From 0a13c4d89876f1ed399d2ec3cc46bda933a539b8 Mon Sep 17 00:00:00 2001
From: Tim Deschryver <28659384+timdeschryver@users.noreply.github.com>
Date: Mon, 1 May 2023 13:41:58 +0200
Subject: [PATCH] feat(store): add selectSignal options

---
 modules/store/spec/types/select_signal.spec.ts | 16 ++++++++++++++++
 modules/store/src/models.ts                    |  9 +++++++++
 modules/store/src/store.ts                     | 15 ++++++++++++---
 3 files changed, 37 insertions(+), 3 deletions(-)

diff --git a/modules/store/spec/types/select_signal.spec.ts b/modules/store/spec/types/select_signal.spec.ts
index 1d7409ad5b..f7e0551584 100644
--- a/modules/store/spec/types/select_signal.spec.ts
+++ b/modules/store/spec/types/select_signal.spec.ts
@@ -41,6 +41,12 @@ describe('Store.selectSignal()', () => {
           `const selector = store.selectSignal(s => s.foo.bar);`
         ).toInfer('selector', 'Signal<{ baz: []; }>');
       });
+
+      it('should infer correctly (with options)', () => {
+        expectSnippet(
+          `const selector = store.selectSignal(s => s.foo, {equal: (a, b) => a === b});`
+        ).toInfer('selector', 'Signal<{ bar: { baz: []; }; }>');
+      });
     });
 
     describe('with selectors', () => {
@@ -53,6 +59,16 @@ describe('Store.selectSignal()', () => {
           `const selector = store.selectSignal(barSelector);`
         ).toInfer('selector', 'Signal<{ baz: []; }>');
       });
+
+      it('should infer correctly (with options)', () => {
+        expectSnippet(
+          `const selector = store.selectSignal(fooSelector, {equal: (a,b) => a === b});`
+        ).toInfer('selector', 'Signal<{ bar: { baz: []; }; }>');
+
+        expectSnippet(
+          `const selector = store.selectSignal(barSelector);`
+        ).toInfer('selector', 'Signal<{ baz: []; }>');
+      });
     });
   });
 });
diff --git a/modules/store/src/models.ts b/modules/store/src/models.ts
index a5adf058db..4b923773d6 100644
--- a/modules/store/src/models.ts
+++ b/modules/store/src/models.ts
@@ -1,3 +1,5 @@
+import { type ValueEqualityFn } from '@angular/core';
+
 export interface Action {
   type: string;
 }
@@ -169,3 +171,10 @@ export interface RuntimeChecks {
    */
   strictActionTypeUniqueness?: boolean;
 }
+
+export interface SelectSignalOptions<T> {
+  /**
+   *  A comparison function which defines equality for select results.
+   */
+  equal?: ValueEqualityFn<T>;
+}
diff --git a/modules/store/src/store.ts b/modules/store/src/store.ts
index 72fb47f6c3..77696b1b4c 100644
--- a/modules/store/src/store.ts
+++ b/modules/store/src/store.ts
@@ -4,7 +4,12 @@ import { Observable, Observer, Operator } from 'rxjs';
 import { distinctUntilChanged, map, pluck } from 'rxjs/operators';
 
 import { ActionsSubject } from './actions_subject';
-import { Action, ActionReducer, FunctionIsNotAllowed } from './models';
+import {
+  Action,
+  ActionReducer,
+  SelectSignalOptions,
+  FunctionIsNotAllowed,
+} from './models';
 import { ReducerManager } from './reducer_manager';
 import { StateObservable } from './state';
 import { toSignal } from './to_signal';
@@ -101,9 +106,13 @@ export class Store<T = object>
    * Returns a signal of the provided selector.
    *
    * @param selector selector function
+   * @param options select signal options
    */
-  selectSignal<K>(selector: (state: T) => K): Signal<K> {
-    return computed(() => selector(this.state()));
+  selectSignal<K>(
+    selector: (state: T) => K,
+    options?: SelectSignalOptions<K>
+  ): Signal<K> {
+    return computed(() => selector(this.state()), { equal: options?.equal });
   }
 
   override lift<R>(operator: Operator<T, R>): Store<R> {