substance/model/IncrementalData.js

Substance is a JavaScript library for web-based content editing. It provides building blocks for realizing custom text editors and web-based publishing system. It is developed to power our online editing platform [Substance](http://substance.io).

import isString from '../util/isString'
import isArray from '../util/isArray'
import cloneDeep from '../util/cloneDeep'
import Data from './Data'
import ObjectOperation from './ObjectOperation'
import ArrayOperation from './ArrayOperation'
import TextOperation from './TextOperation'
import CoordinateOperation from './CoordinateOperation'

/**
  Incremental data storage implemention.

  @internal
 */
class IncrementalData extends Data {
  /**
    Create a new node.

    @param {object} nodeData
    @returns {ObjectOperation} The applied operation.
   */
  create (nodeData) {
    if (nodeData._isNode) {
      nodeData = nodeData.toJSON()
    }
    const op = ObjectOperation.Create([nodeData.id], nodeData)
    this.apply(op)
    return op
  }

  /**
    Delete a node.

    @param {String} nodeId
    @returns {ObjectOperation} The applied operation.
   */
  delete (nodeId) {
    var op = null
    var node = this.get(nodeId)
    if (node) {
      var nodeData = node.toJSON()
      op = ObjectOperation.Delete([nodeId], nodeData)
      this.apply(op)
    }
    return op
  }

  /**
    Update a property incrementally.

    The diff can be of the following forms (depending on the updated property type):
      - String:
        - `{ insert: { offset: Number, value: Object } }`
        - `{ delete: { start: Number, end: Number } }`
      - Array:
        - `{ insert: { offset: Number, value: Object } }`
        - `{ delete: { offset: Number } }`

    @param {array} path
    @param {object} diff
    @returns {ObjectOperation} The applied operation.
  */
  update (path, diff) {
    var diffOp = this._getDiffOp(path, diff)
    var op = ObjectOperation.Update(path, diffOp)
    this.apply(op)
    return op
  }

  /**
    Set a property to a new value

    @param {Array} path
    @param {Object} newValue
    @returns {ObjectOperation} The applied operation.
   */
  set (path, newValue) {
    var oldValue = this.get(path)
    var op = ObjectOperation.Set(path, oldValue, newValue)
    this.apply(op)
    return op
  }

  /**
    Apply a given operation.

    @param {ObjectOperation} op
   */
  apply (op) {
    if (op.type === ObjectOperation.NOP) return
    else if (op.type === ObjectOperation.CREATE) {
      // clone here as the operations value must not be changed
      super.create(cloneDeep(op.val))
    } else if (op.type === ObjectOperation.DELETE) {
      super.delete(op.val.id)
    } else if (op.type === ObjectOperation.UPDATE) {
      const diff = op.diff
      super.update(op.path, diff)
    } else if (op.type === ObjectOperation.SET) {
      super.set(op.path, op.val)
    } else {
      throw new Error('Illegal state.')
    }
    this.emit('operation:applied', op, this)
  }

  /**
    Creates proper operation based on provided node path and diff.

    @param {Array} path
    @param {Object} diff
    @returns {ObjectOperation} operation.
    @private
  */
  _getDiffOp (path, diff) {
    var diffOp = null
    if (diff._isOperation) {
      diffOp = diff
    } else {
      var value = this.get(path)
      diff = this._normalizeDiff(value, diff)
      if (value === null || value === undefined) {
        throw new Error('Property has not been initialized: ' + JSON.stringify(path))
      } else if (isString(value)) {
        switch (diff.type) {
          case 'delete': {
            diffOp = TextOperation.Delete(diff.start, value.substring(diff.start, diff.end))
            break
          }
          case 'insert': {
            diffOp = TextOperation.Insert(diff.start, diff.text)
            break
          }
          default:
            throw new Error('Unknown diff type')
        }
      } else if (isArray(value)) {
        switch (diff.type) {
          case 'delete': {
            diffOp = ArrayOperation.Delete(diff.pos, value[diff.pos])
            break
          }
          case 'insert': {
            diffOp = ArrayOperation.Insert(diff.pos, diff.value)
            break
          }
          default:
            throw new Error('Unknown diff type')
        }
      } else if (value._isCoordinate) {
        switch (diff.type) {
          case 'shift': {
            diffOp = CoordinateOperation.Shift(diff.value)
            break
          }
          default:
            throw new Error('Unknown diff type')
        }
      }
    }
    if (!diffOp) {
      throw new Error('Unsupported diff: ' + JSON.stringify(diff))
    }
    return diffOp
  }
}

export default IncrementalData