return Code.size() > 188 && Code[0] == 0x47 && Code[188] == 0x47;
+}
+
 tooling::Replacements sortIncludes(const FormatStyle &Style, StringRef Code,
                                    ArrayRef<tooling::Range> Ranges,
                                    StringRef FileName, unsigned *Cursor) {
   tooling::Replacements Replaces;
   if (!Style.SortIncludes)
     return Replaces;
+  if (Style.Language == FormatStyle::LanguageKind::LK_JavaScript &&
+      isMpegTS(Code))
+    return Replaces;
   if (Style.Language == FormatStyle::LanguageKind::LK_JavaScript)
     return sortJavaScriptImports(Style, Code, Ranges, FileName);
   sortCppIncludes(Style, Code, Ranges, FileName, Replaces, Cursor);
@@ -1813,7 +1823,8 @@ tooling::Replacements reformat(const FormatStyle &Style, StringRef Code,
   FormatStyle Expanded = expandPresets(Style);
   if (Expanded.DisableFormat)
     return tooling::Replacements();
-
+  if (Expanded.Language == FormatStyle::LK_JavaScript && isMpegTS(Code))
+    return tooling::Replacements();
   auto Env = Environment::CreateVirtualEnvironment(Code, FileName, Ranges);
 
   if (Style.Language == FormatStyle::LK_JavaScript &&

clang/tools/clang-format/ClangFormat.cpp

@@ -256,6 +256,7 @@ static bool format(StringRef FileName) {
     llvm::errs() << llvm::toString(FormatStyle.takeError()) << "\n";
     return true;
   }
+
   if (SortIncludes.getNumOccurrences() != 0)
     FormatStyle->SortIncludes = SortIncludes;
   unsigned CursorPosition = Cursor;

clang/unittests/Format/FormatTestJS.cpp

@@ -1036,6 +1036,15 @@ TEST_F(FormatTestJS, RegexLiteralExamples) {
   verifyFormat("var regex = search.match(/(?:\?|&)times=([^?&]+)/i);");
 }
 
+TEST_F(FormatTestJS, IgnoresMpegTS) {
+  std::string MpegTS(200, ' ');
+  MpegTS.replace(0, strlen("nearlyLooks  +   like +   ts + code;  "),
+                 "nearlyLooks  +   like +   ts + code;  ");
+  MpegTS[0] = 0x47;
+  MpegTS[188] = 0x47;
+  verifyFormat(MpegTS, MpegTS);
+}
+
 TEST_F(FormatTestJS, TypeAnnotations) {
   verifyFormat("var x: string;");
   verifyFormat("var x: {a: string; b: number;} = {};");