Move PersitentValueMap into seperate header, to avoid excessive polution

include/v8-util.h

Index: include/v8-util.h
diff --git a/include/v8-util.h b/include/v8-util.h
new file mode 100644
index 0000000000000000000000000000000000000000..71851cb81f356f4135eeeffdcf7a699d097608fd
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+++ b/include/v8-util.h
@@ -0,0 +1,296 @@
+// Copyright 2014 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
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef V8_UTIL_H_
+#define V8_UTIL_H_
+
+#include "v8.h"
+
+/**
+ * Support for Persistent containers.
+ *
+ * C++11 embedders can use STL containers with UniquePersistent values,
+ * but pre-C++11 does not support the required move semantic and hence
+ * may want these container classes.
+ */
+namespace v8 {
+
+typedef uintptr_t PersistentContainerValue;
+static const uintptr_t kPersistentContainerNotFound = 0;
+
+
+namespace util {
+
+
+/**
+ * A map traits class suitable for PersistentValueMap based on an STL-compliant
+ * container.
+ */
+template<typename K, typename V,
+         typename Map = std::map<K, PersistentContainerValue> >
+class StdMapTraits {
+ public:
+  typedef Map 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); }  // NOLINT
+  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 v8::PersistentContainerValue Value(Iterator it) { return it->second; }
+  static v8::PersistentContainerValue Set(Impl* impl, K key,
+      v8::PersistentContainerValue value) {
+    std::pair<Iterator, bool> res = impl->insert(std::make_pair(key, value));
+    v8::PersistentContainerValue old_value = v8::kPersistentContainerNotFound;
+    if (!res.second) {
+      old_value = res.first->second;
+      res.first->second = value;
+    }
+    return old_value;
+  }
+  static v8::PersistentContainerValue Get(Impl* impl, K key) {
+    Iterator it = impl->find(key);
+    if (it == impl->end()) return v8::kPersistentContainerNotFound;
+    return it->second;
+  }
+  static v8::PersistentContainerValue Remove(Impl* impl, K key) {
+    Iterator it = impl->find(key);
+    if (it == impl->end()) return v8::kPersistentContainerNotFound;
+    v8::PersistentContainerValue value = it->second;
+    impl->erase(it);
+    return value;
+  }
+};
+
+/**
+ * A dispose traits class suitable for PersistentValueMap that does not use
+ * weak callbacks and requires no special dispose handling.
+ * Can be used as is, or as a base class for more specialized implementations.
+ */
+template<typename K, typename V, typename Impl>
+class DefaultDisposeTraits {
+ public:
+  static const bool kIsWeak = false;
+  typedef void WeakCallbackDataType;
+  static void Dispose(v8::Isolate* isolate, v8::UniquePersistent<V> value,
+      Impl* impl, K key) {}
+  static WeakCallbackDataType* WeakCallbackParameter(Impl* impl, const K& key,
+      Local<V> value) {
+    return NULL;
+  }
+  static Impl* ImplFromWeakCallbackData(
+      const v8::WeakCallbackData<V, WeakCallbackDataType>& data) {
+    return NULL;
+  }
+  static K KeyFromWeakCallbackData(
+      const v8::WeakCallbackData<V, WeakCallbackDataType>& data) {
+    return K();
+  }
+  static void DisposeCallbackData(WeakCallbackDataType* data) {
+  }
+};
+
+}  // namespace util
+
+/**
+ * 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 MapTraits = util::StdMapTraits<K, V>,
+         class DisposeTraits =
+             util::DefaultDisposeTraits<K, V, typename MapTraits::Impl> >
+class PersistentValueMap {
+ public:
+  V8_INLINE explicit PersistentValueMap(Isolate* isolate) : isolate_(isolate) {}
+
+  V8_INLINE ~PersistentValueMap() { Clear(); }
+
+  V8_INLINE Isolate* GetIsolate() { return isolate_; }
+
+  static const bool kIsWeak = DisposeTraits::kIsWeak;
+
+  /**
+   * Return size of the map.
+   */
+  V8_INLINE size_t Size() { return MapTraits::Size(&impl_); }
+
+  /**
+   * Get value stored in map.
+   */
+  V8_INLINE Local<V> Get(const K& key) {
+    return Local<V>::New(isolate_, FromVal(MapTraits::Get(&impl_, key)));
+  }
+
+  /**
+   * Check whether a value is contained in the map.
+   */
+  V8_INLINE bool Contains(const K& key) {
+    return MapTraits::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) {
+    PersistentContainerValue value = MapTraits::Get(&impl_, key);
+    bool hasValue = value != 0;
+    if (hasValue) {
+      returnValue.SetInternal(
+          *reinterpret_cast<internal::Object**>(FromVal(value)));
+    }
+    return hasValue;
+  }
+
+  /**
+   * 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(MapTraits::Get(&impl_, key))));
+  }
+
+  /**
+   * Put value into map. Depending on DisposeTraits::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(MapTraits::Remove(&impl_, key)).Pass();
+  }
+
+  /**
+  * Traverses the map repeatedly,
+  * in case side effects of disposal cause insertions.
+  **/
+  void Clear() {
+    typedef typename MapTraits::Iterator It;
+    HandleScope handle_scope(isolate_);
+    // TODO(dcarney): figure out if this swap and loop is necessary.
+    while (!MapTraits::Empty(&impl_)) {
+      typename MapTraits::Impl impl;
+      MapTraits::Swap(impl_, impl);
+      for (It i = MapTraits::Begin(&impl); i != MapTraits::End(&impl); ++i) {
+        DisposeTraits::Dispose(isolate_, Release(MapTraits::Value(i)).Pass(),
+                               &impl, MapTraits::Key(i));
+      }
+    }
+  }
+
+ private:
+  PersistentValueMap(PersistentValueMap&);
+  void operator=(PersistentValueMap&);
+
+  /**
+   * Put the value into the map, and set the 'weak' callback when demanded
+   * by the DisposeTraits class.
+   */
+  UniquePersistent<V> SetUnique(const K& key, UniquePersistent<V>* persistent) {
+    if (DisposeTraits::kIsWeak) {
+      Local<V> value(Local<V>::New(isolate_, *persistent));
+      persistent->
+          template SetWeak<typename DisposeTraits::WeakCallbackDataType>(
+              DisposeTraits::WeakCallbackParameter(&impl_, key, value),
+              &WeakCallback);
+    }
+    PersistentContainerValue old_value =
+        MapTraits::Set(&impl_, key, ClearAndLeak(persistent));
+    return Release(old_value).Pass();
+  }
+
+  V8_INLINE static void WeakCallback(
+      const WeakCallbackData<V,
+          typename DisposeTraits::WeakCallbackDataType>& data) {
+    typename MapTraits::Impl* impl =
+        DisposeTraits::ImplFromWeakCallbackData(data);
+    K key = DisposeTraits::KeyFromWeakCallbackData(data);
+    PersistentContainerValue value = MapTraits::Remove(impl, key);
+    DisposeTraits::Dispose(data.GetIsolate(), Release(value).Pass(), impl, key);
+  }
+
+  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 (DisposeTraits::kIsWeak && !p.IsEmpty()) {
+      DisposeTraits::DisposeCallbackData(
+          p.template ClearWeak<typename DisposeTraits::WeakCallbackDataType>());
+    }
+    return p.Pass();
+  }
+
+  Isolate* isolate_;
+  typename MapTraits::Impl impl_;
+};
+
+}  // namespace v8
+
+#endif  // V8_UTIL_H_