Blink-compatible serialization of dictionary-like objects.

src/value-serializer.h

 // Copyright 2016 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_VALUE_SERIALIZER_H_
 #define V8_VALUE_SERIALIZER_H_
 
 #include <cstdint>
 #include <vector>
 
 #include "include/v8.h"
 #include "src/base/compiler-specific.h"
 #include "src/base/macros.h"
+#include "src/identity-map.h"
 #include "src/vector.h"
+#include "src/zone.h"
 
 namespace v8 {
 namespace internal {
 
 class HeapNumber;
 class Isolate;
 class Object;
 class Oddball;
 class Smi;
 
 enum class SerializationTag : uint8_t;
 
 /**
  * Writes V8 objects in a binary format that allows the objects to be cloned
  * according to the HTML structured clone algorithm.
  *
  * Format is based on Blink's previous serialization logic.
  */
 class ValueSerializer {
  public:
-  ValueSerializer();
+  explicit ValueSerializer(Isolate* isolate);
   ~ValueSerializer();
 
   /*
    * Writes out a header, which includes the format version.
    */
   void WriteHeader();
 
   /*
    * Serializes a V8 object into the buffer.
    */
@@ skipping 15 matching lines @@
   void WriteDouble(double value);
   void WriteOneByteString(Vector<const uint8_t> chars);
   void WriteTwoByteString(Vector<const uc16> chars);
   uint8_t* ReserveRawBytes(size_t bytes);
 
   // Writing V8 objects of various kinds.
   void WriteOddball(Oddball* oddball);
   void WriteSmi(Smi* smi);
   void WriteHeapNumber(HeapNumber* number);
   void WriteString(Handle<String> string);
+  Maybe<bool> WriteJSReceiver(Handle<JSReceiver> receiver) WARN_UNUSED_RESULT;
+  Maybe<bool> WriteJSObject(Handle<JSObject> object) WARN_UNUSED_RESULT;
 
+  /*
+   * Reads the specified keys from the object and writes key-value pairs to the
+   * buffer.
+   */
+  Maybe<bool> WriteJSObjectProperties(
+      Handle<JSObject> object, Handle<FixedArray> keys) WARN_UNUSED_RESULT;
+
+  Isolate* const isolate_;
   std::vector<uint8_t> buffer_;
+  Zone zone_;
+
+  // To avoid extra lookups in the identity map, ID+1 is actually stored in the
+  // map (checking if the used identity is zero is the fast way of checking if
+  // the entry is new).
+  IdentityMap<uint32_t> id_map_;
+  uint32_t next_id_ = 0;
 
   DISALLOW_COPY_AND_ASSIGN(ValueSerializer);
 };
 
 /*
  * Deserializes values from data written with ValueSerializer, or a compatible
  * implementation.
  */
 class ValueDeserializer {
  public:
   ValueDeserializer(Isolate* isolate, Vector<const uint8_t> data);
   ~ValueDeserializer();
 
   /*
    * Runs version detection logic, which may fail if the format is invalid.
    */
   Maybe<bool> ReadHeader() WARN_UNUSED_RESULT;
 
   /*
    * Deserializes a V8 object from the buffer.
    */
   MaybeHandle<Object> ReadObject() WARN_UNUSED_RESULT;
 
  private:
   // Reading the wire format.
+  Maybe<SerializationTag> PeekTag() const WARN_UNUSED_RESULT;
   Maybe<SerializationTag> ReadTag() WARN_UNUSED_RESULT;
   template <typename T>
   Maybe<T> ReadVarint() WARN_UNUSED_RESULT;
   template <typename T>
   Maybe<T> ReadZigZag() WARN_UNUSED_RESULT;
   Maybe<double> ReadDouble() WARN_UNUSED_RESULT;
   Maybe<Vector<const uint8_t>> ReadRawBytes(int size) WARN_UNUSED_RESULT;
 
   // Reading V8 objects of specific kinds.
   // The tag is assumed to have already been read.
   MaybeHandle<String> ReadUtf8String() WARN_UNUSED_RESULT;
   MaybeHandle<String> ReadTwoByteString() WARN_UNUSED_RESULT;
+  MaybeHandle<JSObject> ReadJSObject() WARN_UNUSED_RESULT;
+
+  /*
+   * Includes common logic for reading a receiver, which may be complex and may
+   * recurse. Accepts a functor which does object-specific decoding given the ID
+   * that the object should be stored with. The functor must store the object
+   * before any additional references to it could be encountered.
+   */
+  template <typename T, typename Functor>
+  MaybeHandle<T> ReadJSReceiver(const Functor& functor) WARN_UNUSED_RESULT;
+
+  /*
+   * Reads key-value pairs into the object until the specified end tag is
+   * encountered. If successful, returns the number of properties read.
+   */
+  Maybe<uint32_t> ReadJSObjectProperties(Handle<JSObject> object,
+                                         SerializationTag end_tag);
+
+  // Manipulating the map from IDs to reified objects.
+  bool HasObjectWithID(uint32_t id);
+  MaybeHandle<JSReceiver> GetObjectWithID(uint32_t id);
+  void AddObjectWithID(uint32_t id, Handle<JSReceiver> object);
 
   Isolate* const isolate_;
   const uint8_t* position_;
   const uint8_t* const end_;
   uint32_t version_ = 0;
+  Handle<SeededNumberDictionary> id_map_;  // always a global handle
+  uint32_t next_id_ = 0;
 
   DISALLOW_COPY_AND_ASSIGN(ValueDeserializer);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_VALUE_SERIALIZER_H_