NodeIterator.cpp 5.5 KB

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  1. /*
  2. * Copyright (c) 2022, Andreas Kling <kling@serenityos.org>
  3. *
  4. * SPDX-License-Identifier: BSD-2-Clause
  5. */
  6. #include <LibWeb/Bindings/DOMExceptionWrapper.h>
  7. #include <LibWeb/Bindings/IDLAbstractOperations.h>
  8. #include <LibWeb/Bindings/NodeWrapper.h>
  9. #include <LibWeb/Bindings/NodeWrapperFactory.h>
  10. #include <LibWeb/DOM/Node.h>
  11. #include <LibWeb/DOM/NodeIterator.h>
  12. namespace Web::DOM {
  13. NodeIterator::NodeIterator(Node& root)
  14. : m_root(root)
  15. , m_reference(root)
  16. {
  17. }
  18. // https://dom.spec.whatwg.org/#dom-document-createnodeiterator
  19. NonnullRefPtr<NodeIterator> NodeIterator::create(Node& root, unsigned what_to_show, RefPtr<NodeFilter> filter)
  20. {
  21. // 1. Let iterator be a new NodeIterator object.
  22. // 2. Set iterator’s root and iterator’s reference to root.
  23. auto iterator = adopt_ref(*new NodeIterator(root));
  24. // 3. Set iterator’s pointer before reference to true.
  25. iterator->m_pointer_before_reference = true;
  26. // 4. Set iterator’s whatToShow to whatToShow.
  27. iterator->m_what_to_show = what_to_show;
  28. // 5. Set iterator’s filter to filter.
  29. iterator->m_filter = move(filter);
  30. // 6. Return iterator.
  31. return iterator;
  32. }
  33. // https://dom.spec.whatwg.org/#dom-nodeiterator-detach
  34. void NodeIterator::detach()
  35. {
  36. // The detach() method steps are to do nothing.
  37. // Its functionality (disabling a NodeIterator object) was removed, but the method itself is preserved for compatibility.
  38. }
  39. // https://dom.spec.whatwg.org/#concept-nodeiterator-traverse
  40. JS::ThrowCompletionOr<RefPtr<Node>> NodeIterator::traverse(Direction direction)
  41. {
  42. // 1. Let node be iterator’s reference.
  43. auto node = m_reference;
  44. // 2. Let beforeNode be iterator’s pointer before reference.
  45. auto before_node = m_pointer_before_reference;
  46. // 3. While true:
  47. while (true) {
  48. // 4. Branch on direction:
  49. if (direction == Direction::Next) {
  50. // next
  51. // If beforeNode is false, then set node to the first node following node in iterator’s iterator collection.
  52. // If there is no such node, then return null.
  53. if (!before_node) {
  54. auto* next_node = node->next_in_pre_order(m_root.ptr());
  55. if (!next_node)
  56. return RefPtr<Node> {};
  57. node = *next_node;
  58. } else {
  59. // If beforeNode is true, then set it to false.
  60. before_node = false;
  61. }
  62. } else {
  63. // previous
  64. // If beforeNode is true, then set node to the first node preceding node in iterator’s iterator collection.
  65. // If there is no such node, then return null.
  66. if (before_node) {
  67. if (node == m_root.ptr())
  68. return nullptr;
  69. auto* previous_node = node->previous_in_pre_order();
  70. if (!previous_node)
  71. return RefPtr<Node> {};
  72. node = *previous_node;
  73. } else {
  74. // If beforeNode is false, then set it to true.
  75. before_node = true;
  76. }
  77. }
  78. // 2. Let result be the result of filtering node within iterator.
  79. auto result = filter(*node);
  80. if (result.is_throw_completion())
  81. return result.release_error();
  82. // 3. If result is FILTER_ACCEPT, then break.
  83. if (result.value() == NodeFilter::FILTER_ACCEPT)
  84. break;
  85. }
  86. // 4. Set iterator’s reference to node.
  87. m_reference = node;
  88. // 5. Set iterator’s pointer before reference to beforeNode.
  89. m_pointer_before_reference = before_node;
  90. // 6. Return node.
  91. return RefPtr<Node> { node };
  92. }
  93. // https://dom.spec.whatwg.org/#concept-node-filter
  94. JS::ThrowCompletionOr<NodeFilter::Result> NodeIterator::filter(Node& node)
  95. {
  96. VERIFY(wrapper());
  97. auto& global_object = wrapper()->global_object();
  98. // 1. If traverser’s active flag is set, then throw an "InvalidStateError" DOMException.
  99. if (m_active)
  100. return JS::throw_completion(wrap(global_object, InvalidStateError::create("NodeIterator is already active")));
  101. // 2. Let n be node’s nodeType attribute value − 1.
  102. auto n = node.node_type() - 1;
  103. // 3. If the nth bit (where 0 is the least significant bit) of traverser’s whatToShow is not set, then return FILTER_SKIP.
  104. if (!(m_what_to_show & (1u << n)))
  105. return NodeFilter::FILTER_SKIP;
  106. // 4. If traverser’s filter is null, then return FILTER_ACCEPT.
  107. if (!m_filter)
  108. return NodeFilter::FILTER_ACCEPT;
  109. // 5. Set traverser’s active flag.
  110. m_active = true;
  111. // 6. Let result be the return value of call a user object’s operation with traverser’s filter, "acceptNode", and « node ».
  112. // If this throws an exception, then unset traverser’s active flag and rethrow the exception.
  113. auto result = Bindings::IDL::call_user_object_operation(m_filter->callback(), "acceptNode", {}, wrap(global_object, node));
  114. if (result.is_abrupt()) {
  115. m_active = false;
  116. return result;
  117. }
  118. // 7. Unset traverser’s active flag.
  119. m_active = false;
  120. // 8. Return result.
  121. auto result_value = TRY(result.value()->to_i32(global_object));
  122. return static_cast<NodeFilter::Result>(result_value);
  123. }
  124. // https://dom.spec.whatwg.org/#dom-nodeiterator-nextnode
  125. JS::ThrowCompletionOr<RefPtr<Node>> NodeIterator::next_node()
  126. {
  127. return traverse(Direction::Next);
  128. }
  129. // https://dom.spec.whatwg.org/#dom-nodeiterator-previousnode
  130. JS::ThrowCompletionOr<RefPtr<Node>> NodeIterator::previous_node()
  131. {
  132. return traverse(Direction::Previous);
  133. }
  134. }