ladybird/Userland/Libraries/LibWeb/DOM/NodeIterator.cpp
Linus Groh 40a70461a0 LibWeb: Replace GlobalObject with Realm in wrapper functions
Similar to create() in LibJS, wrap() et al. are on a low enough level to
warrant passing a Realm directly instead of relying on the current realm
from the VM, as a wrapper may need to be allocated while no JS is being
executed.
2022-08-23 13:58:30 +01:00

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/*
* Copyright (c) 2022, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <LibWeb/Bindings/DOMExceptionWrapper.h>
#include <LibWeb/Bindings/IDLAbstractOperations.h>
#include <LibWeb/Bindings/NodeWrapper.h>
#include <LibWeb/Bindings/NodeWrapperFactory.h>
#include <LibWeb/DOM/Node.h>
#include <LibWeb/DOM/NodeIterator.h>
namespace Web::DOM {
NodeIterator::NodeIterator(Node& root)
: m_root(root)
, m_reference({ root })
{
root.document().register_node_iterator({}, *this);
}
NodeIterator::~NodeIterator()
{
m_root->document().unregister_node_iterator({}, *this);
}
// https://dom.spec.whatwg.org/#dom-document-createnodeiterator
NonnullRefPtr<NodeIterator> NodeIterator::create(Node& root, unsigned what_to_show, RefPtr<NodeFilter> filter)
{
// 1. Let iterator be a new NodeIterator object.
// 2. Set iterators root and iterators reference to root.
// 3. Set iterators pointer before reference to true.
auto iterator = adopt_ref(*new NodeIterator(root));
// 4. Set iterators whatToShow to whatToShow.
iterator->m_what_to_show = what_to_show;
// 5. Set iterators filter to filter.
iterator->m_filter = move(filter);
// 6. Return iterator.
return iterator;
}
// https://dom.spec.whatwg.org/#dom-nodeiterator-detach
void NodeIterator::detach()
{
// The detach() method steps are to do nothing.
// Its functionality (disabling a NodeIterator object) was removed, but the method itself is preserved for compatibility.
}
// https://dom.spec.whatwg.org/#concept-nodeiterator-traverse
JS::ThrowCompletionOr<RefPtr<Node>> NodeIterator::traverse(Direction direction)
{
// 1. Let node be iterators reference.
// 2. Let beforeNode be iterators pointer before reference.
m_traversal_pointer = m_reference;
RefPtr<Node> candidate;
// 3. While true:
while (true) {
// 4. Branch on direction:
if (direction == Direction::Next) {
// next
// If beforeNode is false, then set node to the first node following node in iterators iterator collection.
// If there is no such node, then return null.
if (!m_traversal_pointer->is_before_node) {
auto* next_node = m_traversal_pointer->node->next_in_pre_order(m_root.ptr());
if (!next_node)
return nullptr;
m_traversal_pointer->node = *next_node;
} else {
// If beforeNode is true, then set it to false.
m_traversal_pointer->is_before_node = false;
}
} else {
// previous
// If beforeNode is true, then set node to the first node preceding node in iterators iterator collection.
// If there is no such node, then return null.
if (m_traversal_pointer->is_before_node) {
if (m_traversal_pointer->node == m_root.ptr())
return nullptr;
auto* previous_node = m_traversal_pointer->node->previous_in_pre_order();
if (!previous_node)
return nullptr;
m_traversal_pointer->node = *previous_node;
} else {
// If beforeNode is false, then set it to true.
m_traversal_pointer->is_before_node = true;
}
}
// NOTE: If the NodeFilter deletes the iterator's current traversal pointer,
// we will automatically retarget it. However, in that case, we're expected
// to return the node passed to the filter, not the adjusted traversal pointer's
// node after the filter returns!
candidate = m_traversal_pointer->node;
// 2. Let result be the result of filtering node within iterator.
auto result = TRY(filter(*m_traversal_pointer->node));
// 3. If result is FILTER_ACCEPT, then break.
if (result == NodeFilter::FILTER_ACCEPT)
break;
}
// 4. Set iterators reference to node.
// 5. Set iterators pointer before reference to beforeNode.
m_reference = m_traversal_pointer.release_value();
// 6. Return node.
return candidate;
}
// https://dom.spec.whatwg.org/#concept-node-filter
JS::ThrowCompletionOr<NodeFilter::Result> NodeIterator::filter(Node& node)
{
VERIFY(wrapper());
auto& vm = wrapper()->vm();
auto& realm = *vm.current_realm();
// 1. If traversers active flag is set, then throw an "InvalidStateError" DOMException.
if (m_active)
return JS::throw_completion(wrap(realm, InvalidStateError::create("NodeIterator is already active")));
// 2. Let n be nodes nodeType attribute value 1.
auto n = node.node_type() - 1;
// 3. If the nth bit (where 0 is the least significant bit) of traversers whatToShow is not set, then return FILTER_SKIP.
if (!(m_what_to_show & (1u << n)))
return NodeFilter::FILTER_SKIP;
// 4. If traversers filter is null, then return FILTER_ACCEPT.
if (!m_filter)
return NodeFilter::FILTER_ACCEPT;
// 5. Set traversers active flag.
m_active = true;
// 6. Let result be the return value of call a user objects operation with traversers filter, "acceptNode", and « node ».
// If this throws an exception, then unset traversers active flag and rethrow the exception.
auto result = Bindings::IDL::call_user_object_operation(m_filter->callback(), "acceptNode", {}, wrap(realm, node));
if (result.is_abrupt()) {
m_active = false;
return result;
}
// 7. Unset traversers active flag.
m_active = false;
// 8. Return result.
auto result_value = TRY(result.value()->to_i32(vm));
return static_cast<NodeFilter::Result>(result_value);
}
// https://dom.spec.whatwg.org/#dom-nodeiterator-nextnode
JS::ThrowCompletionOr<RefPtr<Node>> NodeIterator::next_node()
{
return traverse(Direction::Next);
}
// https://dom.spec.whatwg.org/#dom-nodeiterator-previousnode
JS::ThrowCompletionOr<RefPtr<Node>> NodeIterator::previous_node()
{
return traverse(Direction::Previous);
}
void NodeIterator::run_pre_removing_steps_with_node_pointer(Node& to_be_removed_node, NodePointer& pointer)
{
// NOTE: This function tries to match the behavior of other engines, but not the DOM specification
// as it's a known issue that the spec doesn't match how major browsers behave.
// Spec bug: https://github.com/whatwg/dom/issues/907
if (!to_be_removed_node.is_descendant_of(root()))
return;
if (!to_be_removed_node.is_inclusive_ancestor_of(pointer.node))
return;
if (pointer.is_before_node) {
if (auto* node = to_be_removed_node.next_in_pre_order(root())) {
while (node && node->is_descendant_of(to_be_removed_node))
node = node->next_in_pre_order(root());
if (node)
pointer.node = *node;
return;
}
if (auto* node = to_be_removed_node.previous_in_pre_order()) {
if (to_be_removed_node.is_ancestor_of(pointer.node)) {
while (node && node->is_descendant_of(to_be_removed_node))
node = node->previous_in_pre_order();
}
if (node) {
pointer = {
.node = *node,
.is_before_node = false,
};
}
}
return;
}
if (auto* node = to_be_removed_node.previous_in_pre_order()) {
if (to_be_removed_node.is_ancestor_of(pointer.node)) {
while (node && node->is_descendant_of(to_be_removed_node))
node = node->previous_in_pre_order();
}
if (node)
pointer.node = *node;
return;
}
auto* node = to_be_removed_node.next_in_pre_order(root());
if (to_be_removed_node.is_ancestor_of(pointer.node)) {
while (node && node->is_descendant_of(to_be_removed_node))
node = node->previous_in_pre_order();
}
if (node)
pointer.node = *node;
}
// https://dom.spec.whatwg.org/#nodeiterator-pre-removing-steps
void NodeIterator::run_pre_removing_steps(Node& to_be_removed_node)
{
// NOTE: If we're in the middle of traversal, we have to adjust the traversal pointer in response to node removal.
if (m_traversal_pointer.has_value())
run_pre_removing_steps_with_node_pointer(to_be_removed_node, *m_traversal_pointer);
run_pre_removing_steps_with_node_pointer(to_be_removed_node, m_reference);
}
}