From 08759e2d5c5e1b9c7455240214f9021eab5ed451 Mon Sep 17 00:00:00 2001
From: Aria Minaei <aria.minaei@gmail.com>
Date: Fri, 2 Jul 2021 20:27:10 +0200
Subject: [PATCH] New: Make SheetObject an IdentityChangeProvider

---
 theatre/core/src/sheetObjects/SheetObject.ts | 21 +++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/theatre/core/src/sheetObjects/SheetObject.ts b/theatre/core/src/sheetObjects/SheetObject.ts
index da23103..244c5e2 100644
--- a/theatre/core/src/sheetObjects/SheetObject.ts
+++ b/theatre/core/src/sheetObjects/SheetObject.ts
@@ -13,7 +13,12 @@ import type {
   SerializableValue,
 } from '@theatre/shared/utils/types'
 import {valToAtom} from '@theatre/shared/utils/valToAtom'
-import type {IDerivation, Pointer} from '@theatre/dataverse'
+import type {
+  IdentityDerivationProvider,
+  IDerivation,
+  Pointer,
+} from '@theatre/dataverse'
+
 import {Atom, getPointerParts, pointer, prism, val} from '@theatre/dataverse'
 import type SheetObjectTemplate from './SheetObjectTemplate'
 import TheatreSheetObject from './TheatreSheetObject'
@@ -25,11 +30,11 @@ import TheatreSheetObject from './TheatreSheetObject'
 //   sequenced: SerializableMap
 // }
 
-export default class SheetObject {
+export default class SheetObject implements IdentityDerivationProvider {
   get type(): 'Theatre_SheetObject' {
     return 'Theatre_SheetObject'
   }
-
+  readonly $$isIdentityDerivationProvider: true = true
   readonly address: SheetObjectAddress
   readonly publicApi: TheatreSheetObject<$IntentionalAny>
   private readonly _initialValue = new Atom<SerializableMap>({})
@@ -130,6 +135,16 @@ export default class SheetObject {
     return val(pointerDeep(allValuesP as $FixMe, path)) as SerializableMap
   }
 
+  getIdentityDerivation(path: Array<string | number>): IDerivation<unknown> {
+    /**
+     * @todo perf: Too much indirection here.
+     */
+    return prism(() => {
+      const allValuesP = val(this.getValues())
+      return val(pointerDeep(allValuesP as $FixMe, path)) as SerializableMap
+    })
+  }
+
   /**
    * Returns values of props that are sequenced.
    */