v8-util.h

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// 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 <assert.h>
 
#include <map>
#include <vector>
 
#include "v8-function-callback.h"  // NOLINT(build/include_directory)
#include "v8-persistent-handle.h"  // NOLINT(build/include_directory)

namespace v8 {
 
template <typename K, typename V, typename Traits>
class GlobalValueMap;
 
typedef uintptr_t PersistentContainerValue;
static const uintptr_t kPersistentContainerNotFound = 0;
enum PersistentContainerCallbackType {
  kNotWeak,
  // These correspond to v8::WeakCallbackType
  kWeakWithParameter,
  kWeakWithInternalFields
};

template<typename K, typename V>
class StdMapTraits {
 public:
  // STL map & related:
  typedef std::map<K, PersistentContainerValue> Impl;
  typedef typename Impl::iterator Iterator;
 
  static bool Empty(Impl* impl) { return impl->empty(); }
  static size_t Size(Impl* impl) { return impl->size(); }
  static void Swap(Impl& a, Impl& b) { std::swap(a, b); }
  static Iterator Begin(Impl* impl) { return impl->begin(); }
  static Iterator End(Impl* impl) { return impl->end(); }
  static K Key(Iterator it) { return it->first; }
  static PersistentContainerValue Value(Iterator it) { return it->second; }
  static PersistentContainerValue Set(Impl* impl, K key,
      PersistentContainerValue value) {
    std::pair<Iterator, bool> res = impl->insert(std::make_pair(key, value));
    PersistentContainerValue old_value = kPersistentContainerNotFound;
    if (!res.second) {
      old_value = res.first->second;
      res.first->second = value;
    }
    return old_value;
  }
  static PersistentContainerValue Get(Impl* impl, K key) {
    Iterator it = impl->find(key);
    if (it == impl->end()) return kPersistentContainerNotFound;
    return it->second;
  }
  static PersistentContainerValue Remove(Impl* impl, K key) {
    Iterator it = impl->find(key);
    if (it == impl->end()) return kPersistentContainerNotFound;
    PersistentContainerValue value = it->second;
    impl->erase(it);
    return value;
  }
};
 

template<typename K, typename V>
class DefaultPersistentValueMapTraits : public StdMapTraits<K, V> {
 public:
  // Weak callback & friends:
  static const PersistentContainerCallbackType kCallbackType = kNotWeak;
  typedef PersistentValueMap<K, V, DefaultPersistentValueMapTraits<K, V> >
      MapType;
  typedef void WeakCallbackDataType;
 
  static WeakCallbackDataType* WeakCallbackParameter(
      MapType* map, const K& key, Local<V> value) {
    return nullptr;
  }
  static MapType* MapFromWeakCallbackInfo(
      const WeakCallbackInfo<WeakCallbackDataType>& data) {
    return nullptr;
  }
  static K KeyFromWeakCallbackInfo(
      const WeakCallbackInfo<WeakCallbackDataType>& data) {
    return K();
  }
  static void DisposeCallbackData(WeakCallbackDataType* data) { }
  static void Dispose(Isolate* isolate, Global<V> value, K key) {}
};
 
 
template <typename K, typename V>
class DefaultGlobalMapTraits : public StdMapTraits<K, V> {
 private:
  template <typename T>
  struct RemovePointer;
 
 public:
  // Weak callback & friends:
  static const PersistentContainerCallbackType kCallbackType = kNotWeak;
  typedef GlobalValueMap<K, V, DefaultGlobalMapTraits<K, V> > MapType;
  typedef void WeakCallbackDataType;
 
  static WeakCallbackDataType* WeakCallbackParameter(MapType* map, const K& key,
                                                     Local<V> value) {
    return nullptr;
  }
  static MapType* MapFromWeakCallbackInfo(
      const WeakCallbackInfo<WeakCallbackDataType>& data) {
    return nullptr;
  }
  static K KeyFromWeakCallbackInfo(
      const WeakCallbackInfo<WeakCallbackDataType>& data) {
    return K();
  }
  static void DisposeCallbackData(WeakCallbackDataType* data) {}
  static void OnWeakCallback(
      const WeakCallbackInfo<WeakCallbackDataType>& data) {}
  static void Dispose(Isolate* isolate, Global<V> value, K key) {}
  // This is a second pass callback, so SetSecondPassCallback cannot be called.
  static void DisposeWeak(const WeakCallbackInfo<WeakCallbackDataType>& data) {}
 
 private:
  template <typename T>
  struct RemovePointer<T*> {
    typedef T Type;
  };
};
 

template <typename K, typename V, typename Traits>
class PersistentValueMapBase {
 public:
  Isolate* GetIsolate() { return isolate_; }

  size_t Size() { return Traits::Size(&impl_); }

  bool IsWeak() { return Traits::kCallbackType != kNotWeak; }

  Local<V> Get(const K& key) {
    V* p = FromVal(Traits::Get(&impl_, key));
#ifdef V8_ENABLE_DIRECT_HANDLE
    if (p == nullptr) return Local<V>();
#endif
    return Local<V>::New(isolate_, p);
  }

  bool Contains(const K& key) {
    return Traits::Get(&impl_, key) != kPersistentContainerNotFound;
  }

  bool SetReturnValue(const K& key,
      ReturnValue<Value> returnValue) {
    return SetReturnValueFromVal(&returnValue, Traits::Get(&impl_, key));
  }

  Global<V> Remove(const K& key) {
    return Release(Traits::Remove(&impl_, key)).Pass();
  }

  void 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(),
                        Traits::Key(i));
      }
    }
  }

  class PersistentValueReference {
   public:
    PersistentValueReference() : value_(kPersistentContainerNotFound) { }
    PersistentValueReference(const PersistentValueReference& other)
        : value_(other.value_) { }
 
    Local<V> NewLocal(Isolate* isolate) const {
      return Local<V>::New(isolate,
                           internal::ValueHelper::SlotAsValue<V>(
                               reinterpret_cast<internal::Address*>(value_)));
    }
    bool IsEmpty() const {
      return value_ == kPersistentContainerNotFound;
    }
    template<typename T>
    bool SetReturnValue(ReturnValue<T> returnValue) {
      return SetReturnValueFromVal(&returnValue, value_);
    }
    void Reset() {
      value_ = kPersistentContainerNotFound;
    }
    void operator=(const PersistentValueReference& other) {
      value_ = other.value_;
    }
 
   private:
    friend class PersistentValueMapBase;
    friend class PersistentValueMap<K, V, Traits>;
    friend class GlobalValueMap<K, V, Traits>;
 
    explicit PersistentValueReference(PersistentContainerValue value)
        : value_(value) { }
 
    void operator=(PersistentContainerValue value) {
      value_ = value;
    }
 
    PersistentContainerValue value_;
  };

  PersistentValueReference GetReference(const K& key) {
    return PersistentValueReference(Traits::Get(&impl_, key));
  }
 
 protected:
  explicit PersistentValueMapBase(Isolate* isolate)
      : isolate_(isolate), label_(nullptr) {}
  PersistentValueMapBase(Isolate* isolate, const char* label)
      : isolate_(isolate), label_(label) {}
 
  ~PersistentValueMapBase() { Clear(); }
 
  Isolate* isolate() { return isolate_; }
  typename Traits::Impl* impl() { return &impl_; }
 
  static V* FromVal(PersistentContainerValue v) {
    return internal::ValueHelper::SlotAsValue<V>(
        reinterpret_cast<internal::Address*>(v));
  }
 
  static PersistentContainerValue ClearAndLeak(Global<V>* persistent) {
    internal::Address* address = persistent->slot();
    persistent->Clear();
    return reinterpret_cast<PersistentContainerValue>(address);
  }
 
  static PersistentContainerValue Leak(Global<V>* persistent) {
    return reinterpret_cast<PersistentContainerValue>(persistent->slot());
  }

  static Global<V> Release(PersistentContainerValue v) {
    Global<V> p;
    p.slot() = reinterpret_cast<internal::Address*>(v);
    if (Traits::kCallbackType != kNotWeak && p.IsWeak()) {
      Traits::DisposeCallbackData(
          p.template ClearWeak<typename Traits::WeakCallbackDataType>());
    }
    return p.Pass();
  }
 
  void RemoveWeak(const K& key) {
    Global<V> p;
    p.slot() =
        reinterpret_cast<internal::Address*>(Traits::Remove(&impl_, key));
    p.Reset();
  }
 
  void AnnotateStrongRetainer(Global<V>* persistent) {
    persistent->AnnotateStrongRetainer(label_);
  }
 
 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::Address*>(value));
    }
    return hasValue;
  }
 
  Isolate* isolate_;
  typename Traits::Impl impl_;
  const char* label_;
};
 
template <typename K, typename V, typename Traits>
class PersistentValueMap : public PersistentValueMapBase<K, V, Traits> {
 public:
  explicit PersistentValueMap(Isolate* isolate)
      : PersistentValueMapBase<K, V, Traits>(isolate) {}
  PersistentValueMap(Isolate* isolate, const char* label)
      : PersistentValueMapBase<K, V, Traits>(isolate, label) {}
 
  typedef
      typename PersistentValueMapBase<K, V, Traits>::PersistentValueReference
          PersistentValueReference;

  Global<V> Set(const K& key, Local<V> value) {
    Global<V> persistent(this->isolate(), value);
    return SetUnique(key, &persistent);
  }

  Global<V> Set(const K& key, Global<V> value) {
    return SetUnique(key, &value);
  }

  Global<V> SetUnique(const K& key, Global<V>* persistent) {
    if (Traits::kCallbackType == kNotWeak) {
      this->AnnotateStrongRetainer(persistent);
    } else {
      WeakCallbackType callback_type =
          Traits::kCallbackType == kWeakWithInternalFields
              ? WeakCallbackType::kInternalFields
              : WeakCallbackType::kParameter;
      auto value = Local<V>::New(this->isolate(), *persistent);
      persistent->template SetWeak<typename Traits::WeakCallbackDataType>(
          Traits::WeakCallbackParameter(this, key, value), WeakCallback,
          callback_type);
    }
    PersistentContainerValue old_value =
        Traits::Set(this->impl(), key, this->ClearAndLeak(persistent));
    return this->Release(old_value).Pass();
  }

  Global<V> Set(const K& key, Global<V> value,
                PersistentValueReference* reference) {
    *reference = this->Leak(&value);
    return SetUnique(key, &value);
  }
 
 private:
  static void WeakCallback(
      const WeakCallbackInfo<typename Traits::WeakCallbackDataType>& data) {
    if (Traits::kCallbackType != kNotWeak) {
      PersistentValueMap<K, V, Traits>* persistentValueMap =
          Traits::MapFromWeakCallbackInfo(data);
      K key = Traits::KeyFromWeakCallbackInfo(data);
      Traits::Dispose(data.GetIsolate(),
                      persistentValueMap->Remove(key).Pass(), key);
      Traits::DisposeCallbackData(data.GetParameter());
    }
  }
};
 
 
template <typename K, typename V, typename Traits>
class GlobalValueMap : public PersistentValueMapBase<K, V, Traits> {
 public:
  explicit GlobalValueMap(Isolate* isolate)
      : PersistentValueMapBase<K, V, Traits>(isolate) {}
  GlobalValueMap(Isolate* isolate, const char* label)
      : PersistentValueMapBase<K, V, Traits>(isolate, label) {}
 
  typedef
      typename PersistentValueMapBase<K, V, Traits>::PersistentValueReference
          PersistentValueReference;

  Global<V> Set(const K& key, Local<V> value) {
    Global<V> persistent(this->isolate(), value);
    return SetUnique(key, &persistent);
  }

  Global<V> Set(const K& key, Global<V> value) {
    return SetUnique(key, &value);
  }

  Global<V> SetUnique(const K& key, Global<V>* persistent) {
    if (Traits::kCallbackType == kNotWeak) {
      this->AnnotateStrongRetainer(persistent);
    } else {
      WeakCallbackType callback_type =
          Traits::kCallbackType == kWeakWithInternalFields
              ? WeakCallbackType::kInternalFields
              : WeakCallbackType::kParameter;
      auto value = Local<V>::New(this->isolate(), *persistent);
      persistent->template SetWeak<typename Traits::WeakCallbackDataType>(
          Traits::WeakCallbackParameter(this, key, value), OnWeakCallback,
          callback_type);
    }
    PersistentContainerValue old_value =
        Traits::Set(this->impl(), key, this->ClearAndLeak(persistent));
    return this->Release(old_value).Pass();
  }

  Global<V> Set(const K& key, Global<V> value,
                PersistentValueReference* reference) {
    *reference = this->Leak(&value);
    return SetUnique(key, &value);
  }
 
 private:
  static void OnWeakCallback(
      const WeakCallbackInfo<typename Traits::WeakCallbackDataType>& data) {
    if (Traits::kCallbackType != kNotWeak) {
      auto map = Traits::MapFromWeakCallbackInfo(data);
      K key = Traits::KeyFromWeakCallbackInfo(data);
      map->RemoveWeak(key);
      Traits::OnWeakCallback(data);
      data.SetSecondPassCallback(SecondWeakCallback);
    }
  }
 
  static void SecondWeakCallback(
      const WeakCallbackInfo<typename Traits::WeakCallbackDataType>& data) {
    Traits::DisposeWeak(data);
  }
};
 

template<typename K, typename V,
    typename Traits = DefaultPersistentValueMapTraits<K, V> >
class StdPersistentValueMap : public PersistentValueMap<K, V, Traits> {
 public:
  explicit StdPersistentValueMap(Isolate* isolate)
      : PersistentValueMap<K, V, Traits>(isolate) {}
};
 

template <typename K, typename V,
          typename Traits = DefaultGlobalMapTraits<K, V> >
class StdGlobalValueMap : public GlobalValueMap<K, V, Traits> {
 public:
  explicit StdGlobalValueMap(Isolate* isolate)
      : GlobalValueMap<K, V, Traits>(isolate) {}
};
 
}  // namespace v8
 
#endif  // V8_UTIL_H