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/*
* Copyright (c) 2020-2021, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <LibJS/Heap/DeferGC.h>
#include <LibJS/Runtime/GlobalObject.h>
#include <LibJS/Runtime/Shape.h>
namespace JS {
Shape* Shape::create_unique_clone() const
{
VERIFY(m_global_object);
auto* new_shape = heap().allocate_without_global_object<Shape>(*m_global_object);
new_shape->m_unique = true;
new_shape->m_prototype = m_prototype;
ensure_property_table();
new_shape->ensure_property_table();
(*new_shape->m_property_table) = *m_property_table;
new_shape->m_property_count = new_shape->m_property_table->size();
return new_shape;
}
Shape* Shape::get_or_prune_cached_forward_transition(TransitionKey const& key)
{
auto it = m_forward_transitions.find(key);
if (it == m_forward_transitions.end())
return nullptr;
if (!it->value) {
// The cached forward transition has gone stale (from garbage collection). Prune it.
m_forward_transitions.remove(it);
return nullptr;
}
return it->value;
}
Shape* Shape::create_put_transition(const StringOrSymbol& property_name, PropertyAttributes attributes)
{
TransitionKey key { property_name, attributes };
if (auto* existing_shape = get_or_prune_cached_forward_transition(key))
return existing_shape;
auto* new_shape = heap().allocate_without_global_object<Shape>(*this, property_name, attributes, TransitionType::Put);
m_forward_transitions.set(key, new_shape);
return new_shape;
}
Shape* Shape::create_configure_transition(const StringOrSymbol& property_name, PropertyAttributes attributes)
{
TransitionKey key { property_name, attributes };
if (auto* existing_shape = get_or_prune_cached_forward_transition(key))
return existing_shape;
auto* new_shape = heap().allocate_without_global_object<Shape>(*this, property_name, attributes, TransitionType::Configure);
m_forward_transitions.set(key, new_shape);
return new_shape;
}
Shape* Shape::create_prototype_transition(Object* new_prototype)
{
return heap().allocate_without_global_object<Shape>(*this, new_prototype);
}
Shape::Shape(ShapeWithoutGlobalObjectTag)
{
}
Shape::Shape(Object& global_object)
: m_global_object(&global_object)
{
}
Shape::Shape(Shape& previous_shape, const StringOrSymbol& property_name, PropertyAttributes attributes, TransitionType transition_type)
: m_attributes(attributes)
, m_transition_type(transition_type)
, m_global_object(previous_shape.m_global_object)
, m_previous(&previous_shape)
, m_property_name(property_name)
, m_prototype(previous_shape.m_prototype)
, m_property_count(transition_type == TransitionType::Put ? previous_shape.m_property_count + 1 : previous_shape.m_property_count)
{
}
Shape::Shape(Shape& previous_shape, Object* new_prototype)
: m_transition_type(TransitionType::Prototype)
, m_global_object(previous_shape.m_global_object)
, m_previous(&previous_shape)
, m_prototype(new_prototype)
, m_property_count(previous_shape.m_property_count)
{
}
Shape::~Shape()
{
}
void Shape::visit_edges(Cell::Visitor& visitor)
{
Cell::visit_edges(visitor);
visitor.visit(m_global_object);
visitor.visit(m_prototype);
visitor.visit(m_previous);
m_property_name.visit_edges(visitor);
if (m_property_table) {
for (auto& it : *m_property_table)
it.key.visit_edges(visitor);
}
}
Optional<PropertyMetadata> Shape::lookup(const StringOrSymbol& property_name) const
{
if (m_property_count == 0)
return {};
auto property = property_table().get(property_name);
if (!property.has_value())
return {};
return property;
}
const HashMap<StringOrSymbol, PropertyMetadata>& Shape::property_table() const
{
ensure_property_table();
return *m_property_table;
}
size_t Shape::property_count() const
{
return m_property_count;
}
Vector<Shape::Property> Shape::property_table_ordered() const
{
auto vec = Vector<Shape::Property>();
vec.resize(property_count());
for (auto& it : property_table()) {
vec[it.value.offset] = { it.key, it.value };
}
return vec;
}
void Shape::ensure_property_table() const
{
if (m_property_table)
return;
m_property_table = make<HashMap<StringOrSymbol, PropertyMetadata>>();
u32 next_offset = 0;
Vector<const Shape*, 64> transition_chain;
for (auto* shape = m_previous; shape; shape = shape->m_previous) {
if (shape->m_property_table) {
*m_property_table = *shape->m_property_table;
next_offset = shape->m_property_count;
break;
}
transition_chain.append(shape);
}
transition_chain.append(this);
for (ssize_t i = transition_chain.size() - 1; i >= 0; --i) {
auto* shape = transition_chain[i];
if (!shape->m_property_name.is_valid()) {
// Ignore prototype transitions as they don't affect the key map.
continue;
}
if (shape->m_transition_type == TransitionType::Put) {
m_property_table->set(shape->m_property_name, { next_offset++, shape->m_attributes });
} else if (shape->m_transition_type == TransitionType::Configure) {
auto it = m_property_table->find(shape->m_property_name);
VERIFY(it != m_property_table->end());
it->value.attributes = shape->m_attributes;
}
}
}
void Shape::add_property_to_unique_shape(const StringOrSymbol& property_name, PropertyAttributes attributes)
{
VERIFY(is_unique());
VERIFY(m_property_table);
VERIFY(!m_property_table->contains(property_name));
m_property_table->set(property_name, { m_property_table->size(), attributes });
++m_property_count;
}
void Shape::reconfigure_property_in_unique_shape(const StringOrSymbol& property_name, PropertyAttributes attributes)
{
VERIFY(is_unique());
VERIFY(m_property_table);
auto it = m_property_table->find(property_name);
VERIFY(it != m_property_table->end());
it->value.attributes = attributes;
m_property_table->set(property_name, it->value);
}
void Shape::remove_property_from_unique_shape(const StringOrSymbol& property_name, size_t offset)
{
VERIFY(is_unique());
VERIFY(m_property_table);
if (m_property_table->remove(property_name))
--m_property_count;
for (auto& it : *m_property_table) {
VERIFY(it.value.offset != offset);
if (it.value.offset > offset)
--it.value.offset;
}
}
void Shape::add_property_without_transition(const StringOrSymbol& property_name, PropertyAttributes attributes)
{
ensure_property_table();
if (m_property_table->set(property_name, { m_property_count, attributes }) == AK::HashSetResult::InsertedNewEntry)
++m_property_count;
}
}
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