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e6d920d87d
We now care (a little bit) about the "configurable" and "writable" property attributes. Property attributes are stored together with the property name in the Shape object. Forward transitions are not attribute-savvy and will cause poor Shape reuse in the case of multiple same-name properties with different attributes. Oh, and this patch also adds Object.getOwnPropertyDescriptor() :^)
121 lines
3.9 KiB
C++
121 lines
3.9 KiB
C++
/*
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* Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <LibJS/Interpreter.h>
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#include <LibJS/Runtime/Shape.h>
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namespace JS {
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Shape* Shape::create_put_transition(const FlyString& property_name, u8 attributes)
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{
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auto* new_shape = m_forward_transitions.get(property_name).value_or(nullptr);
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if (new_shape && new_shape->m_attributes == attributes)
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return new_shape;
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new_shape = heap().allocate<Shape>(this, property_name, attributes);
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m_forward_transitions.set(property_name, new_shape);
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return new_shape;
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}
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Shape* Shape::create_prototype_transition(Object* new_prototype)
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{
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return heap().allocate<Shape>(this, new_prototype);
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}
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Shape::Shape()
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{
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}
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Shape::Shape(Shape* previous_shape, const FlyString& property_name, u8 attributes)
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: m_previous(previous_shape)
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, m_property_name(property_name)
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, m_attributes(attributes)
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, m_prototype(previous_shape->m_prototype)
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{
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}
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Shape::Shape(Shape* previous_shape, Object* new_prototype)
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: m_previous(previous_shape)
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, m_prototype(new_prototype)
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{
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}
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Shape::~Shape()
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{
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}
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void Shape::visit_children(Cell::Visitor& visitor)
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{
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Cell::visit_children(visitor);
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if (m_prototype)
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visitor.visit(m_prototype);
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if (m_previous)
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visitor.visit(m_previous);
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for (auto& it : m_forward_transitions)
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visitor.visit(it.value);
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}
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Optional<PropertyMetadata> Shape::lookup(const FlyString& property_name) const
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{
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return property_table().get(property_name);
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}
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const HashMap<FlyString, PropertyMetadata>& Shape::property_table() const
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{
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ensure_property_table();
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return *m_property_table;
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}
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size_t Shape::property_count() const
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{
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return property_table().size();
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}
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void Shape::ensure_property_table() const
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{
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if (m_property_table)
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return;
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m_property_table = make<HashMap<FlyString, PropertyMetadata>>();
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// FIXME: We need to make sure the GC doesn't collect the transition chain as we're building it.
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// Maybe some kind of RAII "prevent GC for a moment" helper thingy?
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Vector<const Shape*> transition_chain;
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for (auto* shape = this; shape->m_previous; shape = shape->m_previous) {
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transition_chain.append(shape);
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}
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u32 next_offset = 0;
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for (ssize_t i = transition_chain.size() - 1; i >= 0; --i) {
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auto* shape = transition_chain[i];
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if (shape->m_property_name.is_null()) {
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// Ignore prototype transitions as they don't affect the key map.
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continue;
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}
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m_property_table->set(shape->m_property_name, { next_offset++, shape->m_attributes });
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}
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}
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}
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