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

ShowDiff plugin for @atlaskit/editor-core

import { Mapping } from '@atlaskit/editor-prosemirror/transform';
// ProseMirror's assoc value chooses which side of an insertion a mapped boundary stays on.
const FROM_ASSOC = -1;
const TO_ASSOC = 1;

/** Maps a step's range into final-document coordinates when the rollout path supplies step maps. */
export const mapStepRangeToFinal = (from, to, stepIndex, stepMaps) => {
  if (!stepMaps) {
    return {
      fromB: from,
      toB: to
    };
  }

  // The range is already in the document immediately after this step, so skip its own map and
  // apply only the maps from subsequent steps.
  const firstSubsequentStepIndex = stepIndex + 1;
  const finalRange = new Mapping(stepMaps.slice(firstSubsequentStepIndex));
  const fromB = finalRange.mapResult(from, FROM_ASSOC);
  const toB = finalRange.mapResult(to, TO_ASSOC);
  if (fromB.deleted && toB.deleted) {
    return undefined;
  }
  return {
    fromB: fromB.pos,
    toB: toB.pos
  };
};