function textNodesInRange()

in packages/dom/src/highlight-text.ts [75:125]
32 lines of code
10 McCabe index (conditional complexity)

function textNodesInRange(range: Range): Text[] {
  // If the start or end node is a text node and only partly in the range, split it.
  if (isTextNode(range.startContainer) && range.startOffset > 0) {
    const endOffset = range.endOffset; // (this may get lost when the splitting the node)
    const createdNode = range.startContainer.splitText(range.startOffset);
    if (range.endContainer === range.startContainer) {
      // If the end was in the same container, it will now be in the newly created node.
      range.setEnd(createdNode, endOffset - range.startOffset);
    }
    range.setStart(createdNode, 0);
  }
  if (
    isTextNode(range.endContainer) &&
    range.endOffset < range.endContainer.length
  ) {
    range.endContainer.splitText(range.endOffset);
  }

  // Collect the text nodes.
  const walker = ownerDocument(range).createTreeWalker(
    range.commonAncestorContainer,
    NodeFilter.SHOW_TEXT,
    {
      acceptNode: (node) =>
        range.intersectsNode(node)
          ? NodeFilter.FILTER_ACCEPT
          : NodeFilter.FILTER_REJECT,
    },
  );
  walker.currentNode = range.startContainer;

  // // Optimise by skipping nodes that are explicitly outside the range.
  // const NodeTypesWithCharacterOffset = [
  //  Node.TEXT_NODE,
  //  Node.PROCESSING_INSTRUCTION_NODE,
  //  Node.COMMENT_NODE,
  // ];
  // if (!NodeTypesWithCharacterOffset.includes(range.startContainer.nodeType)) {
  //   if (range.startOffset < range.startContainer.childNodes.length) {
  //     walker.currentNode = range.startContainer.childNodes[range.startOffset];
  //   } else {
  //     walker.nextSibling(); // TODO verify this is correct.
  //   }
  // }

  const nodes: Text[] = [];
  if (isTextNode(walker.currentNode)) nodes.push(walker.currentNode);
  while (walker.nextNode() && range.comparePoint(walker.currentNode, 0) !== 1)
    nodes.push(walker.currentNode as Text);
  return nodes;
}