draft-js/lib/removeEntitiesAtEdges.js.flow

A React framework for building text editors.

/**
 * Copyright (c) Facebook, Inc. and its affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * @format
 * @flow
 * @emails oncall+draft_js
 */
'use strict';

import type { BlockNodeRecord } from "./BlockNodeRecord";
import type ContentState from "./ContentState";
import type { EntityMap } from "./EntityMap";
import type SelectionState from "./SelectionState";
import type { List } from "immutable";

const CharacterMetadata = require("./CharacterMetadata");

const findRangesImmutable = require("./findRangesImmutable");

const invariant = require("fbjs/lib/invariant");

function removeEntitiesAtEdges(contentState: ContentState, selectionState: SelectionState): ContentState {
  const blockMap = contentState.getBlockMap();
  const entityMap = contentState.getEntityMap();
  const updatedBlocks = {};
  const startKey = selectionState.getStartKey();
  const startOffset = selectionState.getStartOffset();
  const startBlock = blockMap.get(startKey);
  const updatedStart = removeForBlock(entityMap, startBlock, startOffset);

  if (updatedStart !== startBlock) {
    updatedBlocks[startKey] = updatedStart;
  }

  const endKey = selectionState.getEndKey();
  const endOffset = selectionState.getEndOffset();
  let endBlock = blockMap.get(endKey);

  if (startKey === endKey) {
    endBlock = updatedStart;
  }

  const updatedEnd = removeForBlock(entityMap, endBlock, endOffset);

  if (updatedEnd !== endBlock) {
    updatedBlocks[endKey] = updatedEnd;
  }

  if (!Object.keys(updatedBlocks).length) {
    return contentState.set('selectionAfter', selectionState);
  }

  return contentState.merge({
    blockMap: blockMap.merge(updatedBlocks),
    selectionAfter: selectionState
  });
}
/**
 * Given a list of characters and an offset that is in the middle of an entity,
 * returns the start and end of the entity that is overlapping the offset.
 * Note: This method requires that the offset be in an entity range.
 */


function getRemovalRange(characters: List<CharacterMetadata>, entityKey: ?string, offset: number): {
  start: number,
  end: number,
  ...
} {
  let removalRange; // Iterates through a list looking for ranges of matching items
  // based on the 'isEqual' callback.
  // Then instead of returning the result, call the 'found' callback
  // with each range.
  // Then filters those ranges based on the 'filter' callback
  //
  // Here we use it to find ranges of characters with the same entity key.

  findRangesImmutable(characters, // the list to iterate through
  (a, b) => a.getEntity() === b.getEntity(), // 'isEqual' callback
  element => element.getEntity() === entityKey, // 'filter' callback
  (start: number, end: number) => {
    // 'found' callback
    if (start <= offset && end >= offset) {
      // this entity overlaps the offset index
      removalRange = {
        start,
        end
      };
    }
  });
  invariant(typeof removalRange === 'object', 'Removal range must exist within character list.');
  return removalRange;
}

function removeForBlock(entityMap: EntityMap, block: BlockNodeRecord, offset: number): BlockNodeRecord {
  let chars = block.getCharacterList();
  const charBefore = offset > 0 ? chars.get(offset - 1) : undefined;
  const charAfter = offset < chars.count() ? chars.get(offset) : undefined;
  const entityBeforeCursor = charBefore ? charBefore.getEntity() : undefined;
  const entityAfterCursor = charAfter ? charAfter.getEntity() : undefined;

  if (entityAfterCursor && entityAfterCursor === entityBeforeCursor) {
    const entity = entityMap.__get(entityAfterCursor);

    if (entity.getMutability() !== 'MUTABLE') {
      let {
        start,
        end
      } = getRemovalRange(chars, entityAfterCursor, offset);
      let current;

      while (start < end) {
        current = chars.get(start);
        chars = chars.set(start, CharacterMetadata.applyEntity(current, null));
        start++;
      }

      return block.set('characterList', chars);
    }
  }

  return block;
}

module.exports = removeEntitiesAtEdges;