Files
yjs/src/utils/ListCursor.js
2022-07-19 14:49:46 +02:00

740 lines
21 KiB
JavaScript

import * as error from 'lib0/error'
import {
getItemCleanStart,
createID,
getMovedCoords,
updateMarkerChanges,
getState,
ContentAny,
ContentBinary,
ContentType,
ContentDoc,
Doc,
compareIDs,
createRelativePosition,
RelativePosition, ID, AbstractContent, ContentMove, Transaction, Item, AbstractType // eslint-disable-line
} from '../internals.js'
import { compareRelativePositions } from './RelativePosition.js'
import * as array from 'lib0/array'
const lengthExceeded = error.create('Length exceeded!')
/**
* We keep the moved-stack across several transactions. Local or remote changes can invalidate
* "moved coords" on the moved-stack.
*
* The reason for this is that if assoc < 0, then getMovedCoords will return the target.right item.
* While the computed item is on the stack, it is possible that a user inserts something between target
* and the item on the stack. Then we expect that the newly inserted item is supposed to be on the new
* computed item.
*
* @param {Transaction} tr
* @param {ListCursor} li
*/
const popMovedStack = (tr, li) => {
let { start, end, move } = li.movedStack.pop() || { start: null, end: null, move: null }
if (move) {
const moveContent = /** @type {ContentMove} */ (move.content)
if (
(
moveContent.start.assoc < 0 && (
(start === null && moveContent.start.item !== null) ||
(start !== null && !compareIDs(/** @type {Item} */ (start.left).lastId, moveContent.start.item))
)
) || (
moveContent.end.assoc < 0 && (
(end === null && moveContent.end.item !== null) ||
(end !== null && !compareIDs(/** @type {Item} */ (end.left).lastId, moveContent.end.item))
)
)
) {
const coords = getMovedCoords(moveContent, tr, false)
start = coords.start
end = coords.end
}
}
li.currMove = move
li.currMoveStart = start
li.currMoveEnd = end
li.reachedEnd = false
}
/**
* Structure that helps to iterate through list-like structures. This is a useful abstraction that keeps track of move operations.
*/
export class ListCursor {
/**
* @param {AbstractType<any>} type
*/
constructor (type) {
this.type = type
/**
* Current index-position
*/
this.index = 0
/**
* Relative position to the current item (if item.content.length > 1)
*/
this.rel = 0
/**
* This refers to the current right item, unless reachedEnd is true. Then it refers to the left item.
*
* @public
* @type {Item | null}
*/
this.nextItem = type._start
this.reachedEnd = type._start === null
/**
* @type {Item | null}
*/
this.currMove = null
/**
* @type {Item | null}
*/
this.currMoveStart = null
/**
* @type {Item | null}
*/
this.currMoveEnd = null
/**
* @type {Array<{ start: Item | null, end: Item | null, move: Item }>}
*/
this.movedStack = []
}
clone () {
const iter = new ListCursor(this.type)
iter.index = this.index
iter.rel = this.rel
iter.nextItem = this.nextItem
iter.reachedEnd = this.reachedEnd
iter.currMove = this.currMove
iter.currMoveStart = this.currMoveStart
iter.currMoveEnd = this.currMoveEnd
iter.movedStack = this.movedStack.slice()
return iter
}
/**
* @type {Item | null}
*/
get left () {
if (this.reachedEnd) {
return this.nextItem
} else {
return this.nextItem && this.nextItem.left
}
}
/**
* @type {Item | null}
*/
get right () {
if (this.reachedEnd) {
return null
} else {
return this.nextItem
}
}
/**
* @param {Transaction} tr
* @param {number} index
*/
moveTo (tr, index) {
const diff = index - this.index
if (diff > 0) {
this.forward(tr, diff, true)
} else if (diff < 0) {
this.backward(tr, -diff)
}
}
/**
* When using skipUncountables=false within a "useSearchMarker" call, it is recommended
* to move the marker to the end. @todo do this after each useSearchMarkerCall
*
* @param {Transaction} tr
* @param {number} len
* @param {boolean} skipUncountables Iterate as much as possible iterating over uncountables until we find the next item.
*/
forward (tr, len, skipUncountables) {
if (len === 0 && this.nextItem == null) {
return this
}
if (this.index + len > this.type._length || this.nextItem == null) {
throw lengthExceeded
}
let item = /** @type {Item} */ (this.nextItem)
this.index += len
// eslint-disable-next-line no-unmodified-loop-condition
while ((!this.reachedEnd || this.currMove !== null) && (len > 0 || (skipUncountables && len === 0 && item && (!item.countable || item.deleted || item === this.currMoveEnd || (this.reachedEnd && this.currMoveEnd === null) || item.moved !== this.currMove)))) {
if (item === this.currMoveEnd || (this.currMoveEnd === null && this.reachedEnd && this.currMove)) {
item = /** @type {Item} */ (this.currMove) // we iterate to the right after the current condition
popMovedStack(tr, this)
} else if (item === null) {
error.unexpectedCase() // should never happen
} else if (item.countable && !item.deleted && item.moved === this.currMove && len > 0) {
len -= item.length
if (len < 0) {
this.rel = item.length + len
len = 0
break
}
} else if (item.content.constructor === ContentMove && item.moved === this.currMove) {
if (this.currMove) {
this.movedStack.push({ start: this.currMoveStart, end: this.currMoveEnd, move: this.currMove })
}
const { start, end } = getMovedCoords(item.content, tr, false)
this.currMove = item
this.currMoveStart = start
this.currMoveEnd = end
item = start
continue
}
if (this.reachedEnd) {
throw error.unexpectedCase
}
if (item.right) {
item = item.right
} else {
this.reachedEnd = true
}
}
this.index -= len
this.nextItem = item
return this
}
/**
* We prefer to insert content outside of a moved range.
* Try to escape the moved range by walking to the left over deleted items.
*
* @param {Transaction} tr
*/
reduceMoveDepth (tr) {
let nextItem = this.nextItem
if (nextItem !== null) {
while (this.currMove) {
if (nextItem === this.currMoveStart) {
nextItem = /** @type {Item} */ (this.currMove) // we iterate to the left after the current condition
popMovedStack(tr, this)
continue
}
// check if we can iterate to the left while stepping over deleted items until we find an item === this.currMoveStart
/**
* @type {Item} nextItem
*/
let item = nextItem
while (item.deleted && item.moved === this.currMove && item !== this.currMoveStart) {
item = /** @type {Item} */ (item.left) // this must exist otherwise we miscalculated the move
}
if (item === this.currMoveStart) {
// we only want to iterate over deleted items if we can escape a move
nextItem = item
} else {
break
}
}
this.nextItem = nextItem
}
}
/**
* @param {Transaction} tr
* @param {number} len
* @return {ListCursor}
*/
backward (tr, len) {
if (this.index - len < 0) {
throw lengthExceeded
}
this.index -= len
if (this.reachedEnd) {
const nextItem = /** @type {Item} */ (this.nextItem)
this.rel = nextItem.countable && !nextItem.deleted ? nextItem.length : 0
this.reachedEnd = false
}
if (this.rel >= len) {
this.rel -= len
return this
}
let item = this.nextItem
if (item && item.content.constructor === ContentMove) {
item = item.left
} else {
len += ((item && item.countable && !item.deleted && item.moved === this.currMove) ? item.length : 0) - this.rel
}
this.rel = 0
while (item && len > 0) {
if (item.countable && !item.deleted && item.moved === this.currMove) {
len -= item.length
if (len < 0) {
this.rel = -len
len = 0
}
if (len === 0) {
break
}
} else if (item.content.constructor === ContentMove && item.moved === this.currMove) {
if (this.currMove) {
this.movedStack.push({ start: this.currMoveStart, end: this.currMoveEnd, move: this.currMove })
}
const { start, end } = getMovedCoords(item.content, tr, false)
this.currMove = item
this.currMoveStart = start
this.currMoveEnd = end
item = start
continue
}
if (item === this.currMoveStart) {
item = /** @type {Item} */ (this.currMove) // we iterate to the left after the current condition
popMovedStack(tr, this)
}
item = item.left
}
this.nextItem = item
return this
}
/**
* @template {{length: number}} T
* @param {Transaction} tr
* @param {number} len
* @param {T} value the initial content
* @param {function(AbstractContent, number, number):T} slice
* @param {function(T, T): T} concat
*/
_slice (tr, len, value, slice, concat) {
if (this.index + len > this.type._length) {
throw lengthExceeded
}
this.index += len
/**
* We store nextItem in a variable because this version cannot be null.
*/
let nextItem = /** @type {Item} */ (this.nextItem)
while (len > 0 && !this.reachedEnd) {
while (nextItem.countable && !this.reachedEnd && len > 0 && nextItem !== this.currMoveEnd) {
if (!nextItem.deleted && nextItem.moved === this.currMove) {
const slicedContent = slice(nextItem.content, this.rel, len)
len -= slicedContent.length
value = concat(value, slicedContent)
if (this.rel + slicedContent.length === nextItem.length) {
this.rel = 0
} else {
this.rel += slicedContent.length
continue // do not iterate to item.right
}
}
if (nextItem.right) {
nextItem = nextItem.right
} else {
this.reachedEnd = true
}
}
if ((!this.reachedEnd || this.currMove !== null) && len > 0) {
// always set nextItem before any method call
this.nextItem = nextItem
this.forward(tr, 0, true)
nextItem = this.nextItem
}
}
this.nextItem = nextItem
if (len < 0) {
this.index -= len
}
return value
}
/**
* @param {Transaction} tr
* @param {number} len
*/
delete (tr, len) {
const startLength = len
const sm = this.type._searchMarker
let item = this.nextItem
if (this.index + len > this.type._length) {
throw lengthExceeded
}
while (len > 0) {
while (item && !item.deleted && item.countable && !this.reachedEnd && len > 0 && item.moved === this.currMove && item !== this.currMoveEnd) {
if (this.rel > 0) {
item = getItemCleanStart(tr, createID(item.id.client, item.id.clock + this.rel))
this.rel = 0
}
if (len < item.length) {
getItemCleanStart(tr, createID(item.id.client, item.id.clock + len))
}
len -= item.length
item.delete(tr)
if (item.right) {
item = item.right
} else {
this.reachedEnd = true
}
}
if (len > 0) {
this.nextItem = item
this.forward(tr, 0, true)
item = this.nextItem
}
}
this.nextItem = item
if (sm) {
updateMarkerChanges(sm, this.index, -startLength + len, this)
}
}
/**
* @param {Transaction} tr
*/
_splitRel (tr) {
if (this.rel > 0) {
/**
* @type {ID}
*/
const itemid = /** @type {Item} */ (this.nextItem).id
this.nextItem = getItemCleanStart(tr, createID(itemid.client, itemid.clock + this.rel))
this.rel = 0
}
}
/**
* Important: you must update markers after calling this method!
*
* @param {Transaction} tr
* @param {Array<AbstractContent>} content
*/
insertContents (tr, content) {
this.reduceMoveDepth(tr)
this._splitRel(tr)
const parent = this.type
const store = tr.doc.store
const ownClientId = tr.doc.clientID
/**
* @type {Item | null}
*/
const right = this.right
/**
* @type {Item | null}
*/
let left = this.left
content.forEach(c => {
left = new Item(createID(ownClientId, getState(store, ownClientId)), left, left && left.lastId, right, right && right.id, parent, null, c)
left.integrate(tr, 0)
})
if (right === null) {
this.nextItem = left
this.reachedEnd = true
} else {
this.nextItem = right
}
}
/**
* @param {Transaction} tr
* @param {Array<{ start: RelativePosition, end: RelativePosition }>} ranges
*/
insertMove (tr, ranges) {
this.insertContents(tr, ranges.map(range => new ContentMove(range.start, range.end, -1)))
// @todo is there a better alrogirthm to update searchmarkers? We could simply remove the markers that are in the updated range.
// Also note that searchmarkers are updated in insertContents as well.
const sm = this.type._searchMarker
if (sm) sm.length = 0 // @todo instead, iterate through sm and delete all marked properties on items
}
/**
* @param {Transaction} tr
* @param {Array<Object<string,any>|Array<any>|boolean|number|null|string|Uint8Array>} values
*/
insertArrayValue (tr, values) {
this._splitRel(tr)
const sm = this.type._searchMarker
/**
* @type {Array<AbstractContent>}
*/
const contents = []
/**
* @type {Array<Object|Array<any>|number|null>}
*/
let jsonContent = []
const packJsonContent = () => {
if (jsonContent.length > 0) {
contents.push(new ContentAny(jsonContent))
jsonContent = []
}
}
values.forEach(c => {
if (c === null) {
jsonContent.push(c)
} else {
switch (c.constructor) {
case Number:
case Object:
case Boolean:
case Array:
case String:
jsonContent.push(c)
break
default:
packJsonContent()
switch (c.constructor) {
case Uint8Array:
case ArrayBuffer:
contents.push(new ContentBinary(new Uint8Array(/** @type {Uint8Array} */ (c))))
break
case Doc:
contents.push(new ContentDoc(/** @type {Doc} */ (c)))
break
default:
if (c instanceof AbstractType) {
contents.push(new ContentType(c))
} else {
throw new Error('Unexpected content type in insert operation')
}
}
}
}
})
packJsonContent()
this.insertContents(tr, contents)
this.index += values.length
if (sm) {
updateMarkerChanges(sm, this.index - values.length, values.length, this)
}
}
/**
* @param {Transaction} tr
* @param {number} len
*/
slice (tr, len) {
return this._slice(tr, len, [], sliceArrayContent, concatArrayContent)
}
/**
* @param {Transaction} tr
* @param {function(any, number, any):void} f
*/
forEach (tr, f) {
for (const val of this.values(tr)) {
f(val, this.index, this.type)
}
}
/**
* @template T
* @param {Transaction} tr
* @param {function(any, number, any):T} f
* @return {Array<T>}
*/
map (tr, f) {
const arr = new Array(this.type._length - this.index)
let i = 0
for (const val of this.values(tr)) {
arr[i++] = f(val, this.index, this.type)
}
return arr
}
/**
* @param {Transaction} tr
*/
values (tr) {
return {
[Symbol.iterator] () {
return this
},
next: () => {
if (this.reachedEnd || this.index === this.type._length) {
return { done: true }
}
const [value] = this.slice(tr, 1)
return {
done: false,
value: value
}
}
}
}
}
/**
* @param {AbstractContent} itemcontent
* @param {number} start
* @param {number} len
*/
const sliceArrayContent = (itemcontent, start, len) => {
const content = itemcontent.getContent()
return content.length <= len && start === 0 ? content : content.slice(start, start + len)
}
/**
* @param {Array<any>} content
* @param {Array<any>} added
*/
const concatArrayContent = (content, added) => {
content.push(...added)
return content
}
/**
* Move-ranges must not cross each other.
*
* This function computes the minimal amount of ranges to move a range of content to
* a different place.
*
* Algorithm:
* * Store the current stack in $preStack and $preItem = walker.nextItem
* * Iterate forward $len items.
* * The current stack is stored is $afterStack and $
* * Delete the stack-items that both of them have in common
*
* @param {Transaction} tr
* @param {ListCursor} walker
* @param {number} len
* @return {Array<{ start: RelativePosition, end: RelativePosition }>}
*/
export const getMinimalListViewRanges = (tr, walker, len) => {
if (len === 0) return []
if (walker.index + len > walker.type._length) {
throw lengthExceeded
}
// stepping outside the current move-range as much as possible
walker.reduceMoveDepth(tr)
/**
* @type {Array<{ start: RelativePosition, end: RelativePosition, move: Item | null }>}
*/
const ranges = []
// store relevant information for the beginning, before we iterate forward
/**
* @type {Array<Item>}
*/
const preStack = walker.movedStack.map(si => si.move)
const preMove = walker.currMove
const preItem = /** @type {Item} */ (walker.nextItem)
const preRel = walker.rel
walker.forward(tr, len, false)
// store the same information for the end, after we iterate forward
/**
* @type {Array<Item>}
*/
const afterStack = walker.movedStack.map(si => si.move)
const afterMove = walker.currMove
/**
const nextIsCurrMoveStart = walker.nextItem === walker.currMoveStart
const afterItem = /** @type {Item} / (nextIsCurrMoveStart
? walker.currMove
: (walker.rel > 0 || walker.reachedEnd)
? walker.nextItem
: /** @type {Item} / (walker.nextItem).left
) */
const afterItem = /** @type {Item} */ (
(walker.rel > 0 || walker.reachedEnd)
? walker.nextItem
: /** @type {Item} */ (walker.nextItem).left
)
/**
* afterRel is always > 0
*/
const afterRel = walker.rel > 0
? walker.rel
: afterItem.length
walker.forward(tr, 0, false) // @todo remove once this is done is useSearchMarker
let start = createRelativePosition(walker.type, createID(preItem.id.client, preItem.id.clock + preRel), 0)
let end = createRelativePosition(
walker.type,
createID(afterItem.id.client, afterItem.id.clock + afterRel - 1),
-1
)
if (preMove) {
preStack.push(preMove)
}
if (afterMove) {
afterStack.push(afterMove)
}
// remove common stack-items
while (preStack.length > 0 && preStack[0] === afterStack[0]) {
preStack.shift()
afterStack.shift()
}
const topLevelMove = preStack.length > 0 ? preStack[0].moved : (afterStack.length > 0 ? afterStack[0].moved : null)
// remove stack-items that are useless for our computation (that wouldn't produce meaningful ranges)
// @todo
while (preStack.length > 0) {
const move = /** @type {Item} */ (preStack.pop())
ranges.push({
start,
end: /** @type {ContentMove} */ (move.content).end,
move
})
start = createRelativePosition(walker.type, createID(move.id.client, move.id.clock), -1)
}
const middleMove = { start, end, move: topLevelMove }
ranges.push(middleMove)
while (afterStack.length > 0) {
const move = /** @type {Item} */ (afterStack.pop())
ranges.push({
start: /** @type {ContentMove} */ (move.content).start,
end,
move
})
end = createRelativePosition(walker.type, createID(move.id.client, move.id.clock), 0)
}
// Update end of the center move operation
// Move ranges must be applied in order
middleMove.end = end
const normalizedRanges = array.flatten(ranges.map(range => {
// A subset of a range could be moved by another move with a higher priority.
// If that is the case, we need to ignore those moved items.
const { start, end } = getMovedCoords(range, tr, false)
const move = range.move
const ranges = []
/**
* @type {RelativePosition | null}
*/
let rangeStart = range.start
/**
* @type {Item}
*/
let item = start
while (item !== end) {
if (item.moved !== move && rangeStart != null) {
ranges.push({ start: rangeStart, end: createRelativePosition(walker.type, createID(item.id.client, item.id.clock), 0) })
rangeStart = null
}
if (item.moved === move && rangeStart === null) {
// @todo It might be better to set this to item.left, with assoc -1
rangeStart = createRelativePosition(walker.type, createID(item.id.client, item.id.clock), 0)
}
item = /** @type {Item} */ (item.right)
}
if (rangeStart != null) {
ranges.push({
start: rangeStart,
end: range.end
})
}
return ranges
}))
// filter out unnecessary ranges
return normalizedRanges.filter(range => !compareRelativePositions(range.start, range.end))
}