faster iteration experiment

src/core/current.ts

@@ -21,18 +21,22 @@ function currentImpl(value: any): any {
 	if (!isDraftable(value) || isFrozen(value)) return value
 	const state: ImmerState | undefined = value[DRAFT_STATE]
 	let copy: any
+	let strict = true // we might not know, so true just to be safe
 	if (state) {
 		if (!state.modified_) return state.base_
 		// Optimization: avoid generating new drafts during copying
 		state.finalized_ = true
-		copy = shallowCopy(value, state.scope_.immer_.useStrictShallowCopy_)
-	} else {
-		copy = shallowCopy(value, true)
+		strict = state.scope_.immer_.useStrict_(value)
 	}
+	copy = shallowCopy(value, strict)
 	// recurse
-	each(copy, (key, childValue) => {
-		set(copy, key, currentImpl(childValue))
-	})
+	each(
+		copy,
+		(key, childValue) => {
+			set(copy, key, currentImpl(childValue))
+		},
+		strict
+	)
 	if (state) {
 		state.finalized_ = false
 	}

src/core/finalize.ts

@@ -58,8 +58,11 @@ function finalize(rootScope: ImmerScope, value: any, path?: PatchPath) {
 	const state: ImmerState = value[DRAFT_STATE]
 	// A plain object, might need freezing, might contain drafts
 	if (!state) {
-		each(value, (key, childValue) =>
-			finalizeProperty(rootScope, state, value, key, childValue, path)
+		each(
+			value,
+			(key, childValue) =>
+				finalizeProperty(rootScope, state, value, key, childValue, path),
+			rootScope.immer_.useStrict_(value)
 		)
 		return value
 	}
@@ -86,8 +89,19 @@ function finalize(rootScope: ImmerScope, value: any, path?: PatchPath) {
 			result.clear()
 			isSet = true
 		}
-		each(resultEach, (key, childValue) =>
-			finalizeProperty(rootScope, state, result, key, childValue, path, isSet)
+		each(
+			resultEach,
+			(key, childValue) =>
+				finalizeProperty(
+					rootScope,
+					state,
+					result,
+					key,
+					childValue,
+					path,
+					isSet
+				),
+			state.scope_.immer_.useStrict_(resultEach)
 		)
 		// everything inside is frozen, we can freeze here
 		maybeFreeze(rootScope, result, false)

src/core/immerClass.ts

@@ -23,15 +23,16 @@ import {
 	getCurrentScope,
 	NOTHING,
 	freeze,
-	current
+	current,
+	isPlainObject
 } from "../internal"
 
 interface ProducersFns {
 	produce: IProduce
 	produceWithPatches: IProduceWithPatches
 }
 
-export type StrictMode = boolean | "class_only";
+export type StrictMode = boolean | "class_only"
 
 export class Immer implements ProducersFns {
 	autoFreeze_: boolean = true
@@ -199,6 +200,13 @@ export class Immer implements ProducersFns {
 			applyPatchesImpl(draft, patches)
 		)
 	}
+
+	useStrict_(obj: any): boolean {
+		return (
+			this.useStrictShallowCopy_ === true ||
+			(this.useStrictShallowCopy_ === "class_only" && !isPlainObject(obj))
+		)
+	}
 }
 
 export function createProxy<T extends Objectish>(

src/plugins/patches.ts

@@ -132,21 +132,25 @@ export function enablePatches() {
 		inversePatches: Patch[]
 	) {
 		const {base_, copy_} = state
-		each(state.assigned_!, (key, assignedValue) => {
-			const origValue = get(base_, key)
-			const value = get(copy_!, key)
-			const op = !assignedValue ? REMOVE : has(base_, key) ? REPLACE : ADD
-			if (origValue === value && op === REPLACE) return
-			const path = basePath.concat(key as any)
-			patches.push(op === REMOVE ? {op, path} : {op, path, value})
-			inversePatches.push(
-				op === ADD
-					? {op: REMOVE, path}
-					: op === REMOVE
-					? {op: ADD, path, value: clonePatchValueIfNeeded(origValue)}
-					: {op: REPLACE, path, value: clonePatchValueIfNeeded(origValue)}
-			)
-		})
+		each(
+			state.assigned_!,
+			(key, assignedValue) => {
+				const origValue = get(base_, key)
+				const value = get(copy_!, key)
+				const op = !assignedValue ? REMOVE : has(base_, key) ? REPLACE : ADD
+				if (origValue === value && op === REPLACE) return
+				const path = basePath.concat(key as any)
+				patches.push(op === REMOVE ? {op, path} : {op, path, value})
+				inversePatches.push(
+					op === ADD
+						? {op: REMOVE, path}
+						: op === REMOVE
+						? {op: ADD, path, value: clonePatchValueIfNeeded(origValue)}
+						: {op: REPLACE, path, value: clonePatchValueIfNeeded(origValue)}
+				)
+			},
+			state.scope_.immer_.useStrict_(base_)
+		)
 	}
 
 	function generateSetPatches(

src/utils/common.ts

@@ -68,11 +68,13 @@ export function original(value: Drafted<any>): any {
  */
 export function each<T extends Objectish>(
 	obj: T,
-	iter: (key: string | number, value: any, source: T) => void
+	iter: (key: string | number, value: any, source: T) => void,
+	strict?: boolean
 ): void
-export function each(obj: any, iter: any) {
+export function each(obj: any, iter: any, strict: boolean = true) {
 	if (getArchtype(obj) === ArchType.Object) {
-		Reflect.ownKeys(obj).forEach(key => {
+		const keys = strict ? Reflect.ownKeys(obj) : Object.keys(obj)
+		keys.forEach(key => {
 			iter(key, obj[key], obj)
 		})
 	} else {