@atlaskit/editor-plugin-show-diff/dist/es2019/pm-plugins/calculateDiff/isMarkOnlyChange.js

ShowDiff plugin for @atlaskit/editor-core

/** U+0000 cannot occur in ProseMirror text content, so this cannot collide with document text. */
const NODE_MARKER = '\u0000';

/**
 * Node types and text only; marks and attrs excluded.
 *
 * Text is unprefixed so adjacent runs concatenate — a run only splits because its marks differ, so
 * `strong("hello")` and `strong("hel") + em("lo")` must match. Attrs are excluded because a
 * reconstructed agent edit regenerates `localId`s; `getAttrChangeRanges` reports attrs separately.
 */
const markFreeSignature = (doc, from, to) => {
  const parts = [];
  doc.nodesBetween(from, to, (node, pos) => {
    if (node.isText) {
      var _node$text;
      const start = Math.max(pos, from) - pos;
      const end = Math.min(pos + node.nodeSize, to) - pos;
      parts.push(((_node$text = node.text) !== null && _node$text !== void 0 ? _node$text : '').slice(start, end));
    } else {
      parts.push(`${NODE_MARKER}${node.type.name}`);
    }
    return true;
  });
  return parts.join('');
};

/**
 * Whether a change differs only in marks, with identical structure and text on both sides. Only
 * produced when a mark-aware token encoder is in use.
 */
export const isMarkOnlyChange = ({
  change,
  newDoc,
  originalDoc
}) => {
  const {
    fromA,
    toA,
    fromB,
    toB
  } = change;
  const isPureInsertionOrDeletion = toA === fromA || toB === fromB;
  if (isPureInsertionOrDeletion || toA - fromA !== toB - fromB) {
    return false;
  }
  return markFreeSignature(originalDoc, fromA, toA) === markFreeSignature(newDoc, fromB, toB);
};