planning

node_modules/immer/src/core/current.ts

@@ -0,0 +1,60 @@
+import {
+	die,
+	isDraft,
+	shallowCopy,
+	each,
+	DRAFT_STATE,
+	get,
+	set,
+	ImmerState,
+	isDraftable,
+	Archtype,
+	getArchtype,
+	getPlugin
+} from "../internal"
+
+/** Takes a snapshot of the current state of a draft and finalizes it (but without freezing). This is a great utility to print the current state during debugging (no Proxies in the way). The output of current can also be safely leaked outside the producer. */
+export function current<T>(value: T): T
+export function current(value: any): any {
+	if (!isDraft(value)) die(22, value)
+	return currentImpl(value)
+}
+
+function currentImpl(value: any): any {
+	if (!isDraftable(value)) return value
+	const state: ImmerState | undefined = value[DRAFT_STATE]
+	let copy: any
+	const archType = getArchtype(value)
+	if (state) {
+		if (
+			!state.modified_ &&
+			(state.type_ < 4 || !getPlugin("ES5").hasChanges_(state as any))
+		)
+			return state.base_
+		// Optimization: avoid generating new drafts during copying
+		state.finalized_ = true
+		copy = copyHelper(value, archType)
+		state.finalized_ = false
+	} else {
+		copy = copyHelper(value, archType)
+	}
+
+	each(copy, (key, childValue) => {
+		if (state && get(state.base_, key) === childValue) return // no need to copy or search in something that didn't change
+		set(copy, key, currentImpl(childValue))
+	})
+	// In the future, we might consider freezing here, based on the current settings
+	return archType === Archtype.Set ? new Set(copy) : copy
+}
+
+function copyHelper(value: any, archType: number): any {
+	// creates a shallow copy, even if it is a map or set
+	switch (archType) {
+		case Archtype.Map:
+			return new Map(value)
+		case Archtype.Set:
+			// Set will be cloned as array temporarily, so that we can replace individual items
+			return Array.from(value)
+	}
+	return shallowCopy(value)
+}

node_modules/immer/src/core/finalize.ts

@@ -0,0 +1,168 @@
+import {
+	ImmerScope,
+	DRAFT_STATE,
+	isDraftable,
+	NOTHING,
+	PatchPath,
+	each,
+	has,
+	freeze,
+	ImmerState,
+	isDraft,
+	SetState,
+	set,
+	ProxyType,
+	getPlugin,
+	die,
+	revokeScope,
+	isFrozen,
+	shallowCopy
+} from "../internal"
+
+export function processResult(result: any, scope: ImmerScope) {
+	scope.unfinalizedDrafts_ = scope.drafts_.length
+	const baseDraft = scope.drafts_![0]
+	const isReplaced = result !== undefined && result !== baseDraft
+	if (!scope.immer_.useProxies_)
+		getPlugin("ES5").willFinalizeES5_(scope, result, isReplaced)
+	if (isReplaced) {
+		if (baseDraft[DRAFT_STATE].modified_) {
+			revokeScope(scope)
+			die(4)
+		}
+		if (isDraftable(result)) {
+			// Finalize the result in case it contains (or is) a subset of the draft.
+			result = finalize(scope, result)
+			if (!scope.parent_) maybeFreeze(scope, result)
+		}
+		if (scope.patches_) {
+			getPlugin("Patches").generateReplacementPatches_(
+				baseDraft[DRAFT_STATE].base_,
+				result,
+				scope.patches_,
+				scope.inversePatches_!
+			)
+		}
+	} else {
+		// Finalize the base draft.
+		result = finalize(scope, baseDraft, [])
+	}
+	revokeScope(scope)
+	if (scope.patches_) {
+		scope.patchListener_!(scope.patches_, scope.inversePatches_!)
+	}
+	return result !== NOTHING ? result : undefined
+}
+
+function finalize(rootScope: ImmerScope, value: any, path?: PatchPath) {
+	// Don't recurse in tho recursive data structures
+	if (isFrozen(value)) return value
+
+	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),
+			true // See #590, don't recurse into non-enumerable of non drafted objects
+		)
+		return value
+	}
+	// Never finalize drafts owned by another scope.
+	if (state.scope_ !== rootScope) return value
+	// Unmodified draft, return the (frozen) original
+	if (!state.modified_) {
+		maybeFreeze(rootScope, state.base_, true)
+		return state.base_
+	}
+	// Not finalized yet, let's do that now
+	if (!state.finalized_) {
+		state.finalized_ = true
+		state.scope_.unfinalizedDrafts_--
+		const result =
+			// For ES5, create a good copy from the draft first, with added keys and without deleted keys.
+			state.type_ === ProxyType.ES5Object || state.type_ === ProxyType.ES5Array
+				? (state.copy_ = shallowCopy(state.draft_))
+				: state.copy_
+		// Finalize all children of the copy
+		// For sets we clone before iterating, otherwise we can get in endless loop due to modifying during iteration, see #628
+		// To preserve insertion order in all cases we then clear the set
+		// And we let finalizeProperty know it needs to re-add non-draft children back to the target
+		let resultEach = result
+		let isSet = false
+		if (state.type_ === ProxyType.Set) {
+			resultEach = new Set(result)
+			result.clear()
+			isSet = true
+		}
+		each(resultEach, (key, childValue) =>
+			finalizeProperty(rootScope, state, result, key, childValue, path, isSet)
+		)
+		// everything inside is frozen, we can freeze here
+		maybeFreeze(rootScope, result, false)
+		// first time finalizing, let's create those patches
+		if (path && rootScope.patches_) {
+			getPlugin("Patches").generatePatches_(
+				state,
+				path,
+				rootScope.patches_,
+				rootScope.inversePatches_!
+			)
+		}
+	}
+	return state.copy_
+}
+
+function finalizeProperty(
+	rootScope: ImmerScope,
+	parentState: undefined | ImmerState,
+	targetObject: any,
+	prop: string | number,
+	childValue: any,
+	rootPath?: PatchPath,
+	targetIsSet?: boolean
+) {
+	if (__DEV__ && childValue === targetObject) die(5)
+	if (isDraft(childValue)) {
+		const path =
+			rootPath &&
+			parentState &&
+			parentState!.type_ !== ProxyType.Set && // Set objects are atomic since they have no keys.
+			!has((parentState as Exclude<ImmerState, SetState>).assigned_!, prop) // Skip deep patches for assigned keys.
+				? rootPath!.concat(prop)
+				: undefined
+		// Drafts owned by `scope` are finalized here.
+		const res = finalize(rootScope, childValue, path)
+		set(targetObject, prop, res)
+		// Drafts from another scope must prevented to be frozen
+		// if we got a draft back from finalize, we're in a nested produce and shouldn't freeze
+		if (isDraft(res)) {
+			rootScope.canAutoFreeze_ = false
+		} else return
+	} else if (targetIsSet) {
+		targetObject.add(childValue)
+	}
+	// Search new objects for unfinalized drafts. Frozen objects should never contain drafts.
+	if (isDraftable(childValue) && !isFrozen(childValue)) {
+		if (!rootScope.immer_.autoFreeze_ && rootScope.unfinalizedDrafts_ < 1) {
+			// optimization: if an object is not a draft, and we don't have to
+			// deepfreeze everything, and we are sure that no drafts are left in the remaining object
+			// cause we saw and finalized all drafts already; we can stop visiting the rest of the tree.
+			// This benefits especially adding large data tree's without further processing.
+			// See add-data.js perf test
+			return
+		}
+		finalize(rootScope, childValue)
+		// immer deep freezes plain objects, so if there is no parent state, we freeze as well
+		if (!parentState || !parentState.scope_.parent_)
+			maybeFreeze(rootScope, childValue)
+	}
+}
+
+function maybeFreeze(scope: ImmerScope, value: any, deep = false) {
+	// we never freeze for a non-root scope; as it would prevent pruning for drafts inside wrapping objects
+	if (!scope.parent_ && scope.immer_.autoFreeze_ && scope.canAutoFreeze_) {
+		freeze(value, deep)
+	}
+}

node_modules/immer/src/core/immerClass.ts

@@ -0,0 +1,241 @@
+import {
+	IProduceWithPatches,
+	IProduce,
+	ImmerState,
+	Drafted,
+	isDraftable,
+	processResult,
+	Patch,
+	Objectish,
+	DRAFT_STATE,
+	Draft,
+	PatchListener,
+	isDraft,
+	isMap,
+	isSet,
+	createProxyProxy,
+	getPlugin,
+	die,
+	hasProxies,
+	enterScope,
+	revokeScope,
+	leaveScope,
+	usePatchesInScope,
+	getCurrentScope,
+	NOTHING,
+	freeze,
+	current
+} from "../internal"
+
+interface ProducersFns {
+	produce: IProduce
+	produceWithPatches: IProduceWithPatches
+}
+
+export class Immer implements ProducersFns {
+	useProxies_: boolean = hasProxies
+
+	autoFreeze_: boolean = true
+
+	constructor(config?: {useProxies?: boolean; autoFreeze?: boolean}) {
+		if (typeof config?.useProxies === "boolean")
+			this.setUseProxies(config!.useProxies)
+		if (typeof config?.autoFreeze === "boolean")
+			this.setAutoFreeze(config!.autoFreeze)
+	}
+
+	/**
+	 * The `produce` function takes a value and a "recipe function" (whose
+	 * return value often depends on the base state). The recipe function is
+	 * free to mutate its first argument however it wants. All mutations are
+	 * only ever applied to a __copy__ of the base state.
+	 *
+	 * Pass only a function to create a "curried producer" which relieves you
+	 * from passing the recipe function every time.
+	 *
+	 * Only plain objects and arrays are made mutable. All other objects are
+	 * considered uncopyable.
+	 *
+	 * Note: This function is __bound__ to its `Immer` instance.
+	 *
+	 * @param {any} base - the initial state
+	 * @param {Function} recipe - function that receives a proxy of the base state as first argument and which can be freely modified
+	 * @param {Function} patchListener - optional function that will be called with all the patches produced here
+	 * @returns {any} a new state, or the initial state if nothing was modified
+	 */
+	produce: IProduce = (base: any, recipe?: any, patchListener?: any) => {
+		// curried invocation
+		if (typeof base === "function" && typeof recipe !== "function") {
+			const defaultBase = recipe
+			recipe = base
+
+			const self = this
+			return function curriedProduce(
+				this: any,
+				base = defaultBase,
+				...args: any[]
+			) {
+				return self.produce(base, (draft: Drafted) => recipe.call(this, draft, ...args)) // prettier-ignore
+			}
+		}
+
+		if (typeof recipe !== "function") die(6)
+		if (patchListener !== undefined && typeof patchListener !== "function")
+			die(7)
+
+		let result
+
+		// Only plain objects, arrays, and "immerable classes" are drafted.
+		if (isDraftable(base)) {
+			const scope = enterScope(this)
+			const proxy = createProxy(this, base, undefined)
+			let hasError = true
+			try {
+				result = recipe(proxy)
+				hasError = false
+			} finally {
+				// finally instead of catch + rethrow better preserves original stack
+				if (hasError) revokeScope(scope)
+				else leaveScope(scope)
+			}
+			if (typeof Promise !== "undefined" && result instanceof Promise) {
+				return result.then(
+					result => {
+						usePatchesInScope(scope, patchListener)
+						return processResult(result, scope)
+					},
+					error => {
+						revokeScope(scope)
+						throw error
+					}
+				)
+			}
+			usePatchesInScope(scope, patchListener)
+			return processResult(result, scope)
+		} else if (!base || typeof base !== "object") {
+			result = recipe(base)
+			if (result === undefined) result = base
+			if (result === NOTHING) result = undefined
+			if (this.autoFreeze_) freeze(result, true)
+			if (patchListener) {
+				const p: Patch[] = []
+				const ip: Patch[] = []
+				getPlugin("Patches").generateReplacementPatches_(base, result, p, ip)
+				patchListener(p, ip)
+			}
+			return result
+		} else die(21, base)
+	}
+
+	produceWithPatches: IProduceWithPatches = (base: any, recipe?: any): any => {
+		// curried invocation
+		if (typeof base === "function") {
+			return (state: any, ...args: any[]) =>
+				this.produceWithPatches(state, (draft: any) => base(draft, ...args))
+		}
+
+		let patches: Patch[], inversePatches: Patch[]
+		const result = this.produce(base, recipe, (p: Patch[], ip: Patch[]) => {
+			patches = p
+			inversePatches = ip
+		})
+
+		if (typeof Promise !== "undefined" && result instanceof Promise) {
+			return result.then(nextState => [nextState, patches!, inversePatches!])
+		}
+		return [result, patches!, inversePatches!]
+	}
+
+	createDraft<T extends Objectish>(base: T): Draft<T> {
+		if (!isDraftable(base)) die(8)
+		if (isDraft(base)) base = current(base)
+		const scope = enterScope(this)
+		const proxy = createProxy(this, base, undefined)
+		proxy[DRAFT_STATE].isManual_ = true
+		leaveScope(scope)
+		return proxy as any
+	}
+
+	finishDraft<D extends Draft<any>>(
+		draft: D,
+		patchListener?: PatchListener
+	): D extends Draft<infer T> ? T : never {
+		const state: ImmerState = draft && (draft as any)[DRAFT_STATE]
+		if (__DEV__) {
+			if (!state || !state.isManual_) die(9)
+			if (state.finalized_) die(10)
+		}
+		const {scope_: scope} = state
+		usePatchesInScope(scope, patchListener)
+		return processResult(undefined, scope)
+	}
+
+	/**
+	 * Pass true to automatically freeze all copies created by Immer.
+	 *
+	 * By default, auto-freezing is enabled.
+	 */
+	setAutoFreeze(value: boolean) {
+		this.autoFreeze_ = value
+	}
+
+	/**
+	 * Pass true to use the ES2015 `Proxy` class when creating drafts, which is
+	 * always faster than using ES5 proxies.
+	 *
+	 * By default, feature detection is used, so calling this is rarely necessary.
+	 */
+	setUseProxies(value: boolean) {
+		if (value && !hasProxies) {
+			die(20)
+		}
+		this.useProxies_ = value
+	}
+
+	applyPatches<T extends Objectish>(base: T, patches: Patch[]): T {
+		// If a patch replaces the entire state, take that replacement as base
+		// before applying patches
+		let i: number
+		for (i = patches.length - 1; i >= 0; i--) {
+			const patch = patches[i]
+			if (patch.path.length === 0 && patch.op === "replace") {
+				base = patch.value
+				break
+			}
+		}
+		// If there was a patch that replaced the entire state, start from the
+		// patch after that.
+		if (i > -1) {
+			patches = patches.slice(i + 1)
+		}
+
+		const applyPatchesImpl = getPlugin("Patches").applyPatches_
+		if (isDraft(base)) {
+			// N.B: never hits if some patch a replacement, patches are never drafts
+			return applyPatchesImpl(base, patches)
+		}
+		// Otherwise, produce a copy of the base state.
+		return this.produce(base, (draft: Drafted) =>
+			applyPatchesImpl(draft, patches)
+		)
+	}
+}
+
+export function createProxy<T extends Objectish>(
+	immer: Immer,
+	value: T,
+	parent?: ImmerState
+): Drafted<T, ImmerState> {
+	// precondition: createProxy should be guarded by isDraftable, so we know we can safely draft
+	const draft: Drafted = isMap(value)
+		? getPlugin("MapSet").proxyMap_(value, parent)
+		: isSet(value)
+		? getPlugin("MapSet").proxySet_(value, parent)
+		: immer.useProxies_
+		? createProxyProxy(value, parent)
+		: getPlugin("ES5").createES5Proxy_(value, parent)
+
+	const scope = parent ? parent.scope_ : getCurrentScope()
+	scope.drafts_.push(draft)
+	return draft
+}

node_modules/immer/src/core/proxy.ts

@@ -0,0 +1,280 @@
+import {
+	each,
+	has,
+	is,
+	isDraftable,
+	shallowCopy,
+	latest,
+	ImmerBaseState,
+	ImmerState,
+	Drafted,
+	AnyObject,
+	AnyArray,
+	Objectish,
+	getCurrentScope,
+	DRAFT_STATE,
+	die,
+	createProxy,
+	ProxyType
+} from "../internal"
+
+interface ProxyBaseState extends ImmerBaseState {
+	assigned_: {
+		[property: string]: boolean
+	}
+	parent_?: ImmerState
+	revoke_(): void
+}
+
+export interface ProxyObjectState extends ProxyBaseState {
+	type_: ProxyType.ProxyObject
+	base_: any
+	copy_: any
+	draft_: Drafted<AnyObject, ProxyObjectState>
+}
+
+export interface ProxyArrayState extends ProxyBaseState {
+	type_: ProxyType.ProxyArray
+	base_: AnyArray
+	copy_: AnyArray | null
+	draft_: Drafted<AnyArray, ProxyArrayState>
+}
+
+type ProxyState = ProxyObjectState | ProxyArrayState
+
+/**
+ * Returns a new draft of the `base` object.
+ *
+ * The second argument is the parent draft-state (used internally).
+ */
+export function createProxyProxy<T extends Objectish>(
+	base: T,
+	parent?: ImmerState
+): Drafted<T, ProxyState> {
+	const isArray = Array.isArray(base)
+	const state: ProxyState = {
+		type_: isArray ? ProxyType.ProxyArray : (ProxyType.ProxyObject as any),
+		// Track which produce call this is associated with.
+		scope_: parent ? parent.scope_ : getCurrentScope()!,
+		// True for both shallow and deep changes.
+		modified_: false,
+		// Used during finalization.
+		finalized_: false,
+		// Track which properties have been assigned (true) or deleted (false).
+		assigned_: {},
+		// The parent draft state.
+		parent_: parent,
+		// The base state.
+		base_: base,
+		// The base proxy.
+		draft_: null as any, // set below
+		// The base copy with any updated values.
+		copy_: null,
+		// Called by the `produce` function.
+		revoke_: null as any,
+		isManual_: false
+	}
+
+	// the traps must target something, a bit like the 'real' base.
+	// but also, we need to be able to determine from the target what the relevant state is
+	// (to avoid creating traps per instance to capture the state in closure,
+	// and to avoid creating weird hidden properties as well)
+	// So the trick is to use 'state' as the actual 'target'! (and make sure we intercept everything)
+	// Note that in the case of an array, we put the state in an array to have better Reflect defaults ootb
+	let target: T = state as any
+	let traps: ProxyHandler<object | Array<any>> = objectTraps
+	if (isArray) {
+		target = [state] as any
+		traps = arrayTraps
+	}
+
+	const {revoke, proxy} = Proxy.revocable(target, traps)
+	state.draft_ = proxy as any
+	state.revoke_ = revoke
+	return proxy as any
+}
+
+/**
+ * Object drafts
+ */
+export const objectTraps: ProxyHandler<ProxyState> = {
+	get(state, prop) {
+		if (prop === DRAFT_STATE) return state
+
+		const source = latest(state)
+		if (!has(source, prop)) {
+			// non-existing or non-own property...
+			return readPropFromProto(state, source, prop)
+		}
+		const value = source[prop]
+		if (state.finalized_ || !isDraftable(value)) {
+			return value
+		}
+		// Check for existing draft in modified state.
+		// Assigned values are never drafted. This catches any drafts we created, too.
+		if (value === peek(state.base_, prop)) {
+			prepareCopy(state)
+			return (state.copy_![prop as any] = createProxy(
+				state.scope_.immer_,
+				value,
+				state
+			))
+		}
+		return value
+	},
+	has(state, prop) {
+		return prop in latest(state)
+	},
+	ownKeys(state) {
+		return Reflect.ownKeys(latest(state))
+	},
+	set(
+		state: ProxyObjectState,
+		prop: string /* strictly not, but helps TS */,
+		value
+	) {
+		const desc = getDescriptorFromProto(latest(state), prop)
+		if (desc?.set) {
+			// special case: if this write is captured by a setter, we have
+			// to trigger it with the correct context
+			desc.set.call(state.draft_, value)
+			return true
+		}
+		if (!state.modified_) {
+			// the last check is because we need to be able to distinguish setting a non-existing to undefined (which is a change)
+			// from setting an existing property with value undefined to undefined (which is not a change)
+			const current = peek(latest(state), prop)
+			// special case, if we assigning the original value to a draft, we can ignore the assignment
+			const currentState: ProxyObjectState = current?.[DRAFT_STATE]
+			if (currentState && currentState.base_ === value) {
+				state.copy_![prop] = value
+				state.assigned_[prop] = false
+				return true
+			}
+			if (is(value, current) && (value !== undefined || has(state.base_, prop)))
+				return true
+			prepareCopy(state)
+			markChanged(state)
+		}
+
+		if (
+			(state.copy_![prop] === value &&
+				// special case: handle new props with value 'undefined'
+				(value !== undefined || prop in state.copy_)) ||
+			// special case: NaN
+			(Number.isNaN(value) && Number.isNaN(state.copy_![prop]))
+		)
+			return true
+
+		// @ts-ignore
+		state.copy_![prop] = value
+		state.assigned_[prop] = true
+		return true
+	},
+	deleteProperty(state, prop: string) {
+		// The `undefined` check is a fast path for pre-existing keys.
+		if (peek(state.base_, prop) !== undefined || prop in state.base_) {
+			state.assigned_[prop] = false
+			prepareCopy(state)
+			markChanged(state)
+		} else {
+			// if an originally not assigned property was deleted
+			delete state.assigned_[prop]
+		}
+		// @ts-ignore
+		if (state.copy_) delete state.copy_[prop]
+		return true
+	},
+	// Note: We never coerce `desc.value` into an Immer draft, because we can't make
+	// the same guarantee in ES5 mode.
+	getOwnPropertyDescriptor(state, prop) {
+		const owner = latest(state)
+		const desc = Reflect.getOwnPropertyDescriptor(owner, prop)
+		if (!desc) return desc
+		return {
+			writable: true,
+			configurable: state.type_ !== ProxyType.ProxyArray || prop !== "length",
+			enumerable: desc.enumerable,
+			value: owner[prop]
+		}
+	},
+	defineProperty() {
+		die(11)
+	},
+	getPrototypeOf(state) {
+		return Object.getPrototypeOf(state.base_)
+	},
+	setPrototypeOf() {
+		die(12)
+	}
+}
+
+/**
+ * Array drafts
+ */
+
+const arrayTraps: ProxyHandler<[ProxyArrayState]> = {}
+each(objectTraps, (key, fn) => {
+	// @ts-ignore
+	arrayTraps[key] = function() {
+		arguments[0] = arguments[0][0]
+		return fn.apply(this, arguments)
+	}
+})
+arrayTraps.deleteProperty = function(state, prop) {
+	if (__DEV__ && isNaN(parseInt(prop as any))) die(13)
+	// @ts-ignore
+	return arrayTraps.set!.call(this, state, prop, undefined)
+}
+arrayTraps.set = function(state, prop, value) {
+	if (__DEV__ && prop !== "length" && isNaN(parseInt(prop as any))) die(14)
+	return objectTraps.set!.call(this, state[0], prop, value, state[0])
+}
+
+// Access a property without creating an Immer draft.
+function peek(draft: Drafted, prop: PropertyKey) {
+	const state = draft[DRAFT_STATE]
+	const source = state ? latest(state) : draft
+	return source[prop]
+}
+
+function readPropFromProto(state: ImmerState, source: any, prop: PropertyKey) {
+	const desc = getDescriptorFromProto(source, prop)
+	return desc
+		? `value` in desc
+			? desc.value
+			: // This is a very special case, if the prop is a getter defined by the
+			  // prototype, we should invoke it with the draft as context!
+			  desc.get?.call(state.draft_)
+		: undefined
+}
+
+function getDescriptorFromProto(
+	source: any,
+	prop: PropertyKey
+): PropertyDescriptor | undefined {
+	// 'in' checks proto!
+	if (!(prop in source)) return undefined
+	let proto = Object.getPrototypeOf(source)
+	while (proto) {
+		const desc = Object.getOwnPropertyDescriptor(proto, prop)
+		if (desc) return desc
+		proto = Object.getPrototypeOf(proto)
+	}
+	return undefined
+}
+
+export function markChanged(state: ImmerState) {
+	if (!state.modified_) {
+		state.modified_ = true
+		if (state.parent_) {
+			markChanged(state.parent_)
+		}
+	}
+}
+
+export function prepareCopy(state: {base_: any; copy_: any}) {
+	if (!state.copy_) {
+		state.copy_ = shallowCopy(state.base_)
+	}
+}

node_modules/immer/src/core/scope.ts

@@ -0,0 +1,85 @@
+import {
+	Patch,
+	PatchListener,
+	Drafted,
+	Immer,
+	DRAFT_STATE,
+	ImmerState,
+	ProxyType,
+	getPlugin
+} from "../internal"
+import {die} from "../utils/errors"
+
+/** Each scope represents a `produce` call. */
+
+export interface ImmerScope {
+	patches_?: Patch[]
+	inversePatches_?: Patch[]
+	canAutoFreeze_: boolean
+	drafts_: any[]
+	parent_?: ImmerScope
+	patchListener_?: PatchListener
+	immer_: Immer
+	unfinalizedDrafts_: number
+}
+
+let currentScope: ImmerScope | undefined
+
+export function getCurrentScope() {
+	if (__DEV__ && !currentScope) die(0)
+	return currentScope!
+}
+
+function createScope(
+	parent_: ImmerScope | undefined,
+	immer_: Immer
+): ImmerScope {
+	return {
+		drafts_: [],
+		parent_,
+		immer_,
+		// Whenever the modified draft contains a draft from another scope, we
+		// need to prevent auto-freezing so the unowned draft can be finalized.
+		canAutoFreeze_: true,
+		unfinalizedDrafts_: 0
+	}
+}
+
+export function usePatchesInScope(
+	scope: ImmerScope,
+	patchListener?: PatchListener
+) {
+	if (patchListener) {
+		getPlugin("Patches") // assert we have the plugin
+		scope.patches_ = []
+		scope.inversePatches_ = []
+		scope.patchListener_ = patchListener
+	}
+}
+
+export function revokeScope(scope: ImmerScope) {
+	leaveScope(scope)
+	scope.drafts_.forEach(revokeDraft)
+	// @ts-ignore
+	scope.drafts_ = null
+}
+
+export function leaveScope(scope: ImmerScope) {
+	if (scope === currentScope) {
+		currentScope = scope.parent_
+	}
+}
+
+export function enterScope(immer: Immer) {
+	return (currentScope = createScope(currentScope, immer))
+}
+
+function revokeDraft(draft: Drafted) {
+	const state: ImmerState = draft[DRAFT_STATE]
+	if (
+		state.type_ === ProxyType.ProxyObject ||
+		state.type_ === ProxyType.ProxyArray
+	)
+		state.revoke_()
+	else state.revoked_ = true
+}