Implement PersistentValueMap, a map that stores UniquePersistent values.

include/v8.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 122 matching lines @@
 class Data;
 template<typename T> class PropertyCallbackInfo;
 class StackTrace;
 class StackFrame;
 class Isolate;
 class DeclaredAccessorDescriptor;
 class ObjectOperationDescriptor;
 class RawOperationDescriptor;
 class CallHandlerHelper;
 class EscapableHandleScope;
+template<typename T> class ReturnValue;
 
 namespace internal {
 class Arguments;
 class Heap;
 class HeapObject;
 class Isolate;
 class Object;
 template<typename T> class CustomArguments;
 class PropertyCallbackArguments;
 class FunctionCallbackArguments;
@@ skipping 252 matching lines @@
   template<class F> friend class Handle;
   template<class F> friend class Local;
   template<class F> friend class FunctionCallbackInfo;
   template<class F> friend class PropertyCallbackInfo;
   friend class String;
   friend class Object;
   friend class Context;
   template<class F> friend class internal::CustomArguments;
   friend class HandleScope;
   friend class EscapableHandleScope;
+  template<class F1, class F2, class F3> friend class PersistentValueMap;
 
   V8_INLINE static Local<T> New(Isolate* isolate, T* that);
 };
 
 
 // Eternal handles are set-once handles that live for the life of the isolate.
 template <class T> class Eternal {
  public:
   V8_INLINE Eternal() : index_(kInitialValue) { }
   template<class S>
@@ skipping 95 matching lines @@
   template<typename P>
   V8_INLINE void SetWeak(
       P* parameter,
       typename WeakCallbackData<T, P>::Callback callback);
 
   template<typename S, typename P>
   V8_INLINE void SetWeak(
       P* parameter,
       typename WeakCallbackData<S, P>::Callback callback);
 
-  V8_INLINE void ClearWeak();
+  template<typename P>
+  V8_INLINE P* ClearWeak();
+
+  // TODO(dcarney): remove this.
+  V8_INLINE void ClearWeak() { ClearWeak<void>(); }
 
   /**
    * Marks the reference to this object independent. Garbage collector is free
    * to ignore any object groups containing this object. Weak callback for an
    * independent handle should not assume that it will be preceded by a global
    * GC prologue callback or followed by a global GC epilogue callback.
    */
   V8_INLINE void MarkIndependent();
 
   /**
@@ skipping 28 matching lines @@
 
  private:
   friend class Isolate;
   friend class Utils;
   template<class F> friend class Handle;
   template<class F> friend class Local;
   template<class F1, class F2> friend class Persistent;
   template<class F> friend class UniquePersistent;
   template<class F> friend class PersistentBase;
   template<class F> friend class ReturnValue;
+  template<class F1, class F2, class F3> friend class PersistentValueMap;
 
   explicit V8_INLINE PersistentBase(T* val) : val_(val) {}
   PersistentBase(PersistentBase& other); // NOLINT
   void operator=(PersistentBase&);
   V8_INLINE static T* New(Isolate* isolate, T* that);
 
   T* val_;
 };
 
 
@@ skipping 147 matching lines @@
  * Note: Persistent class hierarchy is subject to future changes.
  */
 template<class T>
 class UniquePersistent : public PersistentBase<T> {
   struct RValue {
     V8_INLINE explicit RValue(UniquePersistent* obj) : object(obj) {}
     UniquePersistent* object;
   };
 
  public:
-    /**
+  /**
    * A UniquePersistent with no storage cell.
    */
   V8_INLINE UniquePersistent() : PersistentBase<T>(0) { }
   /**
    * Construct a UniquePersistent from a Handle.
    * When the Handle is non-empty, a new storage cell is created
    * pointing to the same object, and no flags are set.
    */
   template <class S>
   V8_INLINE UniquePersistent(Isolate* isolate, Handle<S> that)
@@ skipping 17 matching lines @@
     : PersistentBase<T>(rvalue.object->val_) {
     rvalue.object->val_ = 0;
   }
   V8_INLINE ~UniquePersistent() { this->Reset(); }
   /**
    * Move via assignment.
    */
   template<class S>
   V8_INLINE UniquePersistent& operator=(UniquePersistent<S> rhs) {
     TYPE_CHECK(T, S);
+    this->Reset();
     this->val_ = rhs.val_;
     rhs.val_ = 0;
     return *this;
   }
   /**
    * Cast operator for moves.
    */
   V8_INLINE operator RValue() { return RValue(this); }
   /**
    * Pass allows returning uniques from functions, etc.
    */
   V8_INLINE UniquePersistent Pass() { return UniquePersistent(RValue(this)); }
 
  private:
   UniquePersistent(UniquePersistent&);
   void operator=(UniquePersistent&);
 };
 
 
+typedef uintptr_t PersistentContainerValue;
+static const uintptr_t kPersistentContainerNotFound = 0;
+
+/**
+ * A map wrapper that allows using UniquePersistent as a mapped value.
+ * C++11 embedders don't need this class, as they can use UniquePersistent
+ * directly in std containers.
+ *
+ * The map relies on a backing map, whose type and accessors are described
+ * by the Traits class. The backing map will handle values of type
+ * PersistentContainerValue, with all conversion into and out of V8
+ * handles being transparently handled by this class.
+ */
+template<class K, class V, class Traits>
+class PersistentValueMap {
+ public:
+  V8_INLINE explicit PersistentValueMap(Isolate* isolate) : isolate_(isolate) {}
+
+  V8_INLINE ~PersistentValueMap() { Clear(); }
+
+  V8_INLINE Isolate* GetIsolate() { return isolate_; }
+
+  /**
+   * Return size of the map.
+   */
+  V8_INLINE size_t Size() { return Traits::Size(&impl_); }
+
+  /**
+   * Get value stored in map.
+   */
+  V8_INLINE Local<V> Get(const K& key) {
+    return Local<V>::New(isolate_, FromVal(Traits::Get(&impl_, key)));
+  }
+
+  /**
+   * Check whether a value is contained in the map.
+   */
+  V8_INLINE bool Contains(const K& key) {
+    return Traits::Get(&impl_, key) != 0;
+  }
+
+  /**
+   * Get value stored in map and set it in returnValue.
+   * Return true if a value was found.
+   */
+  V8_INLINE bool SetReturnValue(const K& key,
+    ReturnValue<Value>& returnValue);
+
+  /**
+   * Call Isolate::SetReference with the given parent and the map value.
+   */
+  V8_INLINE void SetReference(const K& key,
+      const v8::Persistent<v8::Object>& parent) {
+    GetIsolate()->SetReference(
+      reinterpret_cast<internal::Object**>(parent.val_),
+      reinterpret_cast<internal::Object**>(FromVal(Traits::Get(&impl_, key))));
+  }
+
+  /**
+   * Put value into map. Depending on Traits::kIsWeak, the value will be held
+   * by the map strongly or weakly.
+   * Returns old value as UniquePersistent.
+   */
+  UniquePersistent<V> Set(const K& key, Local<V> value) {
+    UniquePersistent<V> persistent(isolate_, value);
+    return SetUnique(key, &persistent);
+  }
+
+  /**
+   * Put value into map, like Set(const K&, Local<V>).
+   */
+  UniquePersistent<V> Set(const K& key, UniquePersistent<V> value) {
+    return SetUnique(key, &value);
+  }
+
+  /**
+   * Return value for key and remove it from the map.
+   */
+  V8_INLINE UniquePersistent<V> Remove(const K& key) {
+    return Release(Traits::Remove(&impl_, key)).Pass();
+  }
+
+  /**
+  * Traverses the map repeatedly,
+  * in case side effects of disposal cause insertions.
+  **/
+  void Clear();
+
+ private:
+  PersistentValueMap(PersistentValueMap&);
+  void operator=(PersistentValueMap&);
+
+  /**
+   * Put the value into the map, and set the 'weak' callback when demanded
+   * by the Traits class.
+   */
+  UniquePersistent<V> SetUnique(const K& key, UniquePersistent<V>* persistent) {
+    if (Traits::kIsWeak) {
+      Local<V> value(Local<V>::New(isolate_, *persistent));
+      persistent->template SetWeak<typename Traits::WeakCallbackDataType>(
+        Traits::WeakCallbackParameter(&impl_, key, value), WeakCallback);
+    }
+    PersistentContainerValue old_value =
+        Traits::Set(&impl_, key, ClearAndLeak(persistent));
+    return Release(old_value).Pass();
+  }
+
+  static void WeakCallback(
+      const WeakCallbackData<V, typename Traits::WeakCallbackDataType>& data);
+  V8_INLINE static V* FromVal(PersistentContainerValue v) {
+    return reinterpret_cast<V*>(v);
+  }
+  V8_INLINE static PersistentContainerValue ClearAndLeak(
+      UniquePersistent<V>* persistent) {
+    V* v = persistent->val_;
+    persistent->val_ = 0;
+    return reinterpret_cast<PersistentContainerValue>(v);
+  }
+
+  /**
+   * Return a container value as UniquePersistent and make sure the weak
+   * callback is properly disposed of. All remove functionality should go
+   * through this.
+   */
+  V8_INLINE static UniquePersistent<V> Release(PersistentContainerValue v) {
+    UniquePersistent<V> p;
+    p.val_ = FromVal(v);
+    if (Traits::kIsWeak && !p.IsEmpty()) {
+      Traits::DisposeCallbackData(
+          p.template ClearWeak<typename Traits::WeakCallbackDataType>());
+    }
+    return p.Pass();
+  }
+
+  Isolate* isolate_;
+  typename Traits::Impl impl_;
+};
+
+
  /**
  * A stack-allocated class that governs a number of local handles.
  * After a handle scope has been created, all local handles will be
  * allocated within that handle scope until either the handle scope is
  * deleted or another handle scope is created.  If there is already a
  * handle scope and a new one is created, all allocations will take
  * place in the new handle scope until it is deleted.  After that,
  * new handles will again be allocated in the original handle scope.
  *
  * After the handle scope of a local handle has been deleted the
@@ skipping 1550 matching lines @@
   V8_INLINE void SetNull();
   V8_INLINE void SetUndefined();
   V8_INLINE void SetEmptyString();
   // Convenience getter for Isolate
   V8_INLINE Isolate* GetIsolate();
 
  private:
   template<class F> friend class ReturnValue;
   template<class F> friend class FunctionCallbackInfo;
   template<class F> friend class PropertyCallbackInfo;
+  template<class F, class G, class H> friend class PersistentValueMap;
+  V8_INLINE void SetInternal(internal::Object* value) { *value_ = value; }
   V8_INLINE internal::Object* GetDefaultValue();
   V8_INLINE explicit ReturnValue(internal::Object** slot);
   internal::Object** value_;
 };
 
 
 /**
  * The argument information given to function call callbacks.  This
  * class provides access to information about the context of the call,
  * including the receiver, the number and values of arguments, and
@@ skipping 1783 matching lines @@
    * function if --expose_gc was specified.
    *
    * This should only be used for testing purposes and not to enforce a garbage
    * collection schedule. It has strong negative impact on the garbage
    * collection performance. Use IdleNotification() or LowMemoryNotification()
    * instead to influence the garbage collection schedule.
    */
   void RequestGarbageCollectionForTesting(GarbageCollectionType type);
 
  private:
+  template<class K, class V, class Traits> friend class PersistentValueMap;
+
   Isolate();
   Isolate(const Isolate&);
   ~Isolate();
   Isolate& operator=(const Isolate&);
   void* operator new(size_t size);
   void operator delete(void*, size_t);
 
   void SetObjectGroupId(internal::Object** object, UniqueId id);
   void SetReferenceFromGroup(UniqueId id, internal::Object** object);
   void SetReference(internal::Object** parent, internal::Object** child);
@@ skipping 574 matching lines @@
   V8();
 
   static internal::Object** GlobalizeReference(internal::Isolate* isolate,
                                                internal::Object** handle);
   static internal::Object** CopyPersistent(internal::Object** handle);
   static void DisposeGlobal(internal::Object** global_handle);
   typedef WeakCallbackData<Value, void>::Callback WeakCallback;
   static void MakeWeak(internal::Object** global_handle,
                        void* data,
                        WeakCallback weak_callback);
-  static void ClearWeak(internal::Object** global_handle);
+  static void* ClearWeak(internal::Object** global_handle);
   static void Eternalize(Isolate* isolate,
                          Value* handle,
                          int* index);
   static Local<Value> GetEternal(Isolate* isolate, int index);
 
   template <class T> friend class Handle;
   template <class T> friend class Local;
   template <class T> friend class Eternal;
   template <class T> friend class PersistentBase;
   template <class T, class M> friend class Persistent;
@@ skipping 892 matching lines @@
 template <class T>
 template <typename P>
 void PersistentBase<T>::SetWeak(
     P* parameter,
     typename WeakCallbackData<T, P>::Callback callback) {
   SetWeak<T, P>(parameter, callback);
 }
 
 
 template <class T>
-void PersistentBase<T>::ClearWeak() {
-  V8::ClearWeak(reinterpret_cast<internal::Object**>(this->val_));
+template<typename P>
+P* PersistentBase<T>::ClearWeak() {
+  return reinterpret_cast<P*>(
+    V8::ClearWeak(reinterpret_cast<internal::Object**>(this->val_)));
 }
 
 
 template <class T>
 void PersistentBase<T>::MarkIndependent() {
   typedef internal::Internals I;
   if (this->IsEmpty()) return;
   I::UpdateNodeFlag(reinterpret_cast<internal::Object**>(this->val_),
                     true,
                     I::kNodeIsIndependentShift);
@@ skipping 32 matching lines @@
 template <class T>
 uint16_t PersistentBase<T>::WrapperClassId() const {
   typedef internal::Internals I;
   if (this->IsEmpty()) return 0;
   internal::Object** obj = reinterpret_cast<internal::Object**>(this->val_);
   uint8_t* addr = reinterpret_cast<uint8_t*>(obj) + I::kNodeClassIdOffset;
   return *reinterpret_cast<uint16_t*>(addr);
 }
 
 
+template <class K, class V, class Traits>
+bool PersistentValueMap<K, V, Traits>::SetReturnValue(const K& key,
+    ReturnValue<Value>& returnValue) {
+  PersistentContainerValue value = Traits::Get(&impl_, key);
+  bool hasValue = value != 0;
+  if (hasValue) {
+    returnValue.SetInternal(
+        *reinterpret_cast<internal::Object**>(FromVal(value)));
+  }
+  return hasValue;
+}
+
+template <class K, class V, class Traits>
+void PersistentValueMap<K, V, Traits>::Clear() {
+  typedef typename Traits::Iterator It;
+  HandleScope handle_scope(isolate_);
+  // TODO(dcarney): figure out if this swap and loop is necessary.
+  while (!Traits::Empty(&impl_)) {
+    typename Traits::Impl impl;
+    Traits::Swap(impl_, impl);
+    for (It i = Traits::Begin(&impl); i != Traits::End(&impl); ++i) {
+      Traits::Dispose(isolate_, Release(Traits::Value(i)).Pass(), &impl,
+        Traits::Key(i));
+    }
+  }
+}
+
+
+template <class K, class V, class Traits>
+void PersistentValueMap<K, V, Traits>::WeakCallback(
+    const WeakCallbackData<V, typename Traits::WeakCallbackDataType>& data) {
+  typename Traits::Impl* impl = Traits::ImplFromWeakCallbackData(data);
+  K key = Traits::KeyFromWeakCallbackData(data);
+  PersistentContainerValue value = Traits::Remove(impl, key);
+  Traits::Dispose(data.GetIsolate(), Release(value).Pass(), impl, key);
+}
+
+
 template<typename T>
 ReturnValue<T>::ReturnValue(internal::Object** slot) : value_(slot) {}
 
 template<typename T>
 template<typename S>
 void ReturnValue<T>::Set(const Persistent<S>& handle) {
   TYPE_CHECK(T, S);
   if (V8_UNLIKELY(handle.IsEmpty())) {
     *value_ = GetDefaultValue();
   } else {
@@ skipping 689 matching lines @@
  */
 
 
 }  // namespace v8
 
 
 #undef TYPE_CHECK
 
 
 #endif  // V8_H_