yjs/src/Struct/Delete.js

131 lines
3.9 KiB
JavaScript

import { getStructReference } from '../Util/structReferences.js'
import * as ID from '../Util/ID.js'
import { stringifyID } from '../protocols/syncProtocol.js'
import { writeStructToTransaction } from '../Util/Transaction.js'
import * as decoding from '../../lib/decoding.js'
import * as encoding from '../../lib/encoding.js'
/**
* @private
* Delete all items in an ID-range.
* Does not create delete operations!
* TODO: implement getItemCleanStartNode for better performance (only one lookup).
*/
export function deleteItemRange (y, user, clock, range, gcChildren) {
let item = y.os.getItemCleanStart(ID.createID(user, clock))
if (item !== null) {
if (!item._deleted) {
item._splitAt(y, range)
item._delete(y, false, true)
}
let itemLen = item._length
range -= itemLen
clock += itemLen
if (range > 0) {
let node = y.os.findNode(ID.createID(user, clock))
while (node !== null && node.val !== null && range > 0 && node.val._id.equals(ID.createID(user, clock))) {
const nodeVal = node.val
if (!nodeVal._deleted) {
nodeVal._splitAt(y, range)
nodeVal._delete(y, false, gcChildren)
}
const nodeLen = nodeVal._length
range -= nodeLen
clock += nodeLen
node = node.next()
}
}
}
}
/**
* @private
* A Delete change is not a real Item, but it provides the same interface as an
* Item. The only difference is that it will not be saved in the ItemStore
* (OperationStore), but instead it is safed in the DeleteStore.
*/
export default class Delete {
constructor () {
/**
* @type {ID.ID}
*/
this._targetID = null
/**
* @type {import('./Item.js').default}
*/
this._target = null
this._length = null
}
/**
* @private
* Read the next Item in a Decoder and fill this Item with the read data.
*
* This is called when data is received from a remote peer.
*
* @param {import('../Y.js').default} y The Yjs instance that this Item belongs to.
* @param {decoding.Decoder} decoder The decoder object to read data from.
*/
_fromBinary (y, decoder) {
// TODO: set target, and add it to missing if not found
// There is an edge case in p2p networks!
/**
* @type {any}
*/
const targetID = ID.decode(decoder)
this._targetID = targetID
this._length = decoding.readVarUint(decoder)
if (y.os.getItem(targetID) === null) {
return [targetID]
} else {
return []
}
}
/**
* @private
* Transform the properties of this type to binary and write it to an
* BinaryEncoder.
*
* This is called when this Item is sent to a remote peer.
*
* @param {encoding.Encoder} encoder The encoder to write data to.
*/
_toBinary (encoder) {
encoding.writeUint8(encoder, getStructReference(this.constructor))
this._targetID.encode(encoder)
encoding.writeVarUint(encoder, this._length)
}
/**
* @private
* Integrates this Item into the shared structure.
*
* This method actually applies the change to the Yjs instance. In the case of
* Delete it marks the delete target as deleted.
*
* * If created remotely (a remote user deleted something),
* this Delete is applied to all structs in id-range.
* * If created lokally (e.g. when y-array deletes a range of elements),
* this struct is broadcasted only (it is already executed)
*/
_integrate (y, locallyCreated = false) {
if (!locallyCreated) {
// from remote
const id = this._targetID
deleteItemRange(y, id.user, id.clock, this._length, false)
}
writeStructToTransaction(y._transaction, this)
}
/**
* Transform this YXml Type to a readable format.
* Useful for logging as all Items and Delete implement this method.
*
* @private
*/
_logString () {
return `Delete - target: ${stringifyID(this._targetID)}, len: ${this._length}`
}
}