soocrate-core/src/communication/TextManager/RemoveManager.js

this is the core of soocrate application

import { TextEvent } from './TextEvent'
var debug = require('debug')('CRATE:Communication:TextManager:RemoveManager')
export class RemoveManager extends TextEvent {
  constructor(opts) {
    const EventName = opts.EventName || 'Remove'
    super({ EventName, ...opts })

    this._lastSentId = null
    this._textManager = opts.TextManager
    this.action = this.remove
    this._pairs = []
  }

  /*!
     * \brief local deletion of a character from the sequence structure. It 
     * broadcasts the operation to the rest of the network.
     * \param index the index of the element to remove
     * \return the identifier freshly removed
     */
  remove(index) {
    const lseqNode = this._sequence._get(index + 1)
    const isReady = this.getCausalID(lseqNode)
    const reference = this.removeFromSequence(index)
    this._document.delta.ops.splice(index, 1)
    debug('Remove', { index, reference })
    if (reference) {
      this._sequence._c += 1
      this.broadcast({
        id: this._document.uid,
        isReady,
        reference
      })
    }
    this.setLastChangesTime()
  }

  removeFromSequence(index) {
    if (this._sequence.root.subCounter === 2) {
      console.warn('remove from sequence is empty')
    } else if (index >= this._sequence.root.subCounter - 2) {
      console.warn('Lseq, index is out Of Bounds')
    } else {
      const reference = this._sequence.remove(index)
      return reference
    }
    return null
  }

  /*!
     * \brief removal of an element from a remote site.  It emits 'remoteRemove'
     * with the index of the element to remove, -1 if does not exist
     * \param id the result of the remote insert operation
     * \param origin the origin id of the removal
     */
  receive({ id, reference, isReady }) {
    debug('receive remove', { id, reference })
    const index = this._sequence.applyRemove(reference)
    // this.emit('remoteRemove', index);
    this._document.delta.ops.splice(index - 1, 1)

    if (index >= 0) {
      const range = {
        index: index - 1,
        length: 0
      }
      const msg = {
        range,
        id
      }
      this.Event('Caret', msg)
    }

    this.setLastChangesTime()
  }
}