[clang-tools-extra] Refactor to reduce code duplication

[prehistoric-penguin]

Summary

The two functions' bodies are almost the same, so I delegate them to a helper function for reducing.

[prehistoric-penguin]

Refine commit msg

[avogelsgesang]

LGTM

(note that I am rather inexperienced with LLVM, though, so take my approval with a grain of salt)

clang-tools-extra/clang-apply-replacements/lib/Tooling/ApplyReplacements.cpp

 using namespace llvm;
 using namespace clang;
 
 static void eatDiagnostics(const SMDiagnostic &, void *) {}
 
 namespace clang {
 namespace replace {
 
-std::error_code collectReplacementsFromDirectory(
-    const llvm::StringRef Directory, TUReplacements &TUs,
-    TUReplacementFiles &TUFiles, clang::DiagnosticsEngine &Diagnostics) {
+template <typename T>
+std::error_code
+collectReplacementsFromDirectoryImpl(const llvm::StringRef Directory, T &TUs,
+                                     TUReplacementFiles &TUFiles,
+                                     clang::DiagnosticsEngine &Diagnostics) {
   using namespace llvm::sys::fs;
   using namespace llvm::sys::path;
 
   std::error_code ErrorCode;
 
   for (recursive_directory_iterator I(Directory, ErrorCode), E;
        I != E && !ErrorCode; I.increment(ErrorCode)) {
     if (filename(I->path())[0] == '.') {
ErrorOr<std::unique_ptr<MemoryBuffer>> Out =
         MemoryBuffer::getFile(I->path());
     if (std::error_code BufferError = Out.getError()) {
       errs() << "Error reading " << I->path() << ": " << BufferError.message()
              << "\n";
       continue;
     }
 
     yaml::Input YIn(Out.get()->getBuffer(), nullptr, &eatDiagnostics);
-    tooling::TranslationUnitReplacements TU;
+    typename T::value_type TU;
     YIn >> TU;
     if (YIn.error()) {
       // File doesn't appear to be a header change description. Ignore it.
       continue;
     }
 
     // Only keep files that properly parse.
     TUs.push_back(TU);
   }
 
   return ErrorCode;
 }
 
 std::error_code collectReplacementsFromDirectory(
-    const llvm::StringRef Directory, TUDiagnostics &TUs,
+    const llvm::StringRef Directory, TUReplacements &TUs,
     TUReplacementFiles &TUFiles, clang::DiagnosticsEngine &Diagnostics) {
-  using namespace llvm::sys::fs;
-  using namespace llvm::sys::path;
-
-  std::error_code ErrorCode;
-
-  for (recursive_directory_iterator I(Directory, ErrorCode), E;
-       I != E && !ErrorCode; I.increment(ErrorCode)) {
-    if (filename(I->path())[0] == '.') {
-      // Indicate not to descend into directories beginning with '.'
-      I.no_push();
-      continue;
-    }
+  return collectReplacementsFromDirectoryImpl(Directory, TUs, TUFiles,
+                                              Diagnostics);
 
-    if (extension(I->path()) != ".yaml")
-      continue;
-
-    TUFiles.push_back(I->path());
-
-    ErrorOr<std::unique_ptr<MemoryBuffer>> Out =
-        MemoryBuffer::getFile(I->path());
-    if (std::error_code BufferError = Out.getError()) {
-      errs() << "Error reading " << I->path() << ": " << BufferError.message()
-             << "\n";
-      continue;
-    }
-
-    yaml::Input YIn(Out.get()->getBuffer(), nullptr, &eatDiagnostics);
-    tooling::TranslationUnitDiagnostics TU;
-    YIn >> TU;
-    if (YIn.error()) {
-      // File doesn't appear to be a header change description. Ignore it.
-      continue;
-    }
-
-    // Only keep files that properly parse.
-    TUs.push_back(TU);
-  }
-
-  return ErrorCode;
+std::error_code collectReplacementsFromDirectory(
+    const llvm::StringRef Directory, TUDiagnostics &TUs,
+    TUReplacementFiles &TUFiles, clang::DiagnosticsEngine &Diagnostics) {
+  return collectReplacementsFromDirectoryImpl(Directory, TUs, TUFiles,
+                                              Diagnostics);
 }
 
 /// Extract replacements from collected TranslationUnitReplacements and
 /// TranslationUnitDiagnostics and group them per file. Identical replacements
 /// from diagnostics are deduplicated.
 ///
 /// \param[in] TUs Collection of all found and deserialized
 /// TranslationUnitReplacements.