text: //===- llvm/ADT/ValueMap.h - Safe map from Values to data -------*- 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 ValueMap class.  ValueMap maps Value* or any subclass
  // to an arbitrary other type.  It provides the DenseMap interface but updates
  // itself to remain safe when keys are RAUWed or deleted.  By default, when a
  // key is RAUWed from V1 to V2, the old mapping V1->target is removed, and a new
  // mapping V2->target is added.  If V2 already existed, its old target is
  // overwritten.  When a key is deleted, its mapping is removed.
  //
  // You can override a ValueMap's Config parameter to control exactly what
  // happens on RAUW and destruction and to get called back on each event.  It's
  // legal to call back into the ValueMap from a Config's callbacks.  Config
  // parameters should inherit from ValueMapConfig<KeyT> to get default
  // implementations of all the methods ValueMap uses.  See ValueMapConfig for
  // documentation of the functions you can override.
  //
  //===----------------------------------------------------------------------===//
  
  #ifndef LLVM_ADT_VALUEMAP_H
  #define LLVM_ADT_VALUEMAP_H
  
  #include "llvm/ADT/DenseMap.h"
  #include "llvm/Support/ValueHandle.h"
  #include "llvm/Support/type_traits.h"
  #include "llvm/Support/Mutex.h"
  
  #include <iterator>
  
  namespace llvm {
  
  template<typename KeyT, typename ValueT, typename Config, typename ValueInfoT>
  class ValueMapCallbackVH;
  
  template<typename DenseMapT, typename KeyT>
  class ValueMapIterator;
  template<typename DenseMapT, typename KeyT>
  class ValueMapConstIterator;
  
  /// This class defines the default behavior for configurable aspects of
  /// ValueMap<>.  User Configs should inherit from this class to be as compatible
  /// as possible with future versions of ValueMap.
  template<typename KeyT>
  struct ValueMapConfig {
    /// If FollowRAUW is true, the ValueMap will update mappings on RAUW. If it's
    /// false, the ValueMap will leave the original mapping in place.
    enum { FollowRAUW = true };
  
    // All methods will be called with a first argument of type ExtraData.  The
    // default implementations in this class take a templated first argument so
    // that users' subclasses can use any type they want without having to
    // override all the defaults.
    struct ExtraData {};
  
    template<typename ExtraDataT>
    static void onRAUW(const ExtraDataT & /*Data*/, KeyT /*Old*/, KeyT /*New*/) {}
    template<typename ExtraDataT>
    static void onDelete(const ExtraDataT &/*Data*/, KeyT /*Old*/) {}
  
    /// Returns a mutex that should be acquired around any changes to the map.
    /// This is only acquired from the CallbackVH (and held around calls to onRAUW
    /// and onDelete) and not inside other ValueMap methods.  NULL means that no
    /// mutex is necessary.
    template<typename ExtraDataT>
    static sys::Mutex *getMutex(const ExtraDataT &/*Data*/) { return NULL; }
  };
  
  /// See the file comment.
  template<typename KeyT, typename ValueT, typename Config = ValueMapConfig<KeyT>,
           typename ValueInfoT = DenseMapInfo<ValueT> >
  class ValueMap {
    friend class ValueMapCallbackVH<KeyT, ValueT, Config, ValueInfoT>;
    typedef ValueMapCallbackVH<KeyT, ValueT, Config, ValueInfoT> ValueMapCVH;
    typedef DenseMap<ValueMapCVH, ValueT, DenseMapInfo<ValueMapCVH>,
                     ValueInfoT> MapT;
    typedef typename Config::ExtraData ExtraData;
    MapT Map;
    ExtraData Data;
    ValueMap(const ValueMap&); // DO NOT IMPLEMENT
    ValueMap& operator=(const ValueMap&); // DO NOT IMPLEMENT
  public:
    typedef KeyT key_type;
    typedef ValueT mapped_type;
    typedef std::pair<KeyT, ValueT> value_type;
  
    explicit ValueMap(unsigned NumInitBuckets = 64)
      : Map(NumInitBuckets), Data() {}
    explicit ValueMap(const ExtraData &Data, unsigned NumInitBuckets = 64)
      : Map(NumInitBuckets), Data(Data) {}
  
    ~ValueMap() {}
  
    typedef ValueMapIterator<MapT, KeyT> iterator;
    typedef ValueMapConstIterator<MapT, KeyT> const_iterator;
    inline iterator begin() { return iterator(Map.begin()); }
    inline iterator end() { return iterator(Map.end()); }
    inline const_iterator begin() const { return const_iterator(Map.begin()); }
    inline const_iterator end() const { return const_iterator(Map.end()); }
  
    bool empty() const { return Map.empty(); }
    unsigned size() const { return Map.size(); }
  
    /// Grow the map so that it has at least Size buckets. Does not shrink
    void resize(size_t Size) { Map.resize(Size); }
  
    void clear() { Map.clear(); }
  
    /// count - Return true if the specified key is in the map.
    bool count(const KeyT &Val) const {
      return Map.count(Wrap(Val));
    }
  
    iterator find(const KeyT &Val) {
      return iterator(Map.find(Wrap(Val)));
    }
    const_iterator find(const KeyT &Val) const {
      return const_iterator(Map.find(Wrap(Val)));
    }
  
    /// lookup - Return the entry for the specified key, or a default
    /// constructed value if no such entry exists.
    ValueT lookup(const KeyT &Val) const {
      return Map.lookup(Wrap(Val));
    }
  
    // Inserts key,value pair into the map if the key isn't already in the map.
    // If the key is already in the map, it returns false and doesn't update the
    // value.
    std::pair<iterator, bool> insert(const std::pair<KeyT, ValueT> &KV) {
      std::pair<typename MapT::iterator, bool> map_result=
        Map.insert(std::make_pair(Wrap(KV.first), KV.second));
      return std::make_pair(iterator(map_result.first), map_result.second);
    }
  
    /// insert - Range insertion of pairs.
    template<typename InputIt>
    void insert(InputIt I, InputIt E) {
      for (; I != E; ++I)
        insert(*I);
    }
  
  
    bool erase(const KeyT &Val) {
      return Map.erase(Wrap(Val));
    }
    void erase(iterator I) {
      return Map.erase(I.base());
    }
  
    value_type& FindAndConstruct(const KeyT &Key) {
      return Map.FindAndConstruct(Wrap(Key));
    }
  
    ValueT &operator[](const KeyT &Key) {
      return Map[Wrap(Key)];
    }
  
    /// isPointerIntoBucketsArray - Return true if the specified pointer points
    /// somewhere into the ValueMap's array of buckets (i.e. either to a key or
    /// value in the ValueMap).
    bool isPointerIntoBucketsArray(const void *Ptr) const {
      return Map.isPointerIntoBucketsArray(Ptr);
    }
  
    /// getPointerIntoBucketsArray() - Return an opaque pointer into the buckets
    /// array.  In conjunction with the previous method, this can be used to
    /// determine whether an insertion caused the ValueMap to reallocate.
    const void *getPointerIntoBucketsArray() const {
      return Map.getPointerIntoBucketsArray();
    }
  
  private:
    // Takes a key being looked up in the map and wraps it into a
    // ValueMapCallbackVH, the actual key type of the map.  We use a helper
    // function because ValueMapCVH is constructed with a second parameter.
    ValueMapCVH Wrap(KeyT key) const {
      // The only way the resulting CallbackVH could try to modify *this (making
      // the const_cast incorrect) is if it gets inserted into the map.  But then
      // this function must have been called from a non-const method, making the
      // const_cast ok.
      return ValueMapCVH(key, const_cast<ValueMap*>(this));
    }
  };
  
  // This CallbackVH updates its ValueMap when the contained Value changes,
  // according to the user's preferences expressed through the Config object.
  template<typename KeyT, typename ValueT, typename Config, typename ValueInfoT>
  class ValueMapCallbackVH : public CallbackVH {
    friend class ValueMap<KeyT, ValueT, Config, ValueInfoT>;
    friend struct DenseMapInfo<ValueMapCallbackVH>;
    typedef ValueMap<KeyT, ValueT, Config, ValueInfoT> ValueMapT;
    typedef typename llvm::remove_pointer<KeyT>::type KeySansPointerT;
  
    ValueMapT *Map;
  
    ValueMapCallbackVH(KeyT Key, ValueMapT *Map)
        : CallbackVH(const_cast<Value*>(static_cast<const Value*>(Key))),
          Map(Map) {}
  
  public:
    KeyT Unwrap() const { return cast_or_null<KeySansPointerT>(getValPtr()); }
  
    virtual void deleted() {
      // Make a copy that won't get changed even when *this is destroyed.
      ValueMapCallbackVH Copy(*this);
      sys::Mutex *M = Config::getMutex(Copy.Map->Data);
      if (M)
        M->acquire();
      Config::onDelete(Copy.Map->Data, Copy.Unwrap());  // May destroy *this.
      Copy.Map->Map.erase(Copy);  // Definitely destroys *this.
      if (M)
        M->release();
    }
    virtual void allUsesReplacedWith(Value *new_key) {
      assert(isa<KeySansPointerT>(new_key) &&
             "Invalid RAUW on key of ValueMap<>");
      // Make a copy that won't get changed even when *this is destroyed.
      ValueMapCallbackVH Copy(*this);
      sys::Mutex *M = Config::getMutex(Copy.Map->Data);
      if (M)
        M->acquire();
  
      KeyT typed_new_key = cast<KeySansPointerT>(new_key);
      // Can destroy *this:
      Config::onRAUW(Copy.Map->Data, Copy.Unwrap(), typed_new_key);
      if (Config::FollowRAUW) {
        typename ValueMapT::MapT::iterator I = Copy.Map->Map.find(Copy);
        // I could == Copy.Map->Map.end() if the onRAUW callback already
        // removed the old mapping.
        if (I != Copy.Map->Map.end()) {
          ValueT Target(I->second);
          Copy.Map->Map.erase(I);  // Definitely destroys *this.
          Copy.Map->insert(std::make_pair(typed_new_key, Target));
        }
      }
      if (M)
        M->release();
    }
  };
  
  template<typename KeyT, typename ValueT, typename Config, typename ValueInfoT>
  struct DenseMapInfo<ValueMapCallbackVH<KeyT, ValueT, Config, ValueInfoT> > {
    typedef ValueMapCallbackVH<KeyT, ValueT, Config, ValueInfoT> VH;
    typedef DenseMapInfo<KeyT> PointerInfo;
  
    static inline VH getEmptyKey() {
      return VH(PointerInfo::getEmptyKey(), NULL);
    }
    static inline VH getTombstoneKey() {
      return VH(PointerInfo::getTombstoneKey(), NULL);
    }
    static unsigned getHashValue(const VH &Val) {
      return PointerInfo::getHashValue(Val.Unwrap());
    }
    static bool isEqual(const VH &LHS, const VH &RHS) {
      return LHS == RHS;
    }
  };
  
  
  template<typename DenseMapT, typename KeyT>
  class ValueMapIterator :
      public std::iterator<std::forward_iterator_tag,
                           std::pair<KeyT, typename DenseMapT::mapped_type>,
                           ptrdiff_t> {
    typedef typename DenseMapT::iterator BaseT;
    typedef typename DenseMapT::mapped_type ValueT;
    BaseT I;
  public:
    ValueMapIterator() : I() {}
  
    ValueMapIterator(BaseT I) : I(I) {}
  
    BaseT base() const { return I; }
  
    struct ValueTypeProxy {
      const KeyT first;
      ValueT& second;
      ValueTypeProxy *operator->() { return this; }
      operator std::pair<KeyT, ValueT>() const {
        return std::make_pair(first, second);
      }
    };
  
    ValueTypeProxy operator*() const {
      ValueTypeProxy Result = {I->first.Unwrap(), I->second};
      return Result;
    }
  
    ValueTypeProxy operator->() const {
      return operator*();
    }
  
    bool operator==(const ValueMapIterator &RHS) const {
      return I == RHS.I;
    }
    bool operator!=(const ValueMapIterator &RHS) const {
      return I != RHS.I;
    }
  
    inline ValueMapIterator& operator++() {  // Preincrement
      ++I;
      return *this;
    }
    ValueMapIterator operator++(int) {  // Postincrement
      ValueMapIterator tmp = *this; ++*this; return tmp;
    }
  };
  
  template<typename DenseMapT, typename KeyT>
  class ValueMapConstIterator :
      public std::iterator<std::forward_iterator_tag,
                           std::pair<KeyT, typename DenseMapT::mapped_type>,
                           ptrdiff_t> {
    typedef typename DenseMapT::const_iterator BaseT;
    typedef typename DenseMapT::mapped_type ValueT;
    BaseT I;
  public:
    ValueMapConstIterator() : I() {}
    ValueMapConstIterator(BaseT I) : I(I) {}
    ValueMapConstIterator(ValueMapIterator<DenseMapT, KeyT> Other)
      : I(Other.base()) {}
  
    BaseT base() const { return I; }
  
    struct ValueTypeProxy {
      const KeyT first;
      const ValueT& second;
      ValueTypeProxy *operator->() { return this; }
      operator std::pair<KeyT, ValueT>() const {
        return std::make_pair(first, second);
      }
    };
  
    ValueTypeProxy operator*() const {
      ValueTypeProxy Result = {I->first.Unwrap(), I->second};
      return Result;
    }
  
    ValueTypeProxy operator->() const {
      return operator*();
    }
  
    bool operator==(const ValueMapConstIterator &RHS) const {
      return I == RHS.I;
    }
    bool operator!=(const ValueMapConstIterator &RHS) const {
      return I != RHS.I;
    }
  
    inline ValueMapConstIterator& operator++() {  // Preincrement
      ++I;
      return *this;
    }
    ValueMapConstIterator operator++(int) {  // Postincrement
      ValueMapConstIterator tmp = *this; ++*this; return tmp;
    }
  };
  
  } // end namespace llvm
  
  #endif
  