Support old and new weak handle API

include/v8-util.h

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_UTIL_H_
 #define V8_UTIL_H_
 
 #include "v8.h"
 #include <map>
 #include <vector>
@@ skipping 87 matching lines @@
   }
   static K KeyFromWeakCallbackData(
       const WeakCallbackData<V, WeakCallbackDataType>& data) {
     return K();
   }
   static void DisposeCallbackData(WeakCallbackDataType* data) { }
   static void Dispose(Isolate* isolate, UniquePersistent<V> value, K key) { }
 };
 
 
+template <typename K, typename V>
+class DefaultPhantomPersistentValueMapTraits : public StdMapTraits<K, V> {
+ private:
+  template <typename T>
+  struct RemovePointer;
+
+ public:
+  // Weak callback & friends:
+  static const PersistentContainerCallbackType kCallbackType = kNotWeak;
+  typedef PersistentValueMap<
+      K, V, DefaultPhantomPersistentValueMapTraits<K, V> > MapType;
+  typedef void PhantomCallbackDataType;
+
+  static PhantomCallbackDataType* PhantomCallbackParameter(MapType* map,
+                                                           const K& key,
+                                                           Local<V> value) {
+    return NULL;
+  }
+  static MapType* MapFromPhantomCallbackData(
+      const PhantomCallbackData<PhantomCallbackDataType>& data) {
+    return NULL;
+  }
+  static K KeyFromPhantomCallbackData(
+      const PhantomCallbackData<PhantomCallbackDataType>& data) {
+    return K();
+  }
+  static void DisposeCallbackData(PhantomCallbackDataType* data) {}
+  static void Dispose(Isolate* isolate, UniquePersistent<V> value, K key) {}
+
+ private:
+  template <typename T>
+  struct RemovePointer<T*> {
+    typedef T Type;
+  };
+};
+
+
 /**
  * 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<typename K, typename V, typename Traits>
-class PersistentValueMap {
+template <typename K, typename V, typename Traits>
+class PersistentValueMapBase {
  public:
-  explicit PersistentValueMap(Isolate* isolate) : isolate_(isolate) {}
-
-  ~PersistentValueMap() { Clear(); }
-
   Isolate* GetIsolate() { return isolate_; }
 
   /**
    * Return size of the map.
    */
   size_t Size() { return Traits::Size(&impl_); }
 
   /**
    * Return whether the map holds weak persistents.
    */
@@ skipping 26 matching lines @@
    * Call Isolate::SetReference with the given parent and the map value.
    */
   void SetReference(const K& key,
       const Persistent<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.
    */
   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.
   **/
@@ skipping 32 matching lines @@
       return SetReturnValueFromVal(&returnValue, value_);
     }
     void Reset() {
       value_ = kPersistentContainerNotFound;
     }
     void operator=(const PersistentValueReference& other) {
       value_ = other.value_;
     }
 
    private:
-    friend class PersistentValueMap;
+    friend class PersistentValueMapBase;
+    friend class PersistentValueMap<K, V, Traits>;
+    friend class PhantomPersistentValueMap<K, V, Traits>;
 
     explicit PersistentValueReference(PersistentContainerValue value)
         : value_(value) { }
 
     void operator=(PersistentContainerValue value) {
       value_ = value;
     }
 
     PersistentContainerValue value_;
   };
 
   /**
    * Get a reference to a map value. This enables fast, repeated access
    * to a value stored in the map while the map remains unchanged.
    *
    * Careful: This is potentially unsafe, so please use with care.
    * The value will become invalid if the value for this key changes
    * in the underlying map, as a result of Set or Remove for the same
    * key; as a result of the weak callback for the same key; or as a
    * result of calling Clear() or destruction of the map.
    */
   PersistentValueReference GetReference(const K& key) {
     return PersistentValueReference(Traits::Get(&impl_, key));
   }
 
+ protected:
+  explicit PersistentValueMapBase(Isolate* isolate) : isolate_(isolate) {}
+
+  ~PersistentValueMapBase() { Clear(); }
+
+  Isolate* isolate() { return isolate_; }
+  typename Traits::Impl* impl() { return &impl_; }
+
+  static V* FromVal(PersistentContainerValue v) {
+    return reinterpret_cast<V*>(v);
+  }
+
+  static PersistentContainerValue ClearAndLeak(
+      UniquePersistent<V>* persistent) {
+    V* v = persistent->val_;
+    persistent->val_ = 0;
+    return reinterpret_cast<PersistentContainerValue>(v);
+  }
+
+  static PersistentContainerValue Leak(UniquePersistent<V>* persistent) {
+    return reinterpret_cast<PersistentContainerValue>(persistent->val_);
+  }
+
   /**
-   * Put a value into the map and update the reference.
-   * Restrictions of GetReference apply here as well.
+   * Return a container value as UniquePersistent and make sure the weak
+   * callback is properly disposed of. All remove functionality should go
+   * through this.
    */
-  UniquePersistent<V> Set(const K& key, UniquePersistent<V> value,
-                          PersistentValueReference* reference) {
-    *reference = Leak(&value);
+  static UniquePersistent<V> Release(PersistentContainerValue v) {
+    UniquePersistent<V> p;
+    p.val_ = FromVal(v);
+    if (Traits::kCallbackType != kNotWeak && p.IsWeak()) {
+      Traits::DisposeCallbackData(
+          p.template ClearWeak<typename Traits::WeakCallbackDataType>());
+    }
+    return p.Pass();
+  }
+
+ private:
+  PersistentValueMapBase(PersistentValueMapBase&);
+  void operator=(PersistentValueMapBase&);
+
+  static bool SetReturnValueFromVal(ReturnValue<Value>* returnValue,
+                                    PersistentContainerValue value) {
+    bool hasValue = value != kPersistentContainerNotFound;
+    if (hasValue) {
+      returnValue->SetInternal(
+          *reinterpret_cast<internal::Object**>(FromVal(value)));
+    }
+    return hasValue;
+  }
+
+  Isolate* isolate_;
+  typename Traits::Impl impl_;
+};
+
+
+template <typename K, typename V, typename Traits>
+class PersistentValueMap : public PersistentValueMapBase<K, V, Traits> {
+ public:
+  explicit PersistentValueMap(Isolate* isolate)
+      : PersistentValueMapBase<K, V, Traits>(isolate) {}
+
+  typedef
+      typename PersistentValueMapBase<K, V, Traits>::PersistentValueReference
+          PersistentValueReference;
+
+  /**
+   * 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(this->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);
   }
 
- 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::kCallbackType != kNotWeak) {
-      Local<V> value(Local<V>::New(isolate_, *persistent));
+      Local<V> value(Local<V>::New(this->isolate(), *persistent));
       persistent->template SetWeak<typename Traits::WeakCallbackDataType>(
         Traits::WeakCallbackParameter(this, key, value), WeakCallback);
     }
     PersistentContainerValue old_value =
-        Traits::Set(&impl_, key, ClearAndLeak(persistent));
-    return Release(old_value).Pass();
+        Traits::Set(this->impl(), key, this->ClearAndLeak(persistent));
+    return this->Release(old_value).Pass();
   }
 
+  /**
+   * Put a value into the map and update the reference.
+   * Restrictions of GetReference apply here as well.
+   */
+  UniquePersistent<V> Set(const K& key, UniquePersistent<V> value,
+                          PersistentValueReference* reference) {
+    *reference = this->Leak(&value);
+    return SetUnique(key, &value);
+  }
+
+ private:
   static void WeakCallback(
       const WeakCallbackData<V, typename Traits::WeakCallbackDataType>& data) {
     if (Traits::kCallbackType != kNotWeak) {
       PersistentValueMap<K, V, Traits>* persistentValueMap =
           Traits::MapFromWeakCallbackData(data);
       K key = Traits::KeyFromWeakCallbackData(data);
       Traits::Dispose(data.GetIsolate(),
                       persistentValueMap->Remove(key).Pass(), key);
       Traits::DisposeCallbackData(data.GetParameter());
     }
   }
+};
 
-  static V* FromVal(PersistentContainerValue v) {
-    return reinterpret_cast<V*>(v);
-  }
 
-  static bool SetReturnValueFromVal(
-      ReturnValue<Value>* returnValue, PersistentContainerValue value) {
-    bool hasValue = value != kPersistentContainerNotFound;
-    if (hasValue) {
-      returnValue->SetInternal(
-          *reinterpret_cast<internal::Object**>(FromVal(value)));
-    }
-    return hasValue;
-  }
+template <typename K, typename V, typename Traits>
+class PhantomPersistentValueMap : public PersistentValueMapBase<K, V, Traits> {
+ public:
+  explicit PhantomPersistentValueMap(Isolate* isolate)
+      : PersistentValueMapBase<K, V, Traits>(isolate) {}
 
-  static PersistentContainerValue ClearAndLeak(
-      UniquePersistent<V>* persistent) {
-    V* v = persistent->val_;
-    persistent->val_ = 0;
-    return reinterpret_cast<PersistentContainerValue>(v);
-  }
+  typedef
+      typename PersistentValueMapBase<K, V, Traits>::PersistentValueReference
+          PersistentValueReference;
 
-  static PersistentContainerValue Leak(
-      UniquePersistent<V>* persistent) {
-    return reinterpret_cast<PersistentContainerValue>(persistent->val_);
+  /**
+   * 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(this->isolate(), value);
+    return SetUnique(key, &persistent);
   }
 
   /**
-   * Return a container value as UniquePersistent and make sure the weak
-   * callback is properly disposed of. All remove functionality should go
-   * through this.
+   * Put value into map, like Set(const K&, Local<V>).
    */
-  static UniquePersistent<V> Release(PersistentContainerValue v) {
-    UniquePersistent<V> p;
-    p.val_ = FromVal(v);
-    if (Traits::kCallbackType != kNotWeak && p.IsWeak()) {
-      Traits::DisposeCallbackData(
-          p.template ClearWeak<typename Traits::WeakCallbackDataType>());
-    }
-    return p.Pass();
+  UniquePersistent<V> Set(const K& key, UniquePersistent<V> value) {
+    return SetUnique(key, &value);
   }
 
-  Isolate* isolate_;
-  typename Traits::Impl impl_;
+  /**
+   * 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::kCallbackType != kNotWeak) {
+      Local<V> value(Local<V>::New(this->isolate(), *persistent));
+      persistent->template SetPhantom<typename Traits::WeakCallbackDataType>(
+          Traits::WeakCallbackParameter(this, key, value), WeakCallback, 0, 1);
+    }
+    PersistentContainerValue old_value =
+        Traits::Set(this->impl(), key, this->ClearAndLeak(persistent));
+    return this->Release(old_value).Pass();
+  }
+
+  /**
+   * Put a value into the map and update the reference.
+   * Restrictions of GetReference apply here as well.
+   */
+  UniquePersistent<V> Set(const K& key, UniquePersistent<V> value,
+                          PersistentValueReference* reference) {
+    *reference = this->Leak(&value);
+    return SetUnique(key, &value);
+  }
+
+ private:
+  static void WeakCallback(
+      const PhantomCallbackData<typename Traits::WeakCallbackDataType>& data) {
+    if (Traits::kCallbackType != kNotWeak) {
+      PhantomPersistentValueMap<K, V, Traits>* persistentValueMap =
+          Traits::MapFromPhantomCallbackData(data);
+      K key = Traits::KeyFromPhantomCallbackData(data);
+      Traits::Dispose(data.GetIsolate(), persistentValueMap->Remove(key).Pass(),
+                      key);
+      Traits::DisposeCallbackData(data.GetParameter());
+    }
+  }
 };
 
 
 /**
  * A map that uses UniquePersistent as value and std::map as the backing
  * implementation. Persistents are held non-weak.
  *
  * C++11 embedders don't need this class, as they can use
  * UniquePersistent directly in std containers.
  */
@@ skipping 118 matching lines @@
     return reinterpret_cast<V*>(v);
   }
 
   Isolate* isolate_;
   typename Traits::Impl impl_;
 };
 
 }  // namespace v8
 
 #endif  // V8_UTIL_H_