yjs/src/types/YWeakLink.js

447 lines
13 KiB
JavaScript

import { decoding, encoding } from 'lib0'
import * as map from 'lib0/map'
import * as set from 'lib0/set'
import {
YEvent, AbstractType,
transact,
getItemCleanEnd,
getItemCleanStart,
callTypeObservers,
YWeakLinkRefID,
writeID,
readID,
RelativePosition,
ContentString,
rangeDelta,
formatXmlString,
YText,
YXmlText,
Transaction, Item, Doc, ID, Snapshot, UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, YRange, rangeToRelative, // eslint-disable-line
} from '../internals.js'
/**
* @template T extends AbstractType<any>
* @extends YEvent<any>
* Event that describes the changes on a YMap.
*/
export class YWeakLinkEvent extends YEvent {
/**
* @param {YWeakLink<T>} ylink The YWeakLink to which this event was propagated to.
* @param {Transaction} transaction
*/
// eslint-disable-next-line no-useless-constructor
constructor (ylink, transaction) {
super(ylink, transaction)
}
}
/**
* @template T
* @extends AbstractType<YWeakLinkEvent<T>>
*
* Weak link to another value stored somewhere in the document.
*/
export class YWeakLink extends AbstractType {
/**
* @param {RelativePosition} start
* @param {RelativePosition} end
* @param {Item|null} firstItem
*/
constructor (start, end, firstItem) {
super()
/** @type {RelativePosition} */
this._quoteStart = start
/** @type {RelativePosition} */
this._quoteEnd = end
/** @type {Item|null} */
this._firstItem = firstItem
}
/**
* Position descriptor of the start of a quoted range.
*
* @returns {RelativePosition}
*/
get quoteStart () {
return this._quoteStart
}
/**
* Position descriptor of the end of a quoted range.
*
* @returns {RelativePosition}
*/
get quoteEnd () {
return this._quoteEnd
}
/**
* Check if current link contains only a single element.
*
* @returns {boolean}
*/
get isSingle () {
return this._quoteStart.item === this._quoteEnd.item
}
/**
* Returns a reference to an underlying value existing somewhere on in the document.
*
* @return {T|undefined}
*/
deref () {
if (this._firstItem !== null) {
let item = this._firstItem
if (item.parentSub !== null) {
while (item.right !== null) {
item = item.right
}
// we don't support quotations over maps
this._firstItem = item
}
if (!item.deleted) {
return item.content.getContent()[0]
}
}
return undefined
}
/**
* Returns an array of references to all elements quoted by current weak link.
*
* @return {Array<any>}
*/
unquote () {
let result = /** @type {Array<any>} */ ([])
let n = this._firstItem
if (n !== null && this._quoteStart.assoc >= 0) {
// if assoc >= we exclude start from range
n = n.right
}
const end = /** @type {ID} */ (this._quoteEnd.item)
const endAssoc = this._quoteEnd.assoc
// TODO: moved elements
while (n !== null) {
if (endAssoc < 0 && n.id.client === end.client && n.id.clock === end.clock) {
// right side is open (last item excluded)
break
}
if (!n.deleted) {
result = result.concat(n.content.getContent())
}
const lastId = n.lastId
if (endAssoc >= 0 && lastId.client === end.client && lastId.clock === end.clock) {
break
}
n = n.right
}
return result
}
/**
* Integrate this type into the Yjs instance.
*
* * Save this struct in the os
* * This type is sent to other client
* * Observer functions are fired
*
* @param {Doc} y The Yjs instance
* @param {Item|null} item
*/
_integrate (y, item) {
super._integrate(y, item)
if (item !== null) {
transact(y, (transaction) => {
// link may refer to a single element in multi-element block
// in such case we need to cut of the linked element into a
// separate block
let [firstItem, lastItem] = sliceBlocksByRange(transaction, this._quoteStart, this.quoteEnd)
if (firstItem.parentSub !== null) {
// for maps, advance to most recent item
while (firstItem.right !== null) {
firstItem = firstItem.right
}
}
this._firstItem = firstItem
/** @type {Item|null} */
let item = firstItem
for (;item !== null; item = item.right) {
createLink(transaction, item, this)
if (item === lastItem) {
break
}
}
})
}
}
/**
* @return {YWeakLink<T>}
*/
_copy () {
return new YWeakLink(this._quoteStart, this._quoteEnd, this._firstItem)
}
/**
* @return {YWeakLink<T>}
*/
clone () {
return new YWeakLink(this._quoteStart, this._quoteEnd, this._firstItem)
}
/**
* Creates YWeakLinkEvent and calls observers.
*
* @param {Transaction} transaction
* @param {Set<null|string>} parentSubs Keys changed on this type. `null` if list was modified.
*/
_callObserver (transaction, parentSubs) {
super._callObserver(transaction, parentSubs)
callTypeObservers(this, transaction, new YWeakLinkEvent(this, transaction))
}
/**
* @param {UpdateEncoderV1 | UpdateEncoderV2} encoder
*/
_write (encoder) {
encoder.writeTypeRef(YWeakLinkRefID)
const isSingle = this.isSingle
const info = (isSingle ? 0 : 1) | (this._quoteStart.assoc >= 0 ? 2 : 0) | (this._quoteEnd.assoc >= 0 ? 4 : 0)
encoding.writeUint8(encoder.restEncoder, info)
writeID(encoder.restEncoder, /** @type {ID} */ (this._quoteStart.item))
if (!isSingle) {
writeID(encoder.restEncoder, /** @type {ID} */ (this._quoteEnd.item))
}
}
/**
* Returns the unformatted string representation of this quoted text range.
*
* @public
*/
toString () {
let n = this._firstItem
if (n !== null && this._quoteStart.assoc >= 0) {
// if assoc >= we exclude start from range
n = n.right
}
if (n !== null) {
switch (/** @type {AbstractType<any>} */ (n.parent).constructor) {
case YText: {
let str = ''
const end = /** @type {ID} */ (this._quoteEnd.item)
const endAssoc = this._quoteEnd.assoc
while (n !== null) {
if (endAssoc < 0 && n.id.client === end.client && n.id.clock === end.clock) {
// right side is open (last item excluded)
break
}
if (!n.deleted && n.countable && n.content.constructor === ContentString) {
str += /** @type {ContentString} */ (n.content).str
}
if (endAssoc >= 0) {
const lastId = n.lastId
if (lastId.client === end.client && lastId.clock === end.clock) {
// right side is closed (last item included)
break
}
}
n = n.right
}
return str
}
case YXmlText:
return this.toDelta().map(delta => formatXmlString(delta)).join('')
}
} else {
return ''
}
}
/**
* Returns the Delta representation of quoted part of underlying text type.
*
* @param {Snapshot|undefined} [snapshot]
* @param {Snapshot|undefined} [prevSnapshot]
* @param {function('removed' | 'added', ID):any} [computeYChange]
* @returns {Array<any>}
*/
toDelta (snapshot, prevSnapshot, computeYChange) {
if (this._firstItem !== null && this._quoteStart.item !== null && this._quoteEnd.item !== null) {
const parent = /** @type {AbstractType<any>} */ (this._firstItem.parent)
return rangeDelta(parent, this._quoteStart.item, this._quoteEnd.item, snapshot, prevSnapshot, computeYChange)
} else {
return []
}
}
}
/**
* @param {UpdateDecoderV1 | UpdateDecoderV2} decoder
* @return {YWeakLink<any>}
*/
export const readYWeakLink = decoder => {
const info = decoding.readUint8(decoder.restDecoder)
const isSingle = (info & 1) !== 1
const startAssoc = (info & 2) === 2 ? 0 : -1
const endAssoc = (info & 4) === 4 ? 0 : -1
const startID = readID(decoder.restDecoder)
const start = new RelativePosition(null, null, startID, startAssoc)
const end = new RelativePosition(null, null, isSingle ? startID : readID(decoder.restDecoder), endAssoc)
return new YWeakLink(start, end, null)
}
/**
* Returns a {WeakLink} to an YArray element at given index.
*
* @param {AbstractType<any>} parent
* @param {Transaction} transaction
* @param {YRange} range
* @return {YWeakLink<any>}
*/
export const quoteRange = (transaction, parent, range) => {
const [start, end] = rangeToRelative(parent, range)
const [startItem, endItem] = sliceBlocksByRange(transaction, start, end)
const link = new YWeakLink(start, end, startItem)
if (parent.doc !== null) {
transact(parent.doc, (transaction) => {
for (let item = link._firstItem; item !== null; item = item = item.right) {
createLink(transaction, item, link)
if (item === endItem) {
break
}
}
})
}
return link
}
/**
* Checks relative position markers and slices the corresponding struct store items
* across their positions.
*
* @param {Transaction} transaction
* @param {RelativePosition} start
* @param {RelativePosition} end
* @returns {Array<Item>} first and last item that belongs to a sliced range
*/
const sliceBlocksByRange = (transaction, start, end) => {
if (start.item === null || end.item === null) {
throw new Error('this operation requires range to be bounded on both sides')
}
const first = getItemCleanStart(transaction, start.item)
/** @type {Item} */
let last
if (end.assoc >= 0) {
last = getItemCleanEnd(transaction, transaction.doc.store, end.item)
} else {
const item = getItemCleanStart(transaction, end.item)
last = /** @type {Item} */ (item.left)
}
return [first, last]
}
/**
* Returns a {WeakLink} to an YMap element at given key.
*
* @param {AbstractType<any>} parent
* @param {string} key
* @return {YWeakLink<any>|undefined}
*/
export const mapWeakLink = (parent, key) => {
const item = parent._map.get(key)
if (item !== undefined) {
const start = new RelativePosition(null, null, item.id, 0)
const end = new RelativePosition(null, null, item.id, -1)
const link = new YWeakLink(start, end, item)
if (parent.doc !== null) {
transact(parent.doc, (transaction) => {
createLink(transaction, item, link)
})
}
return link
} else {
return undefined
}
}
/**
* Establishes a link between source and weak link reference.
* It assumes that source has already been split if necessary.
*
* @param {Transaction} transaction
* @param {Item} source
* @param {YWeakLink<any>} linkRef
*/
export const createLink = (transaction, source, linkRef) => {
const allLinks = transaction.doc.store.linkedBy
map.setIfUndefined(allLinks, source, set.create).add(linkRef)
source.linked = true
}
/**
* Deletes the link between source and a weak link reference.
*
* @param {Transaction} transaction
* @param {Item} source
* @param {YWeakLink<any>} linkRef
*/
export const unlinkFrom = (transaction, source, linkRef) => {
const allLinks = transaction.doc.store.linkedBy
const linkedBy = allLinks.get(source)
if (linkedBy !== undefined) {
linkedBy.delete(linkRef)
if (linkedBy.size === 0) {
allLinks.delete(source)
source.linked = false
if (source.countable) {
// since linked property is blocking items from merging,
// it may turn out that source item can be merged now
transaction._mergeStructs.push(source)
}
}
}
}
/**
* Rebinds linkedBy links pointed between neighbours of a current item.
* This method expects that current item has both left and right neighbours.
*
* @param {Transaction} transaction
* @param {Item} item
*/
export const joinLinkedRange = (transaction, item) => {
item.linked = true
const allLinks = transaction.doc.store.linkedBy
const leftLinks = allLinks.get(/** @type {Item} */ (item.left))
const rightLinks = allLinks.get(/** @type {Item} */ (item.right))
if (leftLinks && rightLinks) {
const common = new Set()
for (const link of leftLinks) {
if (rightLinks.has(link)) {
// new item existing in a quoted range in between two elements
common.add(link)
} else if (link._quoteEnd.assoc < 0) {
// We're at the right edge of quoted range - right neighbor is not included
// but the left one is. Since quotation is open on the right side, we need to
// include current item.
common.add(link)
}
}
for (const link of rightLinks) {
if (!leftLinks.has(link) && link._firstItem === item.left && link._quoteStart.assoc >= 0) {
// We're at the right edge of quoted range - right neighbor is not included
// but the left one is. Since quotation is open on the right side, we need to
// include current item.
link._firstItem = item // this item is the new most left-wise
common.add(link)
}
}
if (common.size !== 0) {
allLinks.set(item, common)
}
}
}