Index: clang-tools-extra/trunk/clangd/CMakeLists.txt
===================================================================
--- clang-tools-extra/trunk/clangd/CMakeLists.txt
+++ clang-tools-extra/trunk/clangd/CMakeLists.txt
@@ -46,6 +46,7 @@
   index/IndexAction.cpp
   index/MemIndex.cpp
   index/Merge.cpp
+  index/SymbolID.cpp
   index/Serialization.cpp
   index/SymbolCollector.cpp
   index/YAMLSerialization.cpp
Index: clang-tools-extra/trunk/clangd/Protocol.h
===================================================================
--- clang-tools-extra/trunk/clangd/Protocol.h
+++ clang-tools-extra/trunk/clangd/Protocol.h
@@ -25,6 +25,7 @@
 #define LLVM_CLANG_TOOLS_EXTRA_CLANGD_PROTOCOL_H
 
 #include "URI.h"
+#include "index/SymbolID.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/Support/JSON.h"
 #include <bitset>
Index: clang-tools-extra/trunk/clangd/index/Index.h
===================================================================
--- clang-tools-extra/trunk/clangd/index/Index.h
+++ clang-tools-extra/trunk/clangd/index/Index.h
@@ -11,11 +11,11 @@
 #define LLVM_CLANG_TOOLS_EXTRA_CLANGD_INDEX_INDEX_H
 
 #include "ExpectedTypes.h"
+#include "SymbolID.h"
 #include "clang/Index/IndexSymbol.h"
 #include "clang/Lex/Lexer.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/DenseSet.h"
-#include "llvm/ADT/Hashing.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringExtras.h"
@@ -95,53 +95,6 @@
 }
 llvm::raw_ostream &operator<<(llvm::raw_ostream &, const SymbolLocation &);
 
-// The class identifies a particular C++ symbol (class, function, method, etc).
-//
-// As USRs (Unified Symbol Resolution) could be large, especially for functions
-// with long type arguments, SymbolID is using truncated SHA1(USR) values to
-// guarantee the uniqueness of symbols while using a relatively small amount of
-// memory (vs storing USRs directly).
-//
-// SymbolID can be used as key in the symbol indexes to lookup the symbol.
-class SymbolID {
-public:
-  SymbolID() = default;
-  explicit SymbolID(llvm::StringRef USR);
-
-  bool operator==(const SymbolID &Sym) const {
-    return HashValue == Sym.HashValue;
-  }
-  bool operator<(const SymbolID &Sym) const {
-    return HashValue < Sym.HashValue;
-  }
-
-  // The stored hash is truncated to RawSize bytes.
-  // This trades off memory against the number of symbols we can handle.
-  constexpr static size_t RawSize = 8;
-  llvm::StringRef raw() const {
-    return StringRef(reinterpret_cast<const char *>(HashValue.data()), RawSize);
-  }
-  static SymbolID fromRaw(llvm::StringRef);
-
-  // Returns a hex encoded string.
-  std::string str() const;
-  static llvm::Expected<SymbolID> fromStr(llvm::StringRef);
-
-private:
-  std::array<uint8_t, RawSize> HashValue;
-};
-
-inline llvm::hash_code hash_value(const SymbolID &ID) {
-  // We already have a good hash, just return the first bytes.
-  assert(sizeof(size_t) <= SymbolID::RawSize && "size_t longer than SHA1!");
-  size_t Result;
-  memcpy(&Result, ID.raw().data(), sizeof(size_t));
-  return llvm::hash_code(Result);
-}
-
-// Write SymbolID into the given stream. SymbolID is encoded as ID.str().
-llvm::raw_ostream &operator<<(llvm::raw_ostream &OS, const SymbolID &ID);
-
 } // namespace clangd
 } // namespace clang
 namespace llvm {
Index: clang-tools-extra/trunk/clangd/index/Index.cpp
===================================================================
--- clang-tools-extra/trunk/clangd/index/Index.cpp
+++ clang-tools-extra/trunk/clangd/index/Index.cpp
@@ -12,7 +12,6 @@
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/Error.h"
-#include "llvm/Support/SHA1.h"
 #include "llvm/Support/raw_ostream.h"
 
 using namespace llvm;
@@ -43,34 +42,6 @@
             << "-" << L.End.line() << ":" << L.End.column() << ")";
 }
 
-SymbolID::SymbolID(StringRef USR) {
-  auto Hash = SHA1::hash(arrayRefFromStringRef(USR));
-  static_assert(sizeof(Hash) >= RawSize, "RawSize larger than SHA1");
-  memcpy(HashValue.data(), Hash.data(), RawSize);
-}
-
-raw_ostream &operator<<(raw_ostream &OS, const SymbolID &ID) {
-  return OS << toHex(ID.raw());
-}
-
-SymbolID SymbolID::fromRaw(StringRef Raw) {
-  SymbolID ID;
-  assert(Raw.size() == RawSize);
-  memcpy(ID.HashValue.data(), Raw.data(), RawSize);
-  return ID;
-}
-
-std::string SymbolID::str() const { return toHex(raw()); }
-
-Expected<SymbolID> SymbolID::fromStr(StringRef Str) {
-  if (Str.size() != RawSize * 2)
-    return createStringError(inconvertibleErrorCode(), "Bad ID length");
-  for (char C : Str)
-    if (!isHexDigit(C))
-      return createStringError(inconvertibleErrorCode(), "Bad hex ID");
-  return fromRaw(fromHex(Str));
-}
-
 raw_ostream &operator<<(raw_ostream &OS, SymbolOrigin O) {
   if (O == SymbolOrigin::Unknown)
     return OS << "unknown";
Index: clang-tools-extra/trunk/clangd/index/SymbolID.h
===================================================================
--- clang-tools-extra/trunk/clangd/index/SymbolID.h
+++ clang-tools-extra/trunk/clangd/index/SymbolID.h
@@ -0,0 +1,65 @@
+//===--- SymbolID.h ----------------------------------------------*- C++-*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANGD_INDEX_SYMBOLID_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANGD_INDEX_SYMBOLID_H
+
+#include "llvm/ADT/Hashing.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Support/Error.h"
+#include "llvm/Support/raw_ostream.h"
+#include <array>
+#include <string>
+
+namespace clang {
+namespace clangd {
+
+// The class identifies a particular C++ symbol (class, function, method, etc).
+//
+// As USRs (Unified Symbol Resolution) could be large, especially for functions
+// with long type arguments, SymbolID is using truncated SHA1(USR) values to
+// guarantee the uniqueness of symbols while using a relatively small amount of
+// memory (vs storing USRs directly).
+//
+// SymbolID can be used as key in the symbol indexes to lookup the symbol.
+class SymbolID {
+public:
+  SymbolID() = default;
+  explicit SymbolID(llvm::StringRef USR);
+
+  bool operator==(const SymbolID &Sym) const {
+    return HashValue == Sym.HashValue;
+  }
+  bool operator<(const SymbolID &Sym) const {
+    return HashValue < Sym.HashValue;
+  }
+
+  // The stored hash is truncated to RawSize bytes.
+  // This trades off memory against the number of symbols we can handle.
+  constexpr static size_t RawSize = 8;
+  llvm::StringRef raw() const;
+  static SymbolID fromRaw(llvm::StringRef);
+
+  // Returns a hex encoded string.
+  std::string str() const;
+  static llvm::Expected<SymbolID> fromStr(llvm::StringRef);
+
+private:
+  std::array<uint8_t, RawSize> HashValue;
+};
+
+llvm::hash_code hash_value(const SymbolID &ID);
+
+// Write SymbolID into the given stream. SymbolID is encoded as ID.str().
+llvm::raw_ostream &operator<<(llvm::raw_ostream &OS, const SymbolID &ID);
+
+} // namespace clangd
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANGD_INDEX_SYMBOLID_H
Index: clang-tools-extra/trunk/clangd/index/SymbolID.cpp
===================================================================
--- clang-tools-extra/trunk/clangd/index/SymbolID.cpp
+++ clang-tools-extra/trunk/clangd/index/SymbolID.cpp
@@ -0,0 +1,58 @@
+//===--- SymbolID.cpp --------------------------------------------*- C++-*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "SymbolID.h"
+#include "llvm/Support/SHA1.h"
+
+using namespace llvm;
+namespace clang {
+namespace clangd {
+
+SymbolID::SymbolID(StringRef USR) {
+  auto Hash = llvm::SHA1::hash(arrayRefFromStringRef(USR));
+  static_assert(sizeof(Hash) >= RawSize, "RawSize larger than SHA1");
+  memcpy(HashValue.data(), Hash.data(), RawSize);
+}
+
+llvm::StringRef SymbolID::raw() const {
+  return StringRef(reinterpret_cast<const char *>(HashValue.data()), RawSize);
+}
+
+SymbolID SymbolID::fromRaw(StringRef Raw) {
+  SymbolID ID;
+  assert(Raw.size() == RawSize);
+  memcpy(ID.HashValue.data(), Raw.data(), RawSize);
+  return ID;
+}
+
+std::string SymbolID::str() const { return toHex(raw()); }
+
+Expected<SymbolID> SymbolID::fromStr(StringRef Str) {
+  if (Str.size() != RawSize * 2)
+    return createStringError(inconvertibleErrorCode(), "Bad ID length");
+  for (char C : Str)
+    if (!isHexDigit(C))
+      return createStringError(inconvertibleErrorCode(), "Bad hex ID");
+  return fromRaw(fromHex(Str));
+}
+
+raw_ostream &operator<<(raw_ostream &OS, const SymbolID &ID) {
+  return OS << toHex(ID.raw());
+}
+
+llvm::hash_code hash_value(const SymbolID &ID) {
+  // We already have a good hash, just return the first bytes.
+  assert(sizeof(size_t) <= SymbolID::RawSize && "size_t longer than SHA1!");
+  size_t Result;
+  memcpy(&Result, ID.raw().data(), sizeof(size_t));
+  return llvm::hash_code(Result);
+}
+
+} // namespace clangd
+} // namespace clang