803 lines
20 KiB
TypeScript
803 lines
20 KiB
TypeScript
import type Ticker from '../Ticker'
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import type {$IntentionalAny, VoidFn} from '../types'
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import Stack from '../utils/Stack'
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import type {Prism} from './Interface'
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import {isPrism} from './Interface'
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import {
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startIgnoringDependencies,
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stopIgnoringDependencies,
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pushCollector,
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popCollector,
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reportResolutionStart,
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reportResolutionEnd,
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} from './discoveryMechanism'
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type IDependent = (msgComingFrom: Prism<$IntentionalAny>) => void
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const voidFn = () => {}
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class HotHandle<V> {
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private _didMarkDependentsAsStale: boolean = false
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private _isFresh: boolean = false
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protected _cacheOfDendencyValues: Map<Prism<unknown>, unknown> = new Map()
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/**
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* @internal
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*/
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protected _dependents: Set<IDependent> = new Set()
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/**
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* @internal
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*/
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protected _dependencies: Set<Prism<$IntentionalAny>> = new Set()
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protected _possiblyStaleDeps = new Set<Prism<unknown>>()
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private _scope: HotScope = new HotScope(
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this as $IntentionalAny as HotHandle<unknown>,
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)
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/**
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* @internal
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*/
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protected _lastValue: undefined | V = undefined
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/**
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* If true, the prism is stale even though its dependencies aren't
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* marked as such. This is used by `prism.source()` and `prism.state()`
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* to mark the prism as stale.
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*/
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private _forciblySetToStale: boolean = false
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constructor(
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private readonly _fn: () => V,
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private readonly _prismInstance: PrismInstance<V>,
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) {
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for (const d of this._dependencies) {
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d._addDependent(this._reactToDependencyGoingStale)
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}
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startIgnoringDependencies()
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this.getValue()
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stopIgnoringDependencies()
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}
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get hasDependents(): boolean {
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return this._dependents.size > 0
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}
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removeDependent(d: IDependent) {
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this._dependents.delete(d)
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}
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addDependent(d: IDependent) {
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this._dependents.add(d)
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}
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destroy() {
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for (const d of this._dependencies) {
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d._removeDependent(this._reactToDependencyGoingStale)
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}
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cleanupScopeStack(this._scope)
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}
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getValue(): V {
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if (!this._isFresh) {
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const newValue = this._recalculate()
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this._lastValue = newValue
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this._isFresh = true
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this._didMarkDependentsAsStale = false
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this._forciblySetToStale = false
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}
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return this._lastValue!
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}
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_recalculate() {
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let value: V
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if (!this._forciblySetToStale) {
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if (this._possiblyStaleDeps.size > 0) {
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let anActuallyStaleDepWasFound = false
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startIgnoringDependencies()
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for (const dep of this._possiblyStaleDeps) {
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if (this._cacheOfDendencyValues.get(dep) !== dep.getValue()) {
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anActuallyStaleDepWasFound = true
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break
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}
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}
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stopIgnoringDependencies()
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this._possiblyStaleDeps.clear()
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if (!anActuallyStaleDepWasFound) {
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return this._lastValue!
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}
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}
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}
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const newDeps: Set<Prism<unknown>> = new Set()
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this._cacheOfDendencyValues.clear()
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const collector = (observedDep: Prism<unknown>): void => {
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newDeps.add(observedDep)
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this._addDependency(observedDep)
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}
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pushCollector(collector)
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hookScopeStack.push(this._scope)
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try {
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value = this._fn()
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} catch (error) {
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console.error(error)
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} finally {
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const topOfTheStack = hookScopeStack.pop()
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if (topOfTheStack !== this._scope) {
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console.warn(
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// @todo guide the user to report the bug in an issue
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`The Prism hook stack has slipped. This is a bug.`,
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)
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}
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}
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popCollector(collector)
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for (const dep of this._dependencies) {
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if (!newDeps.has(dep)) {
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this._removeDependency(dep)
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}
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}
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this._dependencies = newDeps
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startIgnoringDependencies()
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for (const dep of newDeps) {
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this._cacheOfDendencyValues.set(dep, dep.getValue())
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}
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stopIgnoringDependencies()
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return value!
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}
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forceStale() {
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this._forciblySetToStale = true
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this._markAsStale()
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}
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protected _reactToDependencyGoingStale = (which: Prism<$IntentionalAny>) => {
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this._possiblyStaleDeps.add(which)
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this._markAsStale()
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}
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private _markAsStale() {
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if (this._didMarkDependentsAsStale) return
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this._didMarkDependentsAsStale = true
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this._isFresh = false
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for (const dependent of this._dependents) {
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dependent(this._prismInstance)
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}
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}
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/**
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* @internal
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*/
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protected _addDependency(d: Prism<$IntentionalAny>) {
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if (this._dependencies.has(d)) return
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this._dependencies.add(d)
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d._addDependent(this._reactToDependencyGoingStale)
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}
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/**
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* @internal
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*/
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protected _removeDependency(d: Prism<$IntentionalAny>) {
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if (!this._dependencies.has(d)) return
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this._dependencies.delete(d)
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d._removeDependent(this._reactToDependencyGoingStale)
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}
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}
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const emptyObject = {}
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class PrismInstance<V> implements Prism<V> {
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/**
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* Whether the object is a prism.
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*/
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readonly isPrism: true = true
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private _state:
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| {hot: false; handle: undefined}
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| {hot: true; handle: HotHandle<V>} = {
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hot: false,
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handle: undefined,
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}
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constructor(private readonly _fn: () => V) {}
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/**
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* Whether the prism is hot.
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*/
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get isHot(): boolean {
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return this._state.hot
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}
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onChange(
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ticker: Ticker,
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listener: (v: V) => void,
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immediate: boolean = false,
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): VoidFn {
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const dependent = () => {
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ticker.onThisOrNextTick(refresh)
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}
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let lastValue = emptyObject
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const refresh = () => {
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const newValue = this.getValue()
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if (newValue === lastValue) return
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lastValue = newValue
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listener(newValue)
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}
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this._addDependent(dependent)
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if (immediate) {
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lastValue = this.getValue()
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listener(lastValue as $IntentionalAny as V)
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}
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const unsubscribe = () => {
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this._removeDependent(dependent)
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}
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return unsubscribe
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}
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/**
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* Calls `callback` every time the prism's state goes from `fresh-\>stale.` Returns an `unsubscribe()` function.
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*/
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onStale(callback: () => void): VoidFn {
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const untap = () => {
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this._removeDependent(fn)
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}
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const fn = () => callback()
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this._addDependent(fn)
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return untap
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}
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/**
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* Keep the prism hot, even if there are no tappers (subscribers).
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*/
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keepHot() {
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return this.onStale(() => {})
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}
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/**
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* Add a prism as a dependent of this prism.
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*
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* @param d - The prism to be made a dependent of this prism.
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*
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* @see _removeDependent
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*/
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_addDependent(d: IDependent) {
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if (!this._state.hot) {
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this._goHot()
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}
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this._state.handle!.addDependent(d)
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}
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private _goHot() {
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const hotHandle = new HotHandle(this._fn, this)
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this._state = {
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hot: true,
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handle: hotHandle,
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}
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}
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/**
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* Remove a prism as a dependent of this prism.
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*
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* @param d - The prism to be removed from as a dependent of this prism.
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*
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* @see _addDependent
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*/
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_removeDependent(d: IDependent) {
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const state = this._state
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if (!state.hot) {
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return
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}
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const handle = state.handle
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handle.removeDependent(d)
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if (!handle.hasDependents) {
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this._state = {hot: false, handle: undefined}
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handle.destroy()
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}
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}
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/**
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* Gets the current value of the prism. If the value is stale, it causes the prism to freshen.
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*/
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getValue(): V {
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/**
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* TODO We should prevent (or warn about) a common mistake users make, which is reading the value of
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* a prism in the body of a react component (e.g. `der.getValue()` (often via `val()`) instead of `useVal()`
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* or `uesPrism()`).
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*
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* Although that's the most common example of this mistake, you can also find it outside of react components.
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* Basically the user runs `der.getValue()` assuming the read is detected by a wrapping prism when it's not.
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*
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* Sometiems the prism isn't even hot when the user assumes it is.
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*
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* We can fix this type of mistake by:
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* 1. Warning the user when they call `getValue()` on a cold prism.
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* 2. Warning the user about calling `getValue()` on a hot-but-stale prism
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* if `getValue()` isn't called by a known mechanism like a `PrismEmitter`.
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*
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* Design constraints:
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* - This fix should not have a perf-penalty in production. Perhaps use a global flag + `process.env.NODE_ENV !== 'production'`
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* to enable it.
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* - In the case of `onStale()`, we don't control when the user calls
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* `getValue()` (as opposed to `onChange()` which calls `getValue()` directly).
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* Perhaps we can disable the check in that case.
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* - Probably the best place to add this check is right here in this method plus some changes to `reportResulutionStart()`,
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* which would have to be changed to let the caller know if there is an actual collector (a prism)
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* present in its stack.
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*/
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reportResolutionStart(this)
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const state = this._state
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let val: V
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if (state.hot) {
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val = state.handle.getValue()
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} else {
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val = calculateColdPrism(this._fn)
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}
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reportResolutionEnd(this)
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return val
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}
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}
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interface PrismScope {
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effect(key: string, cb: () => () => void, deps?: unknown[]): void
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memo<T>(
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key: string,
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fn: () => T,
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deps: undefined | $IntentionalAny[] | ReadonlyArray<$IntentionalAny>,
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): T
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state<T>(key: string, initialValue: T): [T, (val: T) => void]
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ref<T>(key: string, initialValue: T): IRef<T>
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sub(key: string): PrismScope
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source<V>(subscribe: (fn: (val: V) => void) => VoidFn, getValue: () => V): V
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}
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class HotScope implements PrismScope {
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constructor(private readonly _hotHandle: HotHandle<unknown>) {}
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protected readonly _refs: Map<string, IRef<unknown>> = new Map()
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ref<T>(key: string, initialValue: T): IRef<T> {
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let ref = this._refs.get(key)
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if (ref !== undefined) {
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return ref as $IntentionalAny as IRef<T>
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} else {
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const ref = {
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current: initialValue,
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}
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this._refs.set(key, ref)
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return ref
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}
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}
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isPrismScope = true
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// NOTE probably not a great idea to eager-allocate all of these objects/maps for every scope,
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// especially because most wouldn't get used in the majority of cases. However, back when these
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// were stored on weakmaps, they were uncomfortable to inspect in the debugger.
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readonly subs: Record<string, HotScope> = {}
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readonly effects: Map<string, IEffect> = new Map()
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effect(key: string, cb: () => () => void, deps?: unknown[]): void {
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let effect = this.effects.get(key)
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if (effect === undefined) {
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effect = {
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cleanup: voidFn,
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deps: undefined,
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}
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this.effects.set(key, effect)
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}
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if (depsHaveChanged(effect.deps, deps)) {
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effect.cleanup()
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startIgnoringDependencies()
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effect.cleanup = safelyRun(cb, voidFn).value
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stopIgnoringDependencies()
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effect.deps = deps
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}
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/**
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* TODO: we should cleanup dangling effects too.
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* Example:
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* ```ts
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* let i = 0
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* prism(() => {
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* if (i === 0) prism.effect("this effect will only run once", () => {}, [])
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* i++
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* })
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* ```
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*/
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}
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readonly memos: Map<string, IMemo> = new Map()
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memo<T>(
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key: string,
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fn: () => T,
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deps: undefined | $IntentionalAny[] | ReadonlyArray<$IntentionalAny>,
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): T {
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let memo = this.memos.get(key)
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if (memo === undefined) {
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memo = {
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cachedValue: null,
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// undefined will always indicate "deps have changed", so we set its initial value as such
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deps: undefined,
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}
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this.memos.set(key, memo)
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}
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if (depsHaveChanged(memo.deps, deps)) {
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startIgnoringDependencies()
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memo.cachedValue = safelyRun(fn, undefined).value
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stopIgnoringDependencies()
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memo.deps = deps
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}
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return memo.cachedValue as $IntentionalAny as T
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}
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state<T>(key: string, initialValue: T): [T, (val: T) => void] {
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const {value, setValue} = this.memo(
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'state/' + key,
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() => {
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const value = {current: initialValue}
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const setValue = (newValue: T) => {
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value.current = newValue
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this._hotHandle.forceStale()
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}
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return {value, setValue}
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},
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[],
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)
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return [value.current, setValue]
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}
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sub(key: string): HotScope {
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if (!this.subs[key]) {
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this.subs[key] = new HotScope(this._hotHandle)
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}
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return this.subs[key]
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}
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cleanupEffects() {
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for (const effect of this.effects.values()) {
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safelyRun(effect.cleanup, undefined)
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}
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this.effects.clear()
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}
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source<V>(subscribe: (fn: (val: V) => void) => VoidFn, getValue: () => V): V {
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const sourceKey = '$$source/blah'
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this.effect(
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sourceKey,
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() => {
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const unsub = subscribe(() => {
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this._hotHandle.forceStale()
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})
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return unsub
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},
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[subscribe],
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)
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return getValue()
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}
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}
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function cleanupScopeStack(scope: HotScope) {
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for (const sub of Object.values(scope.subs)) {
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cleanupScopeStack(sub)
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}
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scope.cleanupEffects()
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}
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function safelyRun<T, U>(
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fn: () => T,
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returnValueInCaseOfError: U,
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): {ok: true; value: T} | {ok: false; value: U} {
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try {
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return {value: fn(), ok: true}
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} catch (error) {
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// Naming this function can allow the error reporter additional context to the user on where this error came from
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setTimeout(function PrismReportThrow() {
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// ensure that the error gets reported, but does not crash the current execution scope
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throw error
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})
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return {value: returnValueInCaseOfError, ok: false}
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}
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}
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const hookScopeStack = new Stack<PrismScope>()
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type IRef<T> = {
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current: T
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}
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type IEffect = {
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deps: undefined | unknown[]
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cleanup: VoidFn
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}
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type IMemo = {
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deps: undefined | unknown[] | ReadonlyArray<unknown>
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cachedValue: unknown
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}
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function ref<T>(key: string, initialValue: T): IRef<T> {
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const scope = hookScopeStack.peek()
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if (!scope) {
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throw new Error(`prism.ref() is called outside of a prism() call.`)
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}
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return scope.ref(key, initialValue)
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}
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/**
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* An effect hook, similar to React's `useEffect()`, but is not sensitive to call order by using `key`.
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*
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* @param key - the key for the effect. Should be uniqe inside of the prism.
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* @param cb - the callback function. Requires returning a cleanup function.
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* @param deps - the dependency array
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*/
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function effect(key: string, cb: () => () => void, deps?: unknown[]): void {
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const scope = hookScopeStack.peek()
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if (!scope) {
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throw new Error(`prism.effect() is called outside of a prism() call.`)
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}
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return scope.effect(key, cb, deps)
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}
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function depsHaveChanged(
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oldDeps: undefined | unknown[] | ReadonlyArray<unknown>,
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newDeps: undefined | unknown[] | ReadonlyArray<unknown>,
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): boolean {
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if (oldDeps === undefined || newDeps === undefined) {
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return true
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}
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const len = oldDeps.length
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if (len !== newDeps.length) return true
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for (let i = 0; i < len; i++) {
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|
if (oldDeps[i] !== newDeps[i]) return true
|
|
}
|
|
|
|
return false
|
|
}
|
|
|
|
/**
|
|
* Store a value to this {@link prism} stack.
|
|
*
|
|
* Unlike hooks seen in popular frameworks like React, you provide an exact `key` so
|
|
* we can call `prism.memo` in any order, and conditionally.
|
|
*
|
|
* @param deps - Passing in `undefined` will always cause a recompute
|
|
*/
|
|
function memo<T>(
|
|
key: string,
|
|
fn: () => T,
|
|
deps: undefined | $IntentionalAny[] | ReadonlyArray<$IntentionalAny>,
|
|
): T {
|
|
const scope = hookScopeStack.peek()
|
|
if (!scope) {
|
|
throw new Error(`prism.memo() is called outside of a prism() call.`)
|
|
}
|
|
|
|
return scope.memo(key, fn, deps)
|
|
}
|
|
|
|
/**
|
|
* A state hook, similar to react's `useState()`.
|
|
*
|
|
* @param key - the key for the state
|
|
* @param initialValue - the initial value
|
|
* @returns [currentState, setState]
|
|
*
|
|
* @example
|
|
* ```ts
|
|
* import {prism} from 'dataverse'
|
|
*
|
|
* // This prism holds the current mouse position and updates when the mouse moves
|
|
* const mousePositionD = prism(() => {
|
|
* const [pos, setPos] = prism.state<[x: number, y: number]>('pos', [0, 0])
|
|
*
|
|
* prism.effect(
|
|
* 'setupListeners',
|
|
* () => {
|
|
* const handleMouseMove = (e: MouseEvent) => {
|
|
* setPos([e.screenX, e.screenY])
|
|
* }
|
|
* document.addEventListener('mousemove', handleMouseMove)
|
|
*
|
|
* return () => {
|
|
* document.removeEventListener('mousemove', handleMouseMove)
|
|
* }
|
|
* },
|
|
* [],
|
|
* )
|
|
*
|
|
* return pos
|
|
* })
|
|
* ```
|
|
*/
|
|
function state<T>(key: string, initialValue: T): [T, (val: T) => void] {
|
|
const scope = hookScopeStack.peek()
|
|
if (!scope) {
|
|
throw new Error(`prism.state() is called outside of a prism() call.`)
|
|
}
|
|
|
|
return scope.state(key, initialValue)
|
|
}
|
|
|
|
/**
|
|
* This is useful to make sure your code is running inside a `prism()` call.
|
|
*
|
|
* @example
|
|
* ```ts
|
|
* import {prism} from '@theatre/dataverse'
|
|
*
|
|
* function onlyUsefulInAPrism() {
|
|
* prism.ensurePrism()
|
|
* }
|
|
*
|
|
* prism(() => {
|
|
* onlyUsefulInAPrism() // will run fine
|
|
* })
|
|
*
|
|
* setTimeout(() => {
|
|
* onlyUsefulInAPrism() // throws an error
|
|
* console.log('This will never get logged')
|
|
* }, 0)
|
|
* ```
|
|
*/
|
|
function ensurePrism(): void {
|
|
const scope = hookScopeStack.peek()
|
|
if (!scope) {
|
|
throw new Error(`The parent function is called outside of a prism() call.`)
|
|
}
|
|
}
|
|
|
|
function scope<T>(key: string, fn: () => T): T {
|
|
const parentScope = hookScopeStack.peek()
|
|
if (!parentScope) {
|
|
throw new Error(`prism.scope() is called outside of a prism() call.`)
|
|
}
|
|
const subScope = parentScope.sub(key)
|
|
hookScopeStack.push(subScope)
|
|
const ret = safelyRun(fn, undefined).value
|
|
hookScopeStack.pop()
|
|
return ret as $IntentionalAny as T
|
|
}
|
|
|
|
function sub<T>(
|
|
key: string,
|
|
fn: () => T,
|
|
deps: undefined | $IntentionalAny[],
|
|
): T {
|
|
return memo(key, () => prism(fn), deps).getValue()
|
|
}
|
|
|
|
function inPrism(): boolean {
|
|
return !!hookScopeStack.peek()
|
|
}
|
|
|
|
const possiblePrismToValue = <P extends Prism<$IntentionalAny> | unknown>(
|
|
input: P,
|
|
): P extends Prism<infer T> ? T : P => {
|
|
if (isPrism(input)) {
|
|
return input.getValue() as $IntentionalAny
|
|
} else {
|
|
return input as $IntentionalAny
|
|
}
|
|
}
|
|
|
|
function source<V>(
|
|
subscribe: (fn: (val: V) => void) => VoidFn,
|
|
getValue: () => V,
|
|
): V {
|
|
const scope = hookScopeStack.peek()
|
|
if (!scope) {
|
|
throw new Error(`prism.source() is called outside of a prism() call.`)
|
|
}
|
|
|
|
return scope.source(subscribe, getValue)
|
|
}
|
|
|
|
type IPrismFn = {
|
|
<T>(fn: () => T): Prism<T>
|
|
ref: typeof ref
|
|
effect: typeof effect
|
|
memo: typeof memo
|
|
ensurePrism: typeof ensurePrism
|
|
state: typeof state
|
|
scope: typeof scope
|
|
sub: typeof sub
|
|
inPrism: typeof inPrism
|
|
source: typeof source
|
|
}
|
|
|
|
/**
|
|
* Creates a prism from the passed function that adds all prisms referenced
|
|
* in it as dependencies, and reruns the function when these change.
|
|
*
|
|
* @param fn - The function to rerun when the prisms referenced in it change.
|
|
*/
|
|
const prism: IPrismFn = (fn) => {
|
|
return new PrismInstance(fn)
|
|
}
|
|
|
|
class ColdScope implements PrismScope {
|
|
effect(key: string, cb: () => () => void, deps?: unknown[]): void {
|
|
console.warn(`prism.effect() does not run in cold prisms`)
|
|
}
|
|
memo<T>(
|
|
key: string,
|
|
fn: () => T,
|
|
deps: any[] | readonly any[] | undefined,
|
|
): T {
|
|
return fn()
|
|
}
|
|
state<T>(key: string, initialValue: T): [T, (val: T) => void] {
|
|
return [initialValue, () => {}]
|
|
}
|
|
ref<T>(key: string, initialValue: T): IRef<T> {
|
|
return {current: initialValue}
|
|
}
|
|
sub(key: string): ColdScope {
|
|
return new ColdScope()
|
|
}
|
|
source<V>(subscribe: (fn: (val: V) => void) => VoidFn, getValue: () => V): V {
|
|
return getValue()
|
|
}
|
|
}
|
|
|
|
function calculateColdPrism<V>(fn: () => V): V {
|
|
const scope = new ColdScope()
|
|
hookScopeStack.push(scope)
|
|
let value: V
|
|
try {
|
|
value = fn()
|
|
} catch (error) {
|
|
console.error(error)
|
|
} finally {
|
|
const topOfTheStack = hookScopeStack.pop()
|
|
if (topOfTheStack !== scope) {
|
|
console.warn(
|
|
// @todo guide the user to report the bug in an issue
|
|
`The Prism hook stack has slipped. This is a bug.`,
|
|
)
|
|
}
|
|
}
|
|
return value!
|
|
}
|
|
|
|
prism.ref = ref
|
|
prism.effect = effect
|
|
prism.memo = memo
|
|
prism.ensurePrism = ensurePrism
|
|
prism.state = state
|
|
prism.scope = scope
|
|
prism.sub = sub
|
|
prism.inPrism = inPrism
|
|
prism.source = source
|
|
|
|
export default prism
|