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first prototype of associative relative positions (left- or right-associative)

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This commit is contained in:
Kevin Jahns 2021-01-08 23:03:16 +01:00
parent 728bb6f1b2
commit 656328631c
3 changed files with 54 additions and 19 deletions
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2
src/index.js
View File

@ -32,8 +32,6 @@ export {
createRelativePositionFromJSON,
createAbsolutePositionFromRelativePosition,
compareRelativePositions,
writeRelativePosition,
readRelativePosition,
ID,
createID,
compareIDs,

68
src/utils/RelativePosition.js
View File

@ -45,8 +45,9 @@ export class RelativePosition {
* @param {ID|null} type
* @param {string|null} tname
* @param {ID|null} item
* @param {number} assoc
*/
constructor (type, tname, item) {
constructor (type, tname, item, assoc = 0) {
/**
* @type {ID|null}
*/
@ -59,6 +60,18 @@ export class RelativePosition {
* @type {ID | null}
*/
this.item = item
/**
* A relative position is associated to a specific character. By default
* assoc >= 0, the relative position is associated to the character
* after the meant position.
* I.e. position 1 in 'ab' is associated to character 'b'.
*
* If assoc < 0, then the relative position is associated to the caharacter
* before the meant position.
*
* @type {number}
*/
this.assoc = assoc
}
}
@ -74,8 +87,9 @@ export class AbsolutePosition {
/**
* @param {AbstractType<any>} type
* @param {number} index
* @param {number} [assoc]
*/
constructor (type, index) {
constructor (type, index, assoc = 0) {
/**
* @type {AbstractType<any>}
*/
@ -84,24 +98,27 @@ export class AbsolutePosition {
* @type {number}
*/
this.index = index
this.assoc = assoc
}
}
/**
* @param {AbstractType<any>} type
* @param {number} index
* @param {number} [assoc]
*
* @function
*/
export const createAbsolutePosition = (type, index) => new AbsolutePosition(type, index)
export const createAbsolutePosition = (type, index, assoc = 0) => new AbsolutePosition(type, index, assoc)
/**
* @param {AbstractType<any>} type
* @param {ID|null} item
* @param {number} [assoc]
*
* @function
*/
export const createRelativePosition = (type, item) => {
export const createRelativePosition = (type, item, assoc) => {
let typeid = null
let tname = null
if (type._item === null) {
@ -109,7 +126,7 @@ export const createRelativePosition = (type, item) => {
} else {
typeid = createID(type._item.id.client, type._item.id.clock)
}
return new RelativePosition(typeid, tname, item)
return new RelativePosition(typeid, tname, item, assoc)
}
/**
@ -117,23 +134,35 @@ export const createRelativePosition = (type, item) => {
*
* @param {AbstractType<any>} type The base type (e.g. YText or YArray).
* @param {number} index The absolute position.
* @param {number} [assoc]
* @return {RelativePosition}
*
* @function
*/
export const createRelativePositionFromTypeIndex = (type, index) => {
export const createRelativePositionFromTypeIndex = (type, index, assoc = 0) => {
let t = type._start
if (assoc < 0) {
// associated to the left character or the beginning of a type, increment index if possible.
if (index === 0) {
return createRelativePosition(type, null, assoc)
}
index++
}
while (t !== null) {
if (!t.deleted && t.countable) {
if (t.length > index) {
// case 1: found position somewhere in the linked list
return createRelativePosition(type, createID(t.id.client, t.id.clock + index))
return createRelativePosition(type, createID(t.id.client, t.id.clock + index), assoc)
}
index -= t.length
}
if (t.right === null && assoc < 0) {
// left-associated position, return last available id
return createRelativePosition(type, t.lastId, assoc)
}
t = t.right
}
return createRelativePosition(type, null)
return createRelativePosition(type, null, assoc)
}
/**
@ -143,7 +172,7 @@ export const createRelativePositionFromTypeIndex = (type, index) => {
* @function
*/
export const writeRelativePosition = (encoder, rpos) => {
const { type, tname, item } = rpos
const { type, tname, item, assoc } = rpos
if (item !== null) {
encoding.writeVarUint(encoder, 0)
writeID(encoder, item)
@ -158,6 +187,7 @@ export const writeRelativePosition = (encoder, rpos) => {
} else {
throw error.unexpectedCase()
}
encoding.writeVarInt(encoder, assoc)
return encoder
}
@ -173,7 +203,7 @@ export const encodeRelativePosition = rpos => {
/**
* @param {decoding.Decoder} decoder
* @return {RelativePosition|null}
* @return {RelativePosition}
*
* @function
*/
@ -195,12 +225,13 @@ export const readRelativePosition = decoder => {
type = readID(decoder)
}
}
return new RelativePosition(type, tname, itemID)
const assoc = decoding.hasContent(decoder) ? decoding.readVarInt(decoder) : 0
return new RelativePosition(type, tname, itemID, assoc)
}
/**
* @param {Uint8Array} uint8Array
* @return {RelativePosition|null}
* @return {RelativePosition}
*/
export const decodeRelativePosition = uint8Array => readRelativePosition(decoding.createDecoder(uint8Array))
@ -216,6 +247,7 @@ export const createAbsolutePositionFromRelativePosition = (rpos, doc) => {
const rightID = rpos.item
const typeID = rpos.type
const tname = rpos.tname
const assoc = rpos.assoc
let type = null
let index = 0
if (rightID !== null) {
@ -229,7 +261,7 @@ export const createAbsolutePositionFromRelativePosition = (rpos, doc) => {
}
type = /** @type {AbstractType<any>} */ (right.parent)
if (type._item === null || !type._item.deleted) {
index = right.deleted || !right.countable ? 0 : res.diff
index = (right.deleted || !right.countable) ? 0 : (res.diff + (assoc >= 0 ? 0 : 1)) // adjust position based on left association if necessary
let n = right.left
while (n !== null) {
if (!n.deleted && n.countable) {
@ -256,9 +288,13 @@ export const createAbsolutePositionFromRelativePosition = (rpos, doc) => {
} else {
throw error.unexpectedCase()
}
index = type._length
if (assoc >= 0) {
index = type._length
} else {
index = 0
}
}
return createAbsolutePosition(type, index)
return createAbsolutePosition(type, index, rpos.assoc)
}
/**
@ -269,5 +305,5 @@ export const createAbsolutePositionFromRelativePosition = (rpos, doc) => {
* @function
*/
export const compareRelativePositions = (a, b) => a === b || (
a !== null && b !== null && a.tname === b.tname && compareIDs(a.item, b.item) && compareIDs(a.type, b.type)
a !== null && b !== null && a.tname === b.tname && compareIDs(a.item, b.item) && compareIDs(a.type, b.type) && a.assoc === b.assoc
)

3
tests/index.js
View File

@ -8,6 +8,7 @@ import * as undoredo from './undo-redo.tests.js'
import * as compatibility from './compatibility.tests.js'
import * as doc from './doc.tests.js'
import * as snapshot from './snapshot.tests.js'
import * as relativePositions from './relativePositions.tests.js'
import { runTests } from 'lib0/testing.js'
import { isBrowser, isNode } from 'lib0/environment.js'
@ -17,7 +18,7 @@ if (isBrowser) {
log.createVConsole(document.body)
}
runTests({
doc, map, array, text, xml, encoding, undoredo, compatibility, snapshot
doc, map, array, text, xml, encoding, undoredo, compatibility, snapshot, relativePositions
}).then(success => {
/* istanbul ignore next */
if (isNode) {