@atlaskit/editor-plugin-show-diff/dist/es2019/pm-plugins/utils/emptyTextBlocks.js

ShowDiff plugin for @atlaskit/editor-core

/**
 * The textblock types whose empty form is a blank line the author put there deliberately, and so
 * worth marking when a change removes it.
 *
 * Deliberately not every textblock: an empty `codeBlock` is an empty code block, which renders as a
 * visible box of its own and needs no stand-in.
 */
const BLANK_LINE_NODE_NAMES = new Set(['paragraph', 'heading']);

/**
 * Structurally empty: no children at all, not merely no measurable content. The two coincide for a
 * real node, and testing both keeps a node whose children report no size from passing as blank.
 */
const isEmptyTextBlock = node => BLANK_LINE_NODE_NAMES.has(node.type.name) && node.content.childCount === 0 && node.content.size === 0;

/**
 * How many empty textblocks a slice holds, or 0 unless that is *all* it holds.
 *
 * Counted rather than tested for one, because a run of adjacent blank lines is reported as a single
 * change covering all of them — the case that made a single-block test miss.
 */
export const countEmptyTextBlockOnlySlice = slice => {
  var _slice$content$childC;
  const childCount = (_slice$content$childC = slice === null || slice === void 0 ? void 0 : slice.content.childCount) !== null && _slice$content$childC !== void 0 ? _slice$content$childC : 0;
  if (!slice || childCount === 0) {
    return 0;
  }
  for (let index = 0; index < childCount; index++) {
    if (!isEmptyTextBlock(slice.content.child(index))) {
      return 0;
    }
  }
  return childCount;
};

/**
 * The content position of every empty textblock lying wholly within `[from, to]`.
 *
 * Used to place a marker on each blank line a change removes. Partially covered blocks are skipped:
 * the change only took part of one, so it still has text of its own, which the inline decoration
 * already marks.
 */
export const emptyTextBlockContentPositions = (doc, from, to) => {
  const positions = [];
  doc.nodesBetween(from, to, (node, pos) => {
    if (node.isTextblock) {
      if (isEmptyTextBlock(node) && pos >= from && pos + node.nodeSize <= to) {
        // +1 steps over the block's own open token, into its (empty) content.
        positions.push(pos + 1);
      }
      // A textblock holds inline content only, so there is nothing below it to visit.
      return false;
    }
    // Keep descending: blank lines nest inside cells, columns and panels.
    return true;
  });
  return positions;
};