src/v8/src/objects/js-collection-iterator.h

// Copyright 2019 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_OBJECTS_JS_COLLECTION_ITERATOR_H_
#define V8_OBJECTS_JS_COLLECTION_ITERATOR_H_

#include "src/common/globals.h"
#include "src/objects/js-objects.h"
#include "src/objects/objects.h"
#include "src/objects/smi.h"

// Has to be the last include (doesn't have include guards):
#include "src/objects/object-macros.h"

namespace v8 {
namespace internal {

class JSCollectionIterator : public JSObject {
 public:
  // [table]: the backing hash table mapping keys to values.
  DECL_ACCESSORS(table, Object)

  // [index]: The index into the data table.
  DECL_ACCESSORS(index, Object)

  void JSCollectionIteratorPrint(std::ostream& os, const char* name);
  DECL_VERIFIER(JSCollectionIterator)

  DEFINE_FIELD_OFFSET_CONSTANTS(JSObject::kHeaderSize,
                                TORQUE_GENERATED_JSCOLLECTION_ITERATOR_FIELDS)

  OBJECT_CONSTRUCTORS(JSCollectionIterator, JSObject);
};

// OrderedHashTableIterator is an iterator that iterates over the keys and
// values of an OrderedHashTable.
//
// The iterator has a reference to the underlying OrderedHashTable data,
// [table], as well as the current [index] the iterator is at.
//
// When the OrderedHashTable is rehashed it adds a reference from the old table
// to the new table as well as storing enough data about the changes so that the
// iterator [index] can be adjusted accordingly.
//
// When the [Next] result from the iterator is requested, the iterator checks if
// there is a newer table that it needs to transition to.
template <class Derived, class TableType>
class OrderedHashTableIterator : public JSCollectionIterator {
 public:
  // Whether the iterator has more elements. This needs to be called before
  // calling |CurrentKey| and/or |CurrentValue|.
  bool HasMore();

  // Move the index forward one.
  void MoveNext() { set_index(Smi::FromInt(Smi::ToInt(index()) + 1)); }

  // Returns the current key of the iterator. This should only be called when
  // |HasMore| returns true.
  inline Object CurrentKey();

 private:
  // Transitions the iterator to the non obsolete backing store. This is a NOP
  // if the [table] is not obsolete.
  void Transition();

  OBJECT_CONSTRUCTORS(OrderedHashTableIterator, JSCollectionIterator);
};

}  // namespace internal
}  // namespace v8

#include "src/objects/object-macros-undef.h"

#endif  // V8_OBJECTS_JS_COLLECTION_ITERATOR_H_