tools/CIndex/CIndex.cpp

//===- CIndex.cpp - Clang-C Source Indexing Library -----------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the Clang-C Source Indexing library.
//
//===----------------------------------------------------------------------===//

#include "clang-c/Index.h"
#include "clang/AST/Decl.h"
#include "clang/AST/DeclVisitor.h"
#include "clang/AST/StmtVisitor.h"
#include "clang/Basic/FileManager.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Basic/Version.h"
#include "clang/Frontend/ASTUnit.h"
#include "clang/Frontend/CompilerInstance.h"
#include "clang/Index/ASTLocation.h"
#include "clang/Index/Indexer.h"
#include "clang/Index/Program.h"
#include "clang/Index/Utils.h"
#include "clang/Sema/CodeCompleteConsumer.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Config/config.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/System/Path.h"
#include "llvm/System/Program.h"

#include <cstdio>
#include <vector>
#include <sstream>

#ifdef LLVM_ON_WIN32
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#else
#include <dlfcn.h>
#endif

using namespace clang;
using namespace idx;

namespace {
static enum CXCursorKind TranslateDeclRefExpr(DeclRefExpr *DRE)
{
  NamedDecl *D = DRE->getDecl();
  if (isa<VarDecl>(D))
    return CXCursor_VarRef;
  else if (isa<FunctionDecl>(D))
    return CXCursor_FunctionRef;
  else if (isa<EnumConstantDecl>(D))
    return CXCursor_EnumConstantRef;
  else
    return CXCursor_NotImplemented;
}

#if 0
// Will be useful one day.
class CRefVisitor : public StmtVisitor<CRefVisitor> {
  CXDecl CDecl;
  CXDeclIterator Callback;
  CXClientData CData;

  void Call(enum CXCursorKind CK, Stmt *SRef) {
    CXCursor C = { CK, CDecl, SRef };
    Callback(CDecl, C, CData);
  }

public:
  CRefVisitor(CXDecl C, CXDeclIterator cback, CXClientData D) :
    CDecl(C), Callback(cback), CData(D) {}

  void VisitStmt(Stmt *S) {
    for (Stmt::child_iterator C = S->child_begin(), CEnd = S->child_end();
         C != CEnd; ++C)
      Visit(*C);
  }
  void VisitDeclRefExpr(DeclRefExpr *Node) {
    Call(TranslateDeclRefExpr(Node), Node);
  }
  void VisitMemberExpr(MemberExpr *Node) {
    Call(CXCursor_MemberRef, Node);
  }
  void VisitObjCMessageExpr(ObjCMessageExpr *Node) {
    Call(CXCursor_ObjCSelectorRef, Node);
  }
  void VisitObjCIvarRefExpr(ObjCIvarRefExpr *Node) {
    Call(CXCursor_ObjCIvarRef, Node);
  }
};
#endif

/// IgnoreDiagnosticsClient - A DiagnosticsClient that just ignores emitted
/// warnings and errors.
class VISIBILITY_HIDDEN IgnoreDiagnosticsClient : public DiagnosticClient {
public:
  virtual ~IgnoreDiagnosticsClient() {}
  virtual void HandleDiagnostic(Diagnostic::Level, const DiagnosticInfo &) {}
};

// Translation Unit Visitor.
class TUVisitor : public DeclVisitor<TUVisitor> {
  CXTranslationUnit TUnit;
  CXTranslationUnitIterator Callback;
  CXClientData CData;

  // MaxPCHLevel - the maximum PCH level of declarations that we will pass on
  // to the visitor. Declarations with a PCH level greater than this value will
  // be suppressed.
  unsigned MaxPCHLevel;

  void Call(enum CXCursorKind CK, NamedDecl *ND) {
    // Filter any declarations that have a PCH level greater than what we allow.
    if (ND->getPCHLevel() > MaxPCHLevel)
      return;

    // Filter any implicit declarations (since the source info will be bogus).
    if (ND->isImplicit())
      return;

    CXCursor C = { CK, ND, 0 };
    Callback(TUnit, C, CData);
  }
public:
  TUVisitor(CXTranslationUnit CTU,
            CXTranslationUnitIterator cback, CXClientData D,
            unsigned MaxPCHLevel) :
    TUnit(CTU), Callback(cback), CData(D), MaxPCHLevel(MaxPCHLevel) {}

  void VisitTranslationUnitDecl(TranslationUnitDecl *D) {
    VisitDeclContext(dyn_cast<DeclContext>(D));
  }
  void VisitDeclContext(DeclContext *DC) {
    for (DeclContext::decl_iterator
           I = DC->decls_begin(), E = DC->decls_end(); I != E; ++I)
      Visit(*I);
  }

  void VisitFunctionDecl(FunctionDecl *ND) {
    Call(ND->isThisDeclarationADefinition() ? CXCursor_FunctionDefn
                                            : CXCursor_FunctionDecl, ND);
  }
  void VisitObjCCategoryDecl(ObjCCategoryDecl *ND) {
    Call(CXCursor_ObjCCategoryDecl, ND);
  }
  void VisitObjCCategoryImplDecl(ObjCCategoryImplDecl *ND) {
    Call(CXCursor_ObjCCategoryDefn, ND);
  }
  void VisitObjCImplementationDecl(ObjCImplementationDecl *ND) {
    Call(CXCursor_ObjCClassDefn, ND);
  }
  void VisitObjCInterfaceDecl(ObjCInterfaceDecl *ND) {
    Call(CXCursor_ObjCInterfaceDecl, ND);
  }
  void VisitObjCProtocolDecl(ObjCProtocolDecl *ND) {
    Call(CXCursor_ObjCProtocolDecl, ND);
  }
  void VisitTagDecl(TagDecl *ND) {
    switch (ND->getTagKind()) {
    case TagDecl::TK_struct:
      Call(CXCursor_StructDecl, ND);
      break;
    case TagDecl::TK_class:
      Call(CXCursor_ClassDecl, ND);
      break;
    case TagDecl::TK_union:
      Call(CXCursor_UnionDecl, ND);
      break;
    case TagDecl::TK_enum:
      Call(CXCursor_EnumDecl, ND);
      break;
    }
  }
  void VisitTypedefDecl(TypedefDecl *ND) {
    Call(CXCursor_TypedefDecl, ND);
  }
  void VisitVarDecl(VarDecl *ND) {
    Call(CXCursor_VarDecl, ND);
  }
};


// Declaration visitor.
class CDeclVisitor : public DeclVisitor<CDeclVisitor> {
  CXDecl CDecl;
  CXDeclIterator Callback;
  CXClientData CData;

  // MaxPCHLevel - the maximum PCH level of declarations that we will pass on
  // to the visitor. Declarations with a PCH level greater than this value will
  // be suppressed.
  unsigned MaxPCHLevel;

  void Call(enum CXCursorKind CK, NamedDecl *ND) {
    // Disable the callback when the context is equal to the visiting decl.
    if (CDecl == ND && !clang_isReference(CK))
      return;

    // Filter any declarations that have a PCH level greater than what we allow.
    if (ND->getPCHLevel() > MaxPCHLevel)
      return;

    CXCursor C = { CK, ND, 0 };
    Callback(CDecl, C, CData);
  }
public:
  CDeclVisitor(CXDecl C, CXDeclIterator cback, CXClientData D,
               unsigned MaxPCHLevel) :
    CDecl(C), Callback(cback), CData(D), MaxPCHLevel(MaxPCHLevel) {}

  void VisitObjCCategoryDecl(ObjCCategoryDecl *ND) {
    // Issue callbacks for the containing class.
    Call(CXCursor_ObjCClassRef, ND);
    // FIXME: Issue callbacks for protocol refs.
    VisitDeclContext(dyn_cast<DeclContext>(ND));
  }
  void VisitObjCInterfaceDecl(ObjCInterfaceDecl *D) {
    // Issue callbacks for super class.
    if (D->getSuperClass())
      Call(CXCursor_ObjCSuperClassRef, D);

    for (ObjCProtocolDecl::protocol_iterator I = D->protocol_begin(),
           E = D->protocol_end(); I != E; ++I)
      Call(CXCursor_ObjCProtocolRef, *I);
    VisitDeclContext(dyn_cast<DeclContext>(D));
  }
  void VisitObjCProtocolDecl(ObjCProtocolDecl *PID) {
    for (ObjCProtocolDecl::protocol_iterator I = PID->protocol_begin(),
           E = PID->protocol_end(); I != E; ++I)
      Call(CXCursor_ObjCProtocolRef, *I);

    VisitDeclContext(dyn_cast<DeclContext>(PID));
  }
  void VisitTagDecl(TagDecl *D) {
    VisitDeclContext(dyn_cast<DeclContext>(D));
  }
  void VisitObjCImplementationDecl(ObjCImplementationDecl *D) {
    VisitDeclContext(dyn_cast<DeclContext>(D));
  }
  void VisitObjCCategoryImplDecl(ObjCCategoryImplDecl *D) {
    VisitDeclContext(dyn_cast<DeclContext>(D));
  }
  void VisitDeclContext(DeclContext *DC) {
    for (DeclContext::decl_iterator
           I = DC->decls_begin(), E = DC->decls_end(); I != E; ++I)
      Visit(*I);
  }
  void VisitEnumConstantDecl(EnumConstantDecl *ND) {
    Call(CXCursor_EnumConstantDecl, ND);
  }
  void VisitFieldDecl(FieldDecl *ND) {
    Call(CXCursor_FieldDecl, ND);
  }
  void VisitVarDecl(VarDecl *ND) {
    Call(CXCursor_VarDecl, ND);
  }
  void VisitParmVarDecl(ParmVarDecl *ND) {
    Call(CXCursor_ParmDecl, ND);
  }
  void VisitObjCPropertyDecl(ObjCPropertyDecl *ND) {
    Call(CXCursor_ObjCPropertyDecl, ND);
  }
  void VisitObjCIvarDecl(ObjCIvarDecl *ND) {
    Call(CXCursor_ObjCIvarDecl, ND);
  }
  void VisitFunctionDecl(FunctionDecl *ND) {
    if (ND->isThisDeclarationADefinition()) {
      VisitDeclContext(dyn_cast<DeclContext>(ND));
#if 0
      // Not currently needed.
      CompoundStmt *Body = dyn_cast<CompoundStmt>(ND->getBody());
      CRefVisitor RVisit(CDecl, Callback, CData);
      RVisit.Visit(Body);
#endif
    }
  }
  void VisitObjCMethodDecl(ObjCMethodDecl *ND) {
    if (ND->getBody()) {
      Call(ND->isInstanceMethod() ? CXCursor_ObjCInstanceMethodDefn
                                  : CXCursor_ObjCClassMethodDefn, ND);
      VisitDeclContext(dyn_cast<DeclContext>(ND));
    } else
      Call(ND->isInstanceMethod() ? CXCursor_ObjCInstanceMethodDecl
                                  : CXCursor_ObjCClassMethodDecl, ND);
  }
};

class CIndexer : public Indexer {
  DiagnosticOptions DiagOpts;
  IgnoreDiagnosticsClient IgnoreDiagClient;
  llvm::OwningPtr<Diagnostic> TextDiags;
  Diagnostic IgnoreDiags;
  bool UseExternalASTGeneration;
  bool OnlyLocalDecls;
  bool DisplayDiagnostics;

  llvm::sys::Path ClangPath;

public:
  explicit CIndexer(Program *prog) : Indexer(*prog),
                                     IgnoreDiags(&IgnoreDiagClient),
                                     UseExternalASTGeneration(false),
                                     OnlyLocalDecls(false),
                                     DisplayDiagnostics(false) {
    TextDiags.reset(
      CompilerInstance::createDiagnostics(DiagOpts, 0, 0));
  }

  virtual ~CIndexer() { delete &getProgram(); }

  /// \brief Whether we only want to see "local" declarations (that did not
  /// come from a previous precompiled header). If false, we want to see all
  /// declarations.
  bool getOnlyLocalDecls() const { return OnlyLocalDecls; }
  void setOnlyLocalDecls(bool Local = true) { OnlyLocalDecls = Local; }

  bool getDisplayDiagnostics() const { return DisplayDiagnostics; }
  void setDisplayDiagnostics(bool Display = true) {
    DisplayDiagnostics = Display;
  }

  bool getUseExternalASTGeneration() const { return UseExternalASTGeneration; }
  void setUseExternalASTGeneration(bool Value) {
    UseExternalASTGeneration = Value;
  }

  Diagnostic &getDiags() {
    return DisplayDiagnostics ? *TextDiags : IgnoreDiags;
  }

  /// \brief Get the path of the clang binary.
  const llvm::sys::Path& getClangPath();

  /// \brief Get the path of the clang resource files.
  std::string getClangResourcesPath();
};

const llvm::sys::Path& CIndexer::getClangPath() {
  // Did we already compute the path?
  if (!ClangPath.empty())
    return ClangPath;

  // Find the location where this library lives (libCIndex.dylib).
#ifdef LLVM_ON_WIN32
  MEMORY_BASIC_INFORMATION mbi;
  char path[MAX_PATH];
  VirtualQuery((void *)(uintptr_t)clang_createTranslationUnit, &mbi,
               sizeof(mbi));
  GetModuleFileNameA((HINSTANCE)mbi.AllocationBase, path, MAX_PATH);

  llvm::sys::Path CIndexPath(path);

  CIndexPath.eraseComponent();
  CIndexPath.appendComponent("clang");
  CIndexPath.appendSuffix("exe");
  CIndexPath.makeAbsolute();
#else
  // This silly cast below avoids a C++ warning.
  Dl_info info;
  if (dladdr((void *)(uintptr_t)clang_createTranslationUnit, &info) == 0)
    assert(0 && "Call to dladdr() failed");

  llvm::sys::Path CIndexPath(info.dli_fname);

  // We now have the CIndex directory, locate clang relative to it.
  CIndexPath.eraseComponent();
  CIndexPath.eraseComponent();
  CIndexPath.appendComponent("bin");
  CIndexPath.appendComponent("clang");
#endif

  // Cache our result.
  ClangPath = CIndexPath;
  return ClangPath;
}

std::string CIndexer::getClangResourcesPath() {
  llvm::sys::Path P = getClangPath();

  if (!P.empty()) {
    P.eraseComponent();  // Remove /clang from foo/bin/clang
    P.eraseComponent();  // Remove /bin   from foo/bin

    // Get foo/lib/clang/<version>/include
    P.appendComponent("lib");
    P.appendComponent("clang");
    P.appendComponent(CLANG_VERSION_STRING);
  }

  return P.str();
}

}

static SourceLocation getLocationFromCursor(CXCursor C,
                                            SourceManager &SourceMgr,
                                            NamedDecl *ND) {
  if (clang_isReference(C.kind)) {
    switch (C.kind) {
    case CXCursor_ObjCClassRef: {
      if (isa<ObjCInterfaceDecl>(ND)) {
        // FIXME: This is a hack (storing the parent decl in the stmt slot).
        NamedDecl *parentDecl = static_cast<NamedDecl *>(C.stmt);
        return parentDecl->getLocation();
      }
      ObjCCategoryDecl *OID = dyn_cast<ObjCCategoryDecl>(ND);
      assert(OID && "clang_getCursorLine(): Missing category decl");
      return OID->getClassInterface()->getLocation();
    }
    case CXCursor_ObjCSuperClassRef: {
      ObjCInterfaceDecl *OID = dyn_cast<ObjCInterfaceDecl>(ND);
      assert(OID && "clang_getCursorLine(): Missing interface decl");
      return OID->getSuperClassLoc();
    }
    case CXCursor_ObjCProtocolRef: {
      ObjCProtocolDecl *OID = dyn_cast<ObjCProtocolDecl>(ND);
      assert(OID && "clang_getCursorLine(): Missing protocol decl");
      return OID->getLocation();
    }
    case CXCursor_ObjCSelectorRef: {
      ObjCMessageExpr *OME = dyn_cast<ObjCMessageExpr>(
        static_cast<Stmt *>(C.stmt));
      assert(OME && "clang_getCursorLine(): Missing message expr");
      return OME->getLeftLoc(); /* FIXME: should be a range */
    }
    case CXCursor_VarRef:
    case CXCursor_FunctionRef:
    case CXCursor_EnumConstantRef: {
      DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(
        static_cast<Stmt *>(C.stmt));
      assert(DRE && "clang_getCursorLine(): Missing decl ref expr");
      return DRE->getLocation();
    }
    default:
      return SourceLocation();
    }
  } else { // We have a declaration or a definition.
    SourceLocation SLoc;
    switch (ND->getKind()) {
    case Decl::ObjCInterface: {
      SLoc = dyn_cast<ObjCInterfaceDecl>(ND)->getClassLoc();
      break;
    }
    case Decl::ObjCProtocol: {
      SLoc = ND->getLocation(); /* FIXME: need to get the name location. */
      break;
    }
    default: {
      SLoc = ND->getLocation();
      break;
    }
    }
    if (SLoc.isInvalid())
      return SourceLocation();
    return SourceMgr.getSpellingLoc(SLoc); // handles macro instantiations.
  }
}

static CXString createCXString(const char *String, bool DupString = false) {
  CXString Str;
  if (DupString) {
    Str.Spelling = strdup(String);
    Str.MustFreeString = 1;
  } else {
    Str.Spelling = String;
    Str.MustFreeString = 0;
  }
  return Str;
}

extern "C" {

CXIndex clang_createIndex(int excludeDeclarationsFromPCH,
                          int displayDiagnostics) {
  CIndexer *CIdxr = new CIndexer(new Program());
  if (excludeDeclarationsFromPCH)
    CIdxr->setOnlyLocalDecls();
  if (displayDiagnostics)
    CIdxr->setDisplayDiagnostics();
  return CIdxr;
}

void clang_disposeIndex(CXIndex CIdx) {
  assert(CIdx && "Passed null CXIndex");
  delete static_cast<CIndexer *>(CIdx);
}

void clang_setUseExternalASTGeneration(CXIndex CIdx, int value) {
  assert(CIdx && "Passed null CXIndex");
  CIndexer *CXXIdx = static_cast<CIndexer *>(CIdx);
  CXXIdx->setUseExternalASTGeneration(value);
}

// FIXME: need to pass back error info.
CXTranslationUnit clang_createTranslationUnit(CXIndex CIdx,
                                              const char *ast_filename) {
  assert(CIdx && "Passed null CXIndex");
  CIndexer *CXXIdx = static_cast<CIndexer *>(CIdx);

  return ASTUnit::LoadFromPCHFile(ast_filename, CXXIdx->getDiags(),
                                  CXXIdx->getOnlyLocalDecls(),
                                  /* UseBumpAllocator = */ true);
}

CXTranslationUnit
clang_createTranslationUnitFromSourceFile(CXIndex CIdx,
                                          const char *source_filename,
                                          int num_command_line_args,
                                          const char **command_line_args) {
  assert(CIdx && "Passed null CXIndex");
  CIndexer *CXXIdx = static_cast<CIndexer *>(CIdx);

  if (!CXXIdx->getUseExternalASTGeneration()) {
    llvm::SmallVector<const char *, 16> Args;

    // The 'source_filename' argument is optional.  If the caller does not
    // specify it then it is assumed that the source file is specified
    // in the actual argument list.
    if (source_filename)
      Args.push_back(source_filename);
    Args.insert(Args.end(), command_line_args,
                command_line_args + num_command_line_args);

    unsigned NumErrors = CXXIdx->getDiags().getNumErrors();
    llvm::OwningPtr<ASTUnit> Unit(
      ASTUnit::LoadFromCommandLine(Args.data(), Args.data() + Args.size(),
                                   CXXIdx->getDiags(),
                                   CXXIdx->getClangResourcesPath(),
                                   CXXIdx->getOnlyLocalDecls(),
                                   /* UseBumpAllocator = */ true));

    // FIXME: Until we have broader testing, just drop the entire AST if we
    // encountered an error.
    if (NumErrors != CXXIdx->getDiags().getNumErrors())
      return 0;

    return Unit.take();
  }

  // Build up the arguments for invoking 'clang'.
  std::vector<const char *> argv;

  // First add the complete path to the 'clang' executable.
  llvm::sys::Path ClangPath = static_cast<CIndexer *>(CIdx)->getClangPath();
  argv.push_back(ClangPath.c_str());

  // Add the '-emit-ast' option as our execution mode for 'clang'.
  argv.push_back("-emit-ast");

  // The 'source_filename' argument is optional.  If the caller does not
  // specify it then it is assumed that the source file is specified
  // in the actual argument list.
  if (source_filename)
    argv.push_back(source_filename);

  // Generate a temporary name for the AST file.
  argv.push_back("-o");
  char astTmpFile[L_tmpnam];
  argv.push_back(tmpnam(astTmpFile));

  // Process the compiler options, stripping off '-o', '-c', '-fsyntax-only'.
  for (int i = 0; i < num_command_line_args; ++i)
    if (const char *arg = command_line_args[i]) {
      if (strcmp(arg, "-o") == 0) {
        ++i; // Also skip the matching argument.
        continue;
      }
      if (strcmp(arg, "-emit-ast") == 0 ||
          strcmp(arg, "-c") == 0 ||
          strcmp(arg, "-fsyntax-only") == 0) {
        continue;
      }

      // Keep the argument.
      argv.push_back(arg);
    }

  // Add the null terminator.
  argv.push_back(NULL);

  // Invoke 'clang'.
  llvm::sys::Path DevNull; // leave empty, causes redirection to /dev/null
                           // on Unix or NUL (Windows).
  std::string ErrMsg;
  const llvm::sys::Path *Redirects[] = { &DevNull, &DevNull, &DevNull, NULL };
  llvm::sys::Program::ExecuteAndWait(ClangPath, &argv[0], /* env */ NULL,
      /* redirects */ !CXXIdx->getDisplayDiagnostics() ? &Redirects[0] : NULL,
      /* secondsToWait */ 0, /* memoryLimits */ 0, &ErrMsg);

  if (CXXIdx->getDisplayDiagnostics() && !ErrMsg.empty()) {
    llvm::errs() << "clang_createTranslationUnitFromSourceFile: " << ErrMsg
                 << '\n' << "Arguments: \n";
    for (std::vector<const char*>::iterator I = argv.begin(), E = argv.end();
         I!=E; ++I) {
      if (*I)
        llvm::errs() << ' ' << *I << '\n';
    }
    llvm::errs() << '\n';
  }

  // Finally, we create the translation unit from the ast file.
  ASTUnit *ATU = static_cast<ASTUnit *>(
    clang_createTranslationUnit(CIdx, astTmpFile));
  if (ATU)
    ATU->unlinkTemporaryFile();
  return ATU;
}

void clang_disposeTranslationUnit(CXTranslationUnit CTUnit) {
  assert(CTUnit && "Passed null CXTranslationUnit");
  delete static_cast<ASTUnit *>(CTUnit);
}

CXString clang_getTranslationUnitSpelling(CXTranslationUnit CTUnit) {
  assert(CTUnit && "Passed null CXTranslationUnit");
  ASTUnit *CXXUnit = static_cast<ASTUnit *>(CTUnit);
  return createCXString(CXXUnit->getOriginalSourceFileName().c_str(), true);
}

void clang_loadTranslationUnit(CXTranslationUnit CTUnit,
                               CXTranslationUnitIterator callback,
                               CXClientData CData) {
  assert(CTUnit && "Passed null CXTranslationUnit");
  ASTUnit *CXXUnit = static_cast<ASTUnit *>(CTUnit);
  ASTContext &Ctx = CXXUnit->getASTContext();

  unsigned PCHLevel = Decl::MaxPCHLevel;

  // Set the PCHLevel to filter out unwanted decls if requested.
  if (CXXUnit->getOnlyLocalDecls()) {
    PCHLevel = 0;

    // If the main input was an AST, bump the level.
    if (CXXUnit->isMainFileAST())
      ++PCHLevel;
  }

  TUVisitor DVisit(CTUnit, callback, CData, PCHLevel);

  // If using a non-AST based ASTUnit, iterate over the stored list of top-level
  // decls.
  if (!CXXUnit->isMainFileAST() && CXXUnit->getOnlyLocalDecls()) {
    const std::vector<Decl*> &TLDs = CXXUnit->getTopLevelDecls();
    for (std::vector<Decl*>::const_iterator it = TLDs.begin(),
           ie = TLDs.end(); it != ie; ++it) {
      DVisit.Visit(*it);
    }
  } else
    DVisit.Visit(Ctx.getTranslationUnitDecl());
}

void clang_loadDeclaration(CXDecl Dcl,
                           CXDeclIterator callback,
                           CXClientData CData) {
  assert(Dcl && "Passed null CXDecl");

  CDeclVisitor DVisit(Dcl, callback, CData,
                      static_cast<Decl *>(Dcl)->getPCHLevel());
  DVisit.Visit(static_cast<Decl *>(Dcl));
}

// Some notes on CXEntity:
//
// - Since the 'ordinary' namespace includes functions, data, typedefs,
// ObjC interfaces, thecurrent algorithm is a bit naive (resulting in one
// entity for 2 different types). For example:
//
// module1.m: @interface Foo @end Foo *x;
// module2.m: void Foo(int);
//
// - Since the unique name spans translation units, static data/functions
// within a CXTranslationUnit are *not* currently represented by entities.
// As a result, there will be no entity for the following:
//
// module.m: static void Foo() { }
//


const char *clang_getDeclarationName(CXEntity) {
  return "";
}

const char *clang_getURI(CXEntity) {
  return "";
}

CXEntity clang_getEntity(const char *URI) {
  return 0;
}

//
// CXDecl Operations.
//

CXEntity clang_getEntityFromDecl(CXDecl) {
  return 0;
}

CXString clang_getDeclSpelling(CXDecl AnonDecl) {
  assert(AnonDecl && "Passed null CXDecl");
  NamedDecl *ND = static_cast<NamedDecl *>(AnonDecl);

  if (ObjCMethodDecl *OMD = dyn_cast<ObjCMethodDecl>(ND))
    return createCXString(OMD->getSelector().getAsString().c_str(), true);

  if (ObjCCategoryImplDecl *CIMP = dyn_cast<ObjCCategoryImplDecl>(ND))
    // No, this isn't the same as the code below. getIdentifier() is non-virtual
    // and returns different names. NamedDecl returns the class name and
    // ObjCCategoryImplDecl returns the category name.
    return createCXString(CIMP->getIdentifier()->getNameStart());

  if (ND->getIdentifier())
    return createCXString(ND->getIdentifier()->getNameStart());

  return createCXString("");
}

unsigned clang_getDeclLine(CXDecl AnonDecl) {
  assert(AnonDecl && "Passed null CXDecl");
  NamedDecl *ND = static_cast<NamedDecl *>(AnonDecl);
  SourceManager &SourceMgr = ND->getASTContext().getSourceManager();
  return SourceMgr.getSpellingLineNumber(ND->getLocation());
}

unsigned clang_getDeclColumn(CXDecl AnonDecl) {
  assert(AnonDecl && "Passed null CXDecl");
  NamedDecl *ND = static_cast<NamedDecl *>(AnonDecl);
  SourceManager &SourceMgr = ND->getASTContext().getSourceManager();
  return SourceMgr.getSpellingColumnNumber(ND->getLocation());
}

const char *clang_getDeclSource(CXDecl AnonDecl) {
  assert(AnonDecl && "Passed null CXDecl");
  FileEntry *FEnt = static_cast<FileEntry *>(clang_getDeclSourceFile(AnonDecl));
  assert (FEnt && "Cannot find FileEntry for Decl");
  return clang_getFileName(FEnt);
}

static const FileEntry *getFileEntryFromSourceLocation(SourceManager &SMgr,
                                                       SourceLocation SLoc) {
  FileID FID;
  if (SLoc.isFileID())
    FID = SMgr.getFileID(SLoc);
  else
    FID = SMgr.getDecomposedSpellingLoc(SLoc).first;
  return SMgr.getFileEntryForID(FID);
}

CXFile clang_getDeclSourceFile(CXDecl AnonDecl) {
  assert(AnonDecl && "Passed null CXDecl");
  NamedDecl *ND = static_cast<NamedDecl *>(AnonDecl);
  SourceManager &SourceMgr = ND->getASTContext().getSourceManager();
  return (void *)getFileEntryFromSourceLocation(SourceMgr, ND->getLocation());
}

const char *clang_getFileName(CXFile SFile) {
  assert(SFile && "Passed null CXFile");
  FileEntry *FEnt = static_cast<FileEntry *>(SFile);
  return FEnt->getName();
}

time_t clang_getFileTime(CXFile SFile) {
  assert(SFile && "Passed null CXFile");
  FileEntry *FEnt = static_cast<FileEntry *>(SFile);
  return FEnt->getModificationTime();
}

CXString clang_getCursorSpelling(CXCursor C) {
  assert(C.decl && "CXCursor has null decl");
  NamedDecl *ND = static_cast<NamedDecl *>(C.decl);

  if (clang_isReference(C.kind)) {
    switch (C.kind) {
    case CXCursor_ObjCSuperClassRef: {
      ObjCInterfaceDecl *OID = dyn_cast<ObjCInterfaceDecl>(ND);
      assert(OID && "clang_getCursorLine(): Missing interface decl");
      return createCXString(OID->getSuperClass()->getIdentifier()
                            ->getNameStart());
    }
    case CXCursor_ObjCClassRef: {
      if (ObjCInterfaceDecl *OID = dyn_cast<ObjCInterfaceDecl>(ND))
        return createCXString(OID->getIdentifier()->getNameStart());

      ObjCCategoryDecl *OCD = dyn_cast<ObjCCategoryDecl>(ND);
      assert(OCD && "clang_getCursorLine(): Missing category decl");
      return createCXString(OCD->getClassInterface()->getIdentifier()
                            ->getNameStart());
    }
    case CXCursor_ObjCProtocolRef: {
      ObjCProtocolDecl *OID = dyn_cast<ObjCProtocolDecl>(ND);
      assert(OID && "clang_getCursorLine(): Missing protocol decl");
      return createCXString(OID->getIdentifier()->getNameStart());
    }
    case CXCursor_ObjCSelectorRef: {
      ObjCMessageExpr *OME = dyn_cast<ObjCMessageExpr>(
        static_cast<Stmt *>(C.stmt));
      assert(OME && "clang_getCursorLine(): Missing message expr");
      return createCXString(OME->getSelector().getAsString().c_str(), true);
    }
    case CXCursor_VarRef:
    case CXCursor_FunctionRef:
    case CXCursor_EnumConstantRef: {
      DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(
        static_cast<Stmt *>(C.stmt));
      assert(DRE && "clang_getCursorLine(): Missing decl ref expr");
      return createCXString(DRE->getDecl()->getIdentifier()->getNameStart());
    }
    default:
      return createCXString("<not implemented>");
    }
  }
  return clang_getDeclSpelling(C.decl);
}

const char *clang_getCursorKindSpelling(enum CXCursorKind Kind) {
  switch (Kind) {
  case CXCursor_FunctionDecl: return "FunctionDecl";
  case CXCursor_TypedefDecl: return "TypedefDecl";
  case CXCursor_EnumDecl: return "EnumDecl";
  case CXCursor_EnumConstantDecl: return "EnumConstantDecl";
  case CXCursor_StructDecl: return "StructDecl";
  case CXCursor_UnionDecl: return "UnionDecl";
  case CXCursor_ClassDecl: return "ClassDecl";
  case CXCursor_FieldDecl: return "FieldDecl";
  case CXCursor_VarDecl: return "VarDecl";
  case CXCursor_ParmDecl: return "ParmDecl";
  case CXCursor_ObjCInterfaceDecl: return "ObjCInterfaceDecl";
  case CXCursor_ObjCCategoryDecl: return "ObjCCategoryDecl";
  case CXCursor_ObjCProtocolDecl: return "ObjCProtocolDecl";
  case CXCursor_ObjCPropertyDecl: return "ObjCPropertyDecl";
  case CXCursor_ObjCIvarDecl: return "ObjCIvarDecl";
  case CXCursor_ObjCInstanceMethodDecl: return "ObjCInstanceMethodDecl";
  case CXCursor_ObjCClassMethodDecl: return "ObjCClassMethodDecl";
  case CXCursor_FunctionDefn: return "FunctionDefn";
  case CXCursor_ObjCInstanceMethodDefn: return "ObjCInstanceMethodDefn";
  case CXCursor_ObjCClassMethodDefn: return "ObjCClassMethodDefn";
  case CXCursor_ObjCClassDefn: return "ObjCClassDefn";
  case CXCursor_ObjCCategoryDefn: return "ObjCCategoryDefn";
  case CXCursor_ObjCSuperClassRef: return "ObjCSuperClassRef";
  case CXCursor_ObjCProtocolRef: return "ObjCProtocolRef";
  case CXCursor_ObjCClassRef: return "ObjCClassRef";
  case CXCursor_ObjCSelectorRef: return "ObjCSelectorRef";

  case CXCursor_VarRef: return "VarRef";
  case CXCursor_FunctionRef: return "FunctionRef";
  case CXCursor_EnumConstantRef: return "EnumConstantRef";
  case CXCursor_MemberRef: return "MemberRef";

  case CXCursor_InvalidFile: return "InvalidFile";
  case CXCursor_NoDeclFound: return "NoDeclFound";
  case CXCursor_NotImplemented: return "NotImplemented";
  default: return "<not implemented>";
  }
}

static enum CXCursorKind TranslateKind(Decl *D) {
  switch (D->getKind()) {
  case Decl::Function: return CXCursor_FunctionDecl;
  case Decl::Typedef: return CXCursor_TypedefDecl;
  case Decl::Enum: return CXCursor_EnumDecl;
  case Decl::EnumConstant: return CXCursor_EnumConstantDecl;
  case Decl::Record: return CXCursor_StructDecl; // FIXME: union/class
  case Decl::Field: return CXCursor_FieldDecl;
  case Decl::Var: return CXCursor_VarDecl;
  case Decl::ParmVar: return CXCursor_ParmDecl;
  case Decl::ObjCInterface: return CXCursor_ObjCInterfaceDecl;
  case Decl::ObjCCategory: return CXCursor_ObjCCategoryDecl;
  case Decl::ObjCProtocol: return CXCursor_ObjCProtocolDecl;
  case Decl::ObjCMethod: {
    ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D);
    if (MD->isInstanceMethod())
      return CXCursor_ObjCInstanceMethodDecl;
    return CXCursor_ObjCClassMethodDecl;
  }
  default: break;
  }
  return CXCursor_NotImplemented;
}
//
// CXCursor Operations.
//

CXCursor clang_getCursor(CXTranslationUnit CTUnit, const char *source_name,
                         unsigned line, unsigned column) {
  assert(CTUnit && "Passed null CXTranslationUnit");
  ASTUnit *CXXUnit = static_cast<ASTUnit *>(CTUnit);

  FileManager &FMgr = CXXUnit->getFileManager();
  const FileEntry *File = FMgr.getFile(source_name,
                                       source_name+strlen(source_name));
  if (!File) {
    CXCursor C = { CXCursor_InvalidFile, 0, 0 };
    return C;
  }
  SourceLocation SLoc =
    CXXUnit->getSourceManager().getLocation(File, line, column);

  ASTLocation LastLoc = CXXUnit->getLastASTLocation();

  ASTLocation ALoc = ResolveLocationInAST(CXXUnit->getASTContext(), SLoc,
                                          &LastLoc);
  if (ALoc.isValid())
    CXXUnit->setLastASTLocation(ALoc);

  Decl *Dcl = ALoc.getParentDecl();
  if (ALoc.isNamedRef())
    Dcl = ALoc.AsNamedRef().ND;
  Stmt *Stm = ALoc.dyn_AsStmt();
  if (Dcl) {
    if (Stm) {
      if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Stm)) {
        CXCursor C = { TranslateDeclRefExpr(DRE), Dcl, Stm };
        return C;
      } else if (ObjCMessageExpr *MExp = dyn_cast<ObjCMessageExpr>(Stm)) {
        CXCursor C = { CXCursor_ObjCSelectorRef, Dcl, MExp };
        return C;
      }
      // Fall through...treat as a decl, not a ref.
    }
    if (ALoc.isNamedRef()) {
      if (isa<ObjCInterfaceDecl>(Dcl)) {
        CXCursor C = { CXCursor_ObjCClassRef, Dcl, ALoc.getParentDecl() };
        return C;
      }
      if (isa<ObjCProtocolDecl>(Dcl)) {
        CXCursor C = { CXCursor_ObjCProtocolRef, Dcl, ALoc.getParentDecl() };
        return C;
      }
    }
    CXCursor C = { TranslateKind(Dcl), Dcl, 0 };
    return C;
  }
  CXCursor C = { CXCursor_NoDeclFound, 0, 0 };
  return C;
}

CXCursor clang_getNullCursor(void) {
  CXCursor C;
  C.kind = CXCursor_InvalidFile;
  C.decl = NULL;
  C.stmt = NULL;
  return C;
}

unsigned clang_equalCursors(CXCursor X, CXCursor Y) {
  return X.kind == Y.kind && X.decl == Y.decl && X.stmt == Y.stmt;
}

CXCursor clang_getCursorFromDecl(CXDecl AnonDecl) {
  assert(AnonDecl && "Passed null CXDecl");
  NamedDecl *ND = static_cast<NamedDecl *>(AnonDecl);

  CXCursor C = { TranslateKind(ND), ND, 0 };
  return C;
}

unsigned clang_isInvalid(enum CXCursorKind K) {
  return K >= CXCursor_FirstInvalid && K <= CXCursor_LastInvalid;
}

unsigned clang_isDeclaration(enum CXCursorKind K) {
  return K >= CXCursor_FirstDecl && K <= CXCursor_LastDecl;
}

unsigned clang_isReference(enum CXCursorKind K) {
  return K >= CXCursor_FirstRef && K <= CXCursor_LastRef;
}

unsigned clang_isDefinition(enum CXCursorKind K) {
  return K >= CXCursor_FirstDefn && K <= CXCursor_LastDefn;
}

CXCursorKind clang_getCursorKind(CXCursor C) {
  return C.kind;
}

static Decl *getDeclFromExpr(Stmt *E) {
  if (DeclRefExpr *RefExpr = dyn_cast<DeclRefExpr>(E))
    return RefExpr->getDecl();
  if (MemberExpr *ME = dyn_cast<MemberExpr>(E))
    return ME->getMemberDecl();
  if (ObjCIvarRefExpr *RE = dyn_cast<ObjCIvarRefExpr>(E))
    return RE->getDecl();

  if (CallExpr *CE = dyn_cast<CallExpr>(E))
    return getDeclFromExpr(CE->getCallee());
  if (CastExpr *CE = dyn_cast<CastExpr>(E))
    return getDeclFromExpr(CE->getSubExpr());
  if (ObjCMessageExpr *OME = dyn_cast<ObjCMessageExpr>(E))
    return OME->getMethodDecl();

  return 0;
}

CXDecl clang_getCursorDecl(CXCursor C) {
  if (clang_isDeclaration(C.kind))
    return C.decl;

  if (clang_isReference(C.kind)) {
    if (C.stmt) {
      if (C.kind == CXCursor_ObjCClassRef ||
          C.kind == CXCursor_ObjCProtocolRef)
        return static_cast<Stmt *>(C.stmt);
      else
        return getDeclFromExpr(static_cast<Stmt *>(C.stmt));
    } else
      return C.decl;
  }
  return 0;
}

unsigned clang_getCursorLine(CXCursor C) {
  assert(C.decl && "CXCursor has null decl");
  NamedDecl *ND = static_cast<NamedDecl *>(C.decl);
  SourceManager &SourceMgr = ND->getASTContext().getSourceManager();

  SourceLocation SLoc = getLocationFromCursor(C, SourceMgr, ND);
  return SourceMgr.getSpellingLineNumber(SLoc);
}

const char *clang_getCString(CXString string) {
  return string.Spelling;
}

void clang_disposeString(CXString string) {
  if (string.MustFreeString)
    free((void*)string.Spelling);
}

unsigned clang_getCursorColumn(CXCursor C) {
  assert(C.decl && "CXCursor has null decl");
  NamedDecl *ND = static_cast<NamedDecl *>(C.decl);
  SourceManager &SourceMgr = ND->getASTContext().getSourceManager();

  SourceLocation SLoc = getLocationFromCursor(C, SourceMgr, ND);
  return SourceMgr.getSpellingColumnNumber(SLoc);
}

const char *clang_getCursorSource(CXCursor C) {
  assert(C.decl && "CXCursor has null decl");
  NamedDecl *ND = static_cast<NamedDecl *>(C.decl);
  SourceManager &SourceMgr = ND->getASTContext().getSourceManager();

  SourceLocation SLoc = getLocationFromCursor(C, SourceMgr, ND);

  if (SLoc.isFileID()) {
    const char *bufferName = SourceMgr.getBufferName(SLoc);
    return bufferName[0] == '<' ? NULL : bufferName;
  }

  // Retrieve the file in which the macro was instantiated, then provide that
  // buffer name.
  // FIXME: Do we want to give specific macro-instantiation information?
  const llvm::MemoryBuffer *Buffer
    = SourceMgr.getBuffer(SourceMgr.getDecomposedSpellingLoc(SLoc).first);
  if (!Buffer)
    return 0;

  return Buffer->getBufferIdentifier();
}

CXFile clang_getCursorSourceFile(CXCursor C) {
  assert(C.decl && "CXCursor has null decl");
  NamedDecl *ND = static_cast<NamedDecl *>(C.decl);
  SourceManager &SourceMgr = ND->getASTContext().getSourceManager();

  return (void *)getFileEntryFromSourceLocation(SourceMgr,
                                                getLocationFromCursor(C,SourceMgr, ND));
}

void clang_getDefinitionSpellingAndExtent(CXCursor C,
                                          const char **startBuf,
                                          const char **endBuf,
                                          unsigned *startLine,
                                          unsigned *startColumn,
                                          unsigned *endLine,
                                          unsigned *endColumn) {
  assert(C.decl && "CXCursor has null decl");
  NamedDecl *ND = static_cast<NamedDecl *>(C.decl);
  FunctionDecl *FD = dyn_cast<FunctionDecl>(ND);
  CompoundStmt *Body = dyn_cast<CompoundStmt>(FD->getBody());

  SourceManager &SM = FD->getASTContext().getSourceManager();
  *startBuf = SM.getCharacterData(Body->getLBracLoc());
  *endBuf = SM.getCharacterData(Body->getRBracLoc());
  *startLine = SM.getSpellingLineNumber(Body->getLBracLoc());
  *startColumn = SM.getSpellingColumnNumber(Body->getLBracLoc());
  *endLine = SM.getSpellingLineNumber(Body->getRBracLoc());
  *endColumn = SM.getSpellingColumnNumber(Body->getRBracLoc());
}

enum CXCompletionChunkKind
clang_getCompletionChunkKind(CXCompletionString completion_string,
                             unsigned chunk_number) {
  CodeCompletionString *CCStr = (CodeCompletionString *)completion_string;
  if (!CCStr || chunk_number >= CCStr->size())
    return CXCompletionChunk_Text;

  switch ((*CCStr)[chunk_number].Kind) {
  case CodeCompletionString::CK_TypedText:
    return CXCompletionChunk_TypedText;
  case CodeCompletionString::CK_Text:
    return CXCompletionChunk_Text;
  case CodeCompletionString::CK_Optional:
    return CXCompletionChunk_Optional;
  case CodeCompletionString::CK_Placeholder:
    return CXCompletionChunk_Placeholder;
  case CodeCompletionString::CK_Informative:
    return CXCompletionChunk_Informative;
  case CodeCompletionString::CK_ResultType:
    return CXCompletionChunk_ResultType;
  case CodeCompletionString::CK_CurrentParameter:
    return CXCompletionChunk_CurrentParameter;
  case CodeCompletionString::CK_LeftParen:
    return CXCompletionChunk_LeftParen;
  case CodeCompletionString::CK_RightParen:
    return CXCompletionChunk_RightParen;
  case CodeCompletionString::CK_LeftBracket:
    return CXCompletionChunk_LeftBracket;
  case CodeCompletionString::CK_RightBracket:
    return CXCompletionChunk_RightBracket;
  case CodeCompletionString::CK_LeftBrace:
    return CXCompletionChunk_LeftBrace;
  case CodeCompletionString::CK_RightBrace:
    return CXCompletionChunk_RightBrace;
  case CodeCompletionString::CK_LeftAngle:
    return CXCompletionChunk_LeftAngle;
  case CodeCompletionString::CK_RightAngle:
    return CXCompletionChunk_RightAngle;
  case CodeCompletionString::CK_Comma:
    return CXCompletionChunk_Comma;
  }

  // Should be unreachable, but let's be careful.
  return CXCompletionChunk_Text;
}

const char *clang_getCompletionChunkText(CXCompletionString completion_string,
                                         unsigned chunk_number) {
  CodeCompletionString *CCStr = (CodeCompletionString *)completion_string;
  if (!CCStr || chunk_number >= CCStr->size())
    return 0;

  switch ((*CCStr)[chunk_number].Kind) {
  case CodeCompletionString::CK_TypedText:
  case CodeCompletionString::CK_Text:
  case CodeCompletionString::CK_Placeholder:
  case CodeCompletionString::CK_CurrentParameter:
  case CodeCompletionString::CK_Informative:
  case CodeCompletionString::CK_LeftParen:
  case CodeCompletionString::CK_RightParen:
  case CodeCompletionString::CK_LeftBracket:
  case CodeCompletionString::CK_RightBracket:
  case CodeCompletionString::CK_LeftBrace:
  case CodeCompletionString::CK_RightBrace:
  case CodeCompletionString::CK_LeftAngle:
  case CodeCompletionString::CK_RightAngle:
  case CodeCompletionString::CK_Comma:
  case CodeCompletionString::CK_ResultType:
    return (*CCStr)[chunk_number].Text;

  case CodeCompletionString::CK_Optional:
    // Note: treated as an empty text block.
    return "";
  }

  // Should be unreachable, but let's be careful.
  return 0;
}

CXCompletionString
clang_getCompletionChunkCompletionString(CXCompletionString completion_string,
                                         unsigned chunk_number) {
  CodeCompletionString *CCStr = (CodeCompletionString *)completion_string;
  if (!CCStr || chunk_number >= CCStr->size())
    return 0;

  switch ((*CCStr)[chunk_number].Kind) {
  case CodeCompletionString::CK_TypedText:
  case CodeCompletionString::CK_Text:
  case CodeCompletionString::CK_Placeholder:
  case CodeCompletionString::CK_CurrentParameter:
  case CodeCompletionString::CK_Informative:
  case CodeCompletionString::CK_LeftParen:
  case CodeCompletionString::CK_RightParen:
  case CodeCompletionString::CK_LeftBracket:
  case CodeCompletionString::CK_RightBracket:
  case CodeCompletionString::CK_LeftBrace:
  case CodeCompletionString::CK_RightBrace:
  case CodeCompletionString::CK_LeftAngle:
  case CodeCompletionString::CK_RightAngle:
  case CodeCompletionString::CK_Comma:
  case CodeCompletionString::CK_ResultType:
    return 0;

  case CodeCompletionString::CK_Optional:
    // Note: treated as an empty text block.
    return (*CCStr)[chunk_number].Optional;
  }

  // Should be unreachable, but let's be careful.
  return 0;
}

unsigned clang_getNumCompletionChunks(CXCompletionString completion_string) {
  CodeCompletionString *CCStr = (CodeCompletionString *)completion_string;
  return CCStr? CCStr->size() : 0;
}

static bool ReadUnsigned(const char *&Memory, const char *MemoryEnd,
                         unsigned &Value) {
  if (Memory + sizeof(unsigned) > MemoryEnd)
    return true;

  memmove(&Value, Memory, sizeof(unsigned));
  Memory += sizeof(unsigned);
  return false;
}

/// \brief The CXCodeCompleteResults structure we allocate internally;
/// the client only sees the initial CXCodeCompleteResults structure.
struct AllocatedCXCodeCompleteResults : public CXCodeCompleteResults {
  /// \brief The memory buffer from which we parsed the results. We
  /// retain this buffer because the completion strings point into it.
  llvm::MemoryBuffer *Buffer;
};

CXCodeCompleteResults *clang_codeComplete(CXIndex CIdx,
                                          const char *source_filename,
                                          int num_command_line_args,
                                          const char **command_line_args,
                                          unsigned num_unsaved_files,
                                          struct CXUnsavedFile *unsaved_files,
                                          const char *complete_filename,
                                          unsigned complete_line,
                                          unsigned complete_column) {
  // The indexer, which is mainly used to determine where diagnostics go.
  CIndexer *CXXIdx = static_cast<CIndexer *>(CIdx);

  // The set of temporary files that we've built.
  std::vector<llvm::sys::Path> TemporaryFiles;

  // Build up the arguments for invoking 'clang'.
  std::vector<const char *> argv;

  // First add the complete path to the 'clang' executable.
  llvm::sys::Path ClangPath = CXXIdx->getClangPath();
  argv.push_back(ClangPath.c_str());

  // Add the '-fsyntax-only' argument so that we only perform a basic
  // syntax check of the code.
  argv.push_back("-fsyntax-only");

  // Add the appropriate '-code-completion-at=file:line:column' argument
  // to perform code completion, with an "-Xclang" preceding it.
  std::string code_complete_at;
  code_complete_at += complete_filename;
  code_complete_at += ":";
  code_complete_at += llvm::utostr(complete_line);
  code_complete_at += ":";
  code_complete_at += llvm::utostr(complete_column);
  argv.push_back("-Xclang");
  argv.push_back("-code-completion-at");
  argv.push_back("-Xclang");
  argv.push_back(code_complete_at.c_str());
  argv.push_back("-Xclang");
  argv.push_back("-no-code-completion-debug-printer");
  argv.push_back("-Xclang");
  argv.push_back("-code-completion-macros");
  
  std::vector<std::string> RemapArgs;
  for (unsigned i = 0; i != num_unsaved_files; ++i) {
    char tmpFile[L_tmpnam];
    char *tmpFileName = tmpnam(tmpFile);

    // Write the contents of this unsaved file into the temporary file.
    llvm::sys::Path SavedFile(tmpFileName);
    std::string ErrorInfo;
    llvm::raw_fd_ostream OS(SavedFile.c_str(), ErrorInfo);
    if (!ErrorInfo.empty())
      continue;
    
    OS.write(unsaved_files[i].Contents, unsaved_files[i].Length);
    OS.close();
    if (OS.has_error()) {
      SavedFile.eraseFromDisk();
      continue;
    }

    // Remap the file.
    std::string RemapArg = unsaved_files[i].Filename;
    RemapArg += ';';
    RemapArg += tmpFileName;
    RemapArgs.push_back("-Xclang");
    RemapArgs.push_back("-remap-file");
    RemapArgs.push_back("-Xclang");
    RemapArgs.push_back(RemapArg);
    TemporaryFiles.push_back(SavedFile);
  }

  // The pointers into the elements of RemapArgs are stable because we
  // won't be adding anything to RemapArgs after this point.
  for (unsigned i = 0, e = RemapArgs.size(); i != e; ++i)
    argv.push_back(RemapArgs[i].c_str());

  // Add the source file name (FIXME: later, we'll want to build temporary
  // file from the buffer, or just feed the source text via standard input).
  if (source_filename)
    argv.push_back(source_filename);

  // Process the compiler options, stripping off '-o', '-c', '-fsyntax-only'.
  for (int i = 0; i < num_command_line_args; ++i)
    if (const char *arg = command_line_args[i]) {
      if (strcmp(arg, "-o") == 0) {
        ++i; // Also skip the matching argument.
        continue;
      }
      if (strcmp(arg, "-emit-ast") == 0 ||
          strcmp(arg, "-c") == 0 ||
          strcmp(arg, "-fsyntax-only") == 0) {
        continue;
      }

      // Keep the argument.
      argv.push_back(arg);
    }

  // Add the null terminator.
  argv.push_back(NULL);

  // Generate a temporary name for the AST file.
  char tmpFile[L_tmpnam];
  char *tmpFileName = tmpnam(tmpFile);
  llvm::sys::Path ResultsFile(tmpFileName);
  TemporaryFiles.push_back(ResultsFile);

  // Invoke 'clang'.
  llvm::sys::Path DevNull; // leave empty, causes redirection to /dev/null
                           // on Unix or NUL (Windows).
  std::string ErrMsg;
  const llvm::sys::Path *Redirects[] = { &DevNull, &ResultsFile, &DevNull, 0 };
  llvm::sys::Program::ExecuteAndWait(ClangPath, &argv[0], /* env */ NULL,
                                     /* redirects */ &Redirects[0],
                                     /* secondsToWait */ 0,
                                     /* memoryLimits */ 0, &ErrMsg);

  if (CXXIdx->getDisplayDiagnostics() && !ErrMsg.empty()) {
    llvm::errs() << "clang_codeComplete: " << ErrMsg
                 << '\n' << "Arguments: \n";
    for (std::vector<const char*>::iterator I = argv.begin(), E = argv.end();
         I!=E; ++I) {
      if (*I)
        llvm::errs() << ' ' << *I << '\n';
    }
    llvm::errs() << '\n';
  }

  // Parse the resulting source file to find code-completion results.
  using llvm::MemoryBuffer;
  using llvm::StringRef;
  AllocatedCXCodeCompleteResults *Results = 0;
  if (MemoryBuffer *F = MemoryBuffer::getFile(ResultsFile.c_str())) {
    llvm::SmallVector<CXCompletionResult, 4> CompletionResults;
    StringRef Buffer = F->getBuffer();
    for (const char *Str = Buffer.data(), *StrEnd = Str + Buffer.size();
         Str < StrEnd;) {
      unsigned KindValue;
      if (ReadUnsigned(Str, StrEnd, KindValue))
        break;

      CodeCompletionString *CCStr 
        = CodeCompletionString::Deserialize(Str, StrEnd);
      if (!CCStr)
        continue;

      if (!CCStr->empty()) {
        // Vend the code-completion result to the caller.
        CXCompletionResult Result;
        Result.CursorKind = (CXCursorKind)KindValue;
        Result.CompletionString = CCStr;
        CompletionResults.push_back(Result);
      }
    };

    // Allocate the results.
    Results = new AllocatedCXCodeCompleteResults;
    Results->Results = new CXCompletionResult [CompletionResults.size()];
    Results->NumResults = CompletionResults.size();
    memcpy(Results->Results, CompletionResults.data(),
           CompletionResults.size() * sizeof(CXCompletionResult));
    Results->Buffer = F;
  }

  for (unsigned i = 0, e = TemporaryFiles.size(); i != e; ++i)
    TemporaryFiles[i].eraseFromDisk();

  return Results;
}

void clang_disposeCodeCompleteResults(CXCodeCompleteResults *ResultsIn) {
  if (!ResultsIn)
    return;

  AllocatedCXCodeCompleteResults *Results
    = static_cast<AllocatedCXCodeCompleteResults*>(ResultsIn);

  for (unsigned I = 0, N = Results->NumResults; I != N; ++I)
    delete (CXCompletionString *)Results->Results[I].CompletionString;
  delete [] Results->Results;

  Results->Results = 0;
  Results->NumResults = 0;
  delete Results->Buffer;
  Results->Buffer = 0;
  delete Results;
}

} // end extern "C"