19 files changed, 1382 insertions, 3 deletions

diff --git a/include/clang/Tooling/CompilationDatabase.h b/include/clang/Tooling/CompilationDatabase.h
new file mode 100644
index 0000000000..3430320b51
--- /dev/null
+++ b/include/clang/Tooling/CompilationDatabase.h
@@ -0,0 +1,164 @@
+//===--- CompilationDatabase.h - --------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file provides an interface and multiple implementations for
+//  CompilationDatabases.
+//
+//  While C++ refactoring and analysis tools are not compilers, and thus
+//  don't run as part of the build system, they need the exact information
+//  of a build in order to be able to correctly understand the C++ code of
+//  the project. This information is provided via the CompilationDatabase
+//  interface.
+//
+//  To create a CompilationDatabase from a build directory one can call
+//  CompilationDatabase::loadFromDirectory(), which deduces the correct
+//  compilation database from the root of the build tree.
+//
+//  See the concrete subclasses of CompilationDatabase for currently supported
+//  formats.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLING_COMPILATION_DATABASE_H
+#define LLVM_CLANG_TOOLING_COMPILATION_DATABASE_H
+
+#include "clang/Basic/LLVM.h"
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/OwningPtr.h"
+#include "llvm/ADT/StringMap.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include <string>
+#include <vector>
+
+namespace llvm {
+class MemoryBuffer;
+} // end namespace llvm
+
+namespace clang {
+namespace tooling {
+
+/// \brief Specifies the working directory and command of a compilation.
+struct CompileCommand {
+  CompileCommand() {}
+  CompileCommand(StringRef Directory, ArrayRef<std::string> CommandLine)
+    : Directory(Directory), CommandLine(CommandLine) {}
+
+  /// \brief The working directory the command was executed from.
+  std::string Directory;
+
+  /// \brief The command line that was executed.
+  std::vector<std::string> CommandLine;
+};
+
+/// \brief Interface for compilation databases.
+///
+/// A compilation database allows the user to retrieve all compile command lines
+/// that a specified file is compiled with in a project.
+/// The retrieved compile command lines can be used to run clang tools over
+/// a subset of the files in a project.
+class CompilationDatabase {
+public:
+  virtual ~CompilationDatabase();
+
+  /// \brief Loads a compilation database from a build directory.
+  ///
+  /// Looks at the specified 'BuildDirectory' and creates a compilation database
+  /// that allows to query compile commands for source files in the
+  /// corresponding source tree.
+  ///
+  /// Returns NULL and sets ErrorMessage if we were not able to build up a
+  /// compilation database for the build directory.
+  ///
+  /// FIXME: Currently only supports JSON compilation databases, which
+  /// are named 'compile_commands.json' in the given directory. Extend this
+  /// for other build types (like ninja build files).
+  static CompilationDatabase *loadFromDirectory(StringRef BuildDirectory,
+                                                std::string &ErrorMessage);
+
+  /// \brief Returns all compile commands in which the specified file was
+  /// compiled.
+  ///
+  /// This includes compile comamnds that span multiple source files.
+  /// For example, consider a project with the following compilations:
+  /// $ clang++ -o test a.cc b.cc t.cc
+  /// $ clang++ -o production a.cc b.cc -DPRODUCTION
+  /// A compilation database representing the project would return both command
+  /// lines for a.cc and b.cc and only the first command line for t.cc.
+  virtual std::vector<CompileCommand> getCompileCommands(
+    StringRef FilePath) const = 0;
+};
+
+/// \brief A JSON based compilation database.
+///
+/// JSON compilation database files must contain a list of JSON objects which
+/// provide the command lines in the attributes 'directory', 'command' and
+/// 'file':
+/// [
+///   { "directory": "<working directory of the compile>",
+///     "command": "<compile command line>",
+///     "file": "<path to source file>"
+///   },
+///   ...
+/// ]
+/// Each object entry defines one compile action. The specified file is
+/// considered to be the main source file for the translation unit.
+///
+/// JSON compilation databases can for example be generated in CMake projects
+/// by setting the flag -DCMAKE_EXPORT_COMPILE_COMMANDS.
+class JSONCompilationDatabase : public CompilationDatabase {
+public:
+
+  /// \brief Loads a JSON compilation database from the specified file.
+  ///
+  /// Returns NULL and sets ErrorMessage if the database could not be
+  /// loaded from the given file.
+  static JSONCompilationDatabase *loadFromFile(StringRef FilePath,
+                                               std::string &ErrorMessage);
+
+  /// \brief Loads a JSON compilation database from a data buffer.
+  ///
+  /// Returns NULL and sets ErrorMessage if the database could not be loaded.
+  static JSONCompilationDatabase *loadFromBuffer(StringRef DatabaseString,
+                                                 std::string &ErrorMessage);
+
+  /// \brief Returns all compile comamnds in which the specified file was
+  /// compiled.
+  ///
+  /// FIXME: Currently FilePath must be an absolute path inside the
+  /// source directory which does not have symlinks resolved.
+  virtual std::vector<CompileCommand> getCompileCommands(
+    StringRef FilePath) const;
+
+private:
+  /// \brief Constructs a JSON compilation database on a memory buffer.
+  JSONCompilationDatabase(llvm::MemoryBuffer *Database)
+    : Database(Database) {}
+
+  /// \brief Parses the database file and creates the index.
+  ///
+  /// Returns whether parsing succeeded. Sets ErrorMessage if parsing
+  /// failed.
+  bool parse(std::string &ErrorMessage);
+
+  // Tuple (directory, commandline) where 'commandline' is a JSON escaped bash
+  // escaped command line.
+  typedef std::pair<StringRef, StringRef> CompileCommandRef;
+
+  // Maps file paths to the compile command lines for that file.
+  llvm::StringMap< std::vector<CompileCommandRef> > IndexByFile;
+
+  llvm::OwningPtr<llvm::MemoryBuffer> Database;
+};
+
+} // end namespace tooling
+} // end namespace clang
+
+#endif // LLVM_CLANG_TOOLING_COMPILATION_DATABASE_H
+
diff --git a/include/clang/Tooling/Tooling.h b/include/clang/Tooling/Tooling.h
new file mode 100644
index 0000000000..868eae3068
--- /dev/null
+++ b/include/clang/Tooling/Tooling.h
@@ -0,0 +1,213 @@
+//===--- Tooling.h - Framework for standalone Clang tools -------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file implements functions to run clang tools standalone instead
+//  of running them as a plugin.
+//
+//  A ClangTool is initialized with a CompilationDatabase and a set of files
+//  to run over. The tool will then run a user-specified FrontendAction over
+//  all TUs in which the given files are compiled.
+//
+//  It is also possible to run a FrontendAction over a snippet of code by
+//  calling runSyntaxOnlyToolOnCode, which is useful for unit testing.
+//
+//  Applications that need more fine grained control over how to run
+//  multiple FrontendActions over code can use ToolInvocation.
+//
+//  Example tools:
+//  - running clang -fsyntax-only over source code from an editor to get
+//    fast syntax checks
+//  - running match/replace tools over C++ code
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLING_TOOLING_H
+#define LLVM_CLANG_TOOLING_TOOLING_H
+
+#include "llvm/ADT/StringMap.h"
+#include "llvm/ADT/Twine.h"
+#include "clang/Basic/FileManager.h"
+#include "clang/Basic/LLVM.h"
+#include "clang/Driver/Util.h"
+#include <string>
+#include <vector>
+
+namespace clang {
+
+namespace driver {
+class Compilation;
+} // end namespace driver
+
+class CompilerInvocation;
+class SourceManager;
+class FrontendAction;
+
+namespace tooling {
+
+class CompilationDatabase;
+
+/// \brief Interface to generate clang::FrontendActions.
+class FrontendActionFactory {
+public:
+  virtual ~FrontendActionFactory();
+
+  /// \brief Returns a new clang::FrontendAction.
+  ///
+  /// The caller takes ownership of the returned action.
+  virtual clang::FrontendAction *create() = 0;
+};
+
+/// \brief Returns a new FrontendActionFactory for a given type.
+///
+/// T must extend clang::FrontendAction.
+///
+/// Example:
+/// FrontendActionFactory *Factory =
+///   newFrontendActionFactory<clang::SyntaxOnlyAction>();
+template <typename T>
+FrontendActionFactory *newFrontendActionFactory();
+
+/// \brief Returns a new FrontendActionFactory for any type that provides an
+/// implementation of newFrontendAction().
+///
+/// FactoryT must implement: FrontendAction *newFrontendAction().
+///
+/// Example:
+/// struct ProvidesFrontendActions {
+///   FrontendAction *newFrontendAction();
+/// } Factory;
+/// FrontendActionFactory *FactoryAdapter =
+///   newFrontendActionFactory(&Factory);
+template <typename FactoryT>
+FrontendActionFactory *newFrontendActionFactory(FactoryT *ActionFactory);
+
+/// \brief Runs (and deletes) the tool on 'Code' with the -fsyntax-only flag.
+///
+/// \param ToolAction The action to run over the code.
+/// \param Code C++ code.
+/// \param FileName The file name which 'Code' will be mapped as.
+///
+/// \return - True if 'ToolAction' was successfully executed.
+bool runToolOnCode(clang::FrontendAction *ToolAction, const Twine &Code,
+                   const Twine &FileName = "input.cc");
+
+/// \brief Utility to run a FrontendAction in a single clang invocation.
+class ToolInvocation {
+ public:
+  /// \brief Create a tool invocation.
+  ///
+  /// \param CommandLine The command line arguments to clang.
+  /// \param ToolAction The action to be executed. Class takes ownership.
+  /// \param Files The FileManager used for the execution. Class does not take
+  /// ownership.
+  ToolInvocation(ArrayRef<std::string> CommandLine, FrontendAction *ToolAction,
+                 FileManager *Files);
+
+  /// \brief Map a virtual file to be used while running the tool.
+  ///
+  /// \param FilePath The path at which the content will be mapped.
+  /// \param Content A null terminated buffer of the file's content.
+  void mapVirtualFile(StringRef FilePath, StringRef Content);
+
+  /// \brief Run the clang invocation.
+  ///
+  /// \returns True if there were no errors during execution.
+  bool run();
+
+ private:
+  void addFileMappingsTo(SourceManager &SourceManager);
+
+  bool runInvocation(const char *BinaryName,
+                     clang::driver::Compilation *Compilation,
+                     clang::CompilerInvocation *Invocation,
+                     const clang::driver::ArgStringList &CC1Args,
+                     clang::FrontendAction *ToolAction);
+
+  std::vector<std::string> CommandLine;
+  llvm::OwningPtr<FrontendAction> ToolAction;
+  FileManager *Files;
+  // Maps <file name> -> <file content>.
+  llvm::StringMap<StringRef> MappedFileContents;
+};
+
+/// \brief Utility to run a FrontendAction over a set of files.
+///
+/// This class is written to be usable for command line utilities.
+class ClangTool {
+ public:
+  /// \brief Constructs a clang tool to run over a list of files.
+  ///
+  /// \param Compilations The CompilationDatabase which contains the compile
+  ///        command lines for the given source paths.
+  /// \param SourcePaths The source files to run over. If a source files is
+  ///        not found in Compilations, it is skipped.
+  ClangTool(const CompilationDatabase &Compilations,
+            ArrayRef<std::string> SourcePaths);
+
+  /// \brief Map a virtual file to be used while running the tool.
+  ///
+  /// \param FilePath The path at which the content will be mapped.
+  /// \param Content A null terminated buffer of the file's content.
+  void mapVirtualFile(StringRef FilePath, StringRef Content);
+
+  /// Runs a frontend action over all files specified in the command line.
+  ///
+  /// \param ActionFactory Factory generating the frontend actions. The function
+  /// takes ownership of this parameter. A new action is generated for every
+  /// processed translation unit.
+  int run(FrontendActionFactory *ActionFactory);
+
+  /// \brief Returns the file manager used in the tool.
+  ///
+  /// The file manager is shared between all translation units.
+  FileManager &getFiles() { return Files; }
+
+ private:
+  // We store command lines as pair (file name, command line).
+  typedef std::pair< std::string, std::vector<std::string> > CommandLine;
+  std::vector<CommandLine> CommandLines;
+
+  FileManager Files;
+  // Contains a list of pairs (<file name>, <file content>).
+  std::vector< std::pair<StringRef, StringRef> > MappedFileContents;
+};
+
+template <typename T>
+FrontendActionFactory *newFrontendActionFactory() {
+  class SimpleFrontendActionFactory : public FrontendActionFactory {
+  public:
+    virtual clang::FrontendAction *create() { return new T; }
+  };
+
+  return new SimpleFrontendActionFactory;
+}
+
+template <typename FactoryT>
+FrontendActionFactory *newFrontendActionFactory(FactoryT *ActionFactory) {
+  class FrontendActionFactoryAdapter : public FrontendActionFactory {
+  public:
+    explicit FrontendActionFactoryAdapter(FactoryT *ActionFactory)
+      : ActionFactory(ActionFactory) {}
+
+    virtual clang::FrontendAction *create() {
+      return ActionFactory->newFrontendAction();
+    }
+
+  private:
+    FactoryT *ActionFactory;
+  };
+
+  return new FrontendActionFactoryAdapter(ActionFactory);
+}
+
+} // end namespace tooling
+} // end namespace clang
+
+#endif // LLVM_CLANG_TOOLING_TOOLING_H
+
diff --git a/lib/CMakeLists.txt b/lib/CMakeLists.txt
index 54d296c3ab..7af01ece6b 100644
--- a/lib/CMakeLists.txt
+++ b/lib/CMakeLists.txt
@@ -13,5 +13,6 @@ add_subdirectory(Driver)
 add_subdirectory(Serialization)
 add_subdirectory(Frontend)
 add_subdirectory(FrontendTool)
+add_subdirectory(Tooling)
 add_subdirectory(Index)
 add_subdirectory(StaticAnalyzer)
diff --git a/lib/Makefile b/lib/Makefile
index 69c5cd5d83..a73c6e6d62 100755
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -10,7 +10,7 @@ CLANG_LEVEL := ..
 
 PARALLEL_DIRS = Headers Basic Lex Parse AST Sema CodeGen Analysis \
                 StaticAnalyzer Edit Rewrite ARCMigrate Serialization Frontend \
-                FrontendTool Index Driver
+                FrontendTool Tooling Index Driver
 
 include $(CLANG_LEVEL)/Makefile
 
diff --git a/lib/Tooling/CMakeLists.txt b/lib/Tooling/CMakeLists.txt
new file mode 100644
index 0000000000..b84b211941
--- /dev/null
+++ b/lib/Tooling/CMakeLists.txt
@@ -0,0 +1,7 @@
+set(LLVM_LINK_COMPONENTS support)
+SET(LLVM_USED_LIBS clangBasic clangFrontend clangAST)
+
+add_clang_library(clangTooling
+  CompilationDatabase.cpp
+  Tooling.cpp
+  )
diff --git a/lib/Tooling/CompilationDatabase.cpp b/lib/Tooling/CompilationDatabase.cpp
new file mode 100644
index 0000000000..eea1055f49
--- /dev/null
+++ b/lib/Tooling/CompilationDatabase.cpp
@@ -0,0 +1,230 @@
+//===--- CompilationDatabase.cpp - ----------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file contains multiple implementations for CompilationDatabases.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Tooling/CompilationDatabase.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/Support/JSONParser.h"
+#include "llvm/Support/Path.h"
+#include "llvm/Support/system_error.h"
+
+namespace clang {
+namespace tooling {
+
+namespace {
+
+/// \brief A parser for JSON escaped strings of command line arguments.
+///
+/// Assumes \-escaping for quoted arguments (see the documentation of
+/// unescapeJSONCommandLine(...)).
+class CommandLineArgumentParser {
+ public:
+  CommandLineArgumentParser(StringRef CommandLine)
+      : Input(CommandLine), Position(Input.begin()-1) {}
+
+  std::vector<std::string> parse() {
+    bool HasMoreInput = true;
+    while (HasMoreInput && nextNonWhitespace()) {
+      std::string Argument;
+      HasMoreInput = parseStringInto(Argument);
+      CommandLine.push_back(Argument);
+    }
+    return CommandLine;
+  }
+
+ private:
+  // All private methods return true if there is more input available.
+
+  bool parseStringInto(std::string &String) {
+    do {
+      if (*Position == '"') {
+        if (!parseQuotedStringInto(String)) return false;
+      } else {
+        if (!parseFreeStringInto(String)) return false;
+      }
+    } while (*Position != ' ');
+    return true;
+  }
+
+  bool parseQuotedStringInto(std::string &String) {
+    if (!next()) return false;
+    while (*Position != '"') {
+      if (!skipEscapeCharacter()) return false;
+      String.push_back(*Position);
+      if (!next()) return false;
+    }
+    return next();
+  }
+
+  bool parseFreeStringInto(std::string &String) {
+    do {
+      if (!skipEscapeCharacter()) return false;
+      String.push_back(*Position);
+      if (!next()) return false;
+    } while (*Position != ' ' && *Position != '"');
+    return true;
+  }
+
+  bool skipEscapeCharacter() {
+    if (*Position == '\\') {
+      return next();
+    }
+    return true;
+  }
+
+  bool nextNonWhitespace() {
+    do {
+      if (!next()) return false;
+    } while (*Position == ' ');
+    return true;
+  }
+
+  bool next() {
+    ++Position;
+    if (Position == Input.end()) return false;
+    // Remove the JSON escaping first. This is done unconditionally.
+    if (*Position == '\\') ++Position;
+    return Position != Input.end();
+  }
+
+  const StringRef Input;
+  StringRef::iterator Position;
+  std::vector<std::string> CommandLine;
+};
+
+std::vector<std::string> unescapeJSONCommandLine(
+    StringRef JSONEscapedCommandLine) {
+  CommandLineArgumentParser parser(JSONEscapedCommandLine);
+  return parser.parse();
+}
+
+} // end namespace
+
+CompilationDatabase::~CompilationDatabase() {}
+
+CompilationDatabase *
+CompilationDatabase::loadFromDirectory(StringRef BuildDirectory,
+                                       std::string &ErrorMessage) {
+  llvm::SmallString<1024> JSONDatabasePath(BuildDirectory);
+  llvm::sys::path::append(JSONDatabasePath, "compile_commands.json");
+  llvm::OwningPtr<CompilationDatabase> Database(
+    JSONCompilationDatabase::loadFromFile(JSONDatabasePath, ErrorMessage));
+  if (!Database) {
+    return NULL;
+  }
+  return Database.take();
+}
+
+JSONCompilationDatabase *
+JSONCompilationDatabase::loadFromFile(StringRef FilePath,
+                                      std::string &ErrorMessage) {
+  llvm::OwningPtr<llvm::MemoryBuffer> DatabaseBuffer;
+  llvm::error_code Result =
+    llvm::MemoryBuffer::getFile(FilePath, DatabaseBuffer);
+  if (Result != 0) {
+    ErrorMessage = "Error while opening JSON database: " + Result.message();
+    return NULL;
+  }
+  llvm::OwningPtr<JSONCompilationDatabase> Database(
+    new JSONCompilationDatabase(DatabaseBuffer.take()));
+  if (!Database->parse(ErrorMessage))
+    return NULL;
+  return Database.take();
+}
+
+JSONCompilationDatabase *
+JSONCompilationDatabase::loadFromBuffer(StringRef DatabaseString,
+                                        std::string &ErrorMessage) {
+  llvm::OwningPtr<llvm::MemoryBuffer> DatabaseBuffer(
+      llvm::MemoryBuffer::getMemBuffer(DatabaseString));
+  llvm::OwningPtr<JSONCompilationDatabase> Database(
+    new JSONCompilationDatabase(DatabaseBuffer.take()));
+  if (!Database->parse(ErrorMessage))
+    return NULL;
+  return Database.take();
+}
+
+std::vector<CompileCommand>
+JSONCompilationDatabase::getCompileCommands(StringRef FilePath) const {
+  llvm::StringMap< std::vector<CompileCommandRef> >::const_iterator
+    CommandsRefI = IndexByFile.find(FilePath);
+  if (CommandsRefI == IndexByFile.end())
+    return std::vector<CompileCommand>();
+  const std::vector<CompileCommandRef> &CommandsRef = CommandsRefI->getValue();
+  std::vector<CompileCommand> Commands;
+  for (int I = 0, E = CommandsRef.size(); I != E; ++I) {
+    Commands.push_back(CompileCommand(
+      // FIXME: Escape correctly:
+      CommandsRef[I].first,
+      unescapeJSONCommandLine(CommandsRef[I].second)));
+  }
+  return Commands;
+}
+
+bool JSONCompilationDatabase::parse(std::string &ErrorMessage) {
+  llvm::SourceMgr SM;
+  llvm::JSONParser Parser(Database->getBuffer(), &SM);
+  llvm::JSONValue *Root = Parser.parseRoot();
+  if (Root == NULL) {
+    ErrorMessage = "Error while parsing JSON.";
+    return false;
+  }
+  llvm::JSONArray *Array = dyn_cast<llvm::JSONArray>(Root);
+  if (Array == NULL) {
+    ErrorMessage = "Expected array.";
+    return false;
+  }
+  for (llvm::JSONArray::const_iterator AI = Array->begin(), AE = Array->end();
+       AI != AE; ++AI) {
+    const llvm::JSONObject *Object = dyn_cast<llvm::JSONObject>(*AI);
+    if (Object == NULL) {
+      ErrorMessage = "Expected object.";
+      return false;
+    }
+    StringRef EntryDirectory;
+    StringRef EntryFile;
+    StringRef EntryCommand;
+    for (llvm::JSONObject::const_iterator KVI = Object->begin(),
+                                          KVE = Object->end();
+         KVI != KVE; ++KVI) {
+      const llvm::JSONValue *Value = (*KVI)->Value;
+      if (Value == NULL) {
+        ErrorMessage = "Expected value.";
+        return false;
+      }
+      const llvm::JSONString *ValueString =
+        dyn_cast<llvm::JSONString>(Value);
+      if (ValueString == NULL) {
+        ErrorMessage = "Expected string as value.";
+        return false;
+      }
+      if ((*KVI)->Key->getRawText() == "directory") {
+        EntryDirectory = ValueString->getRawText();
+      } else if ((*KVI)->Key->getRawText() == "file") {
+        EntryFile = ValueString->getRawText();
+      } else if ((*KVI)->Key->getRawText() == "command") {
+        EntryCommand = ValueString->getRawText();
+      } else {
+        ErrorMessage = (Twine("Unknown key: \"") +
+                        (*KVI)->Key->getRawText() + "\"").str();
+        return false;
+      }
+    }
+    IndexByFile[EntryFile].push_back(
+      CompileCommandRef(EntryDirectory, EntryCommand));
+  }
+  return true;
+}
+
+} // end namespace tooling
+} // end namespace clang
+
diff --git a/lib/Tooling/Makefile b/lib/Tooling/Makefile
new file mode 100644
index 0000000000..0d2e7a29bc
--- /dev/null
+++ b/lib/Tooling/Makefile
@@ -0,0 +1,13 @@
+##===- clang/lib/Tooling/Makefile ---------------------------*- Makefile -*-===##
+#
+#                     The LLVM Compiler Infrastructure
+#
+# This file is distributed under the University of Illinois Open Source
+# License. See LICENSE.TXT for details.
+#
+##===----------------------------------------------------------------------===##
+
+CLANG_LEVEL := ../..
+LIBRARYNAME := clangTooling
+
+include $(CLANG_LEVEL)/Makefile
diff --git a/lib/Tooling/Tooling.cpp b/lib/Tooling/Tooling.cpp
new file mode 100644
index 0000000000..20284daaba
--- /dev/null
+++ b/lib/Tooling/Tooling.cpp
@@ -0,0 +1,291 @@
+//===--- Tooling.cpp - Running clang standalone tools ---------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file implements functions to run clang tools standalone instead
+//  of running them as a plugin.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Tooling/Tooling.h"
+#include "clang/Tooling/CompilationDatabase.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/Support/Host.h"
+#include "llvm/Support/raw_ostream.h"
+#include "clang/Driver/Compilation.h"
+#include "clang/Driver/Driver.h"
+#include "clang/Driver/Tool.h"
+#include "clang/Frontend/CompilerInstance.h"
+#include "clang/Frontend/FrontendAction.h"
+#include "clang/Frontend/FrontendDiagnostic.h"
+#include "clang/Frontend/TextDiagnosticPrinter.h"
+
+namespace clang {
+namespace tooling {
+
+FrontendActionFactory::~FrontendActionFactory() {}
+
+// FIXME: This file contains structural duplication with other parts of the
+// code that sets up a compiler to run tools on it, and we should refactor
+// it to be based on the same framework.
+
+/// \brief Builds a clang driver initialized for running clang tools.
+static clang::driver::Driver *newDriver(clang::DiagnosticsEngine *Diagnostics,
+                                        const char *BinaryName) {
+  const std::string DefaultOutputName = "a.out";
+  clang::driver::Driver *CompilerDriver = new clang::driver::Driver(
+      BinaryName, llvm::sys::getDefaultTargetTriple(),
+      DefaultOutputName, false, *Diagnostics);
+  CompilerDriver->setTitle("clang_based_tool");
+  return CompilerDriver;
+}
+
+/// \brief Retrieves the clang CC1 specific flags out of the compilation's jobs.
+///
+/// Returns NULL on error.
+static const clang::driver::ArgStringList *getCC1Arguments(
+    clang::DiagnosticsEngine *Diagnostics,
+    clang::driver::Compilation *Compilation) {
+  // We expect to get back exactly one Command job, if we didn't something
+  // failed. Extract that job from the Compilation.
+  const clang::driver::JobList &Jobs = Compilation->getJobs();
+  if (Jobs.size() != 1 || !isa<clang::driver::Command>(*Jobs.begin())) {
+    llvm::SmallString<256> error_msg;
+    llvm::raw_svector_ostream error_stream(error_msg);
+    Compilation->PrintJob(error_stream, Compilation->getJobs(), "; ", true);
+    Diagnostics->Report(clang::diag::err_fe_expected_compiler_job)
+        << error_stream.str();
+    return NULL;
+  }
+
+  // The one job we find should be to invoke clang again.
+  const clang::driver::Command *Cmd =
+      cast<clang::driver::Command>(*Jobs.begin());
+  if (StringRef(Cmd->getCreator().getName()) != "clang") {
+    Diagnostics->Report(clang::diag::err_fe_expected_clang_command);
+    return NULL;
+  }
+
+  return &Cmd->getArguments();
+}
+
+/// \brief Returns a clang build invocation initialized from the CC1 flags.
+static clang::CompilerInvocation *newInvocation(
+    clang::DiagnosticsEngine *Diagnostics,
+    const clang::driver::ArgStringList &CC1Args) {
+  assert(!CC1Args.empty() && "Must at least contain the program name!");
+  clang::CompilerInvocation *Invocation = new clang::CompilerInvocation;
+  clang::CompilerInvocation::CreateFromArgs(
+      *Invocation, CC1Args.data() + 1, CC1Args.data() + CC1Args.size(),
+      *Diagnostics);
+  Invocation->getFrontendOpts().DisableFree = false;
+  return Invocation;
+}
+
+bool runToolOnCode(clang::FrontendAction *ToolAction, const Twine &Code,
+                   const Twine &FileName) {
+  SmallString<16> FileNameStorage;
+  StringRef FileNameRef = FileName.toNullTerminatedStringRef(FileNameStorage);
+  const char *const CommandLine[] = {
+      "clang-tool", "-fsyntax-only", FileNameRef.data()
+  };
+  FileManager Files((FileSystemOptions()));
+  ToolInvocation Invocation(
+      std::vector<std::string>(
+          CommandLine,
+          CommandLine + llvm::array_lengthof(CommandLine)),
+      ToolAction, &Files);
+
+  SmallString<1024> CodeStorage;
+  Invocation.mapVirtualFile(FileNameRef,
+                            Code.toNullTerminatedStringRef(CodeStorage));
+  return Invocation.run();
+}
+
+/// \brief Returns the absolute path of 'File', by prepending it with
+/// 'BaseDirectory' if 'File' is not absolute.
+///
+/// Otherwise returns 'File'.
+/// If 'File' starts with "./", the returned path will not contain the "./".
+/// Otherwise, the returned path will contain the literal path-concatenation of
+/// 'BaseDirectory' and 'File'.
+///
+/// \param File Either an absolute or relative path.
+/// \param BaseDirectory An absolute path.
+static std::string getAbsolutePath(
+    StringRef File, StringRef BaseDirectory) {
+  assert(llvm::sys::path::is_absolute(BaseDirectory));
+  if (llvm::sys::path::is_absolute(File)) {
+    return File;
+  }
+  StringRef RelativePath(File);
+  if (RelativePath.startswith("./")) {
+    RelativePath = RelativePath.substr(strlen("./"));
+  }
+  llvm::SmallString<1024> AbsolutePath(BaseDirectory);
+  llvm::sys::path::append(AbsolutePath, RelativePath);
+  return AbsolutePath.str();
+}
+
+ToolInvocation::ToolInvocation(
+    ArrayRef<std::string> CommandLine, FrontendAction *ToolAction,
+    FileManager *Files)
+    : CommandLine(CommandLine.vec()), ToolAction(ToolAction), Files(Files) {
+}
+
+void ToolInvocation::mapVirtualFile(StringRef FilePath, StringRef Content) {
+  MappedFileContents[FilePath] = Content;
+}
+
+bool ToolInvocation::run() {
+  std::vector<const char*> Argv;
+  for (int I = 0, E = CommandLine.size(); I != E; ++I)
+    Argv.push_back(CommandLine[I].c_str());
+  const char *const BinaryName = Argv[0];
+  DiagnosticOptions DefaultDiagnosticOptions;
+  TextDiagnosticPrinter DiagnosticPrinter(
+      llvm::errs(), DefaultDiagnosticOptions);
+  DiagnosticsEngine Diagnostics(llvm::IntrusiveRefCntPtr<clang::DiagnosticIDs>(
+      new DiagnosticIDs()), &DiagnosticPrinter, false);
+
+  const llvm::OwningPtr<clang::driver::Driver> Driver(
+      newDriver(&Diagnostics, BinaryName));
+  // Since the input might only be virtual, don't check whether it exists.
+  Driver->setCheckInputsExist(false);
+  const llvm::OwningPtr<clang::driver::Compilation> Compilation(
+      Driver->BuildCompilation(llvm::makeArrayRef(Argv)));
+  const clang::driver::ArgStringList *const CC1Args = getCC1Arguments(
+      &Diagnostics, Compilation.get());
+  if (CC1Args == NULL) {
+    return false;
+  }
+  llvm::OwningPtr<clang::CompilerInvocation> Invocation(
+      newInvocation(&Diagnostics, *CC1Args));
+  return runInvocation(BinaryName, Compilation.get(),
+                       Invocation.take(), *CC1Args, ToolAction.take());
+}
+
+// Exists solely for the purpose of lookup of the resource path.
+static int StaticSymbol;
+
+bool ToolInvocation::runInvocation(
+    const char *BinaryName,
+    clang::driver::Compilation *Compilation,
+    clang::CompilerInvocation *Invocation,
+    const clang::driver::ArgStringList &CC1Args,
+    clang::FrontendAction *ToolAction) {
+  llvm::OwningPtr<clang::FrontendAction> ScopedToolAction(ToolAction);
+  // Show the invocation, with -v.
+  if (Invocation->getHeaderSearchOpts().Verbose) {
+    llvm::errs() << "clang Invocation:\n";
+    Compilation->PrintJob(llvm::errs(), Compilation->getJobs(), "\n", true);
+    llvm::errs() << "\n";
+  }
+
+  // Create a compiler instance to handle the actual work.
+  clang::CompilerInstance Compiler;
+  Compiler.setInvocation(Invocation);
+  Compiler.setFileManager(Files);
+  // FIXME: What about LangOpts?
+
+  // Create the compilers actual diagnostics engine.
+  Compiler.createDiagnostics(CC1Args.size(),
+                             const_cast<char**>(CC1Args.data()));
+  if (!Compiler.hasDiagnostics())
+    return false;
+
+  Compiler.createSourceManager(*Files);
+  addFileMappingsTo(Compiler.getSourceManager());
+
+  // Infer the builtin include path if unspecified.
+  if (Compiler.getHeaderSearchOpts().UseBuiltinIncludes &&
+      Compiler.getHeaderSearchOpts().ResourceDir.empty()) {
+    // This just needs to be some symbol in the binary.
+    void *const SymbolAddr = &StaticSymbol;
+    Compiler.getHeaderSearchOpts().ResourceDir =
+        clang::CompilerInvocation::GetResourcesPath(BinaryName, SymbolAddr);
+  }
+
+  const bool Success = Compiler.ExecuteAction(*ToolAction);
+
+  Compiler.resetAndLeakFileManager();
+  return Success;
+}
+
+void ToolInvocation::addFileMappingsTo(SourceManager &Sources) {
+  for (llvm::StringMap<StringRef>::const_iterator
+           It = MappedFileContents.begin(), End = MappedFileContents.end();
+       It != End; ++It) {
+    // Inject the code as the given file name into the preprocessor options.
+    const llvm::MemoryBuffer *Input =
+        llvm::MemoryBuffer::getMemBuffer(It->getValue());
+    // FIXME: figure out what '0' stands for.
+    const FileEntry *FromFile = Files->getVirtualFile(
+        It->getKey(), Input->getBufferSize(), 0);
+    // FIXME: figure out memory management ('true').
+    Sources.overrideFileContents(FromFile, Input, true);
+  }
+}
+
+ClangTool::ClangTool(const CompilationDatabase &Compilations,
+                     ArrayRef<std::string> SourcePaths)
+    : Files((FileSystemOptions())) {
+  StringRef BaseDirectory(::getenv("PWD"));
+  for (unsigned I = 0, E = SourcePaths.size(); I != E; ++I) {
+    llvm::SmallString<1024> File(getAbsolutePath(
+        SourcePaths[I], BaseDirectory));
+
+    std::vector<CompileCommand> CompileCommands =
+      Compilations.getCompileCommands(File.str());
+    if (!CompileCommands.empty()) {
+      for (int I = 0, E = CompileCommands.size(); I != E; ++I) {
+        CompileCommand &Command = CompileCommands[I];
+        if (!Command.Directory.empty()) {
+          // FIXME: What should happen if CommandLine includes -working-directory
+          // as well?
+          Command.CommandLine.push_back(
+            "-working-directory=" + Command.Directory);
+        }
+        CommandLines.push_back(std::make_pair(File.str(), Command.CommandLine));
+      }
+    } else {
+      // FIXME: There are two use cases here: doing a fuzzy
+      // "find . -name '*.cc' |xargs tool" match, where as a user I don't care
+      // about the .cc files that were not found, and the use case where I
+      // specify all files I want to run over explicitly, where this should
+      // be an error. We'll want to add an option for this.
+      llvm::outs() << "Skipping " << File << ". Command line not found.\n";
+    }
+  }
+}
+
+void ClangTool::mapVirtualFile(StringRef FilePath, StringRef Content) {
+  MappedFileContents.push_back(std::make_pair(FilePath, Content));
+}
+
+int ClangTool::run(FrontendActionFactory *ActionFactory) {
+  bool ProcessingFailed = false;
+  for (unsigned I = 0; I < CommandLines.size(); ++I) {
+    std::string File = CommandLines[I].first;
+    std::vector<std::string> &CommandLine = CommandLines[I].second;
+    llvm::outs() << "Processing: " << File << ".\n";
+    ToolInvocation Invocation(CommandLine, ActionFactory->create(), &Files);
+    for (int I = 0, E = MappedFileContents.size(); I != E; ++I) {
+      Invocation.mapVirtualFile(MappedFileContents[I].first,
+                                MappedFileContents[I].second);
+    }
+    if (!Invocation.run()) {
+      llvm::outs() << "Error while processing " << File << ".\n";
+      ProcessingFailed = true;
+    }
+  }
+  return ProcessingFailed ? 1 : 0;
+}
+
+} // end namespace tooling
+} // end namespace clang
diff --git a/test/Tooling/clang-check.cpp b/test/Tooling/clang-check.cpp
new file mode 100644
index 0000000000..f3ff43eee4
--- /dev/null
+++ b/test/Tooling/clang-check.cpp
@@ -0,0 +1,8 @@
+// RUN: rm -rf %t
+// RUN: mkdir %t
+// RUN: echo '[{"directory":".","command":"clang++ -c %t/test.cpp","file":"%t/test.cpp"}]' > %t/compile_commands.json
+// RUN: cp "%s" "%t/test.cpp"
+// RUN: clang-check "%t" "%t/test.cpp" 2>&1|FileCheck %s
+// FIXME: Make the above easier.
+
+invalid; // CHECK: C++ requires
diff --git a/tools/CMakeLists.txt b/tools/CMakeLists.txt
index 117d10a603..ab4748d1b9 100644
--- a/tools/CMakeLists.txt
+++ b/tools/CMakeLists.txt
@@ -4,3 +4,4 @@ add_subdirectory(arcmt-test)
 add_subdirectory(c-arcmt-test)
 add_subdirectory(diagtool)
 add_subdirectory(driver)
+add_subdirectory(clang-check)
diff --git a/tools/Makefile b/tools/Makefile
index f647f56a51..5059ade930 100644
--- a/tools/Makefile
+++ b/tools/Makefile
@@ -8,7 +8,8 @@
 ##===----------------------------------------------------------------------===##
 
 CLANG_LEVEL := ..
-DIRS := driver libclang c-index-test arcmt-test c-arcmt-test diagtool
+DIRS := driver libclang c-index-test arcmt-test c-arcmt-test diagtool \
+        clang-check
 
 include $(CLANG_LEVEL)/../../Makefile.config
 
diff --git a/tools/clang-check/CMakeLists.txt b/tools/clang-check/CMakeLists.txt
new file mode 100644
index 0000000000..851d6cdd16
--- /dev/null
+++ b/tools/clang-check/CMakeLists.txt
@@ -0,0 +1,5 @@
+set(LLVM_USED_LIBS clangTooling clangBasic)
+
+add_clang_executable(clang-check
+  ClangCheck.cpp
+  )
diff --git a/tools/clang-check/ClangCheck.cpp b/tools/clang-check/ClangCheck.cpp
new file mode 100644
index 0000000000..b5b6bd5a14
--- /dev/null
+++ b/tools/clang-check/ClangCheck.cpp
@@ -0,0 +1,62 @@
+//===- examples/Tooling/ClangCheck.cpp - Clang check tool -----------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file implements a clang-check tool that runs the
+//  clang::SyntaxOnlyAction over a number of translation units.
+//
+//  Usage:
+//  clang-check <cmake-output-dir> <file1> <file2> ...
+//
+//  Where <cmake-output-dir> is a CMake build directory in which a file named
+//  compile_commands.json exists (enable -DCMAKE_EXPORT_COMPILE_COMMANDS in
+//  CMake to get this output).
+//
+//  <file1> ... specify the paths of files in the CMake source tree. This  path
+//  is looked up in the compile command database. If the path of a file is
+//  absolute, it needs to point into CMake's source tree. If the path is
+//  relative, the current working directory needs to be in the CMake source
+//  tree and the file must be in a subdirectory of the current working
+//  directory. "./" prefixes in the relative files will be automatically
+//  removed, but the rest of a relative path must be a suffix of a path in
+//  the compile command line database.
+//
+//  For example, to use clang-check on all files in a subtree of the source
+//  tree, use:
+//
+//    /path/in/subtree $ find . -name '*.cpp'| xargs clang-check /path/to/source
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/CommandLine.h"
+#include "clang/Frontend/FrontendActions.h"
+#include "clang/Tooling/CompilationDatabase.h"
+#include "clang/Tooling/Tooling.h"
+
+using namespace clang::tooling;
+using namespace llvm;
+
+cl::opt<std::string> BuildPath(
+  cl::Positional,
+  cl::desc("<build-path>"));
+
+cl::list<std::string> SourcePaths(
+  cl::Positional,
+  cl::desc("<source0> [... <sourceN>]"),
+  cl::OneOrMore);
+
+int main(int argc, char **argv) {
+  cl::ParseCommandLineOptions(argc, argv);
+  std::string ErrorMessage;
+  llvm::OwningPtr<CompilationDatabase> Compilations(
+    CompilationDatabase::loadFromDirectory(BuildPath, ErrorMessage));
+  if (!Compilations)
+    llvm::report_fatal_error(ErrorMessage);
+  ClangTool Tool(*Compilations, SourcePaths);
+  return Tool.run(newFrontendActionFactory<clang::SyntaxOnlyAction>());
+}
diff --git a/tools/clang-check/Makefile b/tools/clang-check/Makefile
new file mode 100644
index 0000000000..11dc05e670
--- /dev/null
+++ b/tools/clang-check/Makefile
@@ -0,0 +1,24 @@
+##===- tools/clang-check/Makefile --------------------------*- Makefile -*-===##
+#
+#                     The LLVM Compiler Infrastructure
+#
+# This file is distributed under the University of Illinois Open Source
+# License. See LICENSE.TXT for details.
+#
+##===----------------------------------------------------------------------===##
+
+CLANG_LEVEL := ../..
+
+TOOLNAME = clang-check
+NO_INSTALL = 1
+
+# No plugins, optimize startup time.
+TOOL_NO_EXPORTS = 1
+
+LINK_COMPONENTS := support mc
+USEDLIBS = clangFrontend.a clangSerialization.a clangDriver.a \
+           clangTooling.a clangParse.a clangSema.a clangAnalysis.a \
+           clangAST.a clangLex.a clangBasic.a
+
+include $(CLANG_LEVEL)/Makefile
+
diff --git a/unittests/CMakeLists.txt b/unittests/CMakeLists.txt
index e64fa1c722..0b3eac95d4 100644
--- a/unittests/CMakeLists.txt
+++ b/unittests/CMakeLists.txt
@@ -65,3 +65,9 @@ add_clang_unittest(Frontend
   Frontend/FrontendActionTest.cpp
   USED_LIBS gtest gtest_main clangFrontend
  )
+
+add_clang_unittest(Tooling
+  Tooling/CompilationDatabaseTest.cpp
+  Tooling/ToolingTest.cpp
+  USED_LIBS gtest gtest_main clangTooling
+ )
diff --git a/unittests/Makefile b/unittests/Makefile
index 66c006232d..05449d8ccf 100644
--- a/unittests/Makefile
+++ b/unittests/Makefile
@@ -14,7 +14,7 @@ ifndef CLANG_LEVEL
 
 IS_UNITTEST_LEVEL := 1
 CLANG_LEVEL := ..
-PARALLEL_DIRS = Basic Frontend Lex
+PARALLEL_DIRS = Basic Frontend Lex Tooling
 
 endif  # CLANG_LEVEL
 
diff --git a/unittests/Tooling/CompilationDatabaseTest.cpp b/unittests/Tooling/CompilationDatabaseTest.cpp
new file mode 100644
index 0000000000..9747de2554
--- /dev/null
+++ b/unittests/Tooling/CompilationDatabaseTest.cpp
@@ -0,0 +1,223 @@
+//===- unittest/Tooling/CompilationDatabaseTest.cpp -----------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/AST/ASTConsumer.h"
+#include "clang/AST/DeclCXX.h"
+#include "clang/AST/DeclGroup.h"
+#include "clang/Frontend/FrontendAction.h"
+#include "clang/Tooling/CompilationDatabase.h"
+#include "clang/Tooling/Tooling.h"
+#include "gtest/gtest.h"
+
+namespace clang {
+namespace tooling {
+
+static CompileCommand findCompileArgsInJsonDatabase(StringRef FileName,
+                                                    StringRef JSONDatabase,
+                                                    std::string &ErrorMessage) {
+  llvm::OwningPtr<CompilationDatabase> Database(
+      JSONCompilationDatabase::loadFromBuffer(JSONDatabase, ErrorMessage));
+  if (!Database)
+    return CompileCommand();
+  std::vector<CompileCommand> Commands = Database->getCompileCommands(FileName);
+  EXPECT_LE(Commands.size(), 1u);
+  if (Commands.empty())
+    return CompileCommand();
+  return Commands[0];
+}
+
+TEST(findCompileArgsInJsonDatabase, FindsNothingIfEmpty) {
+  std::string ErrorMessage;
+  CompileCommand NotFound = findCompileArgsInJsonDatabase(
+    "a-file.cpp", "", ErrorMessage);
+  EXPECT_TRUE(NotFound.CommandLine.empty()) << ErrorMessage;
+  EXPECT_TRUE(NotFound.Directory.empty()) << ErrorMessage;
+}
+
+TEST(findCompileArgsInJsonDatabase, ReadsSingleEntry) {
+  StringRef Directory("/some/directory");
+  StringRef FileName("/path/to/a-file.cpp");
+  StringRef Command("/path/to/compiler and some arguments");
+  std::string ErrorMessage;
+  CompileCommand FoundCommand = findCompileArgsInJsonDatabase(
+    FileName,
+    ("[{\"directory\":\"" + Directory + "\"," +
+       "\"command\":\"" + Command + "\","
+       "\"file\":\"" + FileName + "\"}]").str(),
+    ErrorMessage);
+  EXPECT_EQ(Directory, FoundCommand.Directory) << ErrorMessage;
+  ASSERT_EQ(4u, FoundCommand.CommandLine.size()) << ErrorMessage;
+  EXPECT_EQ("/path/to/compiler", FoundCommand.CommandLine[0]) << ErrorMessage;
+  EXPECT_EQ("and", FoundCommand.CommandLine[1]) << ErrorMessage;
+  EXPECT_EQ("some", FoundCommand.CommandLine[2]) << ErrorMessage;
+  EXPECT_EQ("arguments", FoundCommand.CommandLine[3]) << ErrorMessage;
+
+  CompileCommand NotFound = findCompileArgsInJsonDatabase(
+    "a-file.cpp",
+    ("[{\"directory\":\"" + Directory + "\"," +
+       "\"command\":\"" + Command + "\","
+       "\"file\":\"" + FileName + "\"}]").str(),
+    ErrorMessage);
+  EXPECT_TRUE(NotFound.Directory.empty()) << ErrorMessage;
+  EXPECT_TRUE(NotFound.CommandLine.empty()) << ErrorMessage;
+}
+
+TEST(findCompileArgsInJsonDatabase, ReadsCompileCommandLinesWithSpaces) {
+  StringRef Directory("/some/directory");
+  StringRef FileName("/path/to/a-file.cpp");
+  StringRef Command("\\\"/path to compiler\\\" \\\"and an argument\\\"");
+  std::string ErrorMessage;
+  CompileCommand FoundCommand = findCompileArgsInJsonDatabase(
+    FileName,
+    ("[{\"directory\":\"" + Directory + "\"," +
+       "\"command\":\"" + Command + "\","
+       "\"file\":\"" + FileName + "\"}]").str(),
+    ErrorMessage);
+  ASSERT_EQ(2u, FoundCommand.CommandLine.size());
+  EXPECT_EQ("/path to compiler", FoundCommand.CommandLine[0]) << ErrorMessage;
+  EXPECT_EQ("and an argument", FoundCommand.CommandLine[1]) << ErrorMessage;
+}
+
+TEST(findCompileArgsInJsonDatabase, ReadsDirectoryWithSpaces) {
+  StringRef Directory("/some directory / with spaces");
+  StringRef FileName("/path/to/a-file.cpp");
+  StringRef Command("a command");
+  std::string ErrorMessage;
+  CompileCommand FoundCommand = findCompileArgsInJsonDatabase(
+    FileName,
+    ("[{\"directory\":\"" + Directory + "\"," +
+       "\"command\":\"" + Command + "\","
+       "\"file\":\"" + FileName + "\"}]").str(),
+    ErrorMessage);
+  EXPECT_EQ(Directory, FoundCommand.Directory) << ErrorMessage;
+}
+
+TEST(findCompileArgsInJsonDatabase, FindsEntry) {
+  StringRef Directory("directory");
+  StringRef FileName("file");
+  StringRef Command("command");
+  std::string JsonDatabase = "[";
+  for (int I = 0; I < 10; ++I) {
+    if (I > 0) JsonDatabase += ",";
+    JsonDatabase +=
+      ("{\"directory\":\"" + Directory + Twine(I) + "\"," +
+        "\"command\":\"" + Command + Twine(I) + "\","
+        "\"file\":\"" + FileName + Twine(I) + "\"}").str();
+  }
+  JsonDatabase += "]";
+  std::string ErrorMessage;
+  CompileCommand FoundCommand = findCompileArgsInJsonDatabase(
+    "file4", JsonDatabase, ErrorMessage);
+  EXPECT_EQ("directory4", FoundCommand.Directory) << ErrorMessage;
+  ASSERT_EQ(1u, FoundCommand.CommandLine.size()) << ErrorMessage;
+  EXPECT_EQ("command4", FoundCommand.CommandLine[0]) << ErrorMessage;
+}
+
+static std::vector<std::string> unescapeJsonCommandLine(StringRef Command) {
+  std::string JsonDatabase =
+    ("[{\"directory\":\"\", \"file\":\"test\", \"command\": \"" +
+     Command + "\"}]").str();
+  std::string ErrorMessage;
+  CompileCommand FoundCommand = findCompileArgsInJsonDatabase(
+    "test", JsonDatabase, ErrorMessage);
+  EXPECT_TRUE(ErrorMessage.empty()) << ErrorMessage;
+  return FoundCommand.CommandLine;
+}
+
+TEST(unescapeJsonCommandLine, ReturnsEmptyArrayOnEmptyString) {
+  std::vector<std::string> Result = unescapeJsonCommandLine("");
+  EXPECT_TRUE(Result.empty());
+}
+
+TEST(unescapeJsonCommandLine, SplitsOnSpaces) {
+  std::vector<std::string> Result = unescapeJsonCommandLine("a b c");
+  ASSERT_EQ(3ul, Result.size());
+  EXPECT_EQ("a", Result[0]);
+  EXPECT_EQ("b", Result[1]);
+  EXPECT_EQ("c", Result[2]);
+}
+
+TEST(unescapeJsonCommandLine, MungesMultipleSpaces) {
+  std::vector<std::string> Result = unescapeJsonCommandLine("   a   b   ");
+  ASSERT_EQ(2ul, Result.size());
+  EXPECT_EQ("a", Result[0]);
+  EXPECT_EQ("b", Result[1]);
+}
+
+TEST(unescapeJsonCommandLine, UnescapesBackslashCharacters) {
+  std::vector<std::string> Backslash = unescapeJsonCommandLine("a\\\\\\\\");
+  ASSERT_EQ(1ul, Backslash.size());
+  EXPECT_EQ("a\\", Backslash[0]);
+  std::vector<std::string> Quote = unescapeJsonCommandLine("a\\\\\\\"");
+  ASSERT_EQ(1ul, Quote.size());
+  EXPECT_EQ("a\"", Quote[0]);
+}
+
+TEST(unescapeJsonCommandLine, DoesNotMungeSpacesBetweenQuotes) {
+  std::vector<std::string> Result = unescapeJsonCommandLine("\\\"  a  b  \\\"");
+  ASSERT_EQ(1ul, Result.size());
+  EXPECT_EQ("  a  b  ", Result[0]);
+}
+
+TEST(unescapeJsonCommandLine, AllowsMultipleQuotedArguments) {
+  std::vector<std::string> Result = unescapeJsonCommandLine(
+      "  \\\" a \\\"  \\\" b \\\"  ");
+  ASSERT_EQ(2ul, Result.size());
+  EXPECT_EQ(" a ", Result[0]);
+  EXPECT_EQ(" b ", Result[1]);
+}
+
+TEST(unescapeJsonCommandLine, AllowsEmptyArgumentsInQuotes) {
+  std::vector<std::string> Result = unescapeJsonCommandLine(
+      "\\\"\\\"\\\"\\\"");
+  ASSERT_EQ(1ul, Result.size());
+  EXPECT_TRUE(Result[0].empty()) << Result[0];
+}
+
+TEST(unescapeJsonCommandLine, ParsesEscapedQuotesInQuotedStrings) {
+  std::vector<std::string> Result = unescapeJsonCommandLine(
+      "\\\"\\\\\\\"\\\"");
+  ASSERT_EQ(1ul, Result.size());
+  EXPECT_EQ("\"", Result[0]);
+}
+
+TEST(unescapeJsonCommandLine, ParsesMultipleArgumentsWithEscapedCharacters) {
+  std::vector<std::string> Result = unescapeJsonCommandLine(
+      "  \\\\\\\"  \\\"a \\\\\\\" b \\\"     \\\"and\\\\\\\\c\\\"   \\\\\\\"");
+  ASSERT_EQ(4ul, Result.size());
+  EXPECT_EQ("\"", Result[0]);
+  EXPECT_EQ("a \" b ", Result[1]);
+  EXPECT_EQ("and\\c", Result[2]);
+  EXPECT_EQ("\"", Result[3]);
+}
+
+TEST(unescapeJsonCommandLine, ParsesStringsWithoutSpacesIntoSingleArgument) {
+  std::vector<std::string> QuotedNoSpaces = unescapeJsonCommandLine(
+      "\\\"a\\\"\\\"b\\\"");
+  ASSERT_EQ(1ul, QuotedNoSpaces.size());
+  EXPECT_EQ("ab", QuotedNoSpaces[0]);
+
+  std::vector<std::string> MixedNoSpaces = unescapeJsonCommandLine(
+      "\\\"a\\\"bcd\\\"ef\\\"\\\"\\\"\\\"g\\\"");
+  ASSERT_EQ(1ul, MixedNoSpaces.size());
+  EXPECT_EQ("abcdefg", MixedNoSpaces[0]);
+}
+
+TEST(unescapeJsonCommandLine, ParsesQuotedStringWithoutClosingQuote) {
+  std::vector<std::string> Unclosed = unescapeJsonCommandLine("\\\"abc");
+  ASSERT_EQ(1ul, Unclosed.size());
+  EXPECT_EQ("abc", Unclosed[0]);
+
+  std::vector<std::string> Empty = unescapeJsonCommandLine("\\\"");
+  ASSERT_EQ(1ul, Empty.size());
+  EXPECT_EQ("", Empty[0]);
+}
+
+} // end namespace tooling
+} // end namespace clang
diff --git a/unittests/Tooling/Makefile b/unittests/Tooling/Makefile
new file mode 100644
index 0000000000..cc2eeee1d4
--- /dev/null
+++ b/unittests/Tooling/Makefile
@@ -0,0 +1,17 @@
+##===- unittests/Tooling/Makefile --------------------------*- Makefile -*-===##
+#
+#                     The LLVM Compiler Infrastructure
+#
+# This file is distributed under the University of Illinois Open Source
+# License. See LICENSE.TXT for details.
+#
+##===----------------------------------------------------------------------===##
+
+CLANG_LEVEL = ../..
+TESTNAME = Tooling
+LINK_COMPONENTS := support mc
+USEDLIBS = clangTooling.a clangFrontend.a clangSerialization.a clangDriver.a \
+           clangParse.a clangSema.a clangAnalysis.a clangAST.a clangLex.a \
+           clangBasic.a
+
+include $(CLANG_LEVEL)/unittests/Makefile
diff --git a/unittests/Tooling/ToolingTest.cpp b/unittests/Tooling/ToolingTest.cpp
new file mode 100644
index 0000000000..c7b2210a75
--- /dev/null
+++ b/unittests/Tooling/ToolingTest.cpp
@@ -0,0 +1,113 @@
+//===- unittest/Tooling/ToolingTest.cpp - Tooling unit tests --------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/AST/ASTConsumer.h"
+#include "clang/AST/DeclCXX.h"
+#include "clang/AST/DeclGroup.h"
+#include "clang/Frontend/FrontendAction.h"
+#include "clang/Frontend/FrontendActions.h"
+#include "clang/Tooling/CompilationDatabase.h"
+#include "clang/Tooling/Tooling.h"
+#include "gtest/gtest.h"
+
+namespace clang {
+namespace tooling {
+
+namespace {
+/// Takes an ast consumer and returns it from CreateASTConsumer. This only
+/// works with single translation unit compilations.
+class TestAction : public clang::ASTFrontendAction {
+ public:
+  /// Takes ownership of TestConsumer.
+  explicit TestAction(clang::ASTConsumer *TestConsumer)
+      : TestConsumer(TestConsumer) {}
+
+ protected:
+  virtual clang::ASTConsumer* CreateASTConsumer(
+      clang::CompilerInstance& compiler, StringRef dummy) {
+    /// TestConsumer will be deleted by the framework calling us.
+    return TestConsumer;
+  }
+
+ private:
+  clang::ASTConsumer * const TestConsumer;
+};
+
+class FindTopLevelDeclConsumer : public clang::ASTConsumer {
+ public:
+  explicit FindTopLevelDeclConsumer(bool *FoundTopLevelDecl)
+      : FoundTopLevelDecl(FoundTopLevelDecl) {}
+  virtual bool HandleTopLevelDecl(clang::DeclGroupRef DeclGroup) {
+    *FoundTopLevelDecl = true;
+    return true;
+  }
+ private:
+  bool * const FoundTopLevelDecl;
+};
+} // end namespace
+
+TEST(runToolOnCode, FindsTopLevelDeclOnEmptyCode) {
+  bool FoundTopLevelDecl = false;
+  EXPECT_TRUE(runToolOnCode(
+      new TestAction(new FindTopLevelDeclConsumer(&FoundTopLevelDecl)), ""));
+  EXPECT_TRUE(FoundTopLevelDecl);
+}
+
+namespace {
+class FindClassDeclXConsumer : public clang::ASTConsumer {
+ public:
+  FindClassDeclXConsumer(bool *FoundClassDeclX)
+      : FoundClassDeclX(FoundClassDeclX) {}
+  virtual bool HandleTopLevelDecl(clang::DeclGroupRef GroupRef) {
+    if (CXXRecordDecl* Record = dyn_cast<clang::CXXRecordDecl>(
+            *GroupRef.begin())) {
+      if (Record->getName() == "X") {
+        *FoundClassDeclX = true;
+      }
+    }
+    return true;
+  }
+ private:
+  bool *FoundClassDeclX;
+};
+} // end namespace
+
+TEST(runToolOnCode, FindsClassDecl) {
+  bool FoundClassDeclX = false;
+  EXPECT_TRUE(runToolOnCode(new TestAction(
+      new FindClassDeclXConsumer(&FoundClassDeclX)), "class X;"));
+  EXPECT_TRUE(FoundClassDeclX);
+
+  FoundClassDeclX = false;
+  EXPECT_TRUE(runToolOnCode(new TestAction(
+      new FindClassDeclXConsumer(&FoundClassDeclX)), "class Y;"));
+  EXPECT_FALSE(FoundClassDeclX);
+}
+
+TEST(newFrontendActionFactory, CreatesFrontendActionFactoryFromType) {
+  llvm::OwningPtr<FrontendActionFactory> Factory(
+    newFrontendActionFactory<SyntaxOnlyAction>());
+  llvm::OwningPtr<FrontendAction> Action(Factory->create());
+  EXPECT_TRUE(Action.get() != NULL);
+}
+
+struct IndependentFrontendActionCreator {
+  FrontendAction *newFrontendAction() { return new SyntaxOnlyAction; }
+};
+
+TEST(newFrontendActionFactory, CreatesFrontendActionFactoryFromFactoryType) {
+  IndependentFrontendActionCreator Creator;
+  llvm::OwningPtr<FrontendActionFactory> Factory(
+    newFrontendActionFactory(&Creator));
+  llvm::OwningPtr<FrontendAction> Action(Factory->create());
+  EXPECT_TRUE(Action.get() != NULL);
+}
+
+} // end namespace tooling
+} // end namespace clang