refactor(core): remove the at method from the LiveCollection type (#52227)

The at operation is private and doesn't have to be part of the public interface.

PR Close #52227

packages/core/src/render3/instructions/control_flow.ts

@@ -169,11 +169,8 @@ class LiveCollectionLContainerImpl extends
   override get length(): number {
     return this.lContainer.length - CONTAINER_HEADER_OFFSET;
   }
-  override at(index: number): LView<RepeaterContext<unknown>> {
-    return getExistingLViewFromLContainer(this.lContainer, index);
-  }
   override key(index: number): unknown {
-    return this.trackByFn(index, this.at(index)[CONTEXT].$implicit);
+    return this.trackByFn(index, this.getLView(index)[CONTEXT].$implicit);
   }
   override attach(index: number, lView: LView<RepeaterContext<unknown>>): void {
     const dehydratedView = lView[HYDRATION] as DehydratedContainerView;
@@ -198,16 +195,20 @@ class LiveCollectionLContainerImpl extends
     destroyLView(lView[TVIEW], lView);
   }
   override updateValue(index: number, value: unknown): void {
-    this.at(index)[CONTEXT].$implicit = value;
+    this.getLView(index)[CONTEXT].$implicit = value;
   }
 
   updateIndexes() {
     if (this.needsIndexUpdate) {
       for (let i = 0; i < this.length; i++) {
-        this.at(i)[CONTEXT].$index = i;
+        this.getLView(i)[CONTEXT].$index = i;
       }
     }
   }
+
+  private getLView(index: number): LView<RepeaterContext<unknown>> {
+    return getExistingLViewFromLContainer(this.lContainer, index);
+  }
 }
 
 /**

packages/core/src/render3/list_reconciliation.ts

@@ -15,7 +15,6 @@ import {TrackByFunction} from '../change_detection';
  */
 export abstract class LiveCollection<T, V> {
   abstract get length(): number;
-  abstract at(index: number): T;
   abstract key(index: number): unknown;
   abstract attach(index: number, item: T): void;
   abstract detach(index: number): T;

packages/core/test/render3/list_reconciliation_spec.ts

@@ -44,27 +44,22 @@ class LoggingLiveCollection<T, V> extends LiveCollection<T, V> {
   get length(): number {
     return this.arr.length;
   }
-  at(index: number): T {
-    this.operations.at++;
-    const item = this.arr.at(index);
-    assertDefined(item, `Invalid index ${index} - item was undefined`);
-    return item;
-  }
-  key(index: number): unknown {
+
+  override key(index: number): unknown {
     this.operations.key++;
-    return this.trackByFn(index, this.itemFactory.unwrap(this.at(index)));
+    return this.trackByFn(index, this.itemFactory.unwrap(this.getItem(index)));
   }
-  attach(index: number, item: T): void {
+  override attach(index: number, item: T): void {
     this.logs.push(['attach', index, item]);
     this.arr.splice(index, 0, item);
   }
-  detach(index: number): T {
-    const item = this.at(index);
+  override detach(index: number): T {
+    const item = this.getItem(index);
     this.logs.push(['detach', index, item]);
     this.arr.splice(index, 1);
     return item;
   }
-  create(index: number, value: V): T {
+  override create(index: number, value: V): T {
     this.logs.push(['create', index, value]);
     return this.itemFactory.create(index, value);
   }
@@ -72,7 +67,7 @@ class LoggingLiveCollection<T, V> extends LiveCollection<T, V> {
     this.logs.push(['destroy', item]);
   }
   override updateValue(index: number, value: V): void {
-    this.itemFactory.update(this.at(index), index, value);
+    this.itemFactory.update(this.getItem(index), index, value);
   }
 
   getCollection() {
@@ -86,6 +81,13 @@ class LoggingLiveCollection<T, V> extends LiveCollection<T, V> {
   clearLogs() {
     this.logs = [];
   }
+
+  private getItem(index: number): T {
+    this.operations.at++;
+    const item = this.arr.at(index);
+    assertDefined(item, `Invalid index ${index} - item was undefined`);
+    return item;
+  }
 }
 
 function trackByIdentity<T>(index: number, item: T) {