ladybird/Libraries/LibHTML/TreeNode.h
Andreas Kling b3a63e1d50 LibHTML: Add TreeNode<T>::for_each_in_subtree(callback)
This helper invokes a callback for the node and each of its descendants
in pre-order.
2019-10-19 18:14:54 +02:00

143 lines
4.1 KiB
C++

#pragma once
#include <AK/Assertions.h>
#include <AK/NonnullRefPtr.h>
#include <AK/Weakable.h>
template<typename T>
class TreeNode : public Weakable<T> {
public:
void ref()
{
ASSERT(m_ref_count);
++m_ref_count;
}
void deref()
{
ASSERT(m_ref_count);
if (!--m_ref_count) {
if (m_next_sibling)
m_next_sibling->m_previous_sibling = m_previous_sibling;
if (m_previous_sibling)
m_previous_sibling->m_next_sibling = m_next_sibling;
T* next_child;
for (auto* child = m_first_child; child; child = next_child) {
next_child = child->m_next_sibling;
child->m_parent = nullptr;
child->deref();
}
delete static_cast<T*>(this);
}
}
int ref_count() const { return m_ref_count; }
T* parent() { return m_parent; }
const T* 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; }
const T* next_sibling() const { return m_next_sibling; }
const T* previous_sibling() const { return m_previous_sibling; }
const T* first_child() const { return m_first_child; }
const T* last_child() const { return m_last_child; }
bool is_ancestor_of(const TreeNode&) const;
void prepend_child(NonnullRefPtr<T> node, bool call_inserted_into = true);
void append_child(NonnullRefPtr<T> node, bool call_inserted_into = true);
void donate_all_children_to(T& node);
bool is_child_allowed(const T&) const { return true; }
template<typename Callback>
void for_each_in_subtree(Callback callback)
{
callback(static_cast<T&>(*this));
for (auto* child = first_child(); child; child = child->next_sibling()) {
child->for_each_in_subtree(callback);
}
}
protected:
TreeNode() {}
private:
int m_ref_count { 1 };
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>::append_child(NonnullRefPtr<T> node, bool call_inserted_into)
{
ASSERT(!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;
if (call_inserted_into)
node->inserted_into(static_cast<T&>(*this));
(void)node.leak_ref();
}
template<typename T>
inline void TreeNode<T>::prepend_child(NonnullRefPtr<T> node, bool call_inserted_into)
{
ASSERT(!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;
if (call_inserted_into)
node->inserted_into(static_cast<T&>(*this));
(void)node.leak_ref();
}
template<typename T>
inline void TreeNode<T>::donate_all_children_to(T& node)
{
for (T* child = m_first_child; child != nullptr;) {
T* next_child = child->m_next_sibling;
child->m_parent = nullptr;
child->m_next_sibling = nullptr;
child->m_previous_sibling = nullptr;
node.append_child(adopt(*child));
child = next_child;
}
m_first_child = nullptr;
m_last_child = nullptr;
}
template<typename T>
inline bool TreeNode<T>::is_ancestor_of(const TreeNode<T>& other) const
{
for (auto* ancestor = other.parent(); ancestor; ancestor = ancestor->parent()) {
if (ancestor == this)
return true;
}
return false;
}