Initial implementation of a utility for converting native data

structures to and from YAML using traits.  The first client will
be the test suite of lld.  The documentation will show up at:

   http://llvm.org/docs/YamlIO.html




git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@170019 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 882 insertions, 0 deletions

diff --git a/lib/Support/CMakeLists.txt b/lib/Support/CMakeLists.txt
index 6af0f4a..f294a17 100644
--- a/lib/Support/CMakeLists.txt
+++ b/lib/Support/CMakeLists.txt
@@ -50,6 +50,7 @@ add_llvm_library(LLVMSupport
   Triple.cpp
   Twine.cpp
   YAMLParser.cpp
+  YAMLTraits.cpp
   raw_os_ostream.cpp
   raw_ostream.cpp
   regcomp.c
diff --git a/lib/Support/YAMLTraits.cpp b/lib/Support/YAMLTraits.cpp
new file mode 100644
index 0000000..e2be15b
--- /dev/null
+++ b/lib/Support/YAMLTraits.cpp
@@ -0,0 +1,881 @@
+//===- lib/Support/YAMLTraits.cpp -----------------------------------------===//
+//
+//                             The LLVM Linker
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#define BUILDING_YAMLIO
+#include "llvm/Support/YAMLTraits.h"
+
+#include "llvm/ADT/Twine.h"
+#include "llvm/Support/Casting.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/format.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Support/YAMLParser.h"
+
+#include <cstring>
+
+namespace llvm {
+namespace yaml {
+
+
+
+//===----------------------------------------------------------------------===//
+//  IO
+//===----------------------------------------------------------------------===//
+
+IO::IO(void *Context) : Ctxt(Context) {
+}
+
+IO::~IO() {
+}
+
+void *IO::getContext() {
+  return Ctxt;
+}
+
+void IO::setContext(void *Context) {
+  Ctxt = Context;
+}
+
+
+//===----------------------------------------------------------------------===//
+//  Input
+//===----------------------------------------------------------------------===//
+
+Input::Input(StringRef InputContent, void *Ctxt)
+    : IO(Ctxt), CurrentNode(NULL) {
+  Strm = new Stream(InputContent, SrcMgr);
+  DocIterator = Strm->begin();
+}
+
+
+llvm::error_code Input::error() {
+  return EC;
+}
+
+void Input::setDiagHandler(llvm::SourceMgr::DiagHandlerTy Handler, void *Ctxt) {
+  SrcMgr.setDiagHandler(Handler, Ctxt);
+}
+
+bool Input::outputting() {
+  return false;
+}
+
+bool Input::setCurrentDocument() {
+  if ( DocIterator != Strm->end() ) {
+    Node *N = DocIterator->getRoot();
+    if (llvm::isa<NullNode>(N)) {
+      // Empty files are allowed and ignored
+      ++DocIterator;
+      return setCurrentDocument();
+    }
+    CurrentNode = this->createHNodes(N);
+    return true;
+  }
+  return false;
+}
+
+void Input::nextDocument() {
+  ++DocIterator;
+}
+
+void Input::beginMapping() {
+  if ( EC )
+    return;
+  MapHNode *MN = llvm::dyn_cast<MapHNode>(CurrentNode);
+  if ( MN ) {
+    MN->ValidKeys.clear();
+  }
+}
+
+bool Input::preflightKey(const char *Key, bool Required, bool,
+                                          bool &UseDefault, void *&SaveInfo) {
+  UseDefault = false;
+  if ( EC )
+    return false;
+  MapHNode *MN = llvm::dyn_cast<MapHNode>(CurrentNode);
+  if ( !MN ) {
+    setError(CurrentNode, "not a mapping");
+    return false;
+  }
+  MN->ValidKeys.push_back(Key);
+  HNode *Value = MN->Mapping[Key];
+  if ( !Value ) {
+    if ( Required )
+      setError(CurrentNode, Twine("missing required key '") + Key + "'");
+    else
+      UseDefault = true;
+   return false;
+  }
+  SaveInfo = CurrentNode;
+  CurrentNode = Value;
+  return true;
+}
+
+void Input::postflightKey(void *saveInfo) {
+  CurrentNode = reinterpret_cast<HNode*>(saveInfo);
+}
+
+void Input::endMapping() {
+  if ( EC )
+    return;
+  MapHNode *MN = llvm::dyn_cast<MapHNode>(CurrentNode);
+  if ( !MN )
+    return;
+  for (MapHNode::NameToNode::iterator i=MN->Mapping.begin(),
+                                        End=MN->Mapping.end(); i != End; ++i) {
+    if ( ! MN->isValidKey(i->first) ) {
+       setError(i->second, Twine("unknown key '") + i->first + "'" );
+      break;
+    }
+  }
+}
+
+
+unsigned Input::beginSequence() {
+  if ( SequenceHNode *SQ = llvm::dyn_cast<SequenceHNode>(CurrentNode) ) {
+    return SQ->Entries.size();
+  }
+  return 0;
+}
+void Input::endSequence() {
+}
+bool Input::preflightElement(unsigned Index, void *&SaveInfo) {
+  if ( EC )
+    return false;
+  if ( SequenceHNode *SQ = llvm::dyn_cast<SequenceHNode>(CurrentNode) ) {
+    SaveInfo = CurrentNode;
+    CurrentNode = SQ->Entries[Index];
+    return true;
+  }
+  return false;
+}
+void Input::postflightElement(void *SaveInfo) {
+  CurrentNode = reinterpret_cast<HNode*>(SaveInfo);
+}
+
+unsigned Input::beginFlowSequence() {
+   if ( SequenceHNode *SQ = llvm::dyn_cast<SequenceHNode>(CurrentNode) ) {
+    return SQ->Entries.size();
+  }
+  return 0;
+}
+bool Input::preflightFlowElement(unsigned index, void *&SaveInfo) {
+  if ( EC )
+    return false;
+  if ( SequenceHNode *SQ = llvm::dyn_cast<SequenceHNode>(CurrentNode) ) {
+    SaveInfo = CurrentNode;
+    CurrentNode = SQ->Entries[index];
+    return true;
+  }
+  return false;
+}
+void Input::postflightFlowElement(void *SaveInfo) {
+  CurrentNode = reinterpret_cast<HNode*>(SaveInfo);
+}
+void Input::endFlowSequence() {
+}
+
+
+void Input::beginEnumScalar() {
+  ScalarMatchFound = false;
+}
+
+bool Input::matchEnumScalar(const char *Str, bool) {
+  if ( ScalarMatchFound )
+    return false;
+  if ( ScalarHNode *SN = llvm::dyn_cast<ScalarHNode>(CurrentNode) ) {
+    if ( SN->value().equals(Str) ) {
+      ScalarMatchFound = true;
+      return true;
+    }
+  }
+  return false;
+}
+
+void Input::endEnumScalar() {
+  if ( !ScalarMatchFound ) {
+    setError(CurrentNode, "unknown enumerated scalar");
+  }
+}
+
+
+
+bool Input::beginBitSetScalar(bool &DoClear) {
+  BitValuesUsed.clear();
+  if ( SequenceHNode *SQ = llvm::dyn_cast<SequenceHNode>(CurrentNode) ) {
+    BitValuesUsed.insert(BitValuesUsed.begin(), SQ->Entries.size(), false);
+  }
+  else {
+    setError(CurrentNode, "expected sequence of bit values");
+  }
+  DoClear = true;
+  return true;
+}
+
+bool Input::bitSetMatch(const char *Str, bool) {
+  if ( EC )
+    return false;
+  if ( SequenceHNode *SQ = llvm::dyn_cast<SequenceHNode>(CurrentNode) ) {
+    unsigned Index = 0;
+    for (std::vector<HNode*>::iterator i=SQ->Entries.begin(),
+                                       End=SQ->Entries.end(); i != End; ++i) {
+      if ( ScalarHNode *SN = llvm::dyn_cast<ScalarHNode>(*i) ) {
+        if ( SN->value().equals(Str) ) {
+          BitValuesUsed[Index] = true;
+          return true;
+        }
+      }
+      else {
+        setError(CurrentNode, "unexpected scalar in sequence of bit values");
+      }
+      ++Index;
+    }
+  }
+  else {
+    setError(CurrentNode, "expected sequence of bit values");
+  }
+  return false;
+}
+
+void Input::endBitSetScalar() {
+  if ( EC )
+    return;
+  if ( SequenceHNode *SQ = llvm::dyn_cast<SequenceHNode>(CurrentNode) ) {
+    assert(BitValuesUsed.size() == SQ->Entries.size());
+    for ( unsigned i=0; i < SQ->Entries.size(); ++i ) {
+      if ( !BitValuesUsed[i] ) {
+        setError(SQ->Entries[i], "unknown bit value");
+        return;
+      }
+    }
+  }
+}
+
+
+void Input::scalarString(StringRef &S) {
+  if ( ScalarHNode *SN = llvm::dyn_cast<ScalarHNode>(CurrentNode) ) {
+    S = SN->value();
+  }
+  else {
+    setError(CurrentNode, "unexpected scalar");
+  }
+}
+
+void Input::setError(HNode *hnode, const Twine &message) {
+  this->setError(hnode->_node, message);
+}
+
+void Input::setError(Node *node, const Twine &message) {
+  Strm->printError(node, message);
+  EC = make_error_code(errc::invalid_argument);
+}
+
+Input::HNode *Input::createHNodes(Node *N) {
+  llvm::SmallString<128> StringStorage;
+  if ( ScalarNode *SN = llvm::dyn_cast<ScalarNode>(N) ) {
+    StringRef KeyStr = SN->getValue(StringStorage);
+    if ( !StringStorage.empty() ) {
+      // Copy string to permanent storage
+      unsigned Len = StringStorage.size();
+      char* Buf = Allocator.Allocate<char>(Len);
+      memcpy(Buf, &StringStorage[0], Len);
+      KeyStr = StringRef(Buf, Len);
+    }
+    return new (Allocator) ScalarHNode(N, KeyStr);
+  }
+  else if ( SequenceNode *SQ = llvm::dyn_cast<SequenceNode>(N) ) {
+    SequenceHNode *SQHNode = new (Allocator) SequenceHNode(N);
+    for (SequenceNode::iterator i=SQ->begin(),End=SQ->end(); i != End; ++i ) {
+      HNode *Entry = this->createHNodes(i);
+      if ( EC )
+        break;
+      SQHNode->Entries.push_back(Entry);
+    }
+    return SQHNode;
+  }
+  else if ( MappingNode *Map = llvm::dyn_cast<MappingNode>(N) ) {
+    MapHNode *mapHNode = new (Allocator) MapHNode(N);
+    for (MappingNode::iterator i=Map->begin(), End=Map->end(); i != End; ++i ) {
+      ScalarNode *KeyScalar = llvm::dyn_cast<ScalarNode>(i->getKey());
+      StringStorage.clear();
+      llvm::StringRef KeyStr = KeyScalar->getValue(StringStorage);
+      if ( !StringStorage.empty() ) {
+        // Copy string to permanent storage
+        unsigned Len = StringStorage.size();
+        char* Buf = Allocator.Allocate<char>(Len);
+        memcpy(Buf, &StringStorage[0], Len);
+        KeyStr = StringRef(Buf, Len);
+      }
+     HNode *ValueHNode = this->createHNodes(i->getValue());
+      if ( EC )
+        break;
+      mapHNode->Mapping[KeyStr] = ValueHNode;
+    }
+    return mapHNode;
+  }
+  else if ( llvm::isa<NullNode>(N) ) {
+    return new (Allocator) EmptyHNode(N);
+  }
+  else {
+    setError(N, "unknown node kind");
+    return NULL;
+  }
+}
+
+
+bool Input::MapHNode::isValidKey(StringRef Key) {
+  for (SmallVector<const char*, 6>::iterator i=ValidKeys.begin(),
+                                  End=ValidKeys.end(); i != End; ++i) {
+    if ( Key.equals(*i) )
+      return true;
+  }
+  return false;
+}
+
+void Input::setError(const Twine &Message) {
+  this->setError(CurrentNode, Message);
+}
+
+
+//===----------------------------------------------------------------------===//
+//  Output
+//===----------------------------------------------------------------------===//
+
+Output::Output(llvm::raw_ostream &yout, void *context)
+    : IO(context), Out(yout), Column(0), ColumnAtFlowStart(0),
+       NeedBitValueComma(false), NeedFlowSequenceComma(false),
+       EnumerationMatchFound(false), NeedsNewLine(false) {
+}
+
+Output::~Output() {
+}
+
+bool Output::outputting() {
+  return true;
+}
+
+void Output::beginMapping() {
+  StateStack.push_back(inMapFirstKey);
+  NeedsNewLine = true;
+}
+
+void Output::endMapping() {
+  StateStack.pop_back();
+}
+
+
+bool Output::preflightKey(const char *Key, bool Required, bool SameAsDefault,
+                                                bool &UseDefault, void *&) {
+  UseDefault = false;
+  if ( Required || !SameAsDefault ) {
+    this->newLineCheck();
+    this->paddedKey(Key);
+    return true;
+  }
+  return false;
+}
+
+void Output::postflightKey(void*) {
+  if ( StateStack.back() == inMapFirstKey ) {
+    StateStack.pop_back();
+    StateStack.push_back(inMapOtherKey);
+  }
+}
+
+void Output::beginDocuments() {
+  this->outputUpToEndOfLine("---");
+}
+
+bool Output::preflightDocument(unsigned index) {
+  if ( index > 0 )
+    this->outputUpToEndOfLine("\n---");
+  return true;
+}
+
+void Output::postflightDocument() {
+}
+
+void Output::endDocuments() {
+  output("\n...\n");
+}
+
+unsigned Output::beginSequence() {
+  StateStack.push_back(inSeq);
+  NeedsNewLine = true;
+  return 0;
+}
+void Output::endSequence() {
+  StateStack.pop_back();
+}
+bool Output::preflightElement(unsigned , void *&) {
+  return true;
+}
+void Output::postflightElement(void*) {
+}
+
+unsigned Output::beginFlowSequence() {
+  this->newLineCheck();
+  StateStack.push_back(inFlowSeq);
+  ColumnAtFlowStart = Column;
+  output("[ ");
+  NeedFlowSequenceComma = false;
+  return 0;
+}
+void Output::endFlowSequence() {
+  StateStack.pop_back();
+  this->outputUpToEndOfLine(" ]");
+}
+bool Output::preflightFlowElement(unsigned , void *&) {
+  if ( NeedFlowSequenceComma )
+    output(", ");
+  if ( Column > 70 ) {
+    output("\n");
+    for(int  i=0; i < ColumnAtFlowStart; ++i)
+      output(" ");
+    Column = ColumnAtFlowStart;
+    output("  ");
+  }
+  return true;
+}
+void Output::postflightFlowElement(void*) {
+  NeedFlowSequenceComma = true;
+}
+
+
+
+void Output::beginEnumScalar() {
+  EnumerationMatchFound = false;
+}
+
+bool Output::matchEnumScalar(const char *Str, bool Match) {
+  if ( Match && !EnumerationMatchFound ) {
+    this->newLineCheck();
+    this->outputUpToEndOfLine(Str);
+    EnumerationMatchFound = true;
+  }
+  return false;
+}
+
+void Output::endEnumScalar() {
+  if ( !EnumerationMatchFound )
+    llvm_unreachable("bad runtime enum value");
+}
+
+
+
+bool Output::beginBitSetScalar(bool &DoClear) {
+  this->newLineCheck();
+  output("[ ");
+  NeedBitValueComma = false;
+  DoClear = false;
+  return true;
+}
+
+bool Output::bitSetMatch(const char *Str, bool Matches) {
+ if ( Matches ) {
+    if ( NeedBitValueComma )
+      output(", ");
+    this->output(Str);
+    NeedBitValueComma = true;
+  }
+  return false;
+}
+
+void Output::endBitSetScalar() {
+  this->outputUpToEndOfLine(" ]");
+}
+
+void Output::scalarString(StringRef &S) {
+  this->newLineCheck();
+  if (S.find('\n') == StringRef::npos) {
+    // No embedded new-line chars, just print string.
+    this->outputUpToEndOfLine(S);
+    return;
+  }
+  unsigned i = 0;
+  unsigned j = 0;
+  unsigned End = S.size();
+  output("'"); // Starting single quote.
+  const char *Base = S.data();
+  while (j < End) {
+    // Escape a single quote by doubling it.
+    if (S[j] == '\'') {
+      output(StringRef(&Base[i], j - i + 1));
+      output("'");
+      i = j + 1;
+    }
+    ++j;
+  }
+  output(StringRef(&Base[i], j - i));
+  this->outputUpToEndOfLine("'"); // Ending single quote.
+}
+
+void Output::setError(const Twine &message) {
+}
+
+
+void Output::output(StringRef s) {
+  Column += s.size();
+  Out << s;
+}
+
+void Output::outputUpToEndOfLine(StringRef s) {
+  this->output(s);
+  if ( StateStack.back() != inFlowSeq )
+    NeedsNewLine = true;
+}
+
+void Output::outputNewLine() {
+  Out << "\n";
+  Column = 0;
+}
+
+// if seq at top, indent as if map, then add "- "
+// if seq in middle, use "- " if firstKey, else use "  "
+//
+
+void Output::newLineCheck() {
+  if ( ! NeedsNewLine )
+    return;
+  NeedsNewLine = false;
+
+  this->outputNewLine();
+
+  assert(StateStack.size() > 0);
+  unsigned Indent = StateStack.size() - 1;
+  bool OutputDash = false;
+
+  if ( StateStack.back() == inSeq ) {
+    OutputDash = true;
+  }
+  else if ( (StateStack.size() > 1)
+            && (StateStack.back() == inMapFirstKey)
+            && (StateStack[StateStack.size()-2] == inSeq) ) {
+    --Indent;
+    OutputDash = true;
+  }
+
+  for (unsigned i=0; i < Indent; ++i) {
+    output("  ");
+  }
+  if ( OutputDash ) {
+    output("- ");
+  }
+
+}
+
+void Output::paddedKey(StringRef key) {
+  output(key);
+  output(":");
+  const char *spaces = "                ";
+  if ( key.size() < strlen(spaces) )
+    output(&spaces[key.size()]);
+  else
+    output(" ");
+}
+
+//===----------------------------------------------------------------------===//
+//  traits for built-in types
+//===----------------------------------------------------------------------===//
+
+template<>
+struct ScalarTraits<bool> {
+  static void output(const bool &Val, void*, llvm::raw_ostream &Out) {
+    Out << ( Val ? "true" : "false");
+  }
+  static llvm::StringRef input(llvm::StringRef Scalar, void*, bool &Val) {
+    if ( Scalar.equals("true") ) {
+      Val = true;
+      return StringRef();
+    }
+    else if ( Scalar.equals("false") ) {
+      Val = false;
+      return StringRef();
+    }
+    return "invalid boolean";
+  }
+};
+
+
+template<>
+struct ScalarTraits<StringRef> {
+  static void output(const StringRef &Val, void*, llvm::raw_ostream &Out) {
+    Out << Val;
+  }
+  static llvm::StringRef input(llvm::StringRef Scalar, void*, StringRef &Val){
+    Val = Scalar;
+    return StringRef();
+  }
+};
+
+
+template<>
+struct ScalarTraits<uint8_t> {
+  static void output(const uint8_t &Val, void*, llvm::raw_ostream &Out) {
+    // use temp uin32_t because ostream thinks uint8_t is a character
+    uint32_t Num = Val;
+    Out << Num;
+  }
+  static llvm::StringRef input(llvm::StringRef Scalar, void*, uint8_t &Val) {
+    uint64_t n;
+    if ( getAsUnsignedInteger(Scalar, 0, n) )
+      return "invalid number";
+    if ( n > 0xFF )
+      return "out of range number";
+    Val = n;
+    return StringRef();
+  }
+};
+
+
+template<>
+struct ScalarTraits<uint16_t> {
+  static void output(const uint16_t &Val, void*, llvm::raw_ostream &Out) {
+    Out << Val;
+  }
+  static llvm::StringRef input(llvm::StringRef Scalar, void*, uint16_t &Val) {
+    uint64_t n;
+    if ( getAsUnsignedInteger(Scalar, 0, n) )
+      return "invalid number";
+    if ( n > 0xFFFF )
+      return "out of range number";
+    Val = n;
+    return StringRef();
+  }
+};
+
+template<>
+struct ScalarTraits<uint32_t> {
+  static void output(const uint32_t &Val, void*, llvm::raw_ostream &Out) {
+    Out << Val;
+  }
+  static llvm::StringRef input(llvm::StringRef Scalar, void*, uint32_t &Val) {
+    uint64_t n;
+    if ( getAsUnsignedInteger(Scalar, 0, n) )
+      return "invalid number";
+    if ( n > 0xFFFFFFFFUL )
+      return "out of range number";
+    Val = n;
+    return StringRef();
+  }
+};
+
+
+template<>
+struct ScalarTraits<uint64_t> {
+  static void output(const uint64_t &Val, void*, llvm::raw_ostream &Out) {
+    Out << Val;
+  }
+  static llvm::StringRef input(llvm::StringRef Scalar, void*, uint64_t &Val) {
+    if ( getAsUnsignedInteger(Scalar, 0, Val) )
+      return "invalid number";
+    return StringRef();
+  }
+};
+
+
+template<>
+struct ScalarTraits<int8_t> {
+  static void output(const int8_t &Val, void*, llvm::raw_ostream &Out) {
+    // use temp in32_t because ostream thinks int8_t is a character
+    int32_t Num = Val;
+    Out << Num;
+  }
+  static llvm::StringRef input(llvm::StringRef Scalar, void*, int8_t &Val) {
+    int64_t n;
+    if ( getAsSignedInteger(Scalar, 0, n) )
+      return "invalid number";
+    if ( (n > 127) || (n < -128) )
+      return "out of range number";
+    Val = n;
+    return StringRef();
+  }
+};
+
+
+template<>
+struct ScalarTraits<int16_t> {
+  static void output(const int16_t &Val, void*, llvm::raw_ostream &Out) {
+    Out << Val;
+  }
+  static llvm::StringRef input(llvm::StringRef Scalar, void*, int16_t &Val) {
+    int64_t n;
+    if ( getAsSignedInteger(Scalar, 0, n) )
+      return "invalid number";
+    if ( (n > INT16_MAX) || (n < INT16_MIN) )
+      return "out of range number";
+    Val = n;
+    return StringRef();
+  }
+};
+
+
+template<>
+struct ScalarTraits<int32_t> {
+  static void output(const int32_t &Val, void*, llvm::raw_ostream &Out) {
+    Out << Val;
+  }
+  static llvm::StringRef input(llvm::StringRef Scalar, void*, int32_t &Val) {
+    int64_t n;
+    if ( getAsSignedInteger(Scalar, 0, n) )
+      return "invalid number";
+    if ( (n > INT32_MAX) || (n < INT32_MIN) )
+      return "out of range number";
+    Val = n;
+    return StringRef();
+  }
+};
+
+template<>
+struct ScalarTraits<int64_t> {
+  static void output(const int64_t &Val, void*, llvm::raw_ostream &Out) {
+    Out << Val;
+  }
+  static llvm::StringRef input(llvm::StringRef Scalar, void*, int64_t &Val) {
+    if ( getAsSignedInteger(Scalar, 0, Val) )
+      return "invalid number";
+    return StringRef();
+  }
+};
+
+template<>
+struct ScalarTraits<double> {
+  static void output(const double &Val, void*, llvm::raw_ostream &Out) {
+  Out << format("%g", Val);
+  }
+  static llvm::StringRef input(llvm::StringRef Scalar, void*, double &Val) {
+    SmallString<32> buff(Scalar.begin(), Scalar.end());
+    char *end;
+    Val = strtod(buff.c_str(), &end);
+    if ( *end != '\0' )
+      return "invalid floating point number";
+    return StringRef();
+  }
+};
+
+template<>
+struct ScalarTraits<float> {
+  static void output(const float &Val, void*, llvm::raw_ostream &Out) {
+  Out << format("%g", Val);
+  }
+  static llvm::StringRef input(llvm::StringRef Scalar, void*, float &Val) {
+    SmallString<32> buff(Scalar.begin(), Scalar.end());
+    char *end;
+    Val = strtod(buff.c_str(), &end);
+    if ( *end != '\0' )
+      return "invalid floating point number";
+    return StringRef();
+  }
+};
+
+
+
+template<>
+struct ScalarTraits<Hex8> {
+  static void output(const Hex8 &Val, void*, llvm::raw_ostream &Out) {
+    uint8_t Num = Val;
+    Out << format("0x%02X", Num);
+  }
+  static llvm::StringRef input(llvm::StringRef Scalar, void*, Hex8 &Val) {
+    uint64_t n;
+    if ( getAsUnsignedInteger(Scalar, 0, n) )
+      return "invalid hex8 number";
+    if ( n > 0xFF )
+      return "out of range hex8 number";
+    Val = n;
+    return StringRef();
+  }
+};
+
+
+template<>
+struct ScalarTraits<Hex16> {
+  static void output(const Hex16 &Val, void*, llvm::raw_ostream &Out) {
+    uint16_t Num = Val;
+    Out << format("0x%04X", Num);
+  }
+  static llvm::StringRef input(llvm::StringRef Scalar, void*, Hex16 &Val) {
+    uint64_t n;
+    if ( getAsUnsignedInteger(Scalar, 0, n) )
+      return "invalid hex16 number";
+    if ( n > 0xFFFF )
+      return "out of range hex16 number";
+    Val = n;
+    return StringRef();
+  }
+};
+
+template<>
+struct ScalarTraits<Hex32> {
+  static void output(const Hex32 &Val, void*, llvm::raw_ostream &Out) {
+    uint32_t Num = Val;
+    Out << format("0x%08X", Num);
+  }
+  static llvm::StringRef input(llvm::StringRef Scalar, void*, Hex32 &Val) {
+    uint64_t n;
+    if ( getAsUnsignedInteger(Scalar, 0, n) )
+      return "invalid hex32 number";
+    if ( n > 0xFFFFFFFFUL )
+      return "out of range hex32 number";
+    Val = n;
+    return StringRef();
+  }
+};
+
+
+template<>
+struct ScalarTraits<Hex64> {
+  static void output(const Hex64 &Val, void*, llvm::raw_ostream &Out) {
+    uint64_t Num = Val;
+    Out << format("0x%016llX", Num);
+  }
+  static llvm::StringRef input(llvm::StringRef Scalar, void*, Hex64 &Val) {
+    uint64_t Num;
+    if ( getAsUnsignedInteger(Scalar, 0, Num) )
+      return "invalid hex64 number";
+    Val = Num;
+    return StringRef();
+  }
+};
+
+
+
+
+// We want all the ScalarTrait specialized on built-in types
+// to be instantiated here.
+template <typename T>
+struct ForceUse {
+  ForceUse() : oproc(ScalarTraits<T>::output), iproc(ScalarTraits<T>::input) {}
+  void (*oproc)(const T &, void*, llvm::raw_ostream &);
+  llvm::StringRef (*iproc)(llvm::StringRef, void*, T &);
+};
+
+static ForceUse<bool>            Dummy1;
+static ForceUse<llvm::StringRef> Dummy2;
+static ForceUse<uint8_t>         Dummy3;
+static ForceUse<uint16_t>        Dummy4;
+static ForceUse<uint32_t>        Dummy5;
+static ForceUse<uint64_t>        Dummy6;
+static ForceUse<int8_t>          Dummy7;
+static ForceUse<int16_t>         Dummy8;
+static ForceUse<int32_t>         Dummy9;
+static ForceUse<int64_t>         Dummy10;
+static ForceUse<float>           Dummy11;
+static ForceUse<double>          Dummy12;
+static ForceUse<Hex8>            Dummy13;
+static ForceUse<Hex16>           Dummy14;
+static ForceUse<Hex32>           Dummy15;
+static ForceUse<Hex64>           Dummy16;
+
+
+
+} // namespace yaml
+} // namespace llvm
+
+