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vanilla.ts
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import { getUntracked, markToTrack } from 'proxy-compare'
const isObject = (x: unknown): x is object =>
typeof x === 'object' && x !== null
type AnyFunction = (...args: any[]) => any
type AsRef = { $$valtioRef: true }
type ProxyObject = object
type Path = (string | symbol)[]
type Op =
| [op: 'set', path: Path, value: unknown, prevValue: unknown]
| [op: 'delete', path: Path, prevValue: unknown]
| [op: 'resolve', path: Path, value: unknown]
| [op: 'reject', path: Path, error: unknown]
type Listener = (op: Op, nextVersion: number) => void
type SnapshotIgnore =
| Date
| Map<any, any>
| Set<any>
| WeakMap<any, any>
| WeakSet<any>
| AsRef
| Error
| RegExp
| AnyFunction
type Snapshot<T> = T extends SnapshotIgnore
? T
: T extends Promise<unknown>
? Awaited<T>
: T extends object
? { readonly [K in keyof T]: Snapshot<T[K]> }
: T
/**
* This is not a public API.
* It can be changed without any notice.
*/
export type INTERNAL_Snapshot<T> = Snapshot<T>
type HandlePromise = <P extends Promise<any>>(promise: P) => Awaited<P>
type CreateSnapshot = <T extends object>(
target: T,
version: number,
handlePromise?: HandlePromise
) => T
type RemoveListener = () => void
type AddListener = (listener: Listener) => RemoveListener
type ProxyState = readonly [
target: object,
ensureVersion: (nextCheckVersion?: number) => number,
createSnapshot: CreateSnapshot,
addListener: AddListener
]
// shared state
const proxyStateMap = new WeakMap<ProxyObject, ProxyState>()
const refSet = new WeakSet()
const buildProxyFunction = (
objectIs = Object.is,
newProxy = <T extends object>(target: T, handler: ProxyHandler<T>): T =>
new Proxy(target, handler),
canProxy = (x: unknown) =>
isObject(x) &&
!refSet.has(x) &&
(Array.isArray(x) || !(Symbol.iterator in x)) &&
!(x instanceof WeakMap) &&
!(x instanceof WeakSet) &&
!(x instanceof Error) &&
!(x instanceof Number) &&
!(x instanceof Date) &&
!(x instanceof String) &&
!(x instanceof RegExp) &&
!(x instanceof ArrayBuffer),
defaultHandlePromise = <P extends Promise<any>>(
promise: P & {
status?: 'pending' | 'fulfilled' | 'rejected'
value?: Awaited<P>
reason?: unknown
}
) => {
switch (promise.status) {
case 'fulfilled':
return promise.value as Awaited<P>
case 'rejected':
throw promise.reason
default:
throw promise
}
},
snapCache = new WeakMap<object, [version: number, snap: unknown]>(),
createSnapshot: CreateSnapshot = <T extends object>(
target: T,
version: number,
handlePromise: HandlePromise = defaultHandlePromise
): T => {
const cache = snapCache.get(target)
if (cache?.[0] === version) {
return cache[1] as T
}
const snap: any = Array.isArray(target)
? []
: Object.create(Object.getPrototypeOf(target))
markToTrack(snap, true) // mark to track
snapCache.set(target, [version, snap])
Reflect.ownKeys(target).forEach((key) => {
if (Object.getOwnPropertyDescriptor(snap, key)) {
// Only the known case is Array.length so far.
return
}
const value = Reflect.get(target, key)
const desc: PropertyDescriptor = {
value,
enumerable: true,
// This is intentional to avoid copying with proxy-compare.
// It's still non-writable, so it avoids assigning a value.
configurable: true,
}
if (refSet.has(value as object)) {
markToTrack(value as object, false) // mark not to track
} else if (value instanceof Promise) {
delete desc.value
desc.get = () => handlePromise(value)
} else if (proxyStateMap.has(value as object)) {
const [target, ensureVersion] = proxyStateMap.get(
value as object
) as ProxyState
desc.value = createSnapshot(
target,
ensureVersion(),
handlePromise
) as Snapshot<T>
}
Object.defineProperty(snap, key, desc)
})
return snap
},
proxyCache = new WeakMap<object, ProxyObject>(),
versionHolder = [1, 1] as [number, number],
proxyFunction = <T extends object>(initialObject: T): T => {
if (!isObject(initialObject)) {
throw new Error('object required')
}
const found = proxyCache.get(initialObject) as T | undefined
if (found) {
return found
}
let version = versionHolder[0]
const listeners = new Set<Listener>()
const notifyUpdate = (op: Op, nextVersion = ++versionHolder[0]) => {
if (version !== nextVersion) {
version = nextVersion
listeners.forEach((listener) => listener(op, nextVersion))
}
}
let checkVersion = versionHolder[1]
const ensureVersion = (nextCheckVersion = ++versionHolder[1]) => {
if (checkVersion !== nextCheckVersion && !listeners.size) {
checkVersion = nextCheckVersion
propProxyStates.forEach(([propProxyState]) => {
const propVersion = propProxyState[1](nextCheckVersion)
if (propVersion > version) {
version = propVersion
}
})
}
return version
}
const createPropListener =
(prop: string | symbol): Listener =>
(op, nextVersion) => {
const newOp: Op = [...op]
newOp[1] = [prop, ...(newOp[1] as Path)]
notifyUpdate(newOp, nextVersion)
}
const propProxyStates = new Map<
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 removePropListener = (prop: string | symbol) => {
const entry = propProxyStates.get(prop)
if (entry) {
propProxyStates.delete(prop)
entry[1]?.()
}
}
const addListener = (listener: Listener) => {
listeners.add(listener)
if (listeners.size === 1) {
propProxyStates.forEach(([propProxyState, prevRemove], prop) => {
if (import.meta.env?.MODE !== 'production' && prevRemove) {
throw new Error('remove already exists')
}
const remove = propProxyState[3](createPropListener(prop))
propProxyStates.set(prop, [propProxyState, remove])
})
}
const removeListener = () => {
listeners.delete(listener)
if (listeners.size === 0) {
propProxyStates.forEach(([propProxyState, remove], prop) => {
if (remove) {
remove()
propProxyStates.set(prop, [propProxyState])
}
})
}
}
return removeListener
}
const baseObject = Array.isArray(initialObject)
? []
: Object.create(Object.getPrototypeOf(initialObject))
const handler: ProxyHandler<T> = {
deleteProperty(target: T, prop: string | symbol) {
const prevValue = Reflect.get(target, prop)
removePropListener(prop)
const deleted = Reflect.deleteProperty(target, prop)
if (deleted) {
notifyUpdate(['delete', [prop], prevValue])
}
return deleted
},
set(target: T, prop: string | symbol, value: any, receiver: object) {
const hasPrevValue = Reflect.has(target, prop)
const prevValue = Reflect.get(target, prop, receiver)
if (
hasPrevValue &&
(objectIs(prevValue, value) ||
(proxyCache.has(value) &&
objectIs(prevValue, proxyCache.get(value))))
) {
return true
}
removePropListener(prop)
if (isObject(value)) {
value = getUntracked(value) || value
}
let nextValue = value
if (value instanceof Promise) {
value
.then((v) => {
value.status = 'fulfilled'
value.value = v
notifyUpdate(['resolve', [prop], v])
})
.catch((e) => {
value.status = 'rejected'
value.reason = e
notifyUpdate(['reject', [prop], e])
})
} else {
if (!proxyStateMap.has(value) && canProxy(value)) {
nextValue = proxyFunction(value)
}
const childProxyState =
!refSet.has(nextValue) && proxyStateMap.get(nextValue)
if (childProxyState) {
addPropListener(prop, childProxyState)
}
}
Reflect.set(target, prop, nextValue, receiver)
notifyUpdate(['set', [prop], value, prevValue])
return true
},
}
const proxyObject = newProxy(baseObject, handler)
proxyCache.set(initialObject, proxyObject)
const proxyState: ProxyState = [
baseObject,
ensureVersion,
createSnapshot,
addListener,
]
proxyStateMap.set(proxyObject, proxyState)
Reflect.ownKeys(initialObject).forEach((key) => {
const desc = Object.getOwnPropertyDescriptor(
initialObject,
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
}
Object.defineProperty(baseObject, key, desc)
})
return proxyObject
}
) =>
[
// public functions
proxyFunction,
// shared state
proxyStateMap,
refSet,
// internal things
objectIs,
newProxy,
canProxy,
defaultHandlePromise,
snapCache,
createSnapshot,
proxyCache,
versionHolder,
] as const
const [defaultProxyFunction] = buildProxyFunction()
export function proxy<T extends object>(initialObject: T = {} as T): T {
return defaultProxyFunction(initialObject)
}
export function getVersion(proxyObject: unknown): number | undefined {
const proxyState = proxyStateMap.get(proxyObject as object)
return proxyState?.[1]()
}
export function subscribe<T extends object>(
proxyObject: T,
callback: (ops: Op[]) => void,
notifyInSync?: boolean
): () => void {
const proxyState = proxyStateMap.get(proxyObject as object)
if (import.meta.env?.MODE !== 'production' && !proxyState) {
console.warn('Please use proxy object')
}
let promise: Promise<void> | undefined
const ops: Op[] = []
const addListener = (proxyState as ProxyState)[3]
let isListenerActive = false
const listener: Listener = (op) => {
ops.push(op)
if (notifyInSync) {
callback(ops.splice(0))
return
}
if (!promise) {
promise = Promise.resolve().then(() => {
promise = undefined
if (isListenerActive) {
callback(ops.splice(0))
}
})
}
}
const removeListener = addListener(listener)
isListenerActive = true
return () => {
isListenerActive = false
removeListener()
}
}
export function snapshot<T extends object>(
proxyObject: T,
handlePromise?: HandlePromise
): Snapshot<T> {
const proxyState = proxyStateMap.get(proxyObject as object)
if (import.meta.env?.MODE !== 'production' && !proxyState) {
console.warn('Please use proxy object')
}
const [target, ensureVersion, createSnapshot] = proxyState as ProxyState
return createSnapshot(target, ensureVersion(), handlePromise) as Snapshot<T>
}
export function ref<T extends object>(obj: T): T & AsRef {
refSet.add(obj)
return obj as T & AsRef
}
export const unstable_buildProxyFunction = buildProxyFunction