use new ListPosition abstraction in Y.Array .slice and .get

src/types/AbstractType.js

@@ -445,8 +445,8 @@ export class ListPosition {
     while (item && !this.reachedEnd && (len > 0 || (len === 0 && (!item.countable || item.deleted)))) {
       if (item.countable && !item.deleted && item.moved === this.currMove) {
         len -= item.length
-        if (len <= 0) {
-          this.rel = -len
+        if (len < 0) {
+          this.rel = item.length + len
           break
         }
       } else if (item.content.constructor === ContentMove) {
@@ -473,6 +473,10 @@ export class ListPosition {
     }
     this.index -= len
     this.item = item
+    if (len > 0) {
+      throw lengthExceeded
+    }
+    return this
   }
 
   /**
@@ -484,7 +488,7 @@ export class ListPosition {
       while (this.item && this.item.countable && !this.reachedEnd && len > 0) {
         if (!this.item.deleted) {
           const content = this.item.content.getContent()
-          const slicedContent = content.length <= len || this.rel > 0 ? content : content.slice(this.rel, len)
+          const slicedContent = content.length <= len && this.rel === 0 ? content : content.slice(this.rel, this.rel + len)
           len -= slicedContent.length
           result.push(...slicedContent)
           if (content.length !== slicedContent.length) {

src/types/YArray.js

@@ -5,7 +5,6 @@
 import {
   YEvent,
   AbstractType,
-  typeListGet,
   typeListForEach,
   typeListCreateIterator,
   typeListInsertGenerics,
@@ -17,7 +16,6 @@ import {
   ListPosition,
   ArraySearchMarker, UpdateDecoderV1, UpdateDecoderV2, UpdateEncoderV1, UpdateEncoderV2, Doc, Transaction, Item // eslint-disable-line
 } from '../internals.js'
-import { typeListSlice } from './AbstractType.js'
 
 /**
  * Event that describes the changes on a YArray
@@ -179,7 +177,9 @@ export class YArray extends AbstractType {
    * @return {T}
    */
   get (index) {
-    return typeListGet(this, index)
+    return transact(/** @type {Doc} */ (this.doc), tr =>
+      new ListPosition(this, tr).forward(index).slice(1)[0]
+    )
   }
 
   /**
@@ -201,7 +201,9 @@ export class YArray extends AbstractType {
    * @return {Array<T>}
    */
   slice (start = 0, end = this.length) {
-    return typeListSlice(this, start, end)
+    return transact(/** @type {Doc} */ (this.doc), tr =>
+      new ListPosition(this, tr).forward(start).slice(end < 0 ? this.length + end - start : end - start)
+    )
   }
 
   /**

tests/y-array.tests.js

@@ -456,6 +456,8 @@ const getUniqueNumber = () => _uniqueNumber++
 
 /**
  * @type {Array<function(Doc,prng.PRNG,any):void>}
+ *
+ * @todo to replace content to a separate data structure so we know that insert & returns work as expected!!!
  */
 const arrayTransactions = [
   function insert (user, gen) {