[v2] breaking: do not copy initial objects

src/vanilla.ts

@@ -127,11 +127,11 @@ const buildProxyFunction = (
 
   versionHolder = [1, 1] as [number, number],
 
-  proxyFunction = <T extends object>(initialObject: T): T => {
-    if (!isObject(initialObject)) {
+  proxyFunction = <T extends object>(baseObject: T): T => {
+    if (!isObject(baseObject)) {
       throw new Error('object required')
     }
-    const found = proxyCache.get(initialObject) as T | undefined
+    const found = proxyCache.get(baseObject) as T | undefined
     if (found) {
       return found
     }
@@ -167,18 +167,23 @@ const buildProxyFunction = (
       string | symbol,
       readonly [ProxyState, RemoveListener?]
     >()
-    const addPropListener = (
-      prop: string | symbol,
-      propProxyState: ProxyState
-    ) => {
-      if (import.meta.env?.MODE !== 'production' && propProxyStates.has(prop)) {
-        throw new Error('prop listener already exists')
-      }
-      if (listeners.size) {
-        const remove = propProxyState[3](createPropListener(prop))
-        propProxyStates.set(prop, [propProxyState, remove])
-      } else {
-        propProxyStates.set(prop, [propProxyState])
+    const addPropListener = (prop: string | symbol, propValue: unknown) => {
+      const propProxyState =
+        !refSet.has(propValue as object) &&
+        proxyStateMap.get(propValue as object)
+      if (propProxyState) {
+        if (
+          import.meta.env?.MODE !== 'production' &&
+          propProxyStates.has(prop)
+        ) {
+          throw new Error('prop listener already exists')
+        }
+        if (listeners.size) {
+          const remove = propProxyState[3](createPropListener(prop))
+          propProxyStates.set(prop, [propProxyState, remove])
+        } else {
+          propProxyStates.set(prop, [propProxyState])
+        }
       }
     }
     const removePropListener = (prop: string | symbol) => {
@@ -212,9 +217,7 @@ const buildProxyFunction = (
       }
       return removeListener
     }
-    const baseObject = Array.isArray(initialObject)
-      ? []
-      : Object.create(Object.getPrototypeOf(initialObject))
+    let initializing = true
     const handler: ProxyHandler<T> = {
       deleteProperty(target: T, prop: string | symbol) {
         const prevValue = Reflect.get(target, prop)
@@ -226,7 +229,7 @@ const buildProxyFunction = (
         return deleted
       },
       set(target: T, prop: string | symbol, value: any, receiver: object) {
-        const hasPrevValue = Reflect.has(target, prop)
+        const hasPrevValue = !initializing && Reflect.has(target, prop)
         const prevValue = Reflect.get(target, prop, receiver)
         if (
           hasPrevValue &&
@@ -257,40 +260,32 @@ const buildProxyFunction = (
           if (!proxyStateMap.has(value) && canProxy(value)) {
             nextValue = proxyFunction(value)
           }
-          const childProxyState =
-            !refSet.has(nextValue) && proxyStateMap.get(nextValue)
-          if (childProxyState) {
-            addPropListener(prop, childProxyState)
-          }
+          addPropListener(prop, nextValue)
         }
         Reflect.set(target, prop, nextValue, receiver)
         notifyUpdate(['set', [prop], value, prevValue])
         return true
       },
     }
     const proxyObject = newProxy(baseObject, handler)
-    proxyCache.set(initialObject, proxyObject)
+    proxyCache.set(baseObject, proxyObject)
     const proxyState: ProxyState = [
       baseObject,
       ensureVersion,
       createSnapshot,
       addListener,
     ]
     proxyStateMap.set(proxyObject, proxyState)
-    Reflect.ownKeys(initialObject).forEach((key) => {
+    Reflect.ownKeys(baseObject).forEach((key) => {
       const desc = Object.getOwnPropertyDescriptor(
-        initialObject,
+        baseObject,
         key
       ) as PropertyDescriptor
-      if ('value' in desc) {
-        proxyObject[key as keyof T] = initialObject[key as keyof T]
-        // We need to delete desc.value because we already set it,
-        // and delete desc.writable because we want to write it again.
-        delete desc.value
-        delete desc.writable
+      if ('value' in desc && desc.writable) {
+        proxyObject[key as keyof T] = baseObject[key as keyof T]
       }
-      Object.defineProperty(baseObject, key, desc)
     })
+    initializing = false
     return proxyObject
   }
 ) =>
@@ -312,8 +307,8 @@ const buildProxyFunction = (
 
 const [defaultProxyFunction] = buildProxyFunction()
 
-export function proxy<T extends object>(initialObject: T = {} as T): T {
-  return defaultProxyFunction(initialObject)
+export function proxy<T extends object>(baseObject: T = {} as T): T {
+  return defaultProxyFunction(baseObject)
 }
 
 export function getVersion(proxyObject: unknown): number | undefined {

src/vanilla/utils.ts

@@ -4,6 +4,7 @@ export { devtools } from './utils/devtools.ts'
 export { derive, underive, unstable_deriveSubscriptions } from 'derive-valtio'
 export { addComputed_DEPRECATED as addComputed } from './utils/addComputed.ts'
 export { proxyWithComputed_DEPRECATED as proxyWithComputed } from './utils/proxyWithComputed.ts'
+export { deepClone } from './utils/deepClone.ts'
 export { proxyWithHistory } from './utils/proxyWithHistory.ts'
 export { proxySet } from './utils/proxySet.ts'
 export { proxyMap } from './utils/proxyMap.ts'

src/vanilla/utils/deepClone.ts

@@ -0,0 +1,25 @@
+import { unstable_buildProxyFunction as buildProxyFunction } from '../../vanilla.ts'
+
+const isObject = (x: unknown): x is object =>
+  typeof x === 'object' && x !== null
+
+let defaultRefSet: WeakSet<object> | undefined
+const getDefaultRefSet = (): WeakSet<object> => {
+  if (!defaultRefSet) {
+    defaultRefSet = buildProxyFunction()[2]
+  }
+  return defaultRefSet
+}
+
+export const deepClone = <T>(obj: T, getRefSet = getDefaultRefSet): T => {
+  if (!isObject(obj) || getRefSet().has(obj)) {
+    return obj
+  }
+  const baseObject: T = Array.isArray(obj)
+    ? []
+    : Object.create(Object.getPrototypeOf(obj))
+  Reflect.ownKeys(obj).forEach((key) => {
+    baseObject[key as keyof T] = deepClone(obj[key as keyof T], getRefSet)
+  })
+  return baseObject
+}

src/vanilla/utils/proxyWithHistory.ts

@@ -1,36 +1,10 @@
-import {
-  unstable_buildProxyFunction as buildProxyFunction,
-  proxy,
-  ref,
-  snapshot,
-  subscribe,
-} from '../../vanilla.ts'
+import { proxy, ref, snapshot, subscribe } from '../../vanilla.ts'
 import type { INTERNAL_Snapshot as Snapshot } from '../../vanilla.ts'
+import { deepClone } from './deepClone.ts'
 
 type SnapshotOrUndefined<T> = Snapshot<T> | undefined
 type Snapshots<T> = Snapshot<T>[]
 
-const isObject = (x: unknown): x is object =>
-  typeof x === 'object' && x !== null
-
-let refSet: WeakSet<object> | undefined
-
-const deepClone = <T>(obj: T): T => {
-  if (!refSet) {
-    refSet = buildProxyFunction()[2]
-  }
-  if (!isObject(obj) || refSet.has(obj)) {
-    return obj
-  }
-  const baseObject: T = Array.isArray(obj)
-    ? []
-    : Object.create(Object.getPrototypeOf(obj))
-  Reflect.ownKeys(obj).forEach((key) => {
-    baseObject[key as keyof T] = deepClone(obj[key as keyof T])
-  })
-  return baseObject
-}
-
 /**
  * proxyWithHistory
  *