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ladybird/Libraries/LibJS/Runtime/Object.cpp
Matthew Olsson 5ae9419a06 LibJS: Object index properties have descriptors; Handle sparse indices 
This patch adds an IndexedProperties object for storing indexed
properties within an Object. This accomplishes two goals: indexed
properties now have an associated descriptor, and objects now gracefully
handle sparse properties.

The IndexedProperties class is a wrapper around two other classes, one
for simple indexed properties storage, and one for general indexed
property storage. Simple indexed property storage is the common-case,
and is simply a vector of properties which all have attributes of
default_attributes (writable, enumerable, and configurable).

General indexed property storage is for a collection of indexed
properties where EITHER one or more properties have attributes other
than default_attributes OR there is a property with a large index (in
particular, large is '200' or higher).

Indexed properties are now treated relatively the same as storage within
the various Object methods. Additionally, there is a custom iterator
class for IndexedProperties which makes iteration easy. The iterator
skips empty values by default, but can be configured otherwise.
Likewise, it evaluates getters by default, but can be set not to.
2020-05-28 17:17:13 +02:00

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/*
* Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
* 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 THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 THE COPYRIGHT HOLDER 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.
*/
#include <AK/String.h>
#include <LibJS/Heap/Heap.h>
#include <LibJS/Interpreter.h>
#include <LibJS/Runtime/Accessor.h>
#include <LibJS/Runtime/Array.h>
#include <LibJS/Runtime/Error.h>
#include <LibJS/Runtime/GlobalObject.h>
#include <LibJS/Runtime/NativeFunction.h>
#include <LibJS/Runtime/NativeProperty.h>
#include <LibJS/Runtime/Object.h>
#include <LibJS/Runtime/Shape.h>
#include <LibJS/Runtime/StringObject.h>
#include <LibJS/Runtime/Value.h>
namespace JS {
Object* Object::create_empty(Interpreter&, GlobalObject& global_object)
{
return global_object.heap().allocate<Object>(global_object.object_prototype());
}
Object::Object(Object* prototype)
{
if (prototype) {
m_shape = interpreter().global_object().empty_object_shape();
set_prototype(prototype);
} else {
m_shape = interpreter().heap().allocate<Shape>();
}
}
Object::~Object()
{
}
Object* Object::prototype()
{
return shape().prototype();
}
const Object* Object::prototype() const
{
return shape().prototype();
}
void Object::set_prototype(Object* new_prototype)
{
if (prototype() == new_prototype)
return;
if (shape().is_unique()) {
shape().set_prototype_without_transition(new_prototype);
return;
}
m_shape = m_shape->create_prototype_transition(new_prototype);
}
bool Object::has_prototype(const Object* prototype) const
{
for (auto* object = this->prototype(); object; object = object->prototype()) {
if (object == prototype)
return true;
}
return false;
}
Value Object::get_own_property(const Object& this_object, PropertyName property_name) const
{
Value value_here;
if (property_name.is_number()) {
auto existing_property = m_indexed_properties.get(nullptr, property_name.as_number(), false);
if (!existing_property.has_value())
return {};
value_here = existing_property.value().value;
} else {
auto metadata = shape().lookup(property_name.as_string());
if (!metadata.has_value())
return {};
value_here = m_storage[metadata.value().offset];
}
ASSERT(!value_here.is_empty());
if (value_here.is_accessor()) {
return value_here.as_accessor().call_getter(Value(const_cast<Object*>(this)));
}
if (value_here.is_object() && value_here.as_object().is_native_property()) {
auto& native_property = static_cast<const NativeProperty&>(value_here.as_object());
auto& interpreter = const_cast<Object*>(this)->interpreter();
auto& call_frame = interpreter.push_call_frame();
call_frame.this_value = const_cast<Object*>(&this_object);
auto result = native_property.get(interpreter);
interpreter.pop_call_frame();
return result;
}
return value_here;
}
Value Object::get_own_properties(const Object& this_object, GetOwnPropertyMode kind, u8 attributes) const
{
auto* properties_array = Array::create(interpreter().global_object());
// FIXME: Support generic iterables
if (this_object.is_string_object()) {
auto str = static_cast<const StringObject&>(this_object).primitive_string().string();
for (size_t i = 0; i < str.length(); ++i) {
if (kind == GetOwnPropertyMode::Key) {
properties_array->define_property(i, js_string(interpreter(), String::number(i)));
} else if (kind == GetOwnPropertyMode::Value) {
properties_array->define_property(i, js_string(interpreter(), String::format("%c", str[i])));
} else {
auto* entry_array = Array::create(interpreter().global_object());
entry_array->define_property(0, js_string(interpreter(), String::number(i)));
entry_array->define_property(1, js_string(interpreter(), String::format("%c", str[i])));
properties_array->define_property(i, entry_array);
}
}
return properties_array;
}
size_t property_index = 0;
for (auto& entry : m_indexed_properties) {
if (kind == GetOwnPropertyMode::Key) {
properties_array->define_property(property_index, js_string(interpreter(), String::number(entry.index())));
} else if (kind == GetOwnPropertyMode::Value) {
properties_array->define_property(property_index, entry.value_and_attributes(const_cast<Object*>(&this_object)).value);
if (interpreter().exception())
return {};
} else {
auto* entry_array = Array::create(interpreter().global_object());
entry_array->define_property(0, js_string(interpreter(), String::number(entry.index())));
entry_array->define_property(1, entry.value_and_attributes(const_cast<Object*>(&this_object)).value);
if (interpreter().exception())
return {};
properties_array->define_property(property_index, entry_array);
}
++property_index;
}
for (auto& it : this_object.shape().property_table_ordered()) {
if (it.value.attributes & attributes) {
size_t offset = it.value.offset + property_index;
if (kind == GetOwnPropertyMode::Key) {
properties_array->define_property(offset, js_string(interpreter(), it.key));
} else if (kind == GetOwnPropertyMode::Value) {
properties_array->define_property(offset, this_object.get(it.key));
if (interpreter().exception())
return {};
} else {
auto* entry_array = Array::create(interpreter().global_object());
entry_array->define_property(0, js_string(interpreter(), it.key));
entry_array->define_property(1, this_object.get(it.key));
if (interpreter().exception())
return {};
properties_array->define_property(offset, entry_array);
}
}
}
return properties_array;
}
Value Object::get_own_property_descriptor(PropertyName property_name) const
{
Value value;
u8 attributes;
if (property_name.is_number()) {
auto existing_value = m_indexed_properties.get(nullptr, property_name.as_number(), false);
if (!existing_value.has_value())
return js_undefined();
value = existing_value.value().value;
attributes = existing_value.value().attributes;
attributes = default_attributes;
} else {
auto metadata = shape().lookup(property_name.as_string());
if (!metadata.has_value())
return js_undefined();
value = get(property_name);
if (interpreter().exception())
return {};
attributes = metadata.value().attributes;
}
auto* descriptor = Object::create_empty(interpreter(), interpreter().global_object());
descriptor->define_property("enumerable", Value((attributes & Attribute::Enumerable) != 0));
descriptor->define_property("configurable", Value((attributes & Attribute::Configurable) != 0));
if (value.is_accessor()) {
auto& pair = value.as_accessor();
descriptor->define_property("get", pair.getter());
descriptor->define_property("set", pair.setter());
} else {
descriptor->define_property("value", value.value_or(js_undefined()));
descriptor->define_property("writable", Value((attributes & Attribute::Writable) != 0));
}
return descriptor;
}
void Object::set_shape(Shape& new_shape)
{
m_storage.resize(new_shape.property_count());
m_shape = &new_shape;
}
bool Object::define_property(const FlyString& property_name, const Object& descriptor, bool throw_exceptions)
{
bool is_accessor_property = descriptor.has_property("get") || descriptor.has_property("set");
u8 configurable = descriptor.get("configurable").value_or(Value(false)).to_boolean() * Attribute::Configurable;
if (interpreter().exception())
return {};
u8 enumerable = descriptor.get("enumerable").value_or(Value(false)).to_boolean() * Attribute::Enumerable;
if (interpreter().exception())
return {};
u8 attributes = configurable | enumerable;
if (is_accessor_property) {
if (descriptor.has_property("value") || descriptor.has_property("writable")) {
if (throw_exceptions)
interpreter().throw_exception<TypeError>("Accessor property descriptors cannot specify a value or writable key");
return false;
}
auto getter = descriptor.get("get").value_or(js_undefined());
if (interpreter().exception())
return {};
auto setter = descriptor.get("set").value_or(js_undefined());
if (interpreter().exception())
return {};
Function* getter_function { nullptr };
Function* setter_function { nullptr };
if (getter.is_function()) {
getter_function = &getter.as_function();
} else if (!getter.is_undefined()) {
interpreter().throw_exception<TypeError>("Accessor descriptor's 'get' field must be a function or undefined");
return false;
}
if (setter.is_function()) {
setter_function = &setter.as_function();
} else if (!setter.is_undefined()) {
interpreter().throw_exception<TypeError>("Accessor descriptor's 'set' field must be a function or undefined");
return false;
}
dbg() << "Defining new property " << property_name << " with accessor descriptor { attributes=" << attributes << ", "
<< "getter=" << getter.to_string_without_side_effects() << ", "
<< "setter=" << setter.to_string_without_side_effects() << "}";
return define_property(property_name, Accessor::create(interpreter(), getter_function, setter_function), attributes, throw_exceptions);
}
auto value = descriptor.get("value");
if (interpreter().exception())
return {};
u8 writable = descriptor.get("writable").value_or(Value(false)).to_boolean() * Attribute::Writable;
if (interpreter().exception())
return {};
attributes |= writable;
dbg() << "Defining new property " << property_name << " with data descriptor { attributes=" << attributes
<< ", value=" << (value.is_empty() ? "<empty>" : value.to_string_without_side_effects()) << " }";
return define_property(property_name, value, attributes, throw_exceptions);
}
bool Object::define_property(PropertyName property_name, Value value, u8 attributes, bool throw_exceptions)
{
if (property_name.is_number())
return put_own_property_by_index(*this, property_name.as_number(), value, attributes, PutOwnPropertyMode::DefineProperty, throw_exceptions);
bool ok;
i32 property_index = property_name.as_string().to_int(ok);
if (ok && property_index >= 0)
return put_own_property_by_index(*this, property_index, value, attributes, PutOwnPropertyMode::DefineProperty, throw_exceptions);
return put_own_property(*this, property_name.as_string(), value, attributes, PutOwnPropertyMode::DefineProperty, throw_exceptions);
}
bool Object::put_own_property(Object& this_object, const FlyString& property_name, Value value, u8 attributes, PutOwnPropertyMode mode, bool throw_exceptions)
{
ASSERT(!(mode == PutOwnPropertyMode::Put && value.is_accessor()));
if (value.is_accessor()) {
auto& accessor = value.as_accessor();
if (accessor.getter())
attributes |= Attribute::HasGet;
if (accessor.setter())
attributes |= Attribute::HasSet;
}
auto metadata = shape().lookup(property_name);
bool new_property = !metadata.has_value();
if (new_property) {
if (!m_shape->is_unique() && shape().property_count() > 100) {
// If you add more than 100 properties to an object, let's stop doing
// transitions to avoid filling up the heap with shapes.
ensure_shape_is_unique();
}
if (m_shape->is_unique()) {
m_shape->add_property_to_unique_shape(property_name, attributes);
m_storage.resize(m_shape->property_count());
} else {
set_shape(*m_shape->create_put_transition(property_name, attributes));
}
metadata = shape().lookup(property_name);
ASSERT(metadata.has_value());
}
if (!new_property && mode == PutOwnPropertyMode::DefineProperty && !(metadata.value().attributes & Attribute::Configurable) && attributes != metadata.value().attributes) {
dbg() << "Disallow reconfig of non-configurable property";
if (throw_exceptions)
interpreter().throw_exception<TypeError>(String::format("Cannot change attributes of non-configurable property '%s'", property_name.characters()));
return false;
}
if (mode == PutOwnPropertyMode::DefineProperty && attributes != metadata.value().attributes) {
if (m_shape->is_unique()) {
m_shape->reconfigure_property_in_unique_shape(property_name, attributes);
} else {
set_shape(*m_shape->create_configure_transition(property_name, attributes));
}
metadata = shape().lookup(property_name);
dbg() << "Reconfigured property " << property_name << ", new shape says offset is " << metadata.value().offset << " and my storage capacity is " << m_storage.size();
}
auto value_here = m_storage[metadata.value().offset];
if (!new_property && mode == PutOwnPropertyMode::Put && !value_here.is_accessor() && !(metadata.value().attributes & Attribute::Writable)) {
dbg() << "Disallow write to non-writable property";
return false;
}
if (value.is_empty())
return true;
if (value_here.is_object() && value_here.as_object().is_native_property()) {
auto& native_property = static_cast<NativeProperty&>(value_here.as_object());
auto& interpreter = const_cast<Object*>(this)->interpreter();
auto& call_frame = interpreter.push_call_frame();
call_frame.this_value = &this_object;
native_property.set(interpreter, value);
interpreter.pop_call_frame();
} else {
m_storage[metadata.value().offset] = value;
}
return true;
}
bool Object::put_own_property_by_index(Object& this_object, u32 property_index, Value value, u8 attributes, PutOwnPropertyMode mode, bool throw_exceptions)
{
ASSERT(!(mode == PutOwnPropertyMode::Put && value.is_accessor()));
if (value.is_accessor()) {
auto& accessor = value.as_accessor();
if (accessor.getter())
attributes |= Attribute::HasGet;
if (accessor.setter())
attributes |= Attribute::HasSet;
}
auto existing_property = m_indexed_properties.get(nullptr, property_index, false);
auto new_property = !existing_property.has_value();
auto existing_attributes = new_property ? 0 : existing_property.value().attributes;
if (!new_property && mode == PutOwnPropertyMode::DefineProperty && !(existing_attributes & Attribute::Configurable) && attributes != existing_attributes) {
dbg() << "Disallow reconfig of non-configurable property";
if (throw_exceptions)
interpreter().throw_exception<TypeError>(String::format("Cannot change attributes of non-configurable property %d", property_index));
return false;
}
auto value_here = new_property ? Value() : existing_property.value().value;
if (!new_property && mode == PutOwnPropertyMode::Put && !value_here.is_accessor() && !(existing_attributes & Attribute::Writable)) {
dbg() << "Disallow write to non-writable property";
return false;
}
if (value.is_empty())
return true;
if (value_here.is_object() && value_here.as_object().is_native_property()) {
auto& native_property = static_cast<NativeProperty&>(value_here.as_object());
auto& interpreter = const_cast<Object*>(this)->interpreter();
auto& call_frame = interpreter.push_call_frame();
call_frame.this_value = &this_object;
native_property.set(interpreter, value);
interpreter.pop_call_frame();
} else {
m_indexed_properties.put(&this_object, property_index, value, attributes, mode == PutOwnPropertyMode::Put);
}
return true;
}
Value Object::delete_property(PropertyName property_name)
{
ASSERT(property_name.is_valid());
if (property_name.is_number())
return Value(m_indexed_properties.remove(property_name.as_number()));
auto metadata = shape().lookup(property_name.as_string());
if (!metadata.has_value())
return Value(true);
if (!(metadata.value().attributes & Attribute::Configurable))
return Value(false);
size_t deleted_offset = metadata.value().offset;
ensure_shape_is_unique();
shape().remove_property_from_unique_shape(property_name.as_string(), deleted_offset);
m_storage.remove(deleted_offset);
return Value(true);
}
void Object::ensure_shape_is_unique()
{
if (shape().is_unique())
return;
m_shape = m_shape->create_unique_clone();
}
Value Object::get_by_index(u32 property_index) const
{
const Object* object = this;
while (object) {
if (is_string_object()) {
auto& string = static_cast<const StringObject*>(this)->primitive_string().string();
if (property_index < string.length())
return js_string(heap(), string.substring(property_index, 1));
return js_undefined();
}
if (static_cast<size_t>(property_index) < object->m_indexed_properties.array_like_size()) {
auto result = object->m_indexed_properties.get(const_cast<Object*>(this), property_index);
if (interpreter().exception())
return {};
if (result.has_value() && !result.value().value.is_empty())
return result.value().value;
return {};
}
object = object->prototype();
}
return {};
}
Value Object::get(PropertyName property_name) const
{
if (property_name.is_number())
return get_by_index(property_name.as_number());
auto property_string = property_name.to_string();
bool ok;
i32 property_index = property_string.to_int(ok);
if (ok && property_index >= 0)
return get_by_index(property_index);
const Object* object = this;
while (object) {
auto value = object->get_own_property(*this, property_name);
if (!value.is_empty())
return value;
object = object->prototype();
}
return {};
}
bool Object::put_by_index(u32 property_index, Value value)
{
ASSERT(!value.is_empty());
// If there's a setter in the prototype chain, we go to the setter.
// Otherwise, it goes in the own property storage.
Object* object = this;
while (object) {
auto existing_value = object->m_indexed_properties.get(nullptr, property_index, false);
if (existing_value.has_value()) {
auto value_here = existing_value.value();
if (value_here.value.is_accessor()) {
value_here.value.as_accessor().call_setter(object, value);
return true;
}
if (value_here.value.is_object() && value_here.value.as_object().is_native_property()) {
auto& native_property = static_cast<NativeProperty&>(value_here.value.as_object());
auto& interpreter = const_cast<Object*>(this)->interpreter();
auto& call_frame = interpreter.push_call_frame();
call_frame.this_value = this;
native_property.set(interpreter, value);
interpreter.pop_call_frame();
return true;
}
}
object = object->prototype();
}
return put_own_property_by_index(*this, property_index, value, default_attributes, PutOwnPropertyMode::Put);
}
bool Object::put(PropertyName property_name, Value value)
{
if (property_name.is_number())
return put_by_index(property_name.as_number(), value);
ASSERT(!value.is_empty());
auto property_string = property_name.to_string();
bool ok;
i32 property_index = property_string.to_int(ok);
if (ok && property_index >= 0)
return put_by_index(property_index, value);
// If there's a setter in the prototype chain, we go to the setter.
// Otherwise, it goes in the own property storage.
Object* object = this;
while (object) {
auto metadata = object->shape().lookup(property_string);
if (metadata.has_value()) {
auto value_here = object->m_storage[metadata.value().offset];
if (value_here.is_accessor()) {
value_here.as_accessor().call_setter(Value(this), value);
return true;
}
if (value_here.is_object() && value_here.as_object().is_native_property()) {
auto& native_property = static_cast<NativeProperty&>(value_here.as_object());
auto& interpreter = const_cast<Object*>(this)->interpreter();
auto& call_frame = interpreter.push_call_frame();
call_frame.this_value = this;
native_property.set(interpreter, value);
interpreter.pop_call_frame();
return true;
}
}
object = object->prototype();
}
return put_own_property(*this, property_string, value, default_attributes, PutOwnPropertyMode::Put);
}
bool Object::define_native_function(const FlyString& property_name, AK::Function<Value(Interpreter&)> native_function, i32 length, u8 attribute)
{
auto* function = NativeFunction::create(interpreter(), interpreter().global_object(), property_name, move(native_function));
function->define_property("length", Value(length), Attribute::Configurable);
function->define_property("name", js_string(heap(), property_name), Attribute::Configurable);
return define_property(property_name, function, attribute);
}
bool Object::define_native_property(const FlyString& property_name, AK::Function<Value(Interpreter&)> getter, AK::Function<void(Interpreter&, Value)> setter, u8 attribute)
{
return define_property(property_name, heap().allocate<NativeProperty>(move(getter), move(setter)), attribute);
}
void Object::visit_children(Cell::Visitor& visitor)
{
Cell::visit_children(visitor);
visitor.visit(m_shape);
for (auto& value : m_storage)
visitor.visit(value);
for (auto& value : m_indexed_properties.values_unordered())
visitor.visit(value.value);
}
bool Object::has_property(PropertyName property_name) const
{
const Object* object = this;
while (object) {
if (object->has_own_property(property_name))
return true;
object = object->prototype();
}
return false;
}
bool Object::has_own_property(PropertyName property_name) const
{
auto has_indexed_property = [&](u32 index) -> bool {
if (is_string_object())
return index < static_cast<const StringObject*>(this)->primitive_string().string().length();
return m_indexed_properties.has_index(index);
};
if (property_name.is_number())
return has_indexed_property(property_name.as_number());
bool ok;
i32 property_index = property_name.as_string().to_int(ok);
if (ok && property_index >= 0)
return has_indexed_property(property_index);
return shape().lookup(property_name.as_string()).has_value();
}
Value Object::to_primitive(PreferredType preferred_type) const
{
Value result = js_undefined();
switch (preferred_type) {
case PreferredType::Default:
case PreferredType::Number: {
result = value_of();
if (result.is_object()) {
result = to_string();
}
break;
}
case PreferredType::String: {
result = to_string();
if (result.is_object())
result = value_of();
break;
}
}
ASSERT(!result.is_object());
return result;
}
Value Object::to_string() const
{
auto to_string_property = get("toString");
if (to_string_property.is_function()) {
auto& to_string_function = to_string_property.as_function();
auto& interpreter = const_cast<Object*>(this)->interpreter();
auto to_string_result = interpreter.call(to_string_function, const_cast<Object*>(this));
if (to_string_result.is_object())
interpreter.throw_exception<TypeError>("Cannot convert object to string");
if (interpreter.exception())
return {};
auto* string = to_string_result.to_primitive_string(interpreter);
if (interpreter.exception())
return {};
return string;
}
return js_string(heap(), String::format("[object %s]", class_name()));
}
}
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