mirror of
https://github.com/RGBCube/serenity
synced 2025-07-26 22:47:45 +00:00
LibWeb: Make the layout tree GC-allocated
This removes a set of complex reference cycles between DOM, layout tree and browsing context. It also makes lifetimes much easier to reason about, as the DOM and layout trees are now free to keep each other alive.
This commit is contained in:
Andreas Kling
parent
83c5ff57d8
commit
268b9c5d90
72 changed files with 258 additions and 207 deletions
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@ -1,5 +1,5 @@
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/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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* Copyright (c) 2018-2022, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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@ -7,54 +7,27 @@
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#pragma once
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#include <AK/Assertions.h>
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#include <AK/NonnullRefPtr.h>
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#include <AK/TypeCasts.h>
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#include <AK/Weakable.h>
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#include <LibJS/Heap/GCPtr.h>
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#include <LibWeb/Forward.h>
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namespace Web {
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template<typename T>
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class TreeNode : public Weakable<T> {
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class TreeNode {
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public:
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void ref()
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{
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VERIFY(!m_in_removed_last_ref);
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if constexpr (!IsBaseOf<DOM::Node, T>) {
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// NOTE: DOM::Document is allowed to survive with 0 ref count, if one of its descendant nodes are alive.
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VERIFY(m_ref_count);
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}
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++m_ref_count;
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}
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void unref()
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{
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VERIFY(!m_in_removed_last_ref);
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VERIFY(m_ref_count);
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if (!--m_ref_count) {
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if constexpr (IsBaseOf<DOM::Node, T>) {
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m_in_removed_last_ref = true;
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static_cast<T*>(this)->removed_last_ref();
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} else {
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delete static_cast<T*>(this);
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}
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return;
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}
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}
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int ref_count() const { return m_ref_count; }
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T* parent() { return m_parent; }
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const T* parent() const { return m_parent; }
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T const* parent() const { return m_parent; }
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bool has_children() const { return m_first_child; }
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T* next_sibling() { return m_next_sibling; }
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T* previous_sibling() { return m_previous_sibling; }
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T* first_child() { return m_first_child; }
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T* last_child() { return m_last_child; }
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const T* next_sibling() const { return m_next_sibling; }
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const T* previous_sibling() const { return m_previous_sibling; }
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const T* first_child() const { return m_first_child; }
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const T* last_child() const { return m_last_child; }
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T const* next_sibling() const { return m_next_sibling; }
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T const* previous_sibling() const { return m_previous_sibling; }
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T const* first_child() const { return m_first_child; }
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T const* last_child() const { return m_last_child; }
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size_t child_count() const
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{
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@ -75,7 +48,7 @@ public:
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return nullptr;
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}
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const T* child_at_index(int index) const
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T const* child_at_index(int index) const
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{
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return const_cast<TreeNode*>(this)->child_at_index(index);
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}
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@ -90,7 +63,7 @@ public:
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return index;
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}
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Optional<size_t> index_of_child(const T& search_child)
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Optional<size_t> index_of_child(T const& search_child)
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{
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VERIFY(search_child.parent() == this);
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size_t index = 0;
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@ -106,7 +79,7 @@ public:
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}
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template<typename ChildType>
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Optional<size_t> index_of_child(const T& search_child)
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Optional<size_t> index_of_child(T const& search_child)
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{
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VERIFY(search_child.parent() == this);
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size_t index = 0;
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@ -130,12 +103,12 @@ public:
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bool is_following(TreeNode const&) const;
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void append_child(NonnullRefPtr<T> node);
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void prepend_child(NonnullRefPtr<T> node);
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void insert_before(NonnullRefPtr<T> node, RefPtr<T> child);
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void remove_child(NonnullRefPtr<T> node);
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void append_child(JS::NonnullGCPtr<T> node);
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void prepend_child(JS::NonnullGCPtr<T> node);
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void insert_before(JS::NonnullGCPtr<T> node, JS::GCPtr<T> child);
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void remove_child(JS::NonnullGCPtr<T> node);
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bool is_child_allowed(const T&) const { return true; }
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bool is_child_allowed(T const&) const { return true; }
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T* next_in_pre_order()
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{
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@ -230,7 +203,7 @@ public:
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template<typename Callback>
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IterationDecision for_each_in_inclusive_subtree(Callback callback) const
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{
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if (callback(static_cast<const T&>(*this)) == IterationDecision::Break)
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if (callback(static_cast<T const&>(*this)) == IterationDecision::Break)
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return IterationDecision::Break;
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for (auto* child = first_child(); child; child = child->next_sibling()) {
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if (child->for_each_in_inclusive_subtree(callback) == IterationDecision::Break)
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@ -254,7 +227,7 @@ public:
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template<typename U, typename Callback>
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IterationDecision for_each_in_inclusive_subtree_of_type(Callback callback)
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{
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if (is<U>(static_cast<const T&>(*this))) {
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if (is<U>(static_cast<T const&>(*this))) {
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if (callback(static_cast<U&>(*this)) == IterationDecision::Break)
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return IterationDecision::Break;
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}
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@ -268,8 +241,8 @@ public:
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template<typename U, typename Callback>
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IterationDecision for_each_in_inclusive_subtree_of_type(Callback callback) const
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{
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if (is<U>(static_cast<const T&>(*this))) {
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if (callback(static_cast<const U&>(*this)) == IterationDecision::Break)
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if (is<U>(static_cast<T const&>(*this))) {
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if (callback(static_cast<U const&>(*this)) == IterationDecision::Break)
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return IterationDecision::Break;
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}
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for (auto* child = first_child(); child; child = child->next_sibling()) {
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@ -348,7 +321,7 @@ public:
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}
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template<typename U>
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const U* next_sibling_of_type() const
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U const* next_sibling_of_type() const
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{
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return const_cast<TreeNode*>(this)->template next_sibling_of_type<U>();
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}
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@ -364,7 +337,7 @@ public:
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}
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template<typename U>
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const U* previous_sibling_of_type() const
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U const* previous_sibling_of_type() const
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{
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return const_cast<TreeNode*>(this)->template previous_sibling_of_type<U>();
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}
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@ -380,13 +353,13 @@ public:
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}
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template<typename U>
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const U* first_child_of_type() const
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U const* first_child_of_type() const
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{
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return const_cast<TreeNode*>(this)->template first_child_of_type<U>();
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}
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template<typename U>
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const U* last_child_of_type() const
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U const* last_child_of_type() const
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{
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return const_cast<TreeNode*>(this)->template last_child_of_type<U>();
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}
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@ -418,7 +391,7 @@ public:
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}
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template<typename U>
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const U* first_ancestor_of_type() const
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U const* first_ancestor_of_type() const
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{
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return const_cast<TreeNode*>(this)->template first_ancestor_of_type<U>();
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}
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@ -442,25 +415,21 @@ public:
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return false;
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}
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~TreeNode()
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{
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VERIFY(!m_parent);
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T* next_child = nullptr;
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for (auto* child = m_first_child; child; child = next_child) {
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next_child = child->m_next_sibling;
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child->m_parent = nullptr;
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child->unref();
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}
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}
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~TreeNode() = default;
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protected:
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TreeNode() = default;
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bool m_deletion_has_begun { false };
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bool m_in_removed_last_ref { false };
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void visit_edges(JS::Cell::Visitor& visitor)
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{
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visitor.visit(m_parent);
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visitor.visit(m_first_child);
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visitor.visit(m_last_child);
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visitor.visit(m_next_sibling);
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visitor.visit(m_previous_sibling);
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}
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private:
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int m_ref_count { 1 };
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T* m_parent { nullptr };
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T* m_first_child { nullptr };
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T* m_last_child { nullptr };
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@ -469,7 +438,7 @@ private:
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};
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template<typename T>
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inline void TreeNode<T>::remove_child(NonnullRefPtr<T> node)
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inline void TreeNode<T>::remove_child(JS::NonnullGCPtr<T> node)
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{
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VERIFY(node->m_parent == this);
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@ -488,12 +457,10 @@ inline void TreeNode<T>::remove_child(NonnullRefPtr<T> node)
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node->m_next_sibling = nullptr;
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node->m_previous_sibling = nullptr;
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node->m_parent = nullptr;
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node->unref();
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}
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template<typename T>
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inline void TreeNode<T>::append_child(NonnullRefPtr<T> node)
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inline void TreeNode<T>::append_child(JS::NonnullGCPtr<T> node)
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{
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VERIFY(!node->m_parent);
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@ -507,11 +474,10 @@ inline void TreeNode<T>::append_child(NonnullRefPtr<T> node)
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m_last_child = node.ptr();
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if (!m_first_child)
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m_first_child = m_last_child;
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[[maybe_unused]] auto& rc = node.leak_ref();
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}
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template<typename T>
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inline void TreeNode<T>::insert_before(NonnullRefPtr<T> node, RefPtr<T> child)
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inline void TreeNode<T>::insert_before(JS::NonnullGCPtr<T> node, JS::GCPtr<T> child)
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{
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if (!child)
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return append_child(move(node));
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@ -531,11 +497,10 @@ inline void TreeNode<T>::insert_before(NonnullRefPtr<T> node, RefPtr<T> child)
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child->m_previous_sibling = node;
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node->m_parent = static_cast<T*>(this);
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[[maybe_unused]] auto& rc = node.leak_ref();
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}
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template<typename T>
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inline void TreeNode<T>::prepend_child(NonnullRefPtr<T> node)
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inline void TreeNode<T>::prepend_child(JS::NonnullGCPtr<T> node)
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{
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VERIFY(!node->m_parent);
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@ -550,7 +515,6 @@ inline void TreeNode<T>::prepend_child(NonnullRefPtr<T> node)
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if (!m_last_child)
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m_last_child = m_first_child;
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node->inserted_into(static_cast<T&>(*this));
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[[maybe_unused]] auto& rc = node.leak_ref();
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static_cast<T*>(this)->children_changed();
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}
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