lib/Sema/SemaCodeComplete.cpp

//===---------------- SemaCodeComplete.cpp - Code Completion ----*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
//  This file defines the code-completion semantic actions.
//
//===----------------------------------------------------------------------===//
#include "clang/AST/DeclCXX.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/ExprObjC.h"
#include "clang/AST/QualTypeNames.h"
#include "clang/Basic/CharInfo.h"
#include "clang/Lex/HeaderSearch.h"
#include "clang/Lex/MacroInfo.h"
#include "clang/Lex/Preprocessor.h"
#include "clang/Sema/CodeCompleteConsumer.h"
#include "clang/Sema/Lookup.h"
#include "clang/Sema/Overload.h"
#include "clang/Sema/Scope.h"
#include "clang/Sema/ScopeInfo.h"
#include "clang/Sema/SemaInternal.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/SmallBitVector.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/ADT/Twine.h"
#include <list>
#include <map>
#include <vector>

using namespace clang;
using namespace sema;

namespace {
  /// \brief A container of code-completion results.
  class ResultBuilder {
  public:
    /// \brief The type of a name-lookup filter, which can be provided to the
    /// name-lookup routines to specify which declarations should be included in
    /// the result set (when it returns true) and which declarations should be
    /// filtered out (returns false).
    typedef bool (ResultBuilder::*LookupFilter)(const NamedDecl *) const;

    typedef CodeCompletionResult Result;
    
  private:
    /// \brief The actual results we have found.
    std::vector<Result> Results;
    
    /// \brief A record of all of the declarations we have found and placed
    /// into the result set, used to ensure that no declaration ever gets into
    /// the result set twice.
    llvm::SmallPtrSet<const Decl*, 16> AllDeclsFound;
    
    typedef std::pair<const NamedDecl *, unsigned> DeclIndexPair;

    /// \brief An entry in the shadow map, which is optimized to store
    /// a single (declaration, index) mapping (the common case) but
    /// can also store a list of (declaration, index) mappings.
    class ShadowMapEntry {
      typedef SmallVector<DeclIndexPair, 4> DeclIndexPairVector;

      /// \brief Contains either the solitary NamedDecl * or a vector
      /// of (declaration, index) pairs.
      llvm::PointerUnion<const NamedDecl *, DeclIndexPairVector*> DeclOrVector;

      /// \brief When the entry contains a single declaration, this is
      /// the index associated with that entry.
      unsigned SingleDeclIndex;

    public:
      ShadowMapEntry() : DeclOrVector(), SingleDeclIndex(0) { }

      void Add(const NamedDecl *ND, unsigned Index) {
        if (DeclOrVector.isNull()) {
          // 0 - > 1 elements: just set the single element information.
          DeclOrVector = ND;
          SingleDeclIndex = Index;
          return;
        }

        if (const NamedDecl *PrevND =
                DeclOrVector.dyn_cast<const NamedDecl *>()) {
          // 1 -> 2 elements: create the vector of results and push in the
          // existing declaration.
          DeclIndexPairVector *Vec = new DeclIndexPairVector;
          Vec->push_back(DeclIndexPair(PrevND, SingleDeclIndex));
          DeclOrVector = Vec;
        }

        // Add the new element to the end of the vector.
        DeclOrVector.get<DeclIndexPairVector*>()->push_back(
                                                    DeclIndexPair(ND, Index));
      }

      void Destroy() {
        if (DeclIndexPairVector *Vec
              = DeclOrVector.dyn_cast<DeclIndexPairVector *>()) {
          delete Vec;
          DeclOrVector = ((NamedDecl *)nullptr);
        }
      }

      // Iteration.
      class iterator;
      iterator begin() const;
      iterator end() const;
    };

    /// \brief A mapping from declaration names to the declarations that have
    /// this name within a particular scope and their index within the list of
    /// results.
    typedef llvm::DenseMap<DeclarationName, ShadowMapEntry> ShadowMap;
    
    /// \brief The semantic analysis object for which results are being 
    /// produced.
    Sema &SemaRef;

    /// \brief The allocator used to allocate new code-completion strings.
    CodeCompletionAllocator &Allocator;

    CodeCompletionTUInfo &CCTUInfo;
    
    /// \brief If non-NULL, a filter function used to remove any code-completion
    /// results that are not desirable.
    LookupFilter Filter;

    /// \brief Whether we should allow declarations as
    /// nested-name-specifiers that would otherwise be filtered out.
    bool AllowNestedNameSpecifiers;

    /// \brief If set, the type that we would prefer our resulting value
    /// declarations to have.
    ///
    /// Closely matching the preferred type gives a boost to a result's 
    /// priority.
    CanQualType PreferredType;
    
    /// \brief A list of shadow maps, which is used to model name hiding at
    /// different levels of, e.g., the inheritance hierarchy.
    std::list<ShadowMap> ShadowMaps;
    
    /// \brief If we're potentially referring to a C++ member function, the set
    /// of qualifiers applied to the object type.
    Qualifiers ObjectTypeQualifiers;
    
    /// \brief Whether the \p ObjectTypeQualifiers field is active.
    bool HasObjectTypeQualifiers;
    
    /// \brief The selector that we prefer.
    Selector PreferredSelector;
    
    /// \brief The completion context in which we are gathering results.
    CodeCompletionContext CompletionContext;
    
    /// \brief If we are in an instance method definition, the \@implementation
    /// object.
    ObjCImplementationDecl *ObjCImplementation;

    void AdjustResultPriorityForDecl(Result &R);

    void MaybeAddConstructorResults(Result R);
    
  public:
    explicit ResultBuilder(Sema &SemaRef, CodeCompletionAllocator &Allocator,
                           CodeCompletionTUInfo &CCTUInfo,
                           const CodeCompletionContext &CompletionContext,
                           LookupFilter Filter = nullptr)
      : SemaRef(SemaRef), Allocator(Allocator), CCTUInfo(CCTUInfo),
        Filter(Filter), 
        AllowNestedNameSpecifiers(false), HasObjectTypeQualifiers(false), 
        CompletionContext(CompletionContext),
        ObjCImplementation(nullptr)
    { 
      // If this is an Objective-C instance method definition, dig out the 
      // corresponding implementation.
      switch (CompletionContext.getKind()) {
      case CodeCompletionContext::CCC_Expression:
      case CodeCompletionContext::CCC_ObjCMessageReceiver:
      case CodeCompletionContext::CCC_ParenthesizedExpression:
      case CodeCompletionContext::CCC_Statement:
      case CodeCompletionContext::CCC_Recovery:
        if (ObjCMethodDecl *Method = SemaRef.getCurMethodDecl())
          if (Method->isInstanceMethod())
            if (ObjCInterfaceDecl *Interface = Method->getClassInterface())
              ObjCImplementation = Interface->getImplementation();
        break;
          
      default:
        break;
      }
    }

    /// \brief Determine the priority for a reference to the given declaration.
    unsigned getBasePriority(const NamedDecl *D);

    /// \brief Whether we should include code patterns in the completion
    /// results.
    bool includeCodePatterns() const {
      return SemaRef.CodeCompleter && 
             SemaRef.CodeCompleter->includeCodePatterns();
    }
    
    /// \brief Set the filter used for code-completion results.
    void setFilter(LookupFilter Filter) {
      this->Filter = Filter;
    }

    Result *data() { return Results.empty()? nullptr : &Results.front(); }
    unsigned size() const { return Results.size(); }
    bool empty() const { return Results.empty(); }
    
    /// \brief Specify the preferred type.
    void setPreferredType(QualType T) { 
      PreferredType = SemaRef.Context.getCanonicalType(T); 
    }
    
    /// \brief Set the cv-qualifiers on the object type, for us in filtering
    /// calls to member functions.
    ///
    /// When there are qualifiers in this set, they will be used to filter
    /// out member functions that aren't available (because there will be a 
    /// cv-qualifier mismatch) or prefer functions with an exact qualifier
    /// match.
    void setObjectTypeQualifiers(Qualifiers Quals) {
      ObjectTypeQualifiers = Quals;
      HasObjectTypeQualifiers = true;
    }
    
    /// \brief Set the preferred selector.
    ///
    /// When an Objective-C method declaration result is added, and that
    /// method's selector matches this preferred selector, we give that method
    /// a slight priority boost.
    void setPreferredSelector(Selector Sel) {
      PreferredSelector = Sel;
    }
        
    /// \brief Retrieve the code-completion context for which results are
    /// being collected.
    const CodeCompletionContext &getCompletionContext() const { 
      return CompletionContext; 
    }
    
    /// \brief Specify whether nested-name-specifiers are allowed.
    void allowNestedNameSpecifiers(bool Allow = true) {
      AllowNestedNameSpecifiers = Allow;
    }

    /// \brief Return the semantic analysis object for which we are collecting
    /// code completion results.
    Sema &getSema() const { return SemaRef; }
    
    /// \brief Retrieve the allocator used to allocate code completion strings.
    CodeCompletionAllocator &getAllocator() const { return Allocator; }

    CodeCompletionTUInfo &getCodeCompletionTUInfo() const { return CCTUInfo; }
    
    /// \brief Determine whether the given declaration is at all interesting
    /// as a code-completion result.
    ///
    /// \param ND the declaration that we are inspecting.
    ///
    /// \param AsNestedNameSpecifier will be set true if this declaration is
    /// only interesting when it is a nested-name-specifier.
    bool isInterestingDecl(const NamedDecl *ND,
                           bool &AsNestedNameSpecifier) const;
    
    /// \brief Check whether the result is hidden by the Hiding declaration.
    ///
    /// \returns true if the result is hidden and cannot be found, false if
    /// the hidden result could still be found. When false, \p R may be
    /// modified to describe how the result can be found (e.g., via extra
    /// qualification).
    bool CheckHiddenResult(Result &R, DeclContext *CurContext,
                           const NamedDecl *Hiding);
    
    /// \brief Add a new result to this result set (if it isn't already in one
    /// of the shadow maps), or replace an existing result (for, e.g., a 
    /// redeclaration).
    ///
    /// \param R the result to add (if it is unique).
    ///
    /// \param CurContext the context in which this result will be named.
    void MaybeAddResult(Result R, DeclContext *CurContext = nullptr);

    /// \brief Add a new result to this result set, where we already know
    /// the hiding declaration (if any).
    ///
    /// \param R the result to add (if it is unique).
    ///
    /// \param CurContext the context in which this result will be named.
    ///
    /// \param Hiding the declaration that hides the result.
    ///
    /// \param InBaseClass whether the result was found in a base
    /// class of the searched context.
    void AddResult(Result R, DeclContext *CurContext, NamedDecl *Hiding,
                   bool InBaseClass);
    
    /// \brief Add a new non-declaration result to this result set.
    void AddResult(Result R);

    /// \brief Enter into a new scope.
    void EnterNewScope();
    
    /// \brief Exit from the current scope.
    void ExitScope();
    
    /// \brief Ignore this declaration, if it is seen again.
    void Ignore(const Decl *D) { AllDeclsFound.insert(D->getCanonicalDecl()); }

    /// \name Name lookup predicates
    ///
    /// These predicates can be passed to the name lookup functions to filter the
    /// results of name lookup. All of the predicates have the same type, so that
    /// 
    //@{
    bool IsOrdinaryName(const NamedDecl *ND) const;
    bool IsOrdinaryNonTypeName(const NamedDecl *ND) const;
    bool IsIntegralConstantValue(const NamedDecl *ND) const;
    bool IsOrdinaryNonValueName(const NamedDecl *ND) const;
    bool IsNestedNameSpecifier(const NamedDecl *ND) const;
    bool IsEnum(const NamedDecl *ND) const;
    bool IsClassOrStruct(const NamedDecl *ND) const;
    bool IsUnion(const NamedDecl *ND) const;
    bool IsNamespace(const NamedDecl *ND) const;
    bool IsNamespaceOrAlias(const NamedDecl *ND) const;
    bool IsType(const NamedDecl *ND) const;
    bool IsMember(const NamedDecl *ND) const;
    bool IsObjCIvar(const NamedDecl *ND) const;
    bool IsObjCMessageReceiver(const NamedDecl *ND) const;
    bool IsObjCMessageReceiverOrLambdaCapture(const NamedDecl *ND) const;
    bool IsObjCCollection(const NamedDecl *ND) const;
    bool IsImpossibleToSatisfy(const NamedDecl *ND) const;
    //@}    
  };  
}

class ResultBuilder::ShadowMapEntry::iterator {
  llvm::PointerUnion<const NamedDecl *, const DeclIndexPair *> DeclOrIterator;
  unsigned SingleDeclIndex;

public:
  typedef DeclIndexPair value_type;
  typedef value_type reference;
  typedef std::ptrdiff_t difference_type;
  typedef std::input_iterator_tag iterator_category;
        
  class pointer {
    DeclIndexPair Value;

  public:
    pointer(const DeclIndexPair &Value) : Value(Value) { }

    const DeclIndexPair *operator->() const {
      return &Value;
    }
  };

  iterator() : DeclOrIterator((NamedDecl *)nullptr), SingleDeclIndex(0) {}

  iterator(const NamedDecl *SingleDecl, unsigned Index)
    : DeclOrIterator(SingleDecl), SingleDeclIndex(Index) { }

  iterator(const DeclIndexPair *Iterator)
    : DeclOrIterator(Iterator), SingleDeclIndex(0) { }

  iterator &operator++() {
    if (DeclOrIterator.is<const NamedDecl *>()) {
      DeclOrIterator = (NamedDecl *)nullptr;
      SingleDeclIndex = 0;
      return *this;
    }

    const DeclIndexPair *I = DeclOrIterator.get<const DeclIndexPair*>();
    ++I;
    DeclOrIterator = I;
    return *this;
  }

  /*iterator operator++(int) {
    iterator tmp(*this);
    ++(*this);
    return tmp;
  }*/

  reference operator*() const {
    if (const NamedDecl *ND = DeclOrIterator.dyn_cast<const NamedDecl *>())
      return reference(ND, SingleDeclIndex);

    return *DeclOrIterator.get<const DeclIndexPair*>();
  }

  pointer operator->() const {
    return pointer(**this);
  }

  friend bool operator==(const iterator &X, const iterator &Y) {
    return X.DeclOrIterator.getOpaqueValue()
                                  == Y.DeclOrIterator.getOpaqueValue() &&
      X.SingleDeclIndex == Y.SingleDeclIndex;
  }

  friend bool operator!=(const iterator &X, const iterator &Y) {
    return !(X == Y);
  }
};

ResultBuilder::ShadowMapEntry::iterator 
ResultBuilder::ShadowMapEntry::begin() const {
  if (DeclOrVector.isNull())
    return iterator();

  if (const NamedDecl *ND = DeclOrVector.dyn_cast<const NamedDecl *>())
    return iterator(ND, SingleDeclIndex);

  return iterator(DeclOrVector.get<DeclIndexPairVector *>()->begin());
}

ResultBuilder::ShadowMapEntry::iterator 
ResultBuilder::ShadowMapEntry::end() const {
  if (DeclOrVector.is<const NamedDecl *>() || DeclOrVector.isNull())
    return iterator();

  return iterator(DeclOrVector.get<DeclIndexPairVector *>()->end());
}

/// \brief Compute the qualification required to get from the current context
/// (\p CurContext) to the target context (\p TargetContext).
///
/// \param Context the AST context in which the qualification will be used.
///
/// \param CurContext the context where an entity is being named, which is
/// typically based on the current scope.
///
/// \param TargetContext the context in which the named entity actually 
/// resides.
///
/// \returns a nested name specifier that refers into the target context, or
/// NULL if no qualification is needed.
static NestedNameSpecifier *
getRequiredQualification(ASTContext &Context,
                         const DeclContext *CurContext,
                         const DeclContext *TargetContext) {
  SmallVector<const DeclContext *, 4> TargetParents;
  
  for (const DeclContext *CommonAncestor = TargetContext;
       CommonAncestor && !CommonAncestor->Encloses(CurContext);
       CommonAncestor = CommonAncestor->getLookupParent()) {
    if (CommonAncestor->isTransparentContext() ||
        CommonAncestor->isFunctionOrMethod())
      continue;
    
    TargetParents.push_back(CommonAncestor);
  }

  NestedNameSpecifier *Result = nullptr;
  while (!TargetParents.empty()) {
    const DeclContext *Parent = TargetParents.pop_back_val();

    if (const NamespaceDecl *Namespace = dyn_cast<NamespaceDecl>(Parent)) {
      if (!Namespace->getIdentifier())
        continue;

      Result = NestedNameSpecifier::Create(Context, Result, Namespace);
    }
    else if (const TagDecl *TD = dyn_cast<TagDecl>(Parent))
      Result = NestedNameSpecifier::Create(Context, Result,
                                           false,
                                     Context.getTypeDeclType(TD).getTypePtr());
  }  
  return Result;
}

/// Determine whether \p Id is a name reserved for the implementation (C99
/// 7.1.3, C++ [lib.global.names]).
static bool isReservedName(const IdentifierInfo *Id,
                           bool doubleUnderscoreOnly = false) {
  if (Id->getLength() < 2)
    return false;
  const char *Name = Id->getNameStart();
  return Name[0] == '_' &&
         (Name[1] == '_' || (Name[1] >= 'A' && Name[1] <= 'Z' &&
                             !doubleUnderscoreOnly));
}

// Some declarations have reserved names that we don't want to ever show.
// Filter out names reserved for the implementation if they come from a
// system header.
static bool shouldIgnoreDueToReservedName(const NamedDecl *ND, Sema &SemaRef) {
  const IdentifierInfo *Id = ND->getIdentifier();
  if (!Id)
    return false;

  // Ignore reserved names for compiler provided decls.
  if (isReservedName(Id) && ND->getLocation().isInvalid())
    return true;

  // For system headers ignore only double-underscore names.
  // This allows for system headers providing private symbols with a single
  // underscore.
  if (isReservedName(Id, /*doubleUnderscoreOnly=*/true) &&
       SemaRef.SourceMgr.isInSystemHeader(
           SemaRef.SourceMgr.getSpellingLoc(ND->getLocation())))
      return true;

  return false;
}

bool ResultBuilder::isInterestingDecl(const NamedDecl *ND,
                                      bool &AsNestedNameSpecifier) const {
  AsNestedNameSpecifier = false;

  auto *Named = ND;
  ND = ND->getUnderlyingDecl();

  // Skip unnamed entities.
  if (!ND->getDeclName())
    return false;
  
  // Friend declarations and declarations introduced due to friends are never
  // added as results.
  if (ND->getFriendObjectKind() == Decl::FOK_Undeclared)
    return false;
  
  // Class template (partial) specializations are never added as results.
  if (isa<ClassTemplateSpecializationDecl>(ND) ||
      isa<ClassTemplatePartialSpecializationDecl>(ND))
    return false;
  
  // Using declarations themselves are never added as results.
  if (isa<UsingDecl>(ND))
    return false;

  if (shouldIgnoreDueToReservedName(ND, SemaRef))
    return false;

  if (Filter == &ResultBuilder::IsNestedNameSpecifier ||
      (isa<NamespaceDecl>(ND) &&
       Filter != &ResultBuilder::IsNamespace &&
       Filter != &ResultBuilder::IsNamespaceOrAlias &&
       Filter != nullptr))
    AsNestedNameSpecifier = true;

  // Filter out any unwanted results.
  if (Filter && !(this->*Filter)(Named)) {
    // Check whether it is interesting as a nested-name-specifier.
    if (AllowNestedNameSpecifiers && SemaRef.getLangOpts().CPlusPlus && 
        IsNestedNameSpecifier(ND) &&
        (Filter != &ResultBuilder::IsMember ||
         (isa<CXXRecordDecl>(ND) && 
          cast<CXXRecordDecl>(ND)->isInjectedClassName()))) {
      AsNestedNameSpecifier = true;
      return true;
    }

    return false;
  }  
  // ... then it must be interesting!
  return true;
}

bool ResultBuilder::CheckHiddenResult(Result &R, DeclContext *CurContext,
                                      const NamedDecl *Hiding) {
  // In C, there is no way to refer to a hidden name.
  // FIXME: This isn't true; we can find a tag name hidden by an ordinary
  // name if we introduce the tag type.
  if (!SemaRef.getLangOpts().CPlusPlus)
    return true;
  
  const DeclContext *HiddenCtx =
      R.Declaration->getDeclContext()->getRedeclContext();
  
  // There is no way to qualify a name declared in a function or method.
  if (HiddenCtx->isFunctionOrMethod())
    return true;
  
  if (HiddenCtx == Hiding->getDeclContext()->getRedeclContext())
    return true;
  
  // We can refer to the result with the appropriate qualification. Do it.
  R.Hidden = true;
  R.QualifierIsInformative = false;
  
  if (!R.Qualifier)
    R.Qualifier = getRequiredQualification(SemaRef.Context, 
                                           CurContext, 
                                           R.Declaration->getDeclContext());
  return false;
}

/// \brief A simplified classification of types used to determine whether two
/// types are "similar enough" when adjusting priorities.
SimplifiedTypeClass clang::getSimplifiedTypeClass(CanQualType T) {
  switch (T->getTypeClass()) {
  case Type::Builtin:
    switch (cast<BuiltinType>(T)->getKind()) {
      case BuiltinType::Void:
        return STC_Void;
        
      case BuiltinType::NullPtr:
        return STC_Pointer;
        
      case BuiltinType::Overload:
      case BuiltinType::Dependent:
        return STC_Other;
        
      case BuiltinType::ObjCId:
      case BuiltinType::ObjCClass:
      case BuiltinType::ObjCSel:
        return STC_ObjectiveC;
        
      default:
        return STC_Arithmetic;
    }

  case Type::Complex:
    return STC_Arithmetic;
    
  case Type::Pointer:
    return STC_Pointer;
    
  case Type::BlockPointer:
    return STC_Block;
    
  case Type::LValueReference:
  case Type::RValueReference:
    return getSimplifiedTypeClass(T->getAs<ReferenceType>()->getPointeeType());
    
  case Type::ConstantArray:
  case Type::IncompleteArray:
  case Type::VariableArray:
  case Type::DependentSizedArray:
    return STC_Array;
    
  case Type::DependentSizedExtVector:
  case Type::Vector:
  case Type::ExtVector:
    return STC_Arithmetic;
    
  case Type::FunctionProto:
  case Type::FunctionNoProto:
    return STC_Function;
    
  case Type::Record:
    return STC_Record;
    
  case Type::Enum:
    return STC_Arithmetic;
    
  case Type::ObjCObject:
  case Type::ObjCInterface:
  case Type::ObjCObjectPointer:
    return STC_ObjectiveC;
    
  default:
    return STC_Other;
  }
}

/// \brief Get the type that a given expression will have if this declaration
/// is used as an expression in its "typical" code-completion form.
QualType clang::getDeclUsageType(ASTContext &C, const NamedDecl *ND) {
  ND = cast<NamedDecl>(ND->getUnderlyingDecl());
  
  if (const TypeDecl *Type = dyn_cast<TypeDecl>(ND))
    return C.getTypeDeclType(Type);
  if (const ObjCInterfaceDecl *Iface = dyn_cast<ObjCInterfaceDecl>(ND))
    return C.getObjCInterfaceType(Iface);
  
  QualType T;
  if (const FunctionDecl *Function = ND->getAsFunction())
    T = Function->getCallResultType();
  else if (const ObjCMethodDecl *Method = dyn_cast<ObjCMethodDecl>(ND))
    T = Method->getSendResultType();
  else if (const EnumConstantDecl *Enumerator = dyn_cast<EnumConstantDecl>(ND))
    T = C.getTypeDeclType(cast<EnumDecl>(Enumerator->getDeclContext()));
  else if (const ObjCPropertyDecl *Property = dyn_cast<ObjCPropertyDecl>(ND))
    T = Property->getType();
  else if (const ValueDecl *Value = dyn_cast<ValueDecl>(ND))
    T = Value->getType();
  else
    return QualType();

  // Dig through references, function pointers, and block pointers to
  // get down to the likely type of an expression when the entity is
  // used.
  do {
    if (const ReferenceType *Ref = T->getAs<ReferenceType>()) {
      T = Ref->getPointeeType();
      continue;
    }

    if (const PointerType *Pointer = T->getAs<PointerType>()) {
      if (Pointer->getPointeeType()->isFunctionType()) {
        T = Pointer->getPointeeType();
        continue;
      }

      break;
    }

    if (const BlockPointerType *Block = T->getAs<BlockPointerType>()) {
      T = Block->getPointeeType();
      continue;
    }

    if (const FunctionType *Function = T->getAs<FunctionType>()) {
      T = Function->getReturnType();
      continue;
    }

    break;
  } while (true);
    
  return T;
}

unsigned ResultBuilder::getBasePriority(const NamedDecl *ND) {
  if (!ND)
    return CCP_Unlikely;

  // Context-based decisions.
  const DeclContext *LexicalDC = ND->getLexicalDeclContext();
  if (LexicalDC->isFunctionOrMethod()) {
    // _cmd is relatively rare
    if (const ImplicitParamDecl *ImplicitParam =
        dyn_cast<ImplicitParamDecl>(ND))
      if (ImplicitParam->getIdentifier() &&
          ImplicitParam->getIdentifier()->isStr("_cmd"))
        return CCP_ObjC_cmd;

    return CCP_LocalDeclaration;
  }

  const DeclContext *DC = ND->getDeclContext()->getRedeclContext();
  if (DC->isRecord() || isa<ObjCContainerDecl>(DC)) {
    // Explicit destructor calls are very rare.
    if (isa<CXXDestructorDecl>(ND))
      return CCP_Unlikely;
    // Explicit operator and conversion function calls are also very rare.
    auto DeclNameKind = ND->getDeclName().getNameKind();
    if (DeclNameKind == DeclarationName::CXXOperatorName ||
        DeclNameKind == DeclarationName::CXXLiteralOperatorName ||
        DeclNameKind == DeclarationName::CXXConversionFunctionName)
      return CCP_Unlikely;
    return CCP_MemberDeclaration;
  }

  // Content-based decisions.
  if (isa<EnumConstantDecl>(ND))
    return CCP_Constant;

  // Use CCP_Type for type declarations unless we're in a statement, Objective-C
  // message receiver, or parenthesized expression context. There, it's as
  // likely that the user will want to write a type as other declarations.
  if ((isa<TypeDecl>(ND) || isa<ObjCInterfaceDecl>(ND)) &&
      !(CompletionContext.getKind() == CodeCompletionContext::CCC_Statement ||
        CompletionContext.getKind()
          == CodeCompletionContext::CCC_ObjCMessageReceiver ||
        CompletionContext.getKind()
          == CodeCompletionContext::CCC_ParenthesizedExpression))
    return CCP_Type;

  return CCP_Declaration;
}

void ResultBuilder::AdjustResultPriorityForDecl(Result &R) {
  // If this is an Objective-C method declaration whose selector matches our
  // preferred selector, give it a priority boost.
  if (!PreferredSelector.isNull())
    if (const ObjCMethodDecl *Method = dyn_cast<ObjCMethodDecl>(R.Declaration))
      if (PreferredSelector == Method->getSelector())
        R.Priority += CCD_SelectorMatch;
  
  // If we have a preferred type, adjust the priority for results with exactly-
  // matching or nearly-matching types.
  if (!PreferredType.isNull()) {
    QualType T = getDeclUsageType(SemaRef.Context, R.Declaration);
    if (!T.isNull()) {
      CanQualType TC = SemaRef.Context.getCanonicalType(T);
      // Check for exactly-matching types (modulo qualifiers).
      if (SemaRef.Context.hasSameUnqualifiedType(PreferredType, TC))
        R.Priority /= CCF_ExactTypeMatch;
      // Check for nearly-matching types, based on classification of each.
      else if ((getSimplifiedTypeClass(PreferredType)
                                               == getSimplifiedTypeClass(TC)) &&
               !(PreferredType->isEnumeralType() && TC->isEnumeralType()))
        R.Priority /= CCF_SimilarTypeMatch;  
    }
  }  
}

void ResultBuilder::MaybeAddConstructorResults(Result R) {
  if (!SemaRef.getLangOpts().CPlusPlus || !R.Declaration ||
      !CompletionContext.wantConstructorResults())
    return;
  
  ASTContext &Context = SemaRef.Context;
  const NamedDecl *D = R.Declaration;
  const CXXRecordDecl *Record = nullptr;
  if (const ClassTemplateDecl *ClassTemplate = dyn_cast<ClassTemplateDecl>(D))
    Record = ClassTemplate->getTemplatedDecl();
  else if ((Record = dyn_cast<CXXRecordDecl>(D))) {
    // Skip specializations and partial specializations.
    if (isa<ClassTemplateSpecializationDecl>(Record))
      return;
  } else {
    // There are no constructors here.
    return;
  }
  
  Record = Record->getDefinition();
  if (!Record)
    return;

  
  QualType RecordTy = Context.getTypeDeclType(Record);
  DeclarationName ConstructorName
    = Context.DeclarationNames.getCXXConstructorName(
                                           Context.getCanonicalType(RecordTy));
  DeclContext::lookup_result Ctors = Record->lookup(ConstructorName);
  for (DeclContext::lookup_iterator I = Ctors.begin(),
                                          E = Ctors.end();
       I != E; ++I) {
    R.Declaration = *I;
    R.CursorKind = getCursorKindForDecl(R.Declaration);
    Results.push_back(R);
  }
}

void ResultBuilder::MaybeAddResult(Result R, DeclContext *CurContext) {
  assert(!ShadowMaps.empty() && "Must enter into a results scope");
  
  if (R.Kind != Result::RK_Declaration) {
    // For non-declaration results, just add the result.
    Results.push_back(R);
    return;
  }

  // Look through using declarations.
  if (const UsingShadowDecl *Using =
          dyn_cast<UsingShadowDecl>(R.Declaration)) {
    MaybeAddResult(Result(Using->getTargetDecl(),
                          getBasePriority(Using->getTargetDecl()),
                          R.Qualifier),
                   CurContext);
    return;
  }
  
  const Decl *CanonDecl = R.Declaration->getCanonicalDecl();
  unsigned IDNS = CanonDecl->getIdentifierNamespace();

  bool AsNestedNameSpecifier = false;
  if (!isInterestingDecl(R.Declaration, AsNestedNameSpecifier))
    return;
      
  // C++ constructors are never found by name lookup.
  if (isa<CXXConstructorDecl>(R.Declaration))
    return;

  ShadowMap &SMap = ShadowMaps.back();
  ShadowMapEntry::iterator I, IEnd;
  ShadowMap::iterator NamePos = SMap.find(R.Declaration->getDeclName());
  if (NamePos != SMap.end()) {
    I = NamePos->second.begin();
    IEnd = NamePos->second.end();
  }

  for (; I != IEnd; ++I) {
    const NamedDecl *ND = I->first;
    unsigned Index = I->second;
    if (ND->getCanonicalDecl() == CanonDecl) {
      // This is a redeclaration. Always pick the newer declaration.
      Results[Index].Declaration = R.Declaration;
      
      // We're done.
      return;
    }
  }
  
  // This is a new declaration in this scope. However, check whether this
  // declaration name is hidden by a similarly-named declaration in an outer
  // scope.
  std::list<ShadowMap>::iterator SM, SMEnd = ShadowMaps.end();
  --SMEnd;
  for (SM = ShadowMaps.begin(); SM != SMEnd; ++SM) {
    ShadowMapEntry::iterator I, IEnd;
    ShadowMap::iterator NamePos = SM->find(R.Declaration->getDeclName());
    if (NamePos != SM->end()) {
      I = NamePos->second.begin();
      IEnd = NamePos->second.end();
    }
    for (; I != IEnd; ++I) {
      // A tag declaration does not hide a non-tag declaration.
      if (I->first->hasTagIdentifierNamespace() &&
          (IDNS & (Decl::IDNS_Member | Decl::IDNS_Ordinary |
                   Decl::IDNS_LocalExtern | Decl::IDNS_ObjCProtocol)))
        continue;
      
      // Protocols are in distinct namespaces from everything else.
      if (((I->first->getIdentifierNamespace() & Decl::IDNS_ObjCProtocol)
           || (IDNS & Decl::IDNS_ObjCProtocol)) &&
          I->first->getIdentifierNamespace() != IDNS)
        continue;
      
      // The newly-added result is hidden by an entry in the shadow map.
      if (CheckHiddenResult(R, CurContext, I->first))
        return;
      
      break;
    }
  }
  
  // Make sure that any given declaration only shows up in the result set once.
  if (!AllDeclsFound.insert(CanonDecl).second)
    return;

  // If the filter is for nested-name-specifiers, then this result starts a
  // nested-name-specifier.
  if (AsNestedNameSpecifier) {
    R.StartsNestedNameSpecifier = true;
    R.Priority = CCP_NestedNameSpecifier;
  } else 
      AdjustResultPriorityForDecl(R);
      
  // If this result is supposed to have an informative qualifier, add one.
  if (R.QualifierIsInformative && !R.Qualifier &&
      !R.StartsNestedNameSpecifier) {
    const DeclContext *Ctx = R.Declaration->getDeclContext();
    if (const NamespaceDecl *Namespace = dyn_cast<NamespaceDecl>(Ctx))
      R.Qualifier = NestedNameSpecifier::Create(SemaRef.Context, nullptr,
                                                Namespace);
    else if (const TagDecl *Tag = dyn_cast<TagDecl>(Ctx))
      R.Qualifier = NestedNameSpecifier::Create(SemaRef.Context, nullptr,
                      false, SemaRef.Context.getTypeDeclType(Tag).getTypePtr());
    else
      R.QualifierIsInformative = false;
  }
    
  // Insert this result into the set of results and into the current shadow
  // map.
  SMap[R.Declaration->getDeclName()].Add(R.Declaration, Results.size());
  Results.push_back(R);
  
  if (!AsNestedNameSpecifier)
    MaybeAddConstructorResults(R);
}

void ResultBuilder::AddResult(Result R, DeclContext *CurContext, 
                              NamedDecl *Hiding, bool InBaseClass = false) {
  if (R.Kind != Result::RK_Declaration) {
    // For non-declaration results, just add the result.
    Results.push_back(R);
    return;
  }

  // Look through using declarations.
  if (const UsingShadowDecl *Using = dyn_cast<UsingShadowDecl>(R.Declaration)) {
    AddResult(Result(Using->getTargetDecl(),
                     getBasePriority(Using->getTargetDecl()),
                     R.Qualifier),
              CurContext, Hiding);
    return;
  }
  
  bool AsNestedNameSpecifier = false;
  if (!isInterestingDecl(R.Declaration, AsNestedNameSpecifier))
    return;
  
  // C++ constructors are never found by name lookup.
  if (isa<CXXConstructorDecl>(R.Declaration))
    return;

  if (Hiding && CheckHiddenResult(R, CurContext, Hiding))
    return;

  // Make sure that any given declaration only shows up in the result set once.
  if (!AllDeclsFound.insert(R.Declaration->getCanonicalDecl()).second)
    return;
  
  // If the filter is for nested-name-specifiers, then this result starts a
  // nested-name-specifier.
  if (AsNestedNameSpecifier) {
    R.StartsNestedNameSpecifier = true;
    R.Priority = CCP_NestedNameSpecifier;
  }
  else if (Filter == &ResultBuilder::IsMember && !R.Qualifier && InBaseClass &&
           isa<CXXRecordDecl>(R.Declaration->getDeclContext()
                                                  ->getRedeclContext()))
    R.QualifierIsInformative = true;

  // If this result is supposed to have an informative qualifier, add one.
  if (R.QualifierIsInformative && !R.Qualifier &&
      !R.StartsNestedNameSpecifier) {
    const DeclContext *Ctx = R.Declaration->getDeclContext();
    if (const NamespaceDecl *Namespace = dyn_cast<NamespaceDecl>(Ctx))
      R.Qualifier = NestedNameSpecifier::Create(SemaRef.Context, nullptr,
                                                Namespace);
    else if (const TagDecl *Tag = dyn_cast<TagDecl>(Ctx))
      R.Qualifier = NestedNameSpecifier::Create(SemaRef.Context, nullptr, false,
                            SemaRef.Context.getTypeDeclType(Tag).getTypePtr());
    else
      R.QualifierIsInformative = false;
  }
  
  // Adjust the priority if this result comes from a base class.
  if (InBaseClass)
    R.Priority += CCD_InBaseClass;
  
  AdjustResultPriorityForDecl(R);
  
  if (HasObjectTypeQualifiers)
    if (const CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(R.Declaration))
      if (Method->isInstance()) {
        Qualifiers MethodQuals
                        = Qualifiers::fromCVRMask(Method->getTypeQualifiers());
        if (ObjectTypeQualifiers == MethodQuals)
          R.Priority += CCD_ObjectQualifierMatch;
        else if (ObjectTypeQualifiers - MethodQuals) {
          // The method cannot be invoked, because doing so would drop 
          // qualifiers.
          return;
        }
      }
  
  // Insert this result into the set of results.
  Results.push_back(R);
  
  if (!AsNestedNameSpecifier)
    MaybeAddConstructorResults(R);
}

void ResultBuilder::AddResult(Result R) {
  assert(R.Kind != Result::RK_Declaration && 
          "Declaration results need more context");
  Results.push_back(R);
}

/// \brief Enter into a new scope.
void ResultBuilder::EnterNewScope() { ShadowMaps.emplace_back(); }

/// \brief Exit from the current scope.
void ResultBuilder::ExitScope() {
  for (ShadowMap::iterator E = ShadowMaps.back().begin(),
                        EEnd = ShadowMaps.back().end();
       E != EEnd;
       ++E)
    E->second.Destroy();
         
  ShadowMaps.pop_back();
}

/// \brief Determines whether this given declaration will be found by
/// ordinary name lookup.
bool ResultBuilder::IsOrdinaryName(const NamedDecl *ND) const {
  ND = cast<NamedDecl>(ND->getUnderlyingDecl());

  // If name lookup finds a local extern declaration, then we are in a
  // context where it behaves like an ordinary name.
  unsigned IDNS = Decl::IDNS_Ordinary | Decl::IDNS_LocalExtern;
  if (SemaRef.getLangOpts().CPlusPlus)
    IDNS |= Decl::IDNS_Tag | Decl::IDNS_Namespace | Decl::IDNS_Member;
  else if (SemaRef.getLangOpts().ObjC1) {
    if (isa<ObjCIvarDecl>(ND))
      return true;
  }
  
  return ND->getIdentifierNamespace() & IDNS;
}

/// \brief Determines whether this given declaration will be found by
/// ordinary name lookup but is not a type name.
bool ResultBuilder::IsOrdinaryNonTypeName(const NamedDecl *ND) const {
  ND = cast<NamedDecl>(ND->getUnderlyingDecl());
  if (isa<TypeDecl>(ND))
    return false;
  // Objective-C interfaces names are not filtered by this method because they
  // can be used in a class property expression. We can still filter out
  // @class declarations though.
  if (const auto *ID = dyn_cast<ObjCInterfaceDecl>(ND)) {
    if (!ID->getDefinition())
      return false;
  }

  unsigned IDNS = Decl::IDNS_Ordinary | Decl::IDNS_LocalExtern;
  if (SemaRef.getLangOpts().CPlusPlus)
    IDNS |= Decl::IDNS_Tag | Decl::IDNS_Namespace | Decl::IDNS_Member;
  else if (SemaRef.getLangOpts().ObjC1) {
    if (isa<ObjCIvarDecl>(ND))
      return true;
  }
 
  return ND->getIdentifierNamespace() & IDNS;
}

bool ResultBuilder::IsIntegralConstantValue(const NamedDecl *ND) const {
  if (!IsOrdinaryNonTypeName(ND))
    return 0;
  
  if (const ValueDecl *VD = dyn_cast<ValueDecl>(ND->getUnderlyingDecl()))
    if (VD->getType()->isIntegralOrEnumerationType())
      return true;
        
  return false;
}

/// \brief Determines whether this given declaration will be found by
/// ordinary name lookup.
bool ResultBuilder::IsOrdinaryNonValueName(const NamedDecl *ND) const {
  ND = cast<NamedDecl>(ND->getUnderlyingDecl());

  unsigned IDNS = Decl::IDNS_Ordinary | Decl::IDNS_LocalExtern;
  if (SemaRef.getLangOpts().CPlusPlus)
    IDNS |= Decl::IDNS_Tag | Decl::IDNS_Namespace;
  
  return (ND->getIdentifierNamespace() & IDNS) && 
    !isa<ValueDecl>(ND) && !isa<FunctionTemplateDecl>(ND) && 
    !isa<ObjCPropertyDecl>(ND);
}

/// \brief Determines whether the given declaration is suitable as the 
/// start of a C++ nested-name-specifier, e.g., a class or namespace.
bool ResultBuilder::IsNestedNameSpecifier(const NamedDecl *ND) const {
  // Allow us to find class templates, too.
  if (const ClassTemplateDecl *ClassTemplate = dyn_cast<ClassTemplateDecl>(ND))
    ND = ClassTemplate->getTemplatedDecl();
  
  return SemaRef.isAcceptableNestedNameSpecifier(ND);
}

/// \brief Determines whether the given declaration is an enumeration.
bool ResultBuilder::IsEnum(const NamedDecl *ND) const {
  return isa<EnumDecl>(ND);
}

/// \brief Determines whether the given declaration is a class or struct.
bool ResultBuilder::IsClassOrStruct(const NamedDecl *ND) const {
  // Allow us to find class templates, too.
  if (const ClassTemplateDecl *ClassTemplate = dyn_cast<ClassTemplateDecl>(ND))
    ND = ClassTemplate->getTemplatedDecl();

  // For purposes of this check, interfaces match too.
  if (const RecordDecl *RD = dyn_cast<RecordDecl>(ND))
    return RD->getTagKind() == TTK_Class ||
    RD->getTagKind() == TTK_Struct ||
    RD->getTagKind() == TTK_Interface;
  
  return false;
}

/// \brief Determines whether the given declaration is a union.
bool ResultBuilder::IsUnion(const NamedDecl *ND) const {
  // Allow us to find class templates, too.
  if (const ClassTemplateDecl *ClassTemplate = dyn_cast<ClassTemplateDecl>(ND))
    ND = ClassTemplate->getTemplatedDecl();
  
  if (const RecordDecl *RD = dyn_cast<RecordDecl>(ND))
    return RD->getTagKind() == TTK_Union;
  
  return false;
}

/// \brief Determines whether the given declaration is a namespace.
bool ResultBuilder::IsNamespace(const NamedDecl *ND) const {
  return isa<NamespaceDecl>(ND);
}

/// \brief Determines whether the given declaration is a namespace or 
/// namespace alias.
bool ResultBuilder::IsNamespaceOrAlias(const NamedDecl *ND) const {
  return isa<NamespaceDecl>(ND->getUnderlyingDecl());
}

/// \brief Determines whether the given declaration is a type.
bool ResultBuilder::IsType(const NamedDecl *ND) const {
  ND = ND->getUnderlyingDecl();
  return isa<TypeDecl>(ND) || isa<ObjCInterfaceDecl>(ND);
}

/// \brief Determines which members of a class should be visible via
/// "." or "->".  Only value declarations, nested name specifiers, and
/// using declarations thereof should show up.
bool ResultBuilder::IsMember(const NamedDecl *ND) const {
  ND = ND->getUnderlyingDecl();
  return isa<ValueDecl>(ND) || isa<FunctionTemplateDecl>(ND) ||
         isa<ObjCPropertyDecl>(ND);
}

static bool isObjCReceiverType(ASTContext &C, QualType T) {
  T = C.getCanonicalType(T);
  switch (T->getTypeClass()) {
  case Type::ObjCObject: 
  case Type::ObjCInterface:
  case Type::ObjCObjectPointer:
    return true;
      
  case Type::Builtin:
    switch (cast<BuiltinType>(T)->getKind()) {
    case BuiltinType::ObjCId:
    case BuiltinType::ObjCClass:
    case BuiltinType::ObjCSel:
      return true;
      
    default:
      break;
    }
    return false;
      
  default:
    break;
  }
  
  if (!C.getLangOpts().CPlusPlus)
    return false;

  // FIXME: We could perform more analysis here to determine whether a 
  // particular class type has any conversions to Objective-C types. For now,
  // just accept all class types.
  return T->isDependentType() || T->isRecordType();
}

bool ResultBuilder::IsObjCMessageReceiver(const NamedDecl *ND) const {
  QualType T = getDeclUsageType(SemaRef.Context, ND);
  if (T.isNull())
    return false;
  
  T = SemaRef.Context.getBaseElementType(T);
  return isObjCReceiverType(SemaRef.Context, T);
}

bool ResultBuilder::IsObjCMessageReceiverOrLambdaCapture(const NamedDecl *ND) const {
  if (IsObjCMessageReceiver(ND))
    return true;
  
  const VarDecl *Var = dyn_cast<VarDecl>(ND);
  if (!Var)
    return false;
  
  return Var->hasLocalStorage() && !Var->hasAttr<BlocksAttr>();
}

bool ResultBuilder::IsObjCCollection(const NamedDecl *ND) const {
  if ((SemaRef.getLangOpts().CPlusPlus && !IsOrdinaryName(ND)) ||
      (!SemaRef.getLangOpts().CPlusPlus && !IsOrdinaryNonTypeName(ND)))
    return false;
  
  QualType T = getDeclUsageType(SemaRef.Context, ND);
  if (T.isNull())
    return false;
  
  T = SemaRef.Context.getBaseElementType(T);
  return T->isObjCObjectType() || T->isObjCObjectPointerType() ||
         T->isObjCIdType() || 
         (SemaRef.getLangOpts().CPlusPlus && T->isRecordType());
}

bool ResultBuilder::IsImpossibleToSatisfy(const NamedDecl *ND) const {
  return false;
}

/// \brief Determines whether the given declaration is an Objective-C
/// instance variable.
bool ResultBuilder::IsObjCIvar(const NamedDecl *ND) const {
  return isa<ObjCIvarDecl>(ND);
}

namespace {
  /// \brief Visible declaration consumer that adds a code-completion result
  /// for each visible declaration.
  class CodeCompletionDeclConsumer : public VisibleDeclConsumer {
    ResultBuilder &Results;
    DeclContext *CurContext;
    
  public:
    CodeCompletionDeclConsumer(ResultBuilder &Results, DeclContext *CurContext)
      : Results(Results), CurContext(CurContext) { }

    void FoundDecl(NamedDecl *ND, NamedDecl *Hiding, DeclContext *Ctx,
                   bool InBaseClass) override {
      bool Accessible = true;
      if (Ctx)
        Accessible = Results.getSema().IsSimplyAccessible(ND, Ctx);

      ResultBuilder::Result Result(ND, Results.getBasePriority(ND), nullptr,
                                   false, Accessible);
      Results.AddResult(Result, CurContext, Hiding, InBaseClass);
    }
  };
}

/// \brief Add type specifiers for the current language as keyword results.
static void AddTypeSpecifierResults(const LangOptions &LangOpts,
                                    ResultBuilder &Results) {
  typedef CodeCompletionResult Result;
  Results.AddResult(Result("short", CCP_Type));
  Results.AddResult(Result("long", CCP_Type));
  Results.AddResult(Result("signed", CCP_Type));
  Results.AddResult(Result("unsigned", CCP_Type));
  Results.AddResult(Result("void", CCP_Type));
  Results.AddResult(Result("char", CCP_Type));
  Results.AddResult(Result("int", CCP_Type));
  Results.AddResult(Result("float", CCP_Type));
  Results.AddResult(Result("double", CCP_Type));
  Results.AddResult(Result("enum", CCP_Type));
  Results.AddResult(Result("struct", CCP_Type));
  Results.AddResult(Result("union", CCP_Type));
  Results.AddResult(Result("const", CCP_Type));
  Results.AddResult(Result("volatile", CCP_Type));

  if (LangOpts.C99) {
    // C99-specific
    Results.AddResult(Result("_Complex", CCP_Type));
    Results.AddResult(Result("_Imaginary", CCP_Type));
    Results.AddResult(Result("_Bool", CCP_Type));
    Results.AddResult(Result("restrict", CCP_Type));
  }
  
  CodeCompletionBuilder Builder(Results.getAllocator(),
                                Results.getCodeCompletionTUInfo());
  if (LangOpts.CPlusPlus) {
    // C++-specific
    Results.AddResult(Result("bool", CCP_Type + 
                             (LangOpts.ObjC1? CCD_bool_in_ObjC : 0)));
    Results.AddResult(Result("class", CCP_Type));
    Results.AddResult(Result("wchar_t", CCP_Type));
    
    // typename qualified-id
    Builder.AddTypedTextChunk("typename");
    Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
    Builder.AddPlaceholderChunk("qualifier");
    Builder.AddTextChunk("::");
    Builder.AddPlaceholderChunk("name");
    Results.AddResult(Result(Builder.TakeString()));
    
    if (LangOpts.CPlusPlus11) {
      Results.AddResult(Result("auto", CCP_Type));
      Results.AddResult(Result("char16_t", CCP_Type));
      Results.AddResult(Result("char32_t", CCP_Type));
      
      Builder.AddTypedTextChunk("decltype");
      Builder.AddChunk(CodeCompletionString::CK_LeftParen);
      Builder.AddPlaceholderChunk("expression");
      Builder.AddChunk(CodeCompletionString::CK_RightParen);
      Results.AddResult(Result(Builder.TakeString()));
    }
  } else
    Results.AddResult(Result("__auto_type", CCP_Type));

  // GNU extensions
  if (LangOpts.GNUMode) {
    // FIXME: Enable when we actually support decimal floating point.
    //    Results.AddResult(Result("_Decimal32"));
    //    Results.AddResult(Result("_Decimal64"));
    //    Results.AddResult(Result("_Decimal128"));
    
    Builder.AddTypedTextChunk("typeof");
    Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
    Builder.AddPlaceholderChunk("expression");
    Results.AddResult(Result(Builder.TakeString()));

    Builder.AddTypedTextChunk("typeof");
    Builder.AddChunk(CodeCompletionString::CK_LeftParen);
    Builder.AddPlaceholderChunk("type");
    Builder.AddChunk(CodeCompletionString::CK_RightParen);
    Results.AddResult(Result(Builder.TakeString()));
  }

  // Nullability
  Results.AddResult(Result("_Nonnull", CCP_Type));
  Results.AddResult(Result("_Null_unspecified", CCP_Type));
  Results.AddResult(Result("_Nullable", CCP_Type));
}

static void AddStorageSpecifiers(Sema::ParserCompletionContext CCC,
                                 const LangOptions &LangOpts, 
                                 ResultBuilder &Results) {
  typedef CodeCompletionResult Result;
  // Note: we don't suggest either "auto" or "register", because both
  // are pointless as storage specifiers. Elsewhere, we suggest "auto"
  // in C++0x as a type specifier.
  Results.AddResult(Result("extern"));
  Results.AddResult(Result("static"));

  if (LangOpts.CPlusPlus11) {
    CodeCompletionAllocator &Allocator = Results.getAllocator();
    CodeCompletionBuilder Builder(Allocator, Results.getCodeCompletionTUInfo());

    // alignas
    Builder.AddTypedTextChunk("alignas");
    Builder.AddChunk(CodeCompletionString::CK_LeftParen);
    Builder.AddPlaceholderChunk("expression");
    Builder.AddChunk(CodeCompletionString::CK_RightParen);
    Results.AddResult(Result(Builder.TakeString()));

    Results.AddResult(Result("constexpr"));
    Results.AddResult(Result("thread_local"));
  }
}

static void AddFunctionSpecifiers(Sema::ParserCompletionContext CCC,
                                  const LangOptions &LangOpts, 
                                  ResultBuilder &Results) {
  typedef CodeCompletionResult Result;
  switch (CCC) {
  case Sema::PCC_Class:
  case Sema::PCC_MemberTemplate:
    if (LangOpts.CPlusPlus) {
      Results.AddResult(Result("explicit"));
      Results.AddResult(Result("friend"));
      Results.AddResult(Result("mutable"));
      Results.AddResult(Result("virtual"));
    }    
    LLVM_FALLTHROUGH;

  case Sema::PCC_ObjCInterface:
  case Sema::PCC_ObjCImplementation:
  case Sema::PCC_Namespace:
  case Sema::PCC_Template:
    if (LangOpts.CPlusPlus || LangOpts.C99)
      Results.AddResult(Result("inline"));
    break;

  case Sema::PCC_ObjCInstanceVariableList:
  case Sema::PCC_Expression:
  case Sema::PCC_Statement:
  case Sema::PCC_ForInit:
  case Sema::PCC_Condition:
  case Sema::PCC_RecoveryInFunction:
  case Sema::PCC_Type:
  case Sema::PCC_ParenthesizedExpression:
  case Sema::PCC_LocalDeclarationSpecifiers:
    break;
  }
}

static void AddObjCExpressionResults(ResultBuilder &Results, bool NeedAt);
static void AddObjCStatementResults(ResultBuilder &Results, bool NeedAt);
static void AddObjCVisibilityResults(const LangOptions &LangOpts,
                                     ResultBuilder &Results,
                                     bool NeedAt);  
static void AddObjCImplementationResults(const LangOptions &LangOpts,
                                         ResultBuilder &Results,
                                         bool NeedAt);
static void AddObjCInterfaceResults(const LangOptions &LangOpts,
                                    ResultBuilder &Results,
                                    bool NeedAt);
static void AddObjCTopLevelResults(ResultBuilder &Results, bool NeedAt);

static void AddTypedefResult(ResultBuilder &Results) {
  CodeCompletionBuilder Builder(Results.getAllocator(),
                                Results.getCodeCompletionTUInfo());
  Builder.AddTypedTextChunk("typedef");
  Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
  Builder.AddPlaceholderChunk("type");
  Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
  Builder.AddPlaceholderChunk("name");
  Results.AddResult(CodeCompletionResult(Builder.TakeString()));        
}

static bool WantTypesInContext(Sema::ParserCompletionContext CCC,
                               const LangOptions &LangOpts) {
  switch (CCC) {
  case Sema::PCC_Namespace:
  case Sema::PCC_Class:
  case Sema::PCC_ObjCInstanceVariableList:
  case Sema::PCC_Template:
  case Sema::PCC_MemberTemplate:
  case Sema::PCC_Statement:
  case Sema::PCC_RecoveryInFunction:
  case Sema::PCC_Type:
  case Sema::PCC_ParenthesizedExpression:
  case Sema::PCC_LocalDeclarationSpecifiers:
    return true;
    
  case Sema::PCC_Expression:
  case Sema::PCC_Condition:
    return LangOpts.CPlusPlus;
      
  case Sema::PCC_ObjCInterface:
  case Sema::PCC_ObjCImplementation:
    return false;
    
  case Sema::PCC_ForInit:
    return LangOpts.CPlusPlus || LangOpts.ObjC1 || LangOpts.C99;
  }

  llvm_unreachable("Invalid ParserCompletionContext!");
}

static PrintingPolicy getCompletionPrintingPolicy(const ASTContext &Context,
                                                  const Preprocessor &PP) {
  PrintingPolicy Policy = Sema::getPrintingPolicy(Context, PP);
  Policy.AnonymousTagLocations = false;
  Policy.SuppressStrongLifetime = true;
  Policy.SuppressUnwrittenScope = true;
  Policy.SuppressScope = true;
  return Policy;
}

/// \brief Retrieve a printing policy suitable for code completion.
static PrintingPolicy getCompletionPrintingPolicy(Sema &S) {
  return getCompletionPrintingPolicy(S.Context, S.PP);
}

/// \brief Retrieve the string representation of the given type as a string
/// that has the appropriate lifetime for code completion.
///
/// This routine provides a fast path where we provide constant strings for
/// common type names.
static const char *GetCompletionTypeString(QualType T,
                                           ASTContext &Context,
                                           const PrintingPolicy &Policy,
                                           CodeCompletionAllocator &Allocator) {
  if (!T.getLocalQualifiers()) {
    // Built-in type names are constant strings.
    if (const BuiltinType *BT = dyn_cast<BuiltinType>(T))
      return BT->getNameAsCString(Policy);
    
    // Anonymous tag types are constant strings.
    if (const TagType *TagT = dyn_cast<TagType>(T))
      if (TagDecl *Tag = TagT->getDecl())
        if (!Tag->hasNameForLinkage()) {
          switch (Tag->getTagKind()) {
          case TTK_Struct: return "struct <anonymous>";
          case TTK_Interface: return "__interface <anonymous>";
          case TTK_Class:  return "class <anonymous>";
          case TTK_Union:  return "union <anonymous>";
          case TTK_Enum:   return "enum <anonymous>";
          }
        }
  }
  
  // Slow path: format the type as a string.
  std::string Result;
  T.getAsStringInternal(Result, Policy);
  return Allocator.CopyString(Result);
}

/// \brief Add a completion for "this", if we're in a member function.
static void addThisCompletion(Sema &S, ResultBuilder &Results) {
  QualType ThisTy = S.getCurrentThisType();
  if (ThisTy.isNull())
    return;
  
  CodeCompletionAllocator &Allocator = Results.getAllocator();
  CodeCompletionBuilder Builder(Allocator, Results.getCodeCompletionTUInfo());
  PrintingPolicy Policy = getCompletionPrintingPolicy(S);
  Builder.AddResultTypeChunk(GetCompletionTypeString(ThisTy, 
                                                     S.Context, 
                                                     Policy,
                                                     Allocator));
  Builder.AddTypedTextChunk("this");
  Results.AddResult(CodeCompletionResult(Builder.TakeString()));
}

static void AddStaticAssertResult(CodeCompletionBuilder &Builder,
                                  ResultBuilder &Results,
                                  const LangOptions &LangOpts) {
  if (!LangOpts.CPlusPlus11)
    return;

  Builder.AddTypedTextChunk("static_assert");
  Builder.AddChunk(CodeCompletionString::CK_LeftParen);
  Builder.AddPlaceholderChunk("expression");
  Builder.AddChunk(CodeCompletionString::CK_Comma);
  Builder.AddPlaceholderChunk("message");
  Builder.AddChunk(CodeCompletionString::CK_RightParen);
  Results.AddResult(CodeCompletionResult(Builder.TakeString()));
}

/// \brief Add language constructs that show up for "ordinary" names.
static void AddOrdinaryNameResults(Sema::ParserCompletionContext CCC,
                                   Scope *S,
                                   Sema &SemaRef,
                                   ResultBuilder &Results) {
  CodeCompletionAllocator &Allocator = Results.getAllocator();
  CodeCompletionBuilder Builder(Allocator, Results.getCodeCompletionTUInfo());
  
  typedef CodeCompletionResult Result;
  switch (CCC) {
  case Sema::PCC_Namespace:
    if (SemaRef.getLangOpts().CPlusPlus) {
      if (Results.includeCodePatterns()) {
        // namespace <identifier> { declarations }
        Builder.AddTypedTextChunk("namespace");
        Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
        Builder.AddPlaceholderChunk("identifier");
        Builder.AddChunk(CodeCompletionString::CK_LeftBrace);
        Builder.AddPlaceholderChunk("declarations");
        Builder.AddChunk(CodeCompletionString::CK_VerticalSpace);
        Builder.AddChunk(CodeCompletionString::CK_RightBrace);
        Results.AddResult(Result(Builder.TakeString()));
      }
      
      // namespace identifier = identifier ;
      Builder.AddTypedTextChunk("namespace");
      Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
      Builder.AddPlaceholderChunk("name");
      Builder.AddChunk(CodeCompletionString::CK_Equal);
      Builder.AddPlaceholderChunk("namespace");
      Results.AddResult(Result(Builder.TakeString()));

      // Using directives
      Builder.AddTypedTextChunk("using");
      Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
      Builder.AddTextChunk("namespace");
      Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
      Builder.AddPlaceholderChunk("identifier");
      Results.AddResult(Result(Builder.TakeString()));

      // asm(string-literal)      
      Builder.AddTypedTextChunk("asm");
      Builder.AddChunk(CodeCompletionString::CK_LeftParen);
      Builder.AddPlaceholderChunk("string-literal");
      Builder.AddChunk(CodeCompletionString::CK_RightParen);
      Results.AddResult(Result(Builder.TakeString()));

      if (Results.includeCodePatterns()) {
        // Explicit template instantiation
        Builder.AddTypedTextChunk("template");
        Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
        Builder.AddPlaceholderChunk("declaration");
        Results.AddResult(Result(Builder.TakeString()));
      }
    }
      
    if (SemaRef.getLangOpts().ObjC1)
      AddObjCTopLevelResults(Results, true);
      
    AddTypedefResult(Results);
    LLVM_FALLTHROUGH;

  case Sema::PCC_Class:
    if (SemaRef.getLangOpts().CPlusPlus) {
      // Using declaration
      Builder.AddTypedTextChunk("using");
      Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
      Builder.AddPlaceholderChunk("qualifier");
      Builder.AddTextChunk("::");
      Builder.AddPlaceholderChunk("name");
      Results.AddResult(Result(Builder.TakeString()));
      
      // using typename qualifier::name (only in a dependent context)
      if (SemaRef.CurContext->isDependentContext()) {
        Builder.AddTypedTextChunk("using");
        Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
        Builder.AddTextChunk("typename");
        Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
        Builder.AddPlaceholderChunk("qualifier");
        Builder.AddTextChunk("::");
        Builder.AddPlaceholderChunk("name");
        Results.AddResult(Result(Builder.TakeString()));
      }

      AddStaticAssertResult(Builder, Results, SemaRef.getLangOpts());

      if (CCC == Sema::PCC_Class) {
        AddTypedefResult(Results);

        bool IsNotInheritanceScope =
            !(S->getFlags() & Scope::ClassInheritanceScope);
        // public:
        Builder.AddTypedTextChunk("public");
        if (IsNotInheritanceScope && Results.includeCodePatterns())
          Builder.AddChunk(CodeCompletionString::CK_Colon);
        Results.AddResult(Result(Builder.TakeString()));

        // protected:
        Builder.AddTypedTextChunk("protected");
        if (IsNotInheritanceScope && Results.includeCodePatterns())
          Builder.AddChunk(CodeCompletionString::CK_Colon);
        Results.AddResult(Result(Builder.TakeString()));

        // private:
        Builder.AddTypedTextChunk("private");
        if (IsNotInheritanceScope && Results.includeCodePatterns())
          Builder.AddChunk(CodeCompletionString::CK_Colon);
        Results.AddResult(Result(Builder.TakeString()));
      }
    }
    LLVM_FALLTHROUGH;

  case Sema::PCC_Template:
  case Sema::PCC_MemberTemplate:
    if (SemaRef.getLangOpts().CPlusPlus && Results.includeCodePatterns()) {
      // template < parameters >
      Builder.AddTypedTextChunk("template");
      Builder.AddChunk(CodeCompletionString::CK_LeftAngle);
      Builder.AddPlaceholderChunk("parameters");
      Builder.AddChunk(CodeCompletionString::CK_RightAngle);
      Results.AddResult(Result(Builder.TakeString()));
    }

    AddStorageSpecifiers(CCC, SemaRef.getLangOpts(), Results);
    AddFunctionSpecifiers(CCC, SemaRef.getLangOpts(), Results);
    break;

  case Sema::PCC_ObjCInterface:
    AddObjCInterfaceResults(SemaRef.getLangOpts(), Results, true);
    AddStorageSpecifiers(CCC, SemaRef.getLangOpts(), Results);
    AddFunctionSpecifiers(CCC, SemaRef.getLangOpts(), Results);
    break;
      
  case Sema::PCC_ObjCImplementation:
    AddObjCImplementationResults(SemaRef.getLangOpts(), Results, true);
    AddStorageSpecifiers(CCC, SemaRef.getLangOpts(), Results);
    AddFunctionSpecifiers(CCC, SemaRef.getLangOpts(), Results);
    break;
      
  case Sema::PCC_ObjCInstanceVariableList:
    AddObjCVisibilityResults(SemaRef.getLangOpts(), Results, true);
    break;
      
  case Sema::PCC_RecoveryInFunction:
  case Sema::PCC_Statement: {
    AddTypedefResult(Results);

    if (SemaRef.getLangOpts().CPlusPlus && Results.includeCodePatterns() &&
        SemaRef.getLangOpts().CXXExceptions) {
      Builder.AddTypedTextChunk("try");
      Builder.AddChunk(CodeCompletionString::CK_LeftBrace);
      Builder.AddPlaceholderChunk("statements");
      Builder.AddChunk(CodeCompletionString::CK_VerticalSpace);
      Builder.AddChunk(CodeCompletionString::CK_RightBrace);
      Builder.AddTextChunk("catch");
      Builder.AddChunk(CodeCompletionString::CK_LeftParen);
      Builder.AddPlaceholderChunk("declaration");
      Builder.AddChunk(CodeCompletionString::CK_RightParen);
      Builder.AddChunk(CodeCompletionString::CK_LeftBrace);
      Builder.AddPlaceholderChunk("statements");
      Builder.AddChunk(CodeCompletionString::CK_VerticalSpace);
      Builder.AddChunk(CodeCompletionString::CK_RightBrace);
      Results.AddResult(Result(Builder.TakeString()));
    }
    if (SemaRef.getLangOpts().ObjC1)
      AddObjCStatementResults(Results, true);
    
    if (Results.includeCodePatterns()) {
      // if (condition) { statements }
      Builder.AddTypedTextChunk("if");
      Builder.AddChunk(CodeCompletionString::CK_LeftParen);
      if (SemaRef.getLangOpts().CPlusPlus)
        Builder.AddPlaceholderChunk("condition");
      else
        Builder.AddPlaceholderChunk("expression");
      Builder.AddChunk(CodeCompletionString::CK_RightParen);
      Builder.AddChunk(CodeCompletionString::CK_LeftBrace);
      Builder.AddPlaceholderChunk("statements");
      Builder.AddChunk(CodeCompletionString::CK_VerticalSpace);
      Builder.AddChunk(CodeCompletionString::CK_RightBrace);
      Results.AddResult(Result(Builder.TakeString()));

      // switch (condition) { }
      Builder.AddTypedTextChunk("switch");
      Builder.AddChunk(CodeCompletionString::CK_LeftParen);
      if (SemaRef.getLangOpts().CPlusPlus)
        Builder.AddPlaceholderChunk("condition");
      else
        Builder.AddPlaceholderChunk("expression");
      Builder.AddChunk(CodeCompletionString::CK_RightParen);
      Builder.AddChunk(CodeCompletionString::CK_LeftBrace);
      Builder.AddChunk(CodeCompletionString::CK_VerticalSpace);
      Builder.AddChunk(CodeCompletionString::CK_RightBrace);
      Results.AddResult(Result(Builder.TakeString()));
    }
    
    // Switch-specific statements.
    if (!SemaRef.getCurFunction()->SwitchStack.empty()) {
      // case expression:
      Builder.AddTypedTextChunk("case");
      Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
      Builder.AddPlaceholderChunk("expression");
      Builder.AddChunk(CodeCompletionString::CK_Colon);
      Results.AddResult(Result(Builder.TakeString()));

      // default:
      Builder.AddTypedTextChunk("default");
      Builder.AddChunk(CodeCompletionString::CK_Colon);
      Results.AddResult(Result(Builder.TakeString()));
    }

    if (Results.includeCodePatterns()) {
      /// while (condition) { statements }
      Builder.AddTypedTextChunk("while");
      Builder.AddChunk(CodeCompletionString::CK_LeftParen);
      if (SemaRef.getLangOpts().CPlusPlus)
        Builder.AddPlaceholderChunk("condition");
      else
        Builder.AddPlaceholderChunk("expression");
      Builder.AddChunk(CodeCompletionString::CK_RightParen);
      Builder.AddChunk(CodeCompletionString::CK_LeftBrace);
      Builder.AddPlaceholderChunk("statements");
      Builder.AddChunk(CodeCompletionString::CK_VerticalSpace);
      Builder.AddChunk(CodeCompletionString::CK_RightBrace);
      Results.AddResult(Result(Builder.TakeString()));

      // do { statements } while ( expression );
      Builder.AddTypedTextChunk("do");
      Builder.AddChunk(CodeCompletionString::CK_LeftBrace);
      Builder.AddPlaceholderChunk("statements");
      Builder.AddChunk(CodeCompletionString::CK_VerticalSpace);
      Builder.AddChunk(CodeCompletionString::CK_RightBrace);
      Builder.AddTextChunk("while");
      Builder.AddChunk(CodeCompletionString::CK_LeftParen);
      Builder.AddPlaceholderChunk("expression");
      Builder.AddChunk(CodeCompletionString::CK_RightParen);
      Results.AddResult(Result(Builder.TakeString()));

      // for ( for-init-statement ; condition ; expression ) { statements }
      Builder.AddTypedTextChunk("for");
      Builder.AddChunk(CodeCompletionString::CK_LeftParen);
      if (SemaRef.getLangOpts().CPlusPlus || SemaRef.getLangOpts().C99)
        Builder.AddPlaceholderChunk("init-statement");
      else
        Builder.AddPlaceholderChunk("init-expression");
      Builder.AddChunk(CodeCompletionString::CK_SemiColon);
      Builder.AddPlaceholderChunk("condition");
      Builder.AddChunk(CodeCompletionString::CK_SemiColon);
      Builder.AddPlaceholderChunk("inc-expression");
      Builder.AddChunk(CodeCompletionString::CK_RightParen);
      Builder.AddChunk(CodeCompletionString::CK_LeftBrace);
      Builder.AddChunk(CodeCompletionString::CK_VerticalSpace);
      Builder.AddPlaceholderChunk("statements");
      Builder.AddChunk(CodeCompletionString::CK_VerticalSpace);
      Builder.AddChunk(CodeCompletionString::CK_RightBrace);
      Results.AddResult(Result(Builder.TakeString()));
    }
    
    if (S->getContinueParent()) {
      // continue ;
      Builder.AddTypedTextChunk("continue");
      Results.AddResult(Result(Builder.TakeString()));
    }

    if (S->getBreakParent()) {
      // break ;
      Builder.AddTypedTextChunk("break");
      Results.AddResult(Result(Builder.TakeString()));
    }

    // "return expression ;" or "return ;", depending on whether we
    // know the function is void or not.
    bool isVoid = false;
    if (FunctionDecl *Function = dyn_cast<FunctionDecl>(SemaRef.CurContext))
      isVoid = Function->getReturnType()->isVoidType();
    else if (ObjCMethodDecl *Method
                                 = dyn_cast<ObjCMethodDecl>(SemaRef.CurContext))
      isVoid = Method->getReturnType()->isVoidType();
    else if (SemaRef.getCurBlock() && 
             !SemaRef.getCurBlock()->ReturnType.isNull())
      isVoid = SemaRef.getCurBlock()->ReturnType->isVoidType();
    Builder.AddTypedTextChunk("return");
    if (!isVoid) {
      Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
      Builder.AddPlaceholderChunk("expression");
    }
    Results.AddResult(Result(Builder.TakeString()));

    // goto identifier ;
    Builder.AddTypedTextChunk("goto");
    Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
    Builder.AddPlaceholderChunk("label");
    Results.AddResult(Result(Builder.TakeString()));    

    // Using directives
    Builder.AddTypedTextChunk("using");
    Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
    Builder.AddTextChunk("namespace");
    Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
    Builder.AddPlaceholderChunk("identifier");
    Results.AddResult(Result(Builder.TakeString()));

    AddStaticAssertResult(Builder, Results, SemaRef.getLangOpts());
  }
  LLVM_FALLTHROUGH;

  // Fall through (for statement expressions).
  case Sema::PCC_ForInit:
  case Sema::PCC_Condition:
    AddStorageSpecifiers(CCC, SemaRef.getLangOpts(), Results);
    // Fall through: conditions and statements can have expressions.
    LLVM_FALLTHROUGH;

  case Sema::PCC_ParenthesizedExpression:
    if (SemaRef.getLangOpts().ObjCAutoRefCount &&
        CCC == Sema::PCC_ParenthesizedExpression) {
      // (__bridge <type>)<expression>
      Builder.AddTypedTextChunk("__bridge");
      Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
      Builder.AddPlaceholderChunk("type");
      Builder.AddChunk(CodeCompletionString::CK_RightParen);
      Builder.AddPlaceholderChunk("expression");
      Results.AddResult(Result(Builder.TakeString()));      

      // (__bridge_transfer <Objective-C type>)<expression>
      Builder.AddTypedTextChunk("__bridge_transfer");
      Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
      Builder.AddPlaceholderChunk("Objective-C type");
      Builder.AddChunk(CodeCompletionString::CK_RightParen);
      Builder.AddPlaceholderChunk("expression");
      Results.AddResult(Result(Builder.TakeString()));      

      // (__bridge_retained <CF type>)<expression>
      Builder.AddTypedTextChunk("__bridge_retained");
      Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
      Builder.AddPlaceholderChunk("CF type");
      Builder.AddChunk(CodeCompletionString::CK_RightParen);
      Builder.AddPlaceholderChunk("expression");
      Results.AddResult(Result(Builder.TakeString()));      
    }
    // Fall through
    LLVM_FALLTHROUGH;

  case Sema::PCC_Expression: {
    if (SemaRef.getLangOpts().CPlusPlus) {
      // 'this', if we're in a non-static member function.
      addThisCompletion(SemaRef, Results);
      
      // true
      Builder.AddResultTypeChunk("bool");
      Builder.AddTypedTextChunk("true");
      Results.AddResult(Result(Builder.TakeString()));
      
      // false
      Builder.AddResultTypeChunk("bool");
      Builder.AddTypedTextChunk("false");
      Results.AddResult(Result(Builder.TakeString()));

      if (SemaRef.getLangOpts().RTTI) {
        // dynamic_cast < type-id > ( expression )
        Builder.AddTypedTextChunk("dynamic_cast");
        Builder.AddChunk(CodeCompletionString::CK_LeftAngle);
        Builder.AddPlaceholderChunk("type");
        Builder.AddChunk(CodeCompletionString::CK_RightAngle);
        Builder.AddChunk(CodeCompletionString::CK_LeftParen);
        Builder.AddPlaceholderChunk("expression");
        Builder.AddChunk(CodeCompletionString::CK_RightParen);
        Results.AddResult(Result(Builder.TakeString()));      
      }
      
      // static_cast < type-id > ( expression )
      Builder.AddTypedTextChunk("static_cast");
      Builder.AddChunk(CodeCompletionString::CK_LeftAngle);
      Builder.AddPlaceholderChunk("type");
      Builder.AddChunk(CodeCompletionString::CK_RightAngle);
      Builder.AddChunk(CodeCompletionString::CK_LeftParen);
      Builder.AddPlaceholderChunk("expression");
      Builder.AddChunk(CodeCompletionString::CK_RightParen);
      Results.AddResult(Result(Builder.TakeString()));      

      // reinterpret_cast < type-id > ( expression )
      Builder.AddTypedTextChunk("reinterpret_cast");
      Builder.AddChunk(CodeCompletionString::CK_LeftAngle);
      Builder.AddPlaceholderChunk("type");
      Builder.AddChunk(CodeCompletionString::CK_RightAngle);
      Builder.AddChunk(CodeCompletionString::CK_LeftParen);
      Builder.AddPlaceholderChunk("expression");
      Builder.AddChunk(CodeCompletionString::CK_RightParen);
      Results.AddResult(Result(Builder.TakeString()));      

      // const_cast < type-id > ( expression )
      Builder.AddTypedTextChunk("const_cast");
      Builder.AddChunk(CodeCompletionString::CK_LeftAngle);
      Builder.AddPlaceholderChunk("type");
      Builder.AddChunk(CodeCompletionString::CK_RightAngle);
      Builder.AddChunk(CodeCompletionString::CK_LeftParen);
      Builder.AddPlaceholderChunk("expression");
      Builder.AddChunk(CodeCompletionString::CK_RightParen);
      Results.AddResult(Result(Builder.TakeString()));      

      if (SemaRef.getLangOpts().RTTI) {
        // typeid ( expression-or-type )
        Builder.AddResultTypeChunk("std::type_info");
        Builder.AddTypedTextChunk("typeid");
        Builder.AddChunk(CodeCompletionString::CK_LeftParen);
        Builder.AddPlaceholderChunk("expression-or-type");
        Builder.AddChunk(CodeCompletionString::CK_RightParen);
        Results.AddResult(Result(Builder.TakeString()));      
      }
      
      // new T ( ... )
      Builder.AddTypedTextChunk("new");
      Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
      Builder.AddPlaceholderChunk("type");
      Builder.AddChunk(CodeCompletionString::CK_LeftParen);
      Builder.AddPlaceholderChunk("expressions");
      Builder.AddChunk(CodeCompletionString::CK_RightParen);
      Results.AddResult(Result(Builder.TakeString()));      

      // new T [ ] ( ... )
      Builder.AddTypedTextChunk("new");
      Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
      Builder.AddPlaceholderChunk("type");
      Builder.AddChunk(CodeCompletionString::CK_LeftBracket);
      Builder.AddPlaceholderChunk("size");
      Builder.AddChunk(CodeCompletionString::CK_RightBracket);
      Builder.AddChunk(CodeCompletionString::CK_LeftParen);
      Builder.AddPlaceholderChunk("expressions");
      Builder.AddChunk(CodeCompletionString::CK_RightParen);
      Results.AddResult(Result(Builder.TakeString()));      

      // delete expression
      Builder.AddResultTypeChunk("void");
      Builder.AddTypedTextChunk("delete");
      Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
      Builder.AddPlaceholderChunk("expression");
      Results.AddResult(Result(Builder.TakeString()));      

      // delete [] expression
      Builder.AddResultTypeChunk("void");
      Builder.AddTypedTextChunk("delete");
      Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
      Builder.AddChunk(CodeCompletionString::CK_LeftBracket);
      Builder.AddChunk(CodeCompletionString::CK_RightBracket);
      Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
      Builder.AddPlaceholderChunk("expression");
      Results.AddResult(Result(Builder.TakeString()));

      if (SemaRef.getLangOpts().CXXExceptions) {
        // throw expression
        Builder.AddResultTypeChunk("void");
        Builder.AddTypedTextChunk("throw");
        Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
        Builder.AddPlaceholderChunk("expression");
        Results.AddResult(Result(Builder.TakeString()));
      }
     
      // FIXME: Rethrow?

      if (SemaRef.getLangOpts().CPlusPlus11) {
        // nullptr
        Builder.AddResultTypeChunk("std::nullptr_t");
        Builder.AddTypedTextChunk("nullptr");
        Results.AddResult(Result(Builder.TakeString()));

        // alignof
        Builder.AddResultTypeChunk("size_t");
        Builder.AddTypedTextChunk("alignof");
        Builder.AddChunk(CodeCompletionString::CK_LeftParen);
        Builder.AddPlaceholderChunk("type");
        Builder.AddChunk(CodeCompletionString::CK_RightParen);
        Results.AddResult(Result(Builder.TakeString()));

        // noexcept
        Builder.AddResultTypeChunk("bool");
        Builder.AddTypedTextChunk("noexcept");
        Builder.AddChunk(CodeCompletionString::CK_LeftParen);
        Builder.AddPlaceholderChunk("expression");
        Builder.AddChunk(CodeCompletionString::CK_RightParen);
        Results.AddResult(Result(Builder.TakeString()));

        // sizeof... expression
        Builder.AddResultTypeChunk("size_t");
        Builder.AddTypedTextChunk("sizeof...");
        Builder.AddChunk(CodeCompletionString::CK_LeftParen);
        Builder.AddPlaceholderChunk("parameter-pack");
        Builder.AddChunk(CodeCompletionString::CK_RightParen);
        Results.AddResult(Result(Builder.TakeString()));
      }
    }

    if (SemaRef.getLangOpts().ObjC1) {
      // Add "super", if we're in an Objective-C class with a superclass.
      if (ObjCMethodDecl *Method = SemaRef.getCurMethodDecl()) {
        // The interface can be NULL.
        if (ObjCInterfaceDecl *ID = Method->getClassInterface())
          if (ID->getSuperClass()) {
            std::string SuperType;
            SuperType = ID->getSuperClass()->getNameAsString();
            if (Method->isInstanceMethod())
              SuperType += " *";
            
            Builder.AddResultTypeChunk(Allocator.CopyString(SuperType));
            Builder.AddTypedTextChunk("super");
            Results.AddResult(Result(Builder.TakeString()));
          }
      }

      AddObjCExpressionResults(Results, true);
    }

    if (SemaRef.getLangOpts().C11) {
      // _Alignof
      Builder.AddResultTypeChunk("size_t");
      if (SemaRef.PP.isMacroDefined("alignof"))
        Builder.AddTypedTextChunk("alignof");
      else
        Builder.AddTypedTextChunk("_Alignof");
      Builder.AddChunk(CodeCompletionString::CK_LeftParen);
      Builder.AddPlaceholderChunk("type");
      Builder.AddChunk(CodeCompletionString::CK_RightParen);
      Results.AddResult(Result(Builder.TakeString()));
    }

    // sizeof expression
    Builder.AddResultTypeChunk("size_t");
    Builder.AddTypedTextChunk("sizeof");
    Builder.AddChunk(CodeCompletionString::CK_LeftParen);
    Builder.AddPlaceholderChunk("expression-or-type");
    Builder.AddChunk(CodeCompletionString::CK_RightParen);
    Results.AddResult(Result(Builder.TakeString()));
    break;
  }
      
  case Sema::PCC_Type:
  case Sema::PCC_LocalDeclarationSpecifiers:
    break;
  }

  if (WantTypesInContext(CCC, SemaRef.getLangOpts()))
    AddTypeSpecifierResults(SemaRef.getLangOpts(), Results);

  if (SemaRef.getLangOpts().CPlusPlus && CCC != Sema::PCC_Type)
    Results.AddResult(Result("operator"));
}

/// \brief If the given declaration has an associated type, add it as a result 
/// type chunk.
static void AddResultTypeChunk(ASTContext &Context,
                               const PrintingPolicy &Policy,
                               const NamedDecl *ND,
                               QualType BaseType,
                               CodeCompletionBuilder &Result) {
  if (!ND)
    return;

  // Skip constructors and conversion functions, which have their return types
  // built into their names.
  if (isa<CXXConstructorDecl>(ND) || isa<CXXConversionDecl>(ND))
    return;

  // Determine the type of the declaration (if it has a type).
  QualType T;
  if (const FunctionDecl *Function = ND->getAsFunction())
    T = Function->getReturnType();
  else if (const ObjCMethodDecl *Method = dyn_cast<ObjCMethodDecl>(ND)) {
    if (!BaseType.isNull())
      T = Method->getSendResultType(BaseType);
    else
      T = Method->getReturnType();
  } else if (const EnumConstantDecl *Enumerator = dyn_cast<EnumConstantDecl>(ND)) {
    T = Context.getTypeDeclType(cast<TypeDecl>(Enumerator->getDeclContext()));
    T = clang::TypeName::getFullyQualifiedType(T, Context);
  } else if (isa<UnresolvedUsingValueDecl>(ND)) {
    /* Do nothing: ignore unresolved using declarations*/
  } else if (const ObjCIvarDecl *Ivar = dyn_cast<ObjCIvarDecl>(ND)) {
    if (!BaseType.isNull())
      T = Ivar->getUsageType(BaseType);
    else
      T = Ivar->getType();
  } else if (const ValueDecl *Value = dyn_cast<ValueDecl>(ND)) {
    T = Value->getType();
  } else if (const ObjCPropertyDecl *Property = dyn_cast<ObjCPropertyDecl>(ND)) {
    if (!BaseType.isNull())
      T = Property->getUsageType(BaseType);
    else
      T = Property->getType();
  }
  
  if (T.isNull() || Context.hasSameType(T, Context.DependentTy))
    return;
  
  Result.AddResultTypeChunk(GetCompletionTypeString(T, Context, Policy,
                                                    Result.getAllocator()));
}

static void MaybeAddSentinel(Preprocessor &PP,
                             const NamedDecl *FunctionOrMethod,
                             CodeCompletionBuilder &Result) {
  if (SentinelAttr *Sentinel = FunctionOrMethod->getAttr<SentinelAttr>())
    if (Sentinel->getSentinel() == 0) {
      if (PP.getLangOpts().ObjC1 && PP.isMacroDefined("nil"))
        Result.AddTextChunk(", nil");
      else if (PP.isMacroDefined("NULL"))
        Result.AddTextChunk(", NULL");
      else
        Result.AddTextChunk(", (void*)0");
    }
}

static std::string formatObjCParamQualifiers(unsigned ObjCQuals, 
                                             QualType &Type) {
  std::string Result;
  if (ObjCQuals & Decl::OBJC_TQ_In)
    Result += "in ";
  else if (ObjCQuals & Decl::OBJC_TQ_Inout)
    Result += "inout ";
  else if (ObjCQuals & Decl::OBJC_TQ_Out)
    Result += "out ";
  if (ObjCQuals & Decl::OBJC_TQ_Bycopy)
    Result += "bycopy ";
  else if (ObjCQuals & Decl::OBJC_TQ_Byref)
    Result += "byref ";
  if (ObjCQuals & Decl::OBJC_TQ_Oneway)
    Result += "oneway ";
  if (ObjCQuals & Decl::OBJC_TQ_CSNullability) {
    if (auto nullability = AttributedType::stripOuterNullability(Type)) {
      switch (*nullability) {
      case NullabilityKind::NonNull:
        Result += "nonnull ";
        break;

      case NullabilityKind::Nullable:
        Result += "nullable ";
        break;

      case NullabilityKind::Unspecified:
        Result += "null_unspecified ";
        break;
      }
    }
  }
  return Result;
}

/// \brief Tries to find the most appropriate type location for an Objective-C
/// block placeholder.
///
/// This function ignores things like typedefs and qualifiers in order to
/// present the most relevant and accurate block placeholders in code completion
/// results.
static void findTypeLocationForBlockDecl(const TypeSourceInfo *TSInfo,
                                         FunctionTypeLoc &Block,
                                         FunctionProtoTypeLoc &BlockProto,
                                         bool SuppressBlock = false) {
  if (!TSInfo)
    return;
  TypeLoc TL = TSInfo->getTypeLoc().getUnqualifiedLoc();
  while (true) {
    // Look through typedefs.
    if (!SuppressBlock) {
      if (TypedefTypeLoc TypedefTL = TL.getAs<TypedefTypeLoc>()) {
        if (TypeSourceInfo *InnerTSInfo =
                TypedefTL.getTypedefNameDecl()->getTypeSourceInfo()) {
          TL = InnerTSInfo->getTypeLoc().getUnqualifiedLoc();
          continue;
        }
      }

      // Look through qualified types
      if (QualifiedTypeLoc QualifiedTL = TL.getAs<QualifiedTypeLoc>()) {
        TL = QualifiedTL.getUnqualifiedLoc();
        continue;
      }

      if (AttributedTypeLoc AttrTL = TL.getAs<AttributedTypeLoc>()) {
        TL = AttrTL.getModifiedLoc();
        continue;
      }
    }

    // Try to get the function prototype behind the block pointer type,
    // then we're done.
    if (BlockPointerTypeLoc BlockPtr = TL.getAs<BlockPointerTypeLoc>()) {
      TL = BlockPtr.getPointeeLoc().IgnoreParens();
      Block = TL.getAs<FunctionTypeLoc>();
      BlockProto = TL.getAs<FunctionProtoTypeLoc>();
    }
    break;
  }
}

static std::string
formatBlockPlaceholder(const PrintingPolicy &Policy, const NamedDecl *BlockDecl,
                       FunctionTypeLoc &Block, FunctionProtoTypeLoc &BlockProto,
                       bool SuppressBlockName = false,
                       bool SuppressBlock = false,
                       Optional<ArrayRef<QualType>> ObjCSubsts = None);

static std::string FormatFunctionParameter(const PrintingPolicy &Policy,
                                           const ParmVarDecl *Param,
                                           bool SuppressName = false,
                                           bool SuppressBlock = false,
                               Optional<ArrayRef<QualType>> ObjCSubsts = None) {
  bool ObjCMethodParam = isa<ObjCMethodDecl>(Param->getDeclContext());
  if (Param->getType()->isDependentType() ||
      !Param->getType()->isBlockPointerType()) {
    // The argument for a dependent or non-block parameter is a placeholder 
    // containing that parameter's type.
    std::string Result;
    
    if (Param->getIdentifier() && !ObjCMethodParam && !SuppressName)
      Result = Param->getIdentifier()->getName();
    
    QualType Type = Param->getType();
    if (ObjCSubsts)
      Type = Type.substObjCTypeArgs(Param->getASTContext(), *ObjCSubsts,
                                    ObjCSubstitutionContext::Parameter);
    if (ObjCMethodParam) {
      Result = "(" + formatObjCParamQualifiers(Param->getObjCDeclQualifier(),
                                               Type);
      Result += Type.getAsString(Policy) + ")";
      if (Param->getIdentifier() && !SuppressName)
        Result += Param->getIdentifier()->getName();
    } else {
      Type.getAsStringInternal(Result, Policy);
    }
    return Result;
  }

  // The argument for a block pointer parameter is a block literal with
  // the appropriate type.
  FunctionTypeLoc Block;
  FunctionProtoTypeLoc BlockProto;
  findTypeLocationForBlockDecl(Param->getTypeSourceInfo(), Block, BlockProto,
                               SuppressBlock);
  // Try to retrieve the block type information from the property if this is a
  // parameter in a setter.
  if (!Block && ObjCMethodParam &&
      cast<ObjCMethodDecl>(Param->getDeclContext())->isPropertyAccessor()) {
    if (const auto *PD = cast<ObjCMethodDecl>(Param->getDeclContext())
                             ->findPropertyDecl(/*CheckOverrides=*/false))
      findTypeLocationForBlockDecl(PD->getTypeSourceInfo(), Block, BlockProto,
                                   SuppressBlock);
  }

  if (!Block) {
    // We were unable to find a FunctionProtoTypeLoc with parameter names
    // for the block; just use the parameter type as a placeholder.
    std::string Result;
    if (!ObjCMethodParam && Param->getIdentifier())
      Result = Param->getIdentifier()->getName();

    QualType Type = Param->getType().getUnqualifiedType();
    
    if (ObjCMethodParam) {
      Result = Type.getAsString(Policy);
      std::string Quals =
          formatObjCParamQualifiers(Param->getObjCDeclQualifier(), Type);
      if (!Quals.empty())
        Result = "(" + Quals + " " + Result + ")";
      if (Result.back() != ')')
        Result += " ";
      if (Param->getIdentifier())
        Result += Param->getIdentifier()->getName();
    } else {
      Type.getAsStringInternal(Result, Policy);
    }
      
    return Result;
  }

  // We have the function prototype behind the block pointer type, as it was
  // written in the source.
  return formatBlockPlaceholder(Policy, Param, Block, BlockProto,
                                /*SuppressBlockName=*/false, SuppressBlock,
                                ObjCSubsts);
}

/// \brief Returns a placeholder string that corresponds to an Objective-C block
/// declaration.
///
/// \param BlockDecl A declaration with an Objective-C block type.
///
/// \param Block The most relevant type location for that block type.
///
/// \param SuppressBlockName Determines wether or not the name of the block
/// declaration is included in the resulting string.
static std::string
formatBlockPlaceholder(const PrintingPolicy &Policy, const NamedDecl *BlockDecl,
                       FunctionTypeLoc &Block, FunctionProtoTypeLoc &BlockProto,
                       bool SuppressBlockName, bool SuppressBlock,
                       Optional<ArrayRef<QualType>> ObjCSubsts) {
  std::string Result;
  QualType ResultType = Block.getTypePtr()->getReturnType();
  if (ObjCSubsts)
    ResultType =
        ResultType.substObjCTypeArgs(BlockDecl->getASTContext(), *ObjCSubsts,
                                     ObjCSubstitutionContext::Result);
  if (!ResultType->isVoidType() || SuppressBlock)
    ResultType.getAsStringInternal(Result, Policy);

  // Format the parameter list.
  std::string Params;
  if (!BlockProto || Block.getNumParams() == 0) {
    if (BlockProto && BlockProto.getTypePtr()->isVariadic())
      Params = "(...)";
    else
      Params = "(void)";
  } else {
    Params += "(";
    for (unsigned I = 0, N = Block.getNumParams(); I != N; ++I) {
      if (I)
        Params += ", ";
      Params += FormatFunctionParameter(Policy, Block.getParam(I),
                                        /*SuppressName=*/false,
                                        /*SuppressBlock=*/true, ObjCSubsts);

      if (I == N - 1 && BlockProto.getTypePtr()->isVariadic())
        Params += ", ...";
    }
    Params += ")";
  }

  if (SuppressBlock) {
    // Format as a parameter.
    Result = Result + " (^";
    if (!SuppressBlockName && BlockDecl->getIdentifier())
      Result += BlockDecl->getIdentifier()->getName();
    Result += ")";
    Result += Params;
  } else {
    // Format as a block literal argument.
    Result = '^' + Result;
    Result += Params;

    if (!SuppressBlockName && BlockDecl->getIdentifier())
      Result += BlockDecl->getIdentifier()->getName();
  }

  return Result;
}

static std::string GetDefaultValueString(const ParmVarDecl *Param,
                                         const SourceManager &SM,
                                         const LangOptions &LangOpts) {
  const SourceRange SrcRange = Param->getDefaultArgRange();
  CharSourceRange CharSrcRange = CharSourceRange::getTokenRange(SrcRange);
  bool Invalid = CharSrcRange.isInvalid();
  if (Invalid)
    return "";
  StringRef srcText = Lexer::getSourceText(CharSrcRange, SM, LangOpts, &Invalid);
  if (Invalid)
    return "";

  if (srcText.empty() || srcText == "=") {
    // Lexer can't determine the value.
    // This happens if the code is incorrect (for example class is forward declared).
    return "";
  }
  std::string DefValue(srcText.str());
  // FIXME: remove this check if the Lexer::getSourceText value is fixed and
  // this value always has (or always does not have) '=' in front of it
  if (DefValue.at(0) != '=') {
    // If we don't have '=' in front of value.
    // Lexer returns built-in types values without '=' and user-defined types values with it.
    return " = " + DefValue;
  }
  return " " + DefValue;
}

/// \brief Add function parameter chunks to the given code completion string.
static void AddFunctionParameterChunks(Preprocessor &PP,
                                       const PrintingPolicy &Policy,
                                       const FunctionDecl *Function,
                                       CodeCompletionBuilder &Result,
                                       unsigned Start = 0,
                                       bool InOptional = false) {
  bool FirstParameter = true;
  
  for (unsigned P = Start, N = Function->getNumParams(); P != N; ++P) {
    const ParmVarDecl *Param = Function->getParamDecl(P);
    
    if (Param->hasDefaultArg() && !InOptional) {
      // When we see an optional default argument, put that argument and
      // the remaining default arguments into a new, optional string.
      CodeCompletionBuilder Opt(Result.getAllocator(),
                                Result.getCodeCompletionTUInfo());
      if (!FirstParameter)
        Opt.AddChunk(CodeCompletionString::CK_Comma);
      AddFunctionParameterChunks(PP, Policy, Function, Opt, P, true);
      Result.AddOptionalChunk(Opt.TakeString());
      break;
    }
    
    if (FirstParameter)
      FirstParameter = false;
    else
      Result.AddChunk(CodeCompletionString::CK_Comma);
    
    InOptional = false;
    
    // Format the placeholder string.
    std::string PlaceholderStr = FormatFunctionParameter(Policy, Param);
    if (Param->hasDefaultArg())
      PlaceholderStr += GetDefaultValueString(Param, PP.getSourceManager(), PP.getLangOpts());

    if (Function->isVariadic() && P == N - 1)
      PlaceholderStr += ", ...";

    // Add the placeholder string.
    Result.AddPlaceholderChunk(
                             Result.getAllocator().CopyString(PlaceholderStr));
  }
  
  if (const FunctionProtoType *Proto 
        = Function->getType()->getAs<FunctionProtoType>())
    if (Proto->isVariadic()) {
      if (Proto->getNumParams() == 0)
        Result.AddPlaceholderChunk("...");

      MaybeAddSentinel(PP, Function, Result);
    }
}

/// \brief Add template parameter chunks to the given code completion string.
static void AddTemplateParameterChunks(ASTContext &Context,
                                       const PrintingPolicy &Policy,
                                       const TemplateDecl *Template,
                                       CodeCompletionBuilder &Result,
                                       unsigned MaxParameters = 0,
                                       unsigned Start = 0,
                                       bool InDefaultArg = false) {
  bool FirstParameter = true;

  // Prefer to take the template parameter names from the first declaration of
  // the template.
  Template = cast<TemplateDecl>(Template->getCanonicalDecl());

  TemplateParameterList *Params = Template->getTemplateParameters();
  TemplateParameterList::iterator PEnd = Params->end();
  if (MaxParameters)
    PEnd = Params->begin() + MaxParameters;
  for (TemplateParameterList::iterator P = Params->begin() + Start; 
       P != PEnd; ++P) {
    bool HasDefaultArg = false;
    std::string PlaceholderStr;
    if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(*P)) {
      if (TTP->wasDeclaredWithTypename())
        PlaceholderStr = "typename";
      else
        PlaceholderStr = "class";
      
      if (TTP->getIdentifier()) {
        PlaceholderStr += ' ';
        PlaceholderStr += TTP->getIdentifier()->getName();
      }
      
      HasDefaultArg = TTP->hasDefaultArgument();
    } else if (NonTypeTemplateParmDecl *NTTP 
                                    = dyn_cast<NonTypeTemplateParmDecl>(*P)) {
      if (NTTP->getIdentifier())
        PlaceholderStr = NTTP->getIdentifier()->getName();
      NTTP->getType().getAsStringInternal(PlaceholderStr, Policy);
      HasDefaultArg = NTTP->hasDefaultArgument();
    } else {
      assert(isa<TemplateTemplateParmDecl>(*P));
      TemplateTemplateParmDecl *TTP = cast<TemplateTemplateParmDecl>(*P);
      
      // Since putting the template argument list into the placeholder would
      // be very, very long, we just use an abbreviation.
      PlaceholderStr = "template<...> class";
      if (TTP->getIdentifier()) {
        PlaceholderStr += ' ';
        PlaceholderStr += TTP->getIdentifier()->getName();
      }
      
      HasDefaultArg = TTP->hasDefaultArgument();
    }
    
    if (HasDefaultArg && !InDefaultArg) {
      // When we see an optional default argument, put that argument and
      // the remaining default arguments into a new, optional string.
      CodeCompletionBuilder Opt(Result.getAllocator(),
                                Result.getCodeCompletionTUInfo());
      if (!FirstParameter)
        Opt.AddChunk(CodeCompletionString::CK_Comma);
      AddTemplateParameterChunks(Context, Policy, Template, Opt, MaxParameters,
                                 P - Params->begin(), true);
      Result.AddOptionalChunk(Opt.TakeString());
      break;
    }
    
    InDefaultArg = false;
    
    if (FirstParameter)
      FirstParameter = false;
    else
      Result.AddChunk(CodeCompletionString::CK_Comma);
    
    // Add the placeholder string.
    Result.AddPlaceholderChunk(
                              Result.getAllocator().CopyString(PlaceholderStr));
  }    
}

/// \brief Add a qualifier to the given code-completion string, if the
/// provided nested-name-specifier is non-NULL.
static void 
AddQualifierToCompletionString(CodeCompletionBuilder &Result, 
                               NestedNameSpecifier *Qualifier, 
                               bool QualifierIsInformative,
                               ASTContext &Context,
                               const PrintingPolicy &Policy) {
  if (!Qualifier)
    return;
  
  std::string PrintedNNS;
  {
    llvm::raw_string_ostream OS(PrintedNNS);
    Qualifier->print(OS, Policy);
  }
  if (QualifierIsInformative)
    Result.AddInformativeChunk(Result.getAllocator().CopyString(PrintedNNS));
  else
    Result.AddTextChunk(Result.getAllocator().CopyString(PrintedNNS));
}

static void 
AddFunctionTypeQualsToCompletionString(CodeCompletionBuilder &Result,
                                       const FunctionDecl *Function) {
  const FunctionProtoType *Proto
    = Function->getType()->getAs<FunctionProtoType>();
  if (!Proto || !Proto->getTypeQuals())
    return;

  // FIXME: Add ref-qualifier!
  
  // Handle single qualifiers without copying
  if (Proto->getTypeQuals() == Qualifiers::Const) {
    Result.AddInformativeChunk(" const");
    return;
  }

  if (Proto->getTypeQuals() == Qualifiers::Volatile) {
    Result.AddInformativeChunk(" volatile");
    return;
  }

  if (Proto->getTypeQuals() == Qualifiers::Restrict) {
    Result.AddInformativeChunk(" restrict");
    return;
  }

  // Handle multiple qualifiers.
  std::string QualsStr;
  if (Proto->isConst())
    QualsStr += " const";
  if (Proto->isVolatile())
    QualsStr += " volatile";
  if (Proto->isRestrict())
    QualsStr += " restrict";
  Result.AddInformativeChunk(Result.getAllocator().CopyString(QualsStr));
}

/// \brief Add the name of the given declaration 
static void AddTypedNameChunk(ASTContext &Context, const PrintingPolicy &Policy,
                              const NamedDecl *ND,
                              CodeCompletionBuilder &Result) {
  DeclarationName Name = ND->getDeclName();
  if (!Name)
    return;
  
  switch (Name.getNameKind()) {
    case DeclarationName::CXXOperatorName: {
      const char *OperatorName = nullptr;
      switch (Name.getCXXOverloadedOperator()) {
      case OO_None: 
      case OO_Conditional:
      case NUM_OVERLOADED_OPERATORS:
        OperatorName = "operator"; 
        break;
    
#define OVERLOADED_OPERATOR(Name,Spelling,Token,Unary,Binary,MemberOnly) \
      case OO_##Name: OperatorName = "operator" Spelling; break;
#define OVERLOADED_OPERATOR_MULTI(Name,Spelling,Unary,Binary,MemberOnly)
#include "clang/Basic/OperatorKinds.def"
          
      case OO_New:          OperatorName = "operator new"; break;
      case OO_Delete:       OperatorName = "operator delete"; break;
      case OO_Array_New:    OperatorName = "operator new[]"; break;
      case OO_Array_Delete: OperatorName = "operator delete[]"; break;
      case OO_Call:         OperatorName = "operator()"; break;
      case OO_Subscript:    OperatorName = "operator[]"; break;
      }
      Result.AddTypedTextChunk(OperatorName);
      break;
    }
      
  case DeclarationName::Identifier:
  case DeclarationName::CXXConversionFunctionName:
  case DeclarationName::CXXDestructorName:
  case DeclarationName::CXXLiteralOperatorName:
    Result.AddTypedTextChunk(
                      Result.getAllocator().CopyString(ND->getNameAsString()));
    break;
      
  case DeclarationName::CXXDeductionGuideName:
  case DeclarationName::CXXUsingDirective:
  case DeclarationName::ObjCZeroArgSelector:
  case DeclarationName::ObjCOneArgSelector:
  case DeclarationName::ObjCMultiArgSelector:
    break;
      
  case DeclarationName::CXXConstructorName: {
    CXXRecordDecl *Record = nullptr;
    QualType Ty = Name.getCXXNameType();
    if (const RecordType *RecordTy = Ty->getAs<RecordType>())
      Record = cast<CXXRecordDecl>(RecordTy->getDecl());
    else if (const InjectedClassNameType *InjectedTy
                                        = Ty->getAs<InjectedClassNameType>())
      Record = InjectedTy->getDecl();
    else {
      Result.AddTypedTextChunk(
                      Result.getAllocator().CopyString(ND->getNameAsString()));
      break;
    }
    
    Result.AddTypedTextChunk(
                  Result.getAllocator().CopyString(Record->getNameAsString()));
    if (ClassTemplateDecl *Template = Record->getDescribedClassTemplate()) {
      Result.AddChunk(CodeCompletionString::CK_LeftAngle);
      AddTemplateParameterChunks(Context, Policy, Template, Result);
      Result.AddChunk(CodeCompletionString::CK_RightAngle);
    }
    break;