ES6: Add support for Map.prototype.forEach and Set.prototype.forEach

src/objects.cc

 // Copyright 2013 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
@@ skipping 1674 matching lines @@
     case JS_GENERATOR_OBJECT_TYPE:
     case JS_MODULE_TYPE:
     case JS_VALUE_TYPE:
     case JS_DATE_TYPE:
     case JS_ARRAY_TYPE:
     case JS_ARRAY_BUFFER_TYPE:
     case JS_TYPED_ARRAY_TYPE:
     case JS_DATA_VIEW_TYPE:
     case JS_SET_TYPE:
     case JS_MAP_TYPE:
+    case JS_SET_ITERATOR_TYPE:
+    case JS_MAP_ITERATOR_TYPE:
     case JS_WEAK_MAP_TYPE:
     case JS_WEAK_SET_TYPE:
     case JS_REGEXP_TYPE:
     case JS_GLOBAL_PROXY_TYPE:
     case JS_GLOBAL_OBJECT_TYPE:
     case JS_BUILTINS_OBJECT_TYPE:
     case JS_MESSAGE_OBJECT_TYPE:
       JSObject::BodyDescriptor::IterateBody(this, object_size, v);
       break;
     case JS_FUNCTION_TYPE:
@@ skipping 14030 matching lines @@
 }
 
 
 void WeakHashTable::AddEntry(int entry, Object* key, Object* value) {
   set(EntryToIndex(entry), key);
   set(EntryToValueIndex(entry), value);
   ElementAdded();
 }
 
 
-template<class Derived, int entrysize>
-Handle<Derived> OrderedHashTable<Derived, entrysize>::Allocate(
+template<class Derived, class Iterator, int entrysize>
+Handle<Derived> OrderedHashTable<Derived, Iterator, entrysize>::Allocate(
     Isolate* isolate, int capacity, PretenureFlag pretenure) {
   // Capacity must be a power of two, since we depend on being able
   // to divide and multiple by 2 (kLoadFactor) to derive capacity
   // from number of buckets. If we decide to change kLoadFactor
   // to something other than 2, capacity should be stored as another
   // field of this object.
-  const int kMinCapacity = 4;
   capacity = RoundUpToPowerOf2(Max(kMinCapacity, capacity));
   if (capacity > kMaxCapacity) {
     v8::internal::Heap::FatalProcessOutOfMemory("invalid table size", true);
   }
   int num_buckets = capacity / kLoadFactor;
   Handle<FixedArray> backing_store = isolate->factory()->NewFixedArray(
       kHashTableStartIndex + num_buckets + (capacity * kEntrySize), pretenure);
   backing_store->set_map_no_write_barrier(
       isolate->heap()->ordered_hash_table_map());
   Handle<Derived> table = Handle<Derived>::cast(backing_store);
   for (int i = 0; i < num_buckets; ++i) {
     table->set(kHashTableStartIndex + i, Smi::FromInt(kNotFound));
   }
   table->SetNumberOfBuckets(num_buckets);
   table->SetNumberOfElements(0);
   table->SetNumberOfDeletedElements(0);
+  table->set_iterators(isolate->heap()->undefined_value());
   return table;
 }
 
 
-template<class Derived, int entrysize>
-Handle<Derived> OrderedHashTable<Derived, entrysize>::EnsureGrowable(
+template<class Derived, class Iterator, int entrysize>
+Handle<Derived> OrderedHashTable<Derived, Iterator, entrysize>::EnsureGrowable(
     Handle<Derived> table) {
   int nof = table->NumberOfElements();
   int nod = table->NumberOfDeletedElements();
   int capacity = table->Capacity();
   if ((nof + nod) < capacity) return table;
   // Don't need to grow if we can simply clear out deleted entries instead.
   // Note that we can't compact in place, though, so we always allocate
   // a new table.
   return Rehash(table, (nod < (capacity >> 1)) ? capacity << 1 : capacity);
 }
 
 
-template<class Derived, int entrysize>
-Handle<Derived> OrderedHashTable<Derived, entrysize>::Shrink(
+template<class Derived, class Iterator, int entrysize>
+Handle<Derived> OrderedHashTable<Derived, Iterator, entrysize>::Shrink(
     Handle<Derived> table) {
   int nof = table->NumberOfElements();
   int capacity = table->Capacity();
   if (nof > (capacity >> 2)) return table;
   return Rehash(table, capacity / 2);
 }
 
 
-template<class Derived, int entrysize>
-Handle<Derived> OrderedHashTable<Derived, entrysize>::Rehash(
+template<class Derived, class Iterator, int entrysize>
+Handle<Derived> OrderedHashTable<Derived, Iterator, entrysize>::Clear(
+    Handle<Derived> table) {
+  Handle<Derived> new_table =
+      Allocate(table->GetIsolate(),
+               kMinCapacity,
+               table->GetHeap()->InNewSpace(*table) ? NOT_TENURED : TENURED);
+
+  new_table->set_iterators(table->iterators());
+  table->set_iterators(table->GetHeap()->undefined_value());
+
+  DisallowHeapAllocation no_allocation;
+  for (Object* object = new_table->iterators();
+       !object->IsUndefined();
+       object = Iterator::cast(object)->next_iterator()) {
+    Iterator::cast(object)->TableCleared();
+    Iterator::cast(object)->set_table(*new_table);
+  }
+
+  return new_table;
+}
+
+
+template<class Derived, class Iterator, int entrysize>
+Handle<Derived> OrderedHashTable<Derived, Iterator, entrysize>::Rehash(
     Handle<Derived> table, int new_capacity) {
   Handle<Derived> new_table =
       Allocate(table->GetIsolate(),
                new_capacity,
                table->GetHeap()->InNewSpace(*table) ? NOT_TENURED : TENURED);
   int nof = table->NumberOfElements();
   int nod = table->NumberOfDeletedElements();
   int new_buckets = new_table->NumberOfBuckets();
   int new_entry = 0;
   for (int old_entry = 0; old_entry < (nof + nod); ++old_entry) {
     Object* key = table->KeyAt(old_entry);
     if (key->IsTheHole()) continue;
     Object* hash = key->GetHash();
     int bucket = Smi::cast(hash)->value() & (new_buckets - 1);
     Object* chain_entry = new_table->get(kHashTableStartIndex + bucket);
     new_table->set(kHashTableStartIndex + bucket, Smi::FromInt(new_entry));
     int new_index = new_table->EntryToIndex(new_entry);
     int old_index = table->EntryToIndex(old_entry);
     for (int i = 0; i < entrysize; ++i) {
       Object* value = table->get(old_index + i);
       new_table->set(new_index + i, value);
     }
     new_table->set(new_index + kChainOffset, chain_entry);
     ++new_entry;
   }
   new_table->SetNumberOfElements(nof);
+
+  new_table->set_iterators(table->iterators());
+  table->set_iterators(table->GetHeap()->undefined_value());
+
+  DisallowHeapAllocation no_allocation;
+  for (Object* object = new_table->iterators();
+       !object->IsUndefined();
+       object = Iterator::cast(object)->next_iterator()) {
+    Iterator::cast(object)->TableCompacted();
+    Iterator::cast(object)->set_table(*new_table);
+  }
+
   return new_table;
 }
 
 
-template<class Derived, int entrysize>
-int OrderedHashTable<Derived, entrysize>::FindEntry(Object* key) {
+template<class Derived, class Iterator, int entrysize>
+int OrderedHashTable<Derived, Iterator, entrysize>::FindEntry(Object* key) {
   ASSERT(!key->IsTheHole());
   Object* hash = key->GetHash();
   if (hash->IsUndefined()) return kNotFound;
   for (int entry = HashToEntry(Smi::cast(hash)->value());
        entry != kNotFound;
        entry = ChainAt(entry)) {
     Object* candidate = KeyAt(entry);
     if (candidate->SameValue(key))
       return entry;
   }
   return kNotFound;
 }
 
 
-template<class Derived, int entrysize>
-int OrderedHashTable<Derived, entrysize>::AddEntry(int hash) {
-  int entry = NumberOfElements() + NumberOfDeletedElements();
+template<class Derived, class Iterator, int entrysize>
+int OrderedHashTable<Derived, Iterator, entrysize>::AddEntry(int hash) {
+  int entry = UsedCapacity();
   int bucket = HashToBucket(hash);
   int index = EntryToIndex(entry);
   Object* chain_entry = get(kHashTableStartIndex + bucket);
   set(kHashTableStartIndex + bucket, Smi::FromInt(entry));
   set(index + kChainOffset, chain_entry);
   SetNumberOfElements(NumberOfElements() + 1);
   return index;
 }
 
 
-template<class Derived, int entrysize>
-void OrderedHashTable<Derived, entrysize>::RemoveEntry(int entry) {
+template<class Derived, class Iterator, int entrysize>
+void OrderedHashTable<Derived, Iterator, entrysize>::RemoveEntry(int entry) {
   int index = EntryToIndex(entry);
   for (int i = 0; i < entrysize; ++i) {
     set_the_hole(index + i);
   }
   SetNumberOfElements(NumberOfElements() - 1);
   SetNumberOfDeletedElements(NumberOfDeletedElements() + 1);
+
+  DisallowHeapAllocation no_allocation;
+  for (Object* object = iterators();
+       !object->IsUndefined();
+       object = Iterator::cast(object)->next_iterator()) {
+    Iterator::cast(object)->EntryRemoved(entry);
+  }
 }
 
 
-template class OrderedHashTable<OrderedHashSet, 1>;
-template class OrderedHashTable<OrderedHashMap, 2>;
+template<class Derived, class Iterator, int entrysize>
+Handle<Iterator> OrderedHashTable<Derived, Iterator, entrysize>::CreateIterator(
+    Handle<Derived> table,
+    int kind) {
+  Isolate* isolate = table->GetIsolate();
+  Handle<Object> undefined = isolate->factory()->undefined_value();
+  Handle<Iterator> new_iterator = Iterator::Create(isolate);
+  new_iterator->set_previous_iterator(*undefined);
+  new_iterator->set_table(*table);
+  new_iterator->set_index(Smi::FromInt(0));
+  new_iterator->set_count(Smi::FromInt(0));
+  new_iterator->set_kind(Smi::FromInt(kind));
+
+  Handle<Object> old_iterator(table->iterators(), isolate);
+  if (!old_iterator->IsUndefined()) {
+    Handle<Iterator>::cast(old_iterator)->set_previous_iterator(*new_iterator);
+    new_iterator->set_next_iterator(*old_iterator);
+  } else {
+    new_iterator->set_next_iterator(*undefined);
+  }
+
+  table->set_iterators(*new_iterator);
+
+  return new_iterator;
+}
+
+
+template class OrderedHashTable<OrderedHashSet, JSSetIterator, 1>;
+template class OrderedHashTable<OrderedHashMap, JSMapIterator, 2>;
 
 
 bool OrderedHashSet::Contains(Object* key) {
   return FindEntry(key) != kNotFound;
 }
 
 
 Handle<OrderedHashSet> OrderedHashSet::Add(Handle<OrderedHashSet> table,
                                            Handle<Object> key) {
   if (table->FindEntry(*key) != kNotFound) return table;
 
   table = EnsureGrowable(table);
 
   Handle<Object> hash = GetOrCreateHash(key, table->GetIsolate());
   int index = table->AddEntry(Smi::cast(*hash)->value());
   table->set(index, *key);
   return table;
 }
 
 
 Handle<OrderedHashSet> OrderedHashSet::Remove(Handle<OrderedHashSet> table,
                                               Handle<Object> key) {
   int entry = table->FindEntry(*key);
   if (entry == kNotFound) return table;
   table->RemoveEntry(entry);
-  // TODO(adamk): Don't shrink if we're being iterated over
   return Shrink(table);
 }
 
 
 Object* OrderedHashMap::Lookup(Object* key) {
   int entry = FindEntry(key);
   if (entry == kNotFound) return GetHeap()->the_hole_value();
   return ValueAt(entry);
 }
 
 
 Handle<OrderedHashMap> OrderedHashMap::Put(Handle<OrderedHashMap> table,
                                            Handle<Object> key,
                                            Handle<Object> value) {
   int entry = table->FindEntry(*key);
 
   if (value->IsTheHole()) {
     if (entry == kNotFound) return table;
     table->RemoveEntry(entry);
-    // TODO(adamk): Only shrink if not iterating
     return Shrink(table);
   }
 
   if (entry != kNotFound) {
     table->set(table->EntryToIndex(entry) + kValueOffset, *value);
     return table;
   }
 
   table = EnsureGrowable(table);
 
   Handle<Object> hash = GetOrCreateHash(key, table->GetIsolate());
   int index = table->AddEntry(Smi::cast(*hash)->value());
   table->set(index, *key);
   table->set(index + kValueOffset, *value);
   return table;
 }
 
 
+template<class Derived, class TableType>
+void OrderedHashTableIterator<Derived, TableType>::EntryRemoved(int index) {
+  int i = this->index()->value();
+  if (index < i) {
+    set_count(Smi::FromInt(count()->value() - 1));
+  }
+  if (index == i) {
+    Seek();
+  }
+}
+
+
+template<class Derived, class TableType>
+void OrderedHashTableIterator<Derived, TableType>::Close() {
+  if (Closed()) return;
+
+  Isolate* isolate = GetIsolate();
+
+  Handle<Object> undefined = isolate->factory()->undefined_value();

[adamk, 2014/04/14 22:46:38]

Why did these get handlified? I don't see any allocation. Can this function just
get a DisallowHeapAllocation at the top?

[arv (Not doing code reviews), 2014/04/15 00:29:17]

Done.

+  Handle<Object> object(this->table(), isolate);
+  Handle<TableType> table = Handle<TableType>::cast(object);
+  Handle<Object> previous(previous_iterator(), isolate);
+  Handle<Object> next(next_iterator(), isolate);
+
+  if (previous->IsUndefined()) {
+    ASSERT_EQ(table->iterators(), this);
+    table->set_iterators(*next);
+  } else {
+    ASSERT_EQ(Handle<Derived>::cast(previous)->next_iterator(), this);
+    Handle<Derived>::cast(previous)->set_next_iterator(*next);
+  }
+
+  if (!next->IsUndefined()) {
+    ASSERT_EQ(Handle<Derived>::cast(next)->previous_iterator(), this);
+    Handle<Derived>::cast(next)->set_previous_iterator(*previous);
+  }
+
+  set_previous_iterator(*undefined);
+  set_next_iterator(*undefined);
+  set_table(*undefined);
+}
+
+
+template<class Derived, class TableType>
+void OrderedHashTableIterator<Derived, TableType>::Seek() {
+  ASSERT(!Closed());
+
+  Isolate* isolate = GetIsolate();
+
+  int index = this->index()->value();
+
+  Handle<Object> object(this->table(), isolate);

[adamk, 2014/04/14 22:46:38]

Ditto down here, why all the handles?

[arv (Not doing code reviews), 2014/04/15 00:29:17]

Done.

+  Handle<TableType> table = Handle<TableType>::cast(object);
+  int used_capacity = table->UsedCapacity();
+
+  while (index < used_capacity && table->KeyAt(index)->IsTheHole()) {
+    index++;
+  }
+  set_index(Smi::FromInt(index));
+}
+
+
+template<class Derived, class TableType>
+void OrderedHashTableIterator<Derived, TableType>::MoveNext() {
+  ASSERT(!Closed());
+
+  set_index(Smi::FromInt(index()->value() + 1));
+  set_count(Smi::FromInt(count()->value() + 1));
+  Seek();
+}
+
+
+template<class Derived, class TableType>
+Handle<JSObject> OrderedHashTableIterator<Derived, TableType>::Next(
+    Handle<Derived> iterator) {
+  Isolate* isolate = iterator->GetIsolate();
+  Factory* factory = isolate->factory();
+
+  Handle<Object> object(iterator->table(), isolate);
+
+  if (!object->IsUndefined()) {
+    Handle<TableType> table = Handle<TableType>::cast(object);
+    int index = iterator->index()->value();
+    if (index < table->UsedCapacity()) {
+      int entry_index = table->EntryToIndex(index);
+      iterator->MoveNext();
+      Handle<Object> value = Derived::ValueForKind(iterator, entry_index);
+      return factory->CreateIteratorResultObject(value, false);
+    } else {
+      iterator->Close();
+    }
+  }
+
+  return factory->CreateIteratorResultObject(factory->undefined_value(), true);
+}
+
+
+template class OrderedHashTableIterator<JSSetIterator, OrderedHashSet>;
+template class OrderedHashTableIterator<JSMapIterator, OrderedHashMap>;
+
+
+Handle<JSSetIterator> JSSetIterator::Create(Isolate* isolate) {
+  Handle<Map> map(isolate->context()->native_context()->set_iterator_map());

[adamk, 2014/04/14 22:46:38]

You should be able to just say

isolate->set_iterator_map()

[arv (Not doing code reviews), 2014/04/15 00:29:17]

Done.

+  return
+      Handle<JSSetIterator>::cast(isolate->factory()->NewJSObjectFromMap(map));
+}
+
+
+Handle<Object> JSSetIterator::ValueForKind(
+    Handle<JSSetIterator> iterator, int entry_index) {
+  int kind = iterator->kind()->value();
+  // Set.prototype only has values and entries.
+  ASSERT(kind == kKindValues || kind == kKindEntries);
+
+  Isolate* isolate = iterator->GetIsolate();
+  Factory* factory = isolate->factory();
+
+  Handle<Object> object(iterator->table(), isolate);

[adamk, 2014/04/14 22:46:38]

I don't see this used anywhere, you should be able to collapse it into the line
below.

[arv (Not doing code reviews), 2014/04/15 00:29:17]

It is used on the next line.

[adamk, 2014/04/15 01:12:42]

Sorry, I mis-spoke, I meant to say the next line could instead read:

Handle<OrderedHashSet> table(OrderedHashSet::cast(iterator->table()), isolate);

+  Handle<OrderedHashSet> table = Handle<OrderedHashSet>::cast(object);
+
+  Handle<Object> value = Handle<Object>(table->get(entry_index), isolate);
+
+  if (kind == kKindEntries) {
+    Handle<FixedArray> array = factory->NewFixedArray(2);
+    array->set(0, *value);
+    array->set(1, *value);
+    return factory->NewJSArrayWithElements(array);
+  }
+
+  return value;
+}
+
+
+Handle<JSMapIterator> JSMapIterator::Create(Isolate* isolate) {
+  Handle<Map> map(isolate->context()->native_context()->map_iterator_map());

[adamk, 2014/04/14 22:46:38]

isolate->map_iterator_map()

[arv (Not doing code reviews), 2014/04/15 00:29:17]

Done.

+  return Handle<JSMapIterator>::cast(
+      isolate->factory()->NewJSObjectFromMap(map));
+}
+
+
+Handle<Object> JSMapIterator::ValueForKind(
+    Handle<JSMapIterator> iterator, int entry_index) {
+  int kind = iterator->kind()->value();
+  ASSERT(kind == kKindKeys || kind == kKindValues || kind == kKindEntries);
+
+  Isolate* isolate = iterator->GetIsolate();
+  Factory* factory = isolate->factory();
+
+  Handle<Object> object(iterator->table(), isolate);
+  Handle<OrderedHashMap> table = Handle<OrderedHashMap>::cast(object);
+
+  switch (kind) {
+    case kKindKeys:
+      return Handle<Object>(table->get(entry_index), isolate);
+
+    case kKindValues:
+      return Handle<Object>(table->get(entry_index + 1), isolate);
+
+    case kKindEntries: {
+      Handle<Object> key(table->get(entry_index), isolate);
+      Handle<Object> value(table->get(entry_index + 1), isolate);
+      Handle<FixedArray> array = factory->NewFixedArray(2);
+      array->set(0, *key);
+      array->set(1, *value);
+      return factory->NewJSArrayWithElements(array);
+    }
+  }
+
+  UNREACHABLE();
+  return factory->undefined_value();
+}
+
+
 DeclaredAccessorDescriptorIterator::DeclaredAccessorDescriptorIterator(
     DeclaredAccessorDescriptor* descriptor)
     : array_(descriptor->serialized_data()->GetDataStartAddress()),
       length_(descriptor->serialized_data()->length()),
       offset_(0) {
 }
 
 
 const DeclaredAccessorDescriptorData*
   DeclaredAccessorDescriptorIterator::Next() {
@@ skipping 571 matching lines @@
 #define ERROR_MESSAGES_TEXTS(C, T) T,
   static const char* error_messages_[] = {
       ERROR_MESSAGES_LIST(ERROR_MESSAGES_TEXTS)
   };
 #undef ERROR_MESSAGES_TEXTS
   return error_messages_[reason];
 }
 
 
 } }  // namespace v8::internal