yjs/src/structs/ContentString.js
2020-12-29 16:59:27 +01:00

113 lines
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import {
UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, Transaction, Item, StructStore // eslint-disable-line
} from '../internals.js'
/**
* @private
*/
export class ContentString {
/**
* @param {string} str
*/
constructor (str) {
/**
* @type {string}
*/
this.str = str
}
/**
* @return {number}
*/
getLength () {
return this.str.length
}
/**
* @return {Array<any>}
*/
getContent () {
return this.str.split('')
}
/**
* @return {boolean}
*/
isCountable () {
return true
}
/**
* @return {ContentString}
*/
copy () {
return new ContentString(this.str)
}
/**
* @param {number} offset
* @return {ContentString}
*/
splice (offset) {
const right = new ContentString(this.str.slice(offset))
this.str = this.str.slice(0, offset)
// Prevent encoding invalid documents because of splitting of surrogate pairs: https://github.com/yjs/yjs/issues/248
const firstCharCode = this.str.charCodeAt(offset - 1)
if (firstCharCode >= 0xD800 && firstCharCode <= 0xDBFF) {
// Last character of the left split is the start of a surrogate utf16/ucs2 pair.
// We don't support splitting of surrogate pairs because this may lead to invalid documents.
// Replace the invalid character with a unicode replacement character (<28> / U+FFFD)
this.str = this.str.slice(0, offset - 1) + '<27>'
// replace right as well
right.str = '<27>' + right.str.slice(1)
}
return right
}
/**
* @param {ContentString} right
* @return {boolean}
*/
mergeWith (right) {
this.str += right.str
return true
}
/**
* @param {Transaction} transaction
* @param {Item} item
*/
integrate (transaction, item) {}
/**
* @param {Transaction} transaction
*/
delete (transaction) {}
/**
* @param {StructStore} store
*/
gc (store) {}
/**
* @param {UpdateEncoderV1 | UpdateEncoderV2} encoder
* @param {number} offset
*/
write (encoder, offset) {
encoder.writeString(offset === 0 ? this.str : this.str.slice(offset))
}
/**
* @return {number}
*/
getRef () {
return 4
}
}
/**
* @private
*
* @param {UpdateDecoderV1 | UpdateDecoderV2} decoder
* @return {ContentString}
*/
export const readContentString = decoder => new ContentString(decoder.readString())