text: /*
   * Copyright (C) 2013, 2016 Apple, Inc. All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. 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.
   *
   * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``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 APPLE INC. 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. 
   */
  
  #pragma once
  
  #include "IterationKind.h"
  #include "JSMap.h"
  #include "JSObject.h"
  
  namespace JSC {
  
  // Now, it is only used for serialization.
  class JSMapIterator : public JSCell {
      typedef HashMapBucket<HashMapBucketDataKeyValue> HashMapBucketType;
  public:
      using Base = JSCell;
  
      DECLARE_EXPORT_INFO;
  
      static Structure* createStructure(VM& vm, JSGlobalObject* globalObject, JSValue prototype)
      {
          return Structure::create(vm, globalObject, prototype, TypeInfo(ObjectType, StructureFlags), info());
      }
  
      static JSMapIterator* create(VM& vm, Structure* structure, JSMap* iteratedObject, IterationKind kind)
      {
          JSMapIterator* instance = new (NotNull, allocateCell<JSMapIterator>(vm.heap)) JSMapIterator(vm, structure, iteratedObject, kind);
          instance->finishCreation(vm, iteratedObject);
          return instance;
      }
  
      ALWAYS_INLINE HashMapBucketType* advanceIter(ExecState* exec)
      {
          HashMapBucketType* prev = m_iter.get();
          if (!prev)
              return nullptr;
          VM& vm = exec->vm();
          HashMapBucketType* bucket = m_iter->next();
          while (bucket && bucket->deleted())
              bucket = bucket->next();
          if (!bucket) {
              setIterator(vm, nullptr);
              return nullptr;
          }
          setIterator(vm, bucket); // We keep m_iter on the last value since the first thing we do in this function is call next().
          return bucket;
      }
      bool next(ExecState* exec, JSValue& value)
      {
          HashMapBucketType* bucket = advanceIter(exec);
          if (!bucket)
              return false;
  
          if (m_kind == IterateValue)
              value = bucket->value();
          else if (m_kind == IterateKey)
              value = bucket->key();
          else
              value = createPair(exec, bucket->key(), bucket->value());
          return true;
      }
  
      bool nextKeyValue(ExecState* exec, JSValue& key, JSValue& value)
      {
          HashMapBucketType* bucket = advanceIter(exec);
          if (!bucket)
              return false;
  
          key = bucket->key();
          value = bucket->value();
          return true;
      }
  
      IterationKind kind() const { return m_kind; }
      JSValue iteratedValue() const { return m_map.get(); }
  
  private:
      JSMapIterator(VM& vm, Structure* structure, JSMap*, IterationKind kind)
          : Base(vm, structure)
          , m_kind(kind)
      { }
  
      void setIterator(VM& vm, HashMapBucketType* bucket)
      {
          m_iter.setMayBeNull(vm, this, bucket);
      }
  
      JS_EXPORT_PRIVATE void finishCreation(VM&, JSMap*);
      JSValue createPair(CallFrame*, JSValue, JSValue);
      static void visitChildren(JSCell*, SlotVisitor&);
  
      WriteBarrier<JSMap> m_map;
      WriteBarrier<HashMapBucketType> m_iter;
      IterationKind m_kind;
  };
  STATIC_ASSERT_IS_TRIVIALLY_DESTRUCTIBLE(JSMapIterator);
  
  } // namespace JSC
  