text: // Copyright 2012 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_TRANSITIONS_INL_H_
  #define V8_TRANSITIONS_INL_H_
  
  #include "src/transitions.h"
  
  #include "src/ic/handler-configuration-inl.h"
  
  namespace v8 {
  namespace internal {
  
  template <TransitionsAccessor::Encoding enc>
  WeakCell* TransitionsAccessor::GetTargetCell() {
    DCHECK(!needs_reload_);
    if (target_cell_ != nullptr) return target_cell_;
    if (enc == kWeakCell) {
      target_cell_ = WeakCell::cast(raw_transitions_);
    } else if (enc == kTuple3Handler) {
      target_cell_ = StoreHandler::GetTuple3TransitionCell(raw_transitions_);
    } else if (enc == kFixedArrayHandler) {
      target_cell_ = StoreHandler::GetArrayTransitionCell(raw_transitions_);
    } else {
      UNREACHABLE();
    }
    return target_cell_;
  }
  
  TransitionArray* TransitionsAccessor::transitions() {
    DCHECK_EQ(kFullTransitionArray, encoding());
    return TransitionArray::cast(raw_transitions_);
  }
  
  // static
  TransitionArray* TransitionArray::cast(Object* object) {
    DCHECK(object->IsTransitionArray());
    return reinterpret_cast<TransitionArray*>(object);
  }
  
  
  bool TransitionArray::HasPrototypeTransitions() {
    return get(kPrototypeTransitionsIndex) != Smi::kZero;
  }
  
  
  FixedArray* TransitionArray::GetPrototypeTransitions() {
    DCHECK(HasPrototypeTransitions());  // Callers must check first.
    Object* prototype_transitions = get(kPrototypeTransitionsIndex);
    return FixedArray::cast(prototype_transitions);
  }
  
  
  void TransitionArray::SetPrototypeTransitions(FixedArray* transitions) {
    DCHECK(transitions->IsFixedArray());
    set(kPrototypeTransitionsIndex, transitions);
  }
  
  
  Object** TransitionArray::GetPrototypeTransitionsSlot() {
    return RawFieldOfElementAt(kPrototypeTransitionsIndex);
  }
  
  
  Object** TransitionArray::GetKeySlot(int transition_number) {
    DCHECK(transition_number < number_of_transitions());
    return RawFieldOfElementAt(ToKeyIndex(transition_number));
  }
  
  
  Name* TransitionArray::GetKey(int transition_number) {
    DCHECK(transition_number < number_of_transitions());
    return Name::cast(get(ToKeyIndex(transition_number)));
  }
  
  Name* TransitionsAccessor::GetKey(int transition_number) {
    WeakCell* cell = nullptr;
    switch (encoding()) {
      case kPrototypeInfo:
      case kUninitialized:
        UNREACHABLE();
        return nullptr;
      case kWeakCell:
        cell = GetTargetCell<kWeakCell>();
        break;
      case kTuple3Handler:
        cell = GetTargetCell<kTuple3Handler>();
        break;
      case kFixedArrayHandler:
        cell = GetTargetCell<kFixedArrayHandler>();
        break;
      case kFullTransitionArray:
        return transitions()->GetKey(transition_number);
    }
    DCHECK(!cell->cleared());
    return GetSimpleTransitionKey(Map::cast(cell->value()));
  }
  
  void TransitionArray::SetKey(int transition_number, Name* key) {
    DCHECK(transition_number < number_of_transitions());
    set(ToKeyIndex(transition_number), key);
  }
  
  Object** TransitionArray::GetTargetSlot(int transition_number) {
    DCHECK(transition_number < number_of_transitions());
    return RawFieldOfElementAt(ToTargetIndex(transition_number));
  }
  
  // static
  PropertyDetails TransitionsAccessor::GetTargetDetails(Name* name, Map* target) {
    DCHECK(!IsSpecialTransition(name));
    int descriptor = target->LastAdded();
    DescriptorArray* descriptors = target->instance_descriptors();
    // Transitions are allowed only for the last added property.
    DCHECK(descriptors->GetKey(descriptor)->Equals(name));
    return descriptors->GetDetails(descriptor);
  }
  
  // static
  Map* TransitionsAccessor::GetTargetFromRaw(Object* raw) {
    if (raw->IsWeakCell()) {
      return Map::cast(WeakCell::cast(raw)->value());
    } else if (raw->IsTuple3()) {
      return Map::cast(StoreHandler::GetTuple3TransitionCell(raw)->value());
    } else {
      DCHECK(raw->IsFixedArray());
      return Map::cast(StoreHandler::GetArrayTransitionCell(raw)->value());
    }
  }
  
  Object* TransitionArray::GetRawTarget(int transition_number) {
    DCHECK(transition_number < number_of_transitions());
    return get(ToTargetIndex(transition_number));
  }
  
  Map* TransitionArray::GetTarget(int transition_number) {
    Object* raw = GetRawTarget(transition_number);
    return TransitionsAccessor::GetTargetFromRaw(raw);
  }
  
  Map* TransitionsAccessor::GetTarget(int transition_number) {
    WeakCell* cell = nullptr;
    switch (encoding()) {
      case kPrototypeInfo:
      case kUninitialized:
        UNREACHABLE();
        return nullptr;
      case kWeakCell:
        cell = GetTargetCell<kWeakCell>();
        break;
      case kTuple3Handler:
        cell = GetTargetCell<kTuple3Handler>();
        break;
      case kFixedArrayHandler:
        cell = GetTargetCell<kFixedArrayHandler>();
        break;
      case kFullTransitionArray:
        return transitions()->GetTarget(transition_number);
    }
    DCHECK(!cell->cleared());
    return Map::cast(cell->value());
  }
  
  void TransitionArray::SetTarget(int transition_number, Object* value) {
    DCHECK(!value->IsMap());
    DCHECK(transition_number < number_of_transitions());
    set(ToTargetIndex(transition_number), value);
  }
  
  
  int TransitionArray::SearchName(Name* name, int* out_insertion_index) {
    DCHECK(name->IsUniqueName());
    return internal::Search<ALL_ENTRIES>(this, name, number_of_entries(),
                                         out_insertion_index);
  }
  
  int TransitionArray::CompareKeys(Name* key1, uint32_t hash1, PropertyKind kind1,
                                   PropertyAttributes attributes1, Name* key2,
                                   uint32_t hash2, PropertyKind kind2,
                                   PropertyAttributes attributes2) {
    int cmp = CompareNames(key1, hash1, key2, hash2);
    if (cmp != 0) return cmp;
  
    return CompareDetails(kind1, attributes1, kind2, attributes2);
  }
  
  int TransitionArray::CompareNames(Name* key1, uint32_t hash1, Name* key2,
                                    uint32_t hash2) {
    if (key1 != key2) {
      // In case of hash collisions key1 is always "less" than key2.
      return hash1 <= hash2 ? -1 : 1;
    }
  
    return 0;
  }
  
  int TransitionArray::CompareDetails(PropertyKind kind1,
                                      PropertyAttributes attributes1,
                                      PropertyKind kind2,
                                      PropertyAttributes attributes2) {
    if (kind1 != kind2) {
      return static_cast<int>(kind1) < static_cast<int>(kind2) ? -1 : 1;
    }
  
    if (attributes1 != attributes2) {
      return static_cast<int>(attributes1) < static_cast<int>(attributes2) ? -1
                                                                           : 1;
    }
  
    return 0;
  }
  
  void TransitionArray::Set(int transition_number, Name* key, Object* target) {
    set(ToKeyIndex(transition_number), key);
    set(ToTargetIndex(transition_number), target);
  }
  
  int TransitionArray::Capacity() {
    if (length() <= kFirstIndex) return 0;
    return (length() - kFirstIndex) / kTransitionSize;
  }
  
  void TransitionArray::SetNumberOfTransitions(int number_of_transitions) {
    DCHECK(number_of_transitions <= Capacity());
    set(kTransitionLengthIndex, Smi::FromInt(number_of_transitions));
  }
  
  }  // namespace internal
  }  // namespace v8
  
  #endif  // V8_TRANSITIONS_INL_H_
  