Function createOrGetNode

packages/rrdom/src/diff.ts:534–582

(
  rrNode: IRRNode,
  domMirror: NodeMirror,
  rrnodeMirror: Mirror,
)

}

export function createOrGetNode(
  rrNode: IRRNode,
  domMirror: NodeMirror,
  rrnodeMirror: Mirror,
): Node {
  const nodeId = rrnodeMirror.getId(rrNode);
  const sn = rrnodeMirror.getMeta(rrNode);
  let node: Node | null = null;
  // negative ids shouldn't be compared accross mirrors
  if (nodeId > -1) node = domMirror.getNode(nodeId);
  if (node !== null && sameNodeType(node, rrNode)) return node;
  switch (rrNode.RRNodeType) {
    case RRNodeType.Document:
      node = new Document();
      break;
    case RRNodeType.DocumentType:
      node = document.implementation.createDocumentType(
        (rrNode as IRRDocumentType).name,
        (rrNode as IRRDocumentType).publicId,
        (rrNode as IRRDocumentType).systemId,
      );
      break;
    case RRNodeType.Element: {
      let tagName = (rrNode as IRRElement).tagName.toLowerCase();
      tagName = SVGTagMap[tagName] || tagName;
      if (sn && 'isSVG' in sn && sn?.isSVG) {
        node = document.createElementNS(NAMESPACES['svg'], tagName);
      } else node = document.createElement((rrNode as IRRElement).tagName);
      break;
    }
    case RRNodeType.Text:
      node = document.createTextNode((rrNode as IRRText).data);
      break;
    case RRNodeType.Comment:
      node = document.createComment((rrNode as IRRComment).data);
      break;
    case RRNodeType.CDATA:
      node = document.createCDATASection((rrNode as IRRCDATASection).data);
      break;
  }

  if (sn) domMirror.add(node, { ...sn });
  try {
    createdNodeSet?.add(node);
  } catch (e) {
    // Just for safety concern.
  }
  return node;
}

/**
 * To check whether two nodes are the same type of node. If they are both Elements, check wether their tagNames are same or not.