[llvm-objcopy][NFC] Refactor output target parsing

Summary:
Use an enum instead of string to hold the output file format in Config.InputFormat and Config.OutputFormat. It's essential to support other output file formats other than ELF.

Reviewers: espindola, alexshap, rupprecht, jhenderson

Reviewed By: rupprecht, jhenderson

Subscribers: jyknight, compnerd, emaste, arichardson, fedor.sergeev, jakehehrlich, MaskRay, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D63239

llvm-svn: 364254

1 files changed, 8 insertions, 6 deletions

diff --git a/llvm/tools/llvm-objcopy/ELF/ELFObjcopy.cpp b/llvm/tools/llvm-objcopy/ELF/ELFObjcopy.cpp
index b6af729afe8..b366c6e5598 100644
--- a/llvm/tools/llvm-objcopy/ELF/ELFObjcopy.cpp
+++ b/llvm/tools/llvm-objcopy/ELF/ELFObjcopy.cpp
@@ -154,12 +154,14 @@ static std::unique_ptr<Writer> createELFWriter(const CopyConfig &Config,
 static std::unique_ptr<Writer> createWriter(const CopyConfig &Config,
                                             Object &Obj, Buffer &Buf,
                                             ElfType OutputElfType) {
-  using Functor = std::function<std::unique_ptr<Writer>()>;
-  return StringSwitch<Functor>(Config.OutputFormat)
-      .Case("binary", [&] { return llvm::make_unique<BinaryWriter>(Obj, Buf); })
-      .Case("ihex", [&] { return llvm::make_unique<IHexWriter>(Obj, Buf); })
-      .Default(
-          [&] { return createELFWriter(Config, Obj, Buf, OutputElfType); })();
+  switch (Config.OutputFormat) {
+  case FileFormat::Binary:
+    return llvm::make_unique<BinaryWriter>(Obj, Buf);
+  case FileFormat::IHex:
+    return llvm::make_unique<IHexWriter>(Obj, Buf);
+  default:
+    return createELFWriter(Config, Obj, Buf, OutputElfType);
+  }
 }
 
 template <class ELFT>