yjs/src/utils/YEvent.js

279 lines
8.4 KiB
JavaScript

import {
isDeleted,
Item, AbstractType, Transaction, AbstractStruct // eslint-disable-line
} from '../internals.js'
import * as set from 'lib0/set'
import * as array from 'lib0/array'
import * as error from 'lib0/error'
const errorComputeChanges = 'You must not compute changes after the event-handler fired.'
/**
* @template {AbstractType<any>} T
* YEvent describes the changes on a YType.
*/
export class YEvent {
/**
* @param {T} target The changed type.
* @param {Transaction} transaction
*/
constructor (target, transaction) {
/**
* The type on which this event was created on.
* @type {T}
*/
this.target = target
/**
* The current target on which the observe callback is called.
* @type {AbstractType<any>}
*/
this.currentTarget = target
/**
* The transaction that triggered this event.
* @type {Transaction}
*/
this.transaction = transaction
/**
* @type {Object|null}
*/
this._changes = null
/**
* @type {null | Map<string, { action: 'add' | 'update' | 'delete', oldValue: any, newValue: any }>}
*/
this._keys = null
/**
* @type {null | Array<{ insert?: string | Array<any> | object | AbstractType<any>, retain?: number, delete?: number, attributes?: Object<string, any> }>}
*/
this._delta = null
/**
* @type {Array<string|number>|null}
*/
this._path = null
}
/**
* Computes the path from `y` to the changed type.
*
* @todo v14 should standardize on path: Array<{parent, index}> because that is easier to work with.
*
* The following property holds:
* @example
* let type = y
* event.path.forEach(dir => {
* type = type.get(dir)
* })
* type === event.target // => true
*/
get path () {
return this._path || (this._path = getPathTo(this.currentTarget, this.target))
}
/**
* Check if a struct is deleted by this event.
*
* In contrast to change.deleted, this method also returns true if the struct was added and then deleted.
*
* @param {AbstractStruct} struct
* @return {boolean}
*/
deletes (struct) {
return isDeleted(this.transaction.deleteSet, struct.id)
}
/**
* @type {Map<string, { action: 'add' | 'update' | 'delete', oldValue: any, newValue: any }>}
*/
get keys () {
if (this._keys === null) {
if (this.transaction.doc._transactionCleanups.length === 0) {
throw error.create(errorComputeChanges)
}
const keys = new Map()
const target = this.target
const changed = /** @type Set<string|null> */ (this.transaction.changed.get(target))
changed.forEach(key => {
if (key !== null) {
const item = /** @type {Item} */ (target._map.get(key))
/**
* @type {'delete' | 'add' | 'update'}
*/
let action
let oldValue
if (this.adds(item)) {
let prev = item.left
while (prev !== null && this.adds(prev)) {
prev = prev.left
}
if (this.deletes(item)) {
if (prev !== null && this.deletes(prev)) {
action = 'delete'
oldValue = array.last(prev.content.getContent())
} else {
return
}
} else {
if (prev !== null && this.deletes(prev)) {
action = 'update'
oldValue = array.last(prev.content.getContent())
} else {
action = 'add'
oldValue = undefined
}
}
} else {
if (this.deletes(item)) {
action = 'delete'
oldValue = array.last(/** @type {Item} */ item.content.getContent())
} else {
return // nop
}
}
keys.set(key, { action, oldValue })
}
})
this._keys = keys
}
return this._keys
}
/**
* This is a computed property. Note that this can only be safely computed during the
* event call. Computing this property after other changes happened might result in
* unexpected behavior (incorrect computation of deltas). A safe way to collect changes
* is to store the `changes` or the `delta` object. Avoid storing the `transaction` object.
*
* @type {Array<{insert?: string | Array<any> | object | AbstractType<any>, retain?: number, delete?: number, attributes?: Object<string, any>}>}
*/
get delta () {
return this.changes.delta
}
/**
* Check if a struct is added by this event.
*
* In contrast to change.deleted, this method also returns true if the struct was added and then deleted.
*
* @param {AbstractStruct} struct
* @return {boolean}
*/
adds (struct) {
return struct.id.clock >= (this.transaction.beforeState.get(struct.id.client) || 0)
}
/**
* This is a computed property. Note that this can only be safely computed during the
* event call. Computing this property after other changes happened might result in
* unexpected behavior (incorrect computation of deltas). A safe way to collect changes
* is to store the `changes` or the `delta` object. Avoid storing the `transaction` object.
*
* @type {{added:Set<Item>,deleted:Set<Item>,keys:Map<string,{action:'add'|'update'|'delete',oldValue:any}>,delta:Array<{insert?:Array<any>|string, delete?:number, retain?:number}>}}
*/
get changes () {
let changes = this._changes
if (changes === null) {
if (this.transaction.doc._transactionCleanups.length === 0) {
throw error.create(errorComputeChanges)
}
const target = this.target
const added = set.create()
const deleted = set.create()
/**
* @type {Array<{insert:Array<any>}|{delete:number}|{retain:number}>}
*/
const delta = []
changes = {
added,
deleted,
delta,
keys: this.keys
}
const changed = /** @type Set<string|null> */ (this.transaction.changed.get(target))
if (changed.has(null)) {
/**
* @type {any}
*/
let lastOp = null
const packOp = () => {
if (lastOp) {
delta.push(lastOp)
}
}
for (let item = target._start; item !== null; item = item.right) {
if (item.deleted) {
if (this.deletes(item) && !this.adds(item)) {
if (lastOp === null || lastOp.delete === undefined) {
packOp()
lastOp = { delete: 0 }
}
lastOp.delete += item.length
deleted.add(item)
} // else nop
} else {
if (this.adds(item)) {
if (lastOp === null || lastOp.insert === undefined) {
packOp()
lastOp = { insert: [] }
}
lastOp.insert = lastOp.insert.concat(item.content.getContent())
added.add(item)
} else {
if (lastOp === null || lastOp.retain === undefined) {
packOp()
lastOp = { retain: 0 }
}
lastOp.retain += item.length
}
}
}
if (lastOp !== null && lastOp.retain === undefined) {
packOp()
}
}
this._changes = changes
}
return /** @type {any} */ (changes)
}
}
/**
* Compute the path from this type to the specified target.
*
* @example
* // `child` should be accessible via `type.get(path[0]).get(path[1])..`
* const path = type.getPathTo(child)
* // assuming `type instanceof YArray`
* console.log(path) // might look like => [2, 'key1']
* child === type.get(path[0]).get(path[1])
*
* @param {AbstractType<any>} parent
* @param {AbstractType<any>} child target
* @return {Array<string|number>} Path to the target
*
* @private
* @function
*/
const getPathTo = (parent, child) => {
const path = []
while (child._item !== null && child !== parent) {
if (child._item.parentSub !== null) {
// parent is map-ish
path.unshift(child._item.parentSub)
} else {
// parent is array-ish
let i = 0
let c = /** @type {AbstractType<any>} */ (child._item.parent)._start
while (c !== child._item && c !== null) {
if (!c.deleted) {
i++
}
c = c.right
}
path.unshift(i)
}
child = /** @type {AbstractType<any>} */ (child._item.parent)
}
return path
}