ladybird/Userland/Libraries/LibWeb/TreeNode.h
Andreas Kling 268b9c5d90 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.
2022-10-20 15:16:23 +02:00

564 lines
16 KiB
C++

/*
* Copyright (c) 2018-2022, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/Assertions.h>
#include <AK/TypeCasts.h>
#include <LibJS/Heap/GCPtr.h>
#include <LibWeb/Forward.h>
namespace Web {
template<typename T>
class TreeNode {
public:
T* parent() { return m_parent; }
T const* parent() const { return m_parent; }
bool has_children() const { return m_first_child; }
T* next_sibling() { return m_next_sibling; }
T* previous_sibling() { return m_previous_sibling; }
T* first_child() { return m_first_child; }
T* last_child() { return m_last_child; }
T const* next_sibling() const { return m_next_sibling; }
T const* previous_sibling() const { return m_previous_sibling; }
T const* first_child() const { return m_first_child; }
T const* last_child() const { return m_last_child; }
size_t child_count() const
{
size_t count = 0;
for (auto* child = first_child(); child; child = child->next_sibling())
++count;
return count;
}
T* child_at_index(int index)
{
int count = 0;
for (auto* child = first_child(); child; child = child->next_sibling()) {
if (count == index)
return child;
++count;
}
return nullptr;
}
T const* child_at_index(int index) const
{
return const_cast<TreeNode*>(this)->child_at_index(index);
}
// https://dom.spec.whatwg.org/#concept-tree-index
size_t index() const
{
// The index of an object is its number of preceding siblings, or 0 if it has none.
size_t index = 0;
for (auto* node = previous_sibling(); node; node = node->previous_sibling())
++index;
return index;
}
Optional<size_t> index_of_child(T const& search_child)
{
VERIFY(search_child.parent() == this);
size_t index = 0;
auto* child = first_child();
VERIFY(child);
do {
if (child == &search_child)
return index;
index++;
} while (child && (child = child->next_sibling()));
return {};
}
template<typename ChildType>
Optional<size_t> index_of_child(T const& search_child)
{
VERIFY(search_child.parent() == this);
size_t index = 0;
auto* child = first_child();
VERIFY(child);
do {
if (!is<ChildType>(child))
continue;
if (child == &search_child)
return index;
index++;
} while (child && (child = child->next_sibling()));
return {};
}
bool is_ancestor_of(TreeNode const&) const;
bool is_inclusive_ancestor_of(TreeNode const&) const;
bool is_descendant_of(TreeNode const&) const;
bool is_inclusive_descendant_of(TreeNode const&) const;
bool is_following(TreeNode const&) const;
void append_child(JS::NonnullGCPtr<T> node);
void prepend_child(JS::NonnullGCPtr<T> node);
void insert_before(JS::NonnullGCPtr<T> node, JS::GCPtr<T> child);
void remove_child(JS::NonnullGCPtr<T> node);
bool is_child_allowed(T const&) const { return true; }
T* next_in_pre_order()
{
if (first_child())
return first_child();
T* node;
if (!(node = next_sibling())) {
node = parent();
while (node && !node->next_sibling())
node = node->parent();
if (node)
node = node->next_sibling();
}
return node;
}
T* next_in_pre_order(T const* stay_within)
{
if (first_child())
return first_child();
T* node = static_cast<T*>(this);
T* next = nullptr;
while (!(next = node->next_sibling())) {
node = node->parent();
if (!node || node == stay_within)
return nullptr;
}
return next;
}
T const* next_in_pre_order() const
{
return const_cast<TreeNode*>(this)->next_in_pre_order();
}
T const* next_in_pre_order(T const* stay_within) const
{
return const_cast<TreeNode*>(this)->next_in_pre_order(stay_within);
}
T* previous_in_pre_order()
{
if (auto* node = previous_sibling()) {
while (node->last_child())
node = node->last_child();
return node;
}
return parent();
}
T const* previous_in_pre_order() const
{
return const_cast<TreeNode*>(this)->previous_in_pre_order();
}
bool is_before(T const& other) const
{
if (this == &other)
return false;
for (auto* node = this; node; node = node->next_in_pre_order()) {
if (node == &other)
return true;
}
return false;
}
// https://dom.spec.whatwg.org/#concept-tree-preceding (Object A is 'typename U' and Object B is 'this')
template<typename U>
bool has_preceding_node_of_type_in_tree_order() const
{
for (auto* node = previous_in_pre_order(); node; node = node->previous_in_pre_order()) {
if (is<U>(node))
return true;
}
return false;
}
// https://dom.spec.whatwg.org/#concept-tree-following (Object A is 'typename U' and Object B is 'this')
template<typename U>
bool has_following_node_of_type_in_tree_order() const
{
for (auto* node = next_in_pre_order(); node; node = node->next_in_pre_order()) {
if (is<U>(node))
return true;
}
return false;
}
template<typename Callback>
IterationDecision for_each_in_inclusive_subtree(Callback callback) const
{
if (callback(static_cast<T const&>(*this)) == IterationDecision::Break)
return IterationDecision::Break;
for (auto* child = first_child(); child; child = child->next_sibling()) {
if (child->for_each_in_inclusive_subtree(callback) == IterationDecision::Break)
return IterationDecision::Break;
}
return IterationDecision::Continue;
}
template<typename Callback>
IterationDecision for_each_in_inclusive_subtree(Callback callback)
{
if (callback(static_cast<T&>(*this)) == IterationDecision::Break)
return IterationDecision::Break;
for (auto* child = first_child(); child; child = child->next_sibling()) {
if (child->for_each_in_inclusive_subtree(callback) == IterationDecision::Break)
return IterationDecision::Break;
}
return IterationDecision::Continue;
}
template<typename U, typename Callback>
IterationDecision for_each_in_inclusive_subtree_of_type(Callback callback)
{
if (is<U>(static_cast<T const&>(*this))) {
if (callback(static_cast<U&>(*this)) == IterationDecision::Break)
return IterationDecision::Break;
}
for (auto* child = first_child(); child; child = child->next_sibling()) {
if (child->template for_each_in_inclusive_subtree_of_type<U>(callback) == IterationDecision::Break)
return IterationDecision::Break;
}
return IterationDecision::Continue;
}
template<typename U, typename Callback>
IterationDecision for_each_in_inclusive_subtree_of_type(Callback callback) const
{
if (is<U>(static_cast<T const&>(*this))) {
if (callback(static_cast<U const&>(*this)) == IterationDecision::Break)
return IterationDecision::Break;
}
for (auto* child = first_child(); child; child = child->next_sibling()) {
if (child->template for_each_in_inclusive_subtree_of_type<U>(callback) == IterationDecision::Break)
return IterationDecision::Break;
}
return IterationDecision::Continue;
}
template<typename Callback>
IterationDecision for_each_in_subtree(Callback callback) const
{
for (auto* child = first_child(); child; child = child->next_sibling()) {
if (child->for_each_in_inclusive_subtree(callback) == IterationDecision::Break)
return IterationDecision::Break;
}
return IterationDecision::Continue;
}
template<typename Callback>
IterationDecision for_each_in_subtree(Callback callback)
{
for (auto* child = first_child(); child; child = child->next_sibling()) {
if (child->for_each_in_inclusive_subtree(callback) == IterationDecision::Break)
return IterationDecision::Break;
}
return IterationDecision::Continue;
}
template<typename U, typename Callback>
IterationDecision for_each_in_subtree_of_type(Callback callback)
{
for (auto* child = first_child(); child; child = child->next_sibling()) {
if (child->template for_each_in_inclusive_subtree_of_type<U>(callback) == IterationDecision::Break)
return IterationDecision::Break;
}
return IterationDecision::Continue;
}
template<typename U, typename Callback>
IterationDecision for_each_in_subtree_of_type(Callback callback) const
{
for (auto* child = first_child(); child; child = child->next_sibling()) {
if (child->template for_each_in_inclusive_subtree_of_type<U>(callback) == IterationDecision::Break)
return IterationDecision::Break;
}
return IterationDecision::Continue;
}
template<typename Callback>
void for_each_child(Callback callback) const
{
return const_cast<TreeNode*>(this)->template for_each_child(move(callback));
}
template<typename Callback>
void for_each_child(Callback callback)
{
for (auto* node = first_child(); node; node = node->next_sibling())
callback(*node);
}
template<typename U, typename Callback>
void for_each_child_of_type(Callback callback)
{
for (auto* node = first_child(); node; node = node->next_sibling()) {
if (is<U>(node))
callback(verify_cast<U>(*node));
}
}
template<typename U, typename Callback>
void for_each_child_of_type(Callback callback) const
{
return const_cast<TreeNode*>(this)->template for_each_child_of_type<U>(move(callback));
}
template<typename U>
U const* next_sibling_of_type() const
{
return const_cast<TreeNode*>(this)->template next_sibling_of_type<U>();
}
template<typename U>
inline U* next_sibling_of_type()
{
for (auto* sibling = next_sibling(); sibling; sibling = sibling->next_sibling()) {
if (is<U>(*sibling))
return &verify_cast<U>(*sibling);
}
return nullptr;
}
template<typename U>
U const* previous_sibling_of_type() const
{
return const_cast<TreeNode*>(this)->template previous_sibling_of_type<U>();
}
template<typename U>
U* previous_sibling_of_type()
{
for (auto* sibling = previous_sibling(); sibling; sibling = sibling->previous_sibling()) {
if (is<U>(*sibling))
return &verify_cast<U>(*sibling);
}
return nullptr;
}
template<typename U>
U const* first_child_of_type() const
{
return const_cast<TreeNode*>(this)->template first_child_of_type<U>();
}
template<typename U>
U const* last_child_of_type() const
{
return const_cast<TreeNode*>(this)->template last_child_of_type<U>();
}
template<typename U>
U* first_child_of_type()
{
for (auto* child = first_child(); child; child = child->next_sibling()) {
if (is<U>(*child))
return &verify_cast<U>(*child);
}
return nullptr;
}
template<typename U>
U* last_child_of_type()
{
for (auto* child = last_child(); child; child = child->previous_sibling()) {
if (is<U>(*child))
return &verify_cast<U>(*child);
}
return nullptr;
}
template<typename U>
bool has_child_of_type() const
{
return first_child_of_type<U>() != nullptr;
}
template<typename U>
U const* first_ancestor_of_type() const
{
return const_cast<TreeNode*>(this)->template first_ancestor_of_type<U>();
}
template<typename U>
U* first_ancestor_of_type()
{
for (auto* ancestor = parent(); ancestor; ancestor = ancestor->parent()) {
if (is<U>(*ancestor))
return &verify_cast<U>(*ancestor);
}
return nullptr;
}
bool is_parent_of(T const& other) const
{
for (auto* child = first_child(); child; child = child->next_sibling()) {
if (&other == child)
return true;
}
return false;
}
~TreeNode() = default;
protected:
TreeNode() = default;
void visit_edges(JS::Cell::Visitor& visitor)
{
visitor.visit(m_parent);
visitor.visit(m_first_child);
visitor.visit(m_last_child);
visitor.visit(m_next_sibling);
visitor.visit(m_previous_sibling);
}
private:
T* m_parent { nullptr };
T* m_first_child { nullptr };
T* m_last_child { nullptr };
T* m_next_sibling { nullptr };
T* m_previous_sibling { nullptr };
};
template<typename T>
inline void TreeNode<T>::remove_child(JS::NonnullGCPtr<T> node)
{
VERIFY(node->m_parent == this);
if (m_first_child == node)
m_first_child = node->m_next_sibling;
if (m_last_child == node)
m_last_child = node->m_previous_sibling;
if (node->m_next_sibling)
node->m_next_sibling->m_previous_sibling = node->m_previous_sibling;
if (node->m_previous_sibling)
node->m_previous_sibling->m_next_sibling = node->m_next_sibling;
node->m_next_sibling = nullptr;
node->m_previous_sibling = nullptr;
node->m_parent = nullptr;
}
template<typename T>
inline void TreeNode<T>::append_child(JS::NonnullGCPtr<T> node)
{
VERIFY(!node->m_parent);
if (!static_cast<T*>(this)->is_child_allowed(*node))
return;
if (m_last_child)
m_last_child->m_next_sibling = node.ptr();
node->m_previous_sibling = m_last_child;
node->m_parent = static_cast<T*>(this);
m_last_child = node.ptr();
if (!m_first_child)
m_first_child = m_last_child;
}
template<typename T>
inline void TreeNode<T>::insert_before(JS::NonnullGCPtr<T> node, JS::GCPtr<T> child)
{
if (!child)
return append_child(move(node));
VERIFY(!node->m_parent);
VERIFY(child->parent() == this);
node->m_previous_sibling = child->m_previous_sibling;
node->m_next_sibling = child;
if (child->m_previous_sibling)
child->m_previous_sibling->m_next_sibling = node;
if (m_first_child == child)
m_first_child = node;
child->m_previous_sibling = node;
node->m_parent = static_cast<T*>(this);
}
template<typename T>
inline void TreeNode<T>::prepend_child(JS::NonnullGCPtr<T> node)
{
VERIFY(!node->m_parent);
if (!static_cast<T*>(this)->is_child_allowed(*node))
return;
if (m_first_child)
m_first_child->m_previous_sibling = node.ptr();
node->m_next_sibling = m_first_child;
node->m_parent = static_cast<T*>(this);
m_first_child = node.ptr();
if (!m_last_child)
m_last_child = m_first_child;
node->inserted_into(static_cast<T&>(*this));
static_cast<T*>(this)->children_changed();
}
template<typename T>
inline bool TreeNode<T>::is_ancestor_of(TreeNode<T> const& other) const
{
for (auto* ancestor = other.parent(); ancestor; ancestor = ancestor->parent()) {
if (ancestor == this)
return true;
}
return false;
}
template<typename T>
inline bool TreeNode<T>::is_inclusive_ancestor_of(TreeNode<T> const& other) const
{
return &other == this || is_ancestor_of(other);
}
template<typename T>
inline bool TreeNode<T>::is_descendant_of(TreeNode<T> const& other) const
{
return other.is_ancestor_of(*this);
}
template<typename T>
inline bool TreeNode<T>::is_inclusive_descendant_of(TreeNode<T> const& other) const
{
return other.is_inclusive_ancestor_of(*this);
}
// https://dom.spec.whatwg.org/#concept-tree-following
template<typename T>
inline bool TreeNode<T>::is_following(TreeNode<T> const& other) const
{
// An object A is following an object B if A and B are in the same tree and A comes after B in tree order.
for (auto* node = previous_in_pre_order(); node; node = node->previous_in_pre_order()) {
if (node == &other)
return true;
}
return false;
}
}