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Add tests and docs to dataverse

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This commit is contained in:
Aria Minaei 2023-01-21 21:57:28 +01:00
parent bab95ddad9
commit ef279eddff
17 changed files with 1225 additions and 147 deletions
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2
packages/dataverse/README.md
View file

@ -6,4 +6,4 @@ Dataverse is currently an internal library. It is used within Theatre.js, but it
## Documentation
> TODO: Write new docs. Enough has changed between 0.5 and 0.6, that the 0.5 docs are not useful anymore.
* [The exhaustive guide to dataverse](./src/dataverse.test.ts)

176
packages/dataverse/src/Atom.ts
View file

@ -2,14 +2,14 @@ import get from 'lodash-es/get'
import isPlainObject from 'lodash-es/isPlainObject'
import last from 'lodash-es/last'
import type {Prism} from './prism/Interface'
import {isPrism} from './prism/Interface'
import type {Pointer, PointerType} from './pointer'
import type {Pointer} from './pointer'
import {getPointerParts} from './pointer'
import {isPointer} from './pointer'
import pointer, {getPointerMeta} from './pointer'
import pointer from './pointer'
import type {$FixMe, $IntentionalAny} from './types'
import updateDeep from './utils/updateDeep'
import prism from './prism/prism'
import type {PointerToPrismProvider} from './pointerToPrism'
type Listener = (newVal: unknown) => void
@ -19,22 +19,6 @@ enum ValueTypes {
Other,
}
/**
* Interface for objects that can provide a prism at a certain path.
*/
export interface PointerToPrismProvider {
/**
* @internal
* Future: We could consider using a `Symbol.for("dataverse/PointerToPrismProvider")` as a key here, similar to
* how {@link Iterable} works for `of`.
*/
readonly $$isPointerToPrismProvider: true
/**
* Returns a prism of the value at the provided path.
*/
pointerToPrism<P>(pointer: Pointer<P>): Prism<P>
}
const getTypeOfValue = (v: unknown): ValueTypes => {
if (Array.isArray(v)) return ValueTypes.Array
if (isPlainObject(v)) return ValueTypes.Dict
@ -153,8 +137,25 @@ export default class Atom<State> implements PointerToPrismProvider {
return this._currentState
}
getByPointer<S>(fn: (p: Pointer<State>) => Pointer<S>): S {
const pointer = fn(this.pointer)
/**
* Returns the value at the given pointer
*
* @param pointerOrFn - A pointer to the desired path. Could also be a function returning a pointer
*
* Example
* ```ts
* const atom = atom({ a: { b: 1 } })
* atom.getByPointer(atom.pointer.a.b) // 1
* atom.getByPointer((p) => p.a.b) // 1
* ```
*/
getByPointer<S>(
pointerOrFn: Pointer<S> | ((p: Pointer<State>) => Pointer<S>),
): S {
const pointer = isPointer(pointerOrFn)
? pointerOrFn
: (pointerOrFn as $IntentionalAny)(this.pointer)
const path = getPointerParts(pointer).path
return this._getIn(path) as S
}
@ -170,18 +171,48 @@ export default class Atom<State> implements PointerToPrismProvider {
this.set(fn(this.get()))
}
/**
* Reduces the value at the given pointer
*
* @param pointerOrFn - A pointer to the desired path. Could also be a function returning a pointer
*
* Example
* ```ts
* const atom = atom({ a: { b: 1 } })
* atom.reduceByPointer(atom.pointer.a.b, (b) => b + 1) // atom.get().a.b === 2
* atom.reduceByPointer((p) => p.a.b, (b) => b + 1) // atom.get().a.b === 2
* ```
*/
reduceByPointer<S>(
fn: (p: Pointer<State>) => Pointer<S>,
pointerOrFn: Pointer<S> | ((p: Pointer<State>) => Pointer<S>),
reducer: (s: S) => S,
) {
const pointer = fn(this.pointer)
const pointer = isPointer(pointerOrFn)
? pointerOrFn
: (pointerOrFn as $IntentionalAny)(this.pointer)
const path = getPointerParts(pointer).path
const newState = updateDeep(this.get(), path, reducer)
this.set(newState)
}
setByPointer<S>(fn: (p: Pointer<State>) => Pointer<S>, val: S) {
this.reduceByPointer(fn, () => val)
/**
* Sets the value at the given pointer
*
* @param pointerOrFn - A pointer to the desired path. Could also be a function returning a pointer
*
* Example
* ```ts
* const atom = atom({ a: { b: 1 } })
* atom.setByPointer(atom.pointer.a.b, 2) // atom.get().a.b === 2
* atom.setByPointer((p) => p.a.b, 2) // atom.get().a.b === 2
* ```
*/
setByPointer<S>(
pointerOrFn: Pointer<S> | ((p: Pointer<State>) => Pointer<S>),
val: S,
) {
this.reduceByPointer(pointerOrFn, () => val)
}
private _checkUpdates(scope: Scope, oldState: unknown, newState: unknown) {
@ -214,27 +245,33 @@ export default class Atom<State> implements PointerToPrismProvider {
return curScope
}
private _onPathValueChange = (
path: (string | number)[],
cb: (v: unknown) => void,
) => {
private _onPointerValueChange = <P>(
pointer: Pointer<P>,
cb: (v: P) => void,
): (() => void) => {
const {path} = getPointerParts(pointer)
const scope = this._getOrCreateScopeForPath(path)
scope.identityChangeListeners.add(cb)
const untap = () => {
scope.identityChangeListeners.delete(cb)
scope.identityChangeListeners.add(cb as $IntentionalAny)
const unsubscribe = () => {
scope.identityChangeListeners.delete(cb as $IntentionalAny)
}
return untap
return unsubscribe
}
/**
* Returns a new prism of the value at the provided path.
*
* @param path - The path to create the prism at.
* @param pointer - The path to create the prism at.
*
* ```ts
* const pr = atom({ a: { b: 1 } }).pointerToPrism(atom.pointer.a.b)
* pr.getValue() // 1
* ```
*/
pointerToPrism<P>(pointer: Pointer<P>): Prism<P> {
const {path} = getPointerParts(pointer)
const subscribe = (listener: (val: unknown) => void) =>
this._onPathValueChange(path, listener)
this._onPointerValueChange(pointer, listener)
const getValue = () => this._getIn(path)
@ -243,72 +280,3 @@ export default class Atom<State> implements PointerToPrismProvider {
}) as Prism<P>
}
}
const identifyPrismWeakMap = new WeakMap<{}, Prism<unknown>>()
/**
* Returns a prism of the value at the provided pointer. Prisms are
* cached per pointer.
*
* @param pointer - The pointer to return the prism at.
*/
export const pointerToPrism = <P extends PointerType<$IntentionalAny>>(
pointer: P,
): Prism<P extends PointerType<infer T> ? T : void> => {
const meta = getPointerMeta(pointer)
let prismInstance = identifyPrismWeakMap.get(meta)
if (!prismInstance) {
const root = meta.root
if (!isPointerToPrismProvider(root)) {
throw new Error(
`Cannot run pointerToPrism() on a pointer whose root is not an PointerToPrismProvider`,
)
}
prismInstance = root.pointerToPrism(pointer as $IntentionalAny)
identifyPrismWeakMap.set(meta, prismInstance)
}
return prismInstance as $IntentionalAny
}
function isPointerToPrismProvider(val: unknown): val is PointerToPrismProvider {
return (
typeof val === 'object' &&
val !== null &&
(val as $IntentionalAny)['$$isPointerToPrismProvider'] === true
)
}
/**
* Convenience function that returns a plain value from its argument, whether it
* is a pointer, a prism or a plain value itself.
*
* @remarks
* For pointers, the value is returned by first creating a prism, so it is
* reactive e.g. when used in a `prism`.
*
* @param input - The argument to return a value from.
*/
export const val = <
P extends
| PointerType<$IntentionalAny>
| Prism<$IntentionalAny>
| undefined
| null,
>(
input: P,
): P extends PointerType<infer T>
? T
: P extends Prism<infer T>
? T
: P extends undefined | null
? P
: unknown => {
if (isPointer(input)) {
return pointerToPrism(input).getValue() as $IntentionalAny
} else if (isPrism(input)) {
return input.getValue() as $IntentionalAny
} else {
return input as $IntentionalAny
}
}

5
packages/dataverse/src/PointerProxy.ts
View file

@ -1,11 +1,12 @@
import type {PointerToPrismProvider} from './Atom'
import Atom, {val} from './Atom'
import Atom from './Atom'
import {val} from './val'
import type {Pointer} from './pointer'
import {getPointerMeta} from './pointer'
import pointer from './pointer'
import type {$FixMe, $IntentionalAny} from './types'
import prism from './prism/prism'
import type {Prism} from './prism/Interface'
import type {PointerToPrismProvider} from './pointerToPrism'
/**
* Allows creating pointer-prisms where the pointer can be switched out.

3
packages/dataverse/src/atom.typeTest.ts
View file

@ -1,4 +1,5 @@
import Atom, {val} from './Atom'
import Atom from './Atom'
import {val} from './val'
import {expectType, _any} from './utils/typeTestUtils'
;() => {
const p = new Atom<{foo: string; bar: number; optional?: boolean}>(_any)

903
packages/dataverse/src/dataverse.test.ts
View file

@ -1,13 +1,31 @@
import {Atom, prism, Ticker, val} from '@theatre/dataverse'
import type {Pointer, Prism} from '@theatre/dataverse'
import {
isPointer,
isPrism,
pointerToPrism,
Atom,
getPointerParts,
pointer,
prism,
Ticker,
val,
} from '@theatre/dataverse'
// eslint-disable-next-line no-restricted-imports
import {set as lodashSet} from 'lodash'
import {isPointerToPrismProvider} from './pointerToPrism'
describe(`Dataverse guide`, () => {
// Hi there! I'm writing this test suite as an ever-green guide to dataverse. You should be able
// to read it from top to bottom and understand the concepts of dataverse.
describe(`The exhaustive guide to dataverse`, () => {
// Hi there! I'm writing this test suite as an ever-green and thorough guide to dataverse. You should be able
// to read it from top to bottom and learn pretty much all there is to know about dataverse.
//
// This is not a quick-start guide, so feel free to skip around.
//
// Since this is a test suite, you should be able to run it in [debug mode](https://jestjs.io/docs/en/troubleshooting)
// and inspect the value of variables at any point in the test.
// We recommend you follow this guide using VSCode's [Jest extension](https://marketplace.visualstudio.com/items?itemName=Orta.vscode-jest),
// which allows you to run/debug tests from within the editor and see the values of variables in the editor itself.
describe(`Chapter 0 - Concepts`, () => {
describe(`0 - Concepts`, () => {
// There 4 main concepts in dataverse:
// - Atoms, hold the state of your application.
// - Pointers are a type-safe way to get/set/react-to changes in Atoms.
@ -15,7 +33,7 @@ describe(`Dataverse guide`, () => {
// - Tickers are a way to schedule and synchronise computations.
// before we dive into the concepts, let me show you how a simple dataverse setup looks like.
test('A simple dataverse setup', () => {
test('0.1 - A simple dataverse setup', () => {
// In this setup, we're gonna write a program that renders an image of a sunset,
// like this:
// |
@ -96,11 +114,11 @@ describe(`Dataverse guide`, () => {
})
})
describe(`Chapter 1 - What is a prism?`, () => {
describe(`1 - What is a prism?`, () => {
// A Prism is a way to create a value that depends on other values.
// let's start with a simple example:
test(`A pretty useless prism`, async () => {
test(`1.1 - A pretty useless prism`, async () => {
// Each prism has a calculate function that it runs to calculate its value. let's make a simple function that just returns 1
const calculate = jest.fn(() => 1)
@ -133,7 +151,7 @@ describe(`Dataverse guide`, () => {
})
// prisms can depend on other prisms. let's make a prism that depends on another prism.
test(`prisms can depend on other prisms`, async () => {
test(`1.2 - prisms can depend on other prisms`, async () => {
const calculateA = jest.fn(() => 1)
const a = prism(calculateA)
@ -276,15 +294,15 @@ describe(`Dataverse guide`, () => {
unsubcribeFromAOnStale()
})
test('What about state?', () => {
describe('1.3 - What about state?', () => {
// so far, our prisms have not depended on any changing values, so in turn, _their_ values have never changed either.
// but what if we want to create a prism that depends on a changing value?
// we call those values "sources", and we can create them using the `prism.source()` hook:
test('1.3.1 - The wrong way to depend on state', () => {
// let's say we want to create a prism that depends on this value:
let value = 0
{
// the _wrong_ way to do this, is to create a prism that directly reads this value
const p = prism(() => value)
@ -305,10 +323,10 @@ describe(`Dataverse guide`, () => {
expect(p.getValue()).toBe(1)
unsubscribe()
}
})
// so, the _right_ way to do this, is to use the `source` hook:
{
test('1.3.2 - The _less_ wrong way to depend on state', () => {
let value = 0
// the source hook requires a `listen` function, and a `get` function.
// let's skip the `listen` function for now, and just focus on the `getValue` function.
const listen = jest.fn(() => () => {})
@ -350,9 +368,9 @@ describe(`Dataverse guide`, () => {
expect(get).toHaveBeenCalledTimes(0)
unsubscribe()
}
})
{
test('1.3.3 - The right way to depend on state', () => {
let value = 0
// now let's implement an actual `listen` function.
@ -411,7 +429,7 @@ describe(`Dataverse guide`, () => {
// and that's how we create a prism that depends on a changing value.
unsubscribe()
}
})
})
// in practice, we'll almost never need to use the `source` hook directly,
@ -419,11 +437,858 @@ describe(`Dataverse guide`, () => {
// instead, we'll use `Atom`s, which are sources that are already implemented for us.
})
describe(`Chapter 2 - Atoms`, () => {
describe(`2 - Atoms`, () => {
// In the final test of the previous chapter, we learned how to create our own sources of state,
// and make a prism depend on them, using the `prism.source()` hook. In this chapter, we'll learn
// how to use the `Atom` class, which is a source of state that's already implemented for us and comes
// with a lot of useful features.
test(`Using Atoms`, () => {})
test(`2.1 - Using Atoms without prisms`, () => {
const initialState = {foo: 'foo', bar: 0}
// Let's create an atom with an initial state.
const atom = new Atom(initialState)
// We can read our atom's state via `atom.get()` which returns an exact reference to its state
expect(atom.get()).toBe(initialState)
// `atom.set()` will replace the state with a new object.
atom.set({foo: 'foo', bar: 1})
expect(atom.get()).not.toBe(initialState)
expect(atom.get()).toEqual({foo: 'foo', bar: 1})
// Another way to change the state, with the reducer pattern.
atom.reduce(({foo, bar}) => ({foo, bar: bar + 1}))
expect(atom.get()).toEqual({foo: 'foo', bar: 2})
// Having to write `({foo, bar}) => ({foo, bar: bar + 1})` every time we want to change the state
// is a bit annoying. This is one place where pointers come in handy. We'll have a whole chapter
// about pointers later, but for now, let's just say that they're a type-safe way to refer to a sub-prop of our atom's state.
//
// In this example, we're using the `setByPointer()` method to change the `bar` property of the state.
atom.setByPointer((p) => p.bar, 3)
expect(atom.get()).toEqual({foo: 'foo', bar: 3})
// Also, note that there is nothing magical about pointers. They're just a type-safe encoding of `['path', 'to', 'property']`.
// Pointers can even point to non-existent properties, and they'll be created when we use them. Typescript will complain if we
// try to use a pointer to a non-existent property, but in the runtime, there will be no errors.
// Let's silence the typescript error for the sake of the test
// @ts-ignore and refer to `baz`, which doesn't actually exist in our state.
atom.setByPointer((p) => p.baz, 'baz')
// Atom will create the `baz` property for us:
expect(atom.get()).toEqual({foo: 'foo', bar: 3, baz: 'baz'})
// The pointer can also refer to the whole state, and we can use it to replace the whole state.
atom.setByPointer((p) => p, {foo: 'newfoo', bar: -1})
expect(atom.get()).toEqual({foo: 'newfoo', bar: -1})
// `getByPointer()` is to `get()` what `setByPointer()` is to `set()`
expect(atom.getByPointer((p) => p.bar)).toBe(-1)
// `reduceByPointer()` is to `setByPointer()` what `reduce()` is to `set()`
atom.reduceByPointer(
(p) => p.bar,
(bar) => bar + 1,
)
expect(atom.get()).toEqual({foo: 'newfoo', bar: 0})
// we can use external pointers too (which we'll learn how to create in the next Pointers chapter)
const externalPointer = atom.pointer.bar
atom.setByPointer(() => externalPointer, 1)
expect(atom.get()).toEqual({foo: 'newfoo', bar: 1})
let internalPointer
// the pointer passed to `setByPointer()` is the same as the one returned by `atom.pointer`
atom.setByPointer((p) => {
internalPointer = p
return p.bar
}, 2)
expect(internalPointer).toBe(atom.pointer)
expect(atom.pointer).toBe(atom.pointer)
expect(atom.pointer.bar).toBe(atom.pointer.bar)
// pointers don't change when the atom's state changes
const oldPointer = atom.pointer.bar
atom.set({foo: 'foo', bar: 10})
expect(atom.pointer.bar).toBe(oldPointer)
})
// Now that we know how to set/get the state of Atoms, let's learn how to use them with prisms.
test(`2.2 - The hard way to use Atoms with prisms`, () => {
// In Chapter 1.3.3, we learned how to create a prism that depends on a changing value,
// but we had to provide our own `listen` and `get` functions. Now let's see how to do the same
// thing with an Atom.
// Just to learn how things work under the hood, we're still going to use the `prism.source()` hook.
// In the next chapter, we'll learn how to skip that step too.
// Let's create an atom with an initial state.
const atom = new Atom({foo: 'foo', bar: 0})
// The same prism from chapter 1.3.3:
const pr = prism(() => {
return prism.source(listen, get) * 2
})
// now let's define the `listen` and `get` functions that we'll pass to `prism.source()`
function listen(cb: (value: number) => void) {
// `atom._onPointerValueChange()` is a method that we can use to listen to changes in a specific path of the atom's state.
// This is not a public API, so typescript will complain, but we can silence it with `@ts-ignore`.
// _onPointerValueChange() returns an unsubscribe function, so we'll just return that as is.
// @ts-ignore
return atom._onPointerValueChange(
// the path to listen to is just the pointer to the `bar` property of the atom's state.
atom.pointer.bar,
cb,
)
}
// The `get` function will just return the value of the `bar` property of the atom's state.
function get() {
return atom.get().bar
}
// And that's it! We can now use the prism with the atom's state.
// let's make the prism hot
const staleListener = jest.fn()
const unsubscribe = pr.onStale(staleListener)
expect(pr.isHot).toBe(true)
// and let's read its value
expect(pr.getValue()).toBe(0)
// now let's change the value of the source
atom.setByPointer((p) => p.bar, 1)
// our prism will know that the source has changed, and it'll update its value.
expect(pr.getValue()).toBe(2)
unsubscribe()
// and that's how we create a prism that depends on an atom, but that's still
// pretty verbose. Let's see how to do the same thing in a more convenient way.
})
test(`2.3 - The easy way to use Atoms with prisms`, () => {
// In the previous chapter, we learned how to create a prism that depends on an atom,
// but we had to provide our own `listen` and `get` functions. Now let's see how to do the same
// thing with an Atom, but in the idiomatic way. We'll use pointers and `val()`.
// Let's create an atom with an initial state.
const atom = new Atom({foo: 'foo', bar: 0})
// Now instead of using `prism.source()`, we'll use val(atom.pointer):
const pr = prism(() => {
// We'll cover pointers and `val()` soon, but for now, just know that `val(atom.pointer.bar)`
// will return the value of the `bar` property of the atom's state.
return val(atom.pointer.bar) * 2
})
// and that's it!
// let's test that it works as expected
const staleListener = jest.fn()
const unsubscribe = pr.onStale(staleListener)
expect(pr.isHot).toBe(true)
// and let's read its value
expect(pr.getValue()).toBe(0)
// now let's change the value of the source
atom.setByPointer((p) => p.bar, 1)
// this time, our prism will know that the source has changed, and it'll update its value.
expect(pr.getValue()).toBe(2)
unsubscribe()
})
})
describe(`3 - Pointers`, () => {
test('3.0 - Why pointers?', () => {
// We've come across pointers a few times already.
{
// For example, we saw that Atoms provide `set|get|reduceByPointer()` methods:
const atom = new Atom({foo: 'foo', bar: 0})
atom.setByPointer((p) => p.bar, 1)
// or equivalently:
atom.setByPointer(atom.pointer.bar, 1)
}
// You might be wondering why not just use dot-delimited paths like in lodash's `set(val, 'path.to.prop', 1)`?
// The answer is that pointers are much easier to type, and they work well with typescript's autocomplete.
// Another benefit is that pointers are always cached, in so that `pointer.bar === pointer.bar` will always be true,
// which means we can use them to attach metadata to a pointer. We'll see how to do that in a bit.
// Another alternative to pointers is array paths, like in lodash's `set(val, ['path', 'to', 'prop'], 1)`.
// Similar to dot-delimited paths, array paths are also not easy to type, and they don't work well with typescript's autocomplete.
// Another problem is that creating an array path every time we want to access a property is not very efficient.
// The JS engine will have to allocate a new array every time, and then it'll have to iterate over it to find the property.
// Pointers on the other hand, are always cached, so they're allocated only once.
// We'll learn how to take advantage of these benefits in the next sub-chapters.
})
test(`3.1 - Pointers in the runtime`, () => {
// Let's have a look at how pointers work in the runtime.
// Pointers refer to a specific nested property of an object. The object is called the "root" of the pointer,
// and the property is called the "path" of the pointer.
// So for example, if this is our root object:
const root = {foo: 'foo', bar: 0}
// This pointer will refer to the whole object:
const p = pointer({root: root, path: []})
// We can inspect the pointer's root and path using `getPointerParts()`:
const parts = getPointerParts(p)
expect(parts.root).toBe(root)
expect(parts.path).toEqual([])
// This pointer will refer to the `foo` property of the root object:
const pointerToFoo = p.foo
// p.foo is a pointer to the `foo` property of the root object. its only difference to p is that its path is `['foo']`
expect(getPointerParts(pointerToFoo).path).toEqual(['foo'])
expect(getPointerParts(pointerToFoo).root).toBe(root)
// subPointers are cached. Calling `p.foo` twice will return the same pointer:
expect(pointerToFoo).toBe(p.foo)
// we can also manually construct the pointer to foo:
const pointerToFoo2 = pointer({root: root, path: ['foo']})
expect(getPointerParts(pointerToFoo2).path).toEqual(['foo'])
})
test(`3.2 - Pointers in typescript`, () => {
// Pointers become more useful when we properly type them. Let's do that now:
type Data = {str: string; foo?: {bar?: {baz: number}}}
const root: Data = {str: 'some string'}
const p = pointer<Data>({
root,
path: [],
})
// now typescript will error if we try to access a property that doesn't exist
// @ts-expect-error
p.baz
// but accessing known properties and nested properties is fine
p.foo
p.foo.bar.baz
// we don't need to manually type the pointer since pointers are usually provided by Atoms, and those are already typed
const atom = new Atom(root)
// so this will be fine by typescript:
atom.pointer.foo.bar.baz
// while this will error
// @ts-ignore
atom.pointer.foo.bar.baz.nonExistentProperty
})
test(`3.3 - Creating type-safe utility functions with pointers`, () => {
// Now that we know how to create pointers, let's see how to use them to create utility functions.
// Let's create a function that will set a property of an object by a pointer, similar to `lodash.set()`.
// The function will take the root object, the pointer, and the new value.
function setByPointer<Root, Value>(
root: Root,
getPointer: (ptr: Pointer<Root>) => Pointer<Value>,
newValue: Value,
): Root {
// we'll create a pointer to the root object, which would not be efficient
// if `setByPointer` was called many times. We'll see how to improve this in the next sub-chapters.
const rootPointer = pointer({
root: root,
path: [],
}) as Pointer<Root>
// We'll use `getPointerParts()` to get the root and path of the pointer.
const {path} = getPointerParts(getPointer(rootPointer))
// @ts-ignore we'll ignore the typescript error because `lodash.set()` is not typed
return lodashSet(root, path, newValue)
}
// now let's test our utility function
const data = {foo: {bar: 0}}
const newData = setByPointer(data, (p) => p.foo.bar, 1)
expect(newData).toEqual({foo: {bar: 1}})
// Compared to `lodash.set()`, our function is type-safe and plays nicely with intellisense and autocomplete.
})
test('3.4 - Converting pointers to prisms', () => {
// So, how does the `val()` function work?
// Let's look at its implementation:
const val = (input: any) => {
// if the input is a pointer, we'll convert it to a prism and `getValue()` on it
if (isPointer(input)) {
return pointerToPrism(input).getValue()
// otherwise if it's already a prism, we `getValue()` on it
} else if (isPrism(input)) {
return input.getValue()
} else {
// or otherwise we return the input as is.
return input
}
}
// So, the interesting part is the `pointerToPrism()` function. How does it
// convert a pointer to a prism?
// Let's implement it:
function pointerToPrismV1<V>(ptr: Pointer<V>): Prism<V> {
// we'll use `getPointerParts()` to get the root and path of the pointer
const {root} = getPointerParts(ptr)
// Then we check whether the root is an atom
if (!(root instanceof Atom)) {
throw new Error(
`pointerToPrismV1() only supports pointers whose root is an Atom`,
)
}
// We'll need to define the listen/get functions as well
// the listen function will listen to changes on the pointer
const listen = (cb: (newValue: V) => void): (() => void) => {
// @ts-ignore we'll ignore the typescript error because `_onPointerValueChange()` is not a public method
return atom._onPointerValueChange(ptr, cb)
}
const get = (): V => {
return root.getByPointer(ptr)
}
// then we'll create a prism that sources from the atom
return prism(() => {
return prism.source(listen, get)
})
}
// Now let's test it:
const atom = new Atom({foo: {bar: 0}})
const ptr = atom.pointer.foo.bar
const p = pointerToPrismV1(ptr)
expect(p.getValue()).toBe(0)
// It works!
// Now let's see how we can improve it.
// First, we can cache the prism so that we don't create a new prism every time we call `pointerToPrism()`.
// This will improve performance and reduce memory usage.
const cache = new WeakMap<Pointer<any>, Prism<unknown>>()
function pointerToPrismV2<V>(ptr: Pointer<V>): Prism<V> {
// we'll check whether the pointer is already in the cache
const cached = cache.get(ptr as any)
if (cached) {
return cached as any
}
// if not, we'll create a new prism and cache it
const p = pointerToPrismV1(ptr)
cache.set(ptr as any, p)
return p
}
// Now let's test it:
expect(pointerToPrismV2(ptr)).toBe(pointerToPrismV2(ptr)) // the cache works
expect(pointerToPrismV2(ptr).getValue()).toBe(0) // the prism works
// The second improvement would be to decouple `pointerToPrism()` from the implementation of `Atom`.
// Namely, `pointerToPrism()` only calls `Atom._onPointerValueChange()` and `Atom.getByPointer()`, which
// are methods that can be implemented on other objects as well. Instead, we can just define an interface
// that requires these methods to be implemented.
// We call this interface `PointerToPrismProvider`:
// For example, Atom implements this interface:
expect(isPointerToPrismProvider(atom)).toBe(true)
// So our implementation can be updated to:
function pointerToPrismV3<V>(ptr: Pointer<V>): Prism<V> {
const cached = cache.get(ptr as any)
if (cached) {
return cached as any
}
const {root} = getPointerParts(ptr)
if (!isPointerToPrismProvider(root)) {
throw new Error(
`pointerToPrismV3() only supports pointers whose root implements PointerToPrismProvider`,
)
}
// one final improvement is to allow the implementation of `PointerToPrismProvider` to create
// the prism, rather than us calling `prism()`, and `prism.source` directly. This will allow
// the implementation to custmoize and possibly optimise how the prism sources its value.
const pr = root.pointerToPrism(ptr)
cache.set(ptr as any, pr)
return pr
}
// Now let's test it:
expect(pointerToPrismV3(ptr)).toBe(pointerToPrismV3(ptr)) // the cache works
expect(pointerToPrismV3(ptr).getValue()).toBe(0) // the prism works
// To summarize:
// * we've learned how to implement a `val()` function that works with pointers and prisms.
// * we've learned how to implement a `pointerToPrism()` function that converts a pointer to a prism.
// * we've learned how to improve the performance of `pointerToPrism()` by caching the prisms.
// * we've learned how to decouple `pointerToPrism()` from the implementation of `Atom` by using an interface.
})
})
describe('5 - Tickers', () => {
// A ticker is how dataverse allows you to coordinate the timing of your computations.
// For example, let's say we have a prism whose value changes every 5 milliseconds. And we want to
// render the value of that prism every ~16 milliseconds (60fps). A ticker allows us to do that.
test('5.1 - Our prism has gone stale...', () => {
// In order to see how tickers fit into the picture, we should first understand how prisms
// go stale.
const atom = new Atom('1')
const aParsed = prism(() => parseInt(val(atom.pointer)))
// To illustrate how prisms go stale, we'll create a prism that computes the factorial of the atom's value.
// Since factorial is a computationally expensive operation, we'll only want to compute it when we actually
// need it.
function factorial(n: number): number {
if (n === 0) return 1
return n * factorial(n - 1)
}
// we'll want to track how many times our prism actually recalculates its value, so we'll use a jest spy
const recalculateSpy = jest.fn()
const aFactoriel = prism(() => {
recalculateSpy()
return factorial(val(aParsed))
})
// To make it easy to inspect the state of a prism, we'll create a helper function:
const prismState = (
p: Prism<any>,
): 'cold' | 'hot:stale' | 'hot:fresh' => {
// @ts-ignore this is a hack to access the internal state of the prism
const internalState = p._state as any
return internalState.hot === false
? 'cold'
: internalState.handle._isFresh
? 'hot:fresh'
: 'hot:stale'
}
// Every prism starts out as 'cold'
expect(prismState(aFactoriel)).toBe('cold')
expect(prismState(aParsed)).toBe('cold')
{
// as soon as we subscribe to its `onStale` event, it becomes 'hot:fresh'
const unsubscribe = aFactoriel.onStale(jest.fn())
expect(prismState(aFactoriel)).toBe('hot:fresh')
// since its value is fresh, it should have already called our spy
expect(recalculateSpy).toHaveBeenCalledTimes(1)
recalculateSpy.mockClear()
// and if we try to get its value, it won't recalculate it
expect(aFactoriel.getValue()).toBe(1)
expect(recalculateSpy).toHaveBeenCalledTimes(0)
// and if we change the state of our atom,
atom.set('2')
// our prism will go stale:
expect(prismState(aFactoriel)).toBe('hot:stale')
// And so will its dependency:
expect(prismState(aParsed)).toBe('hot:stale')
// Has the recalculate spy been called?
expect(recalculateSpy).toHaveBeenCalledTimes(0)
// it hasn't. It'll only recalculate when we actually need its value:
expect(aFactoriel.getValue()).toBe(2)
expect(recalculateSpy).toHaveBeenCalledTimes(1)
unsubscribe()
}
// So far we have established that instead of recalculating their values, prisms simply go stale when their dependencies change.
// and they'll go fresh again when we call `getValue()` on them.
// tickers are a way to make sure `getValue()` is called at the rate/frequency we want.
const ticker = new Ticker()
const onChange = jest.fn()
// notice how we're using `onChange` only on the prism that we care about, and not on its dependencies.
const unsubscribe = aFactoriel.onChange(ticker, onChange)
// now our prism will go stale every time our atom changes, but it won't recalculate its value until we call `tick()`
atom.set('3')
expect(onChange).toHaveBeenCalledTimes(0)
ticker.tick()
expect(onChange).toHaveBeenCalledTimes(1)
expect(onChange).toHaveBeenCalledWith(6)
// We'd usually create a single ticker for an entire page, and call `tick()` on it every frame.
// For example, on a regular web page, we'd use `requestAnimationFrame()` to `tick()` our ticker.
// On an XR session, we'd use `XRSession.requestAnimationFrame()`.
function tickEveryFrame() {
ticker.tick()
requestAnimationFrame(tickEveryFrame)
}
// now we're not gonna call `tickEveryFrame()` because our tests are running on node, but you get the idea.
unsubscribe()
// Also note that we can have multiple tickers for the same prism:
// `pr.onChange(ticker1, ...); pr.onChange(ticker2, ...);` is perfectly valid.
// And it would be useful if we're using the value of the same prism in multiple places.
})
// That's pretty much it for tickers. If you're curious how they work, have a look at `./Ticker.test.ts`
})
describe('6 - Prism hooks', () => {
// Prism hooks are inspired by [React hooks](https://reactjs.org/docs/hooks-intro.html) ) and work in a similar way.
describe(`6.1 - prism.source()`, () => {
// We've already come across `prism.source()` in chapter 3. `prism.source()` allow a prism to react to changes in
// some external source (other than other prisms). For example, `Atom.pointerToPrism()` uses `prism.source()` to
// create a prism that reacts to changes in the atom's value.
// Here is another example. Let's say we want to create a prism that reacts to changes in the value of an HTML input element:
test(`6.1.1 - Example: listening to changes in an input element`, () => {
function prismFromInputElement(input: HTMLInputElement): Prism<string> {
function subscribe(cb: (value: string) => void) {
const listener = () => {
cb(input.value)
}
input.addEventListener('input', listener)
return () => {
input.removeEventListener('input', listener)
}
}
function get() {
return input.value
}
return prism(() => prism.source(subscribe, get))
}
// And this is how we'd use it:
// const el = document.querySelector('input.our-input')
// const prism = prismFromInputElement(el)
// our prism will start listening to changes in the input element as soon as it goes hot,
// and it will stop listening when it goes cold.
})
test('6.2.2 - Behavior of `prism.source()`', () => {
// Let's use a few spies to see what's going on under the hood:
const events: Array<'get' | 'subscribe' | 'unsubscribe'> = []
const subscribe = () => {
events.push('subscribe')
return () => {
events.push('unsubscribe')
}
}
const get = () => {
events.push('get')
}
const pr = prism(() => prism.source(subscribe, get))
expect(events).toEqual([])
pr.getValue()
// since our prism is cold, it won't subscribe to the source and will only call `get()`
expect(events).toEqual(['get'])
events.length = 0 // reset the events array
// as we know, cold prisms do not cache their values, so calling `getValue()` again will call `get()` again:
pr.getValue()
expect(events).toEqual(['get'])
events.length = 0 // reset the events array
// now let's make our prism hot:
const unsub = pr.onStale(() => {})
// as soon as the prism goes hot, it will subscribe to the source, and it'll also call `get()` for the first time:
expect(events).toEqual(['subscribe', 'get'])
events.length = 0 // reset the events array
pr.getValue()
expect(events).toEqual([])
// now let's make our prism cold again:
unsub()
// as soon as the prism goes cold, it will unsubscribe from the source:
expect(events).toEqual(['unsubscribe'])
})
})
test(`6.2 - prism.ref()`, () => {
// Just like React's `useRef()`, `prism.ref()` allows us to create a prism that holds a reference to some value.
// The only difference is that `prism.ref()` requires a key to be passed into it, whlie `useRef()` doesn't.
// This means that we can call `prism.ref()` in any order, and we can call it multiple times with the same key.
const spy = jest.fn()
const atom = new Atom(0)
const pr = prism(() => {
val(atom.pointer) // just to make our prism depend on the atom. we don't care about the value of the atom.
const elRef = prism.ref<undefined | HTMLElement>('my-key', undefined)
spy(elRef.current)
if (elRef.current === undefined) {
// @ts-ignore - we're just testing the behavior here, we won't create a real dom node
elRef.current = {}
}
})
// now, what happens if we get the value of our prism?
pr.getValue()
expect(spy).toHaveBeenCalledWith(undefined)
spy.mockClear()
// and if we get its value again?
pr.getValue()
expect(spy).toHaveBeenCalledWith(undefined) // the ref is still undefined
spy.mockClear()
// this is because `prism.ref()` only works when the prism is hot, otherwise it'll always return the initial value of the ref.
// So let's make our prism hot:
const unsub = pr.onStale(() => {})
expect(spy).toHaveBeenCalledWith(undefined)
spy.mockClear()
// now let's make the prism go stale
atom.set(1)
// of course the atom won't recalculate as long as we don't call `getValue()` on it:
expect(spy).not.toHaveBeenCalled()
// so let's call `getValue()` on it:
pr.getValue()
expect(spy).toHaveBeenCalledWith({})
// and that's how `prism.ref()` works!
unsub()
})
describe(`6.3 - prism.memo()`, () => {
// `prism.memo()` works just like React's `useMemo()` hook. It's a way to cache the result of a function call.
// The only difference is that `prism.memo()` requires a key to be passed into it, whlie `useMemo()` doesn't.
// This means that we can call `prism.memo()` in any order, and we can call it multiple times with the same key.
test(`6.3.1 - Example: using prism.memo()`, () => {
const atom = new Atom(1)
function factorial(n: number): number {
if (n === 0) return 1
return n * factorial(n - 1)
}
const spy = jest.fn()
const pr = prism(() => {
// num will be between 0 and 9. This is so we can test what happens when the atom's value changes, but
// the memoized value doesn't change.
const num = val(atom.pointer)
const numMod10 = num % 10
const value = prism.memo(
// we need a string key to identify the hook. This allows us to call `prism.memo()` in any order, or even conditionally.
'factorial',
// the function to memoize
() => {
spy()
return factorial(numMod10)
},
// the dependencies of the function. If any of the dependencies change, the function will be called again.
[numMod10],
)
return `number is ${num}, num % 10 is ${numMod10} and its factorial is ${value}`
})
// firts let's test our prism when it's cold:
expect(pr.getValue()).toBe(
'number is 1, num % 10 is 1 and its factorial is 1',
)
expect(spy).toHaveBeenCalledTimes(1)
// since cold prisms don't cache their values, calling `getValue()` again will call the factorial function again:
expect(pr.getValue()).toBe(
'number is 1, num % 10 is 1 and its factorial is 1',
)
expect(spy).toHaveBeenCalledTimes(2)
spy.mockClear()
// now let's make our prism hot:
const unsub = pr.onStale(() => {})
pr.getValue()
expect(spy).toHaveBeenCalledTimes(1)
spy.mockClear()
// if the memo's dependencies don't change, the memoized function won't be called again:
pr.getValue()
expect(spy).toHaveBeenCalledTimes(0)
// now let's change the atom's value, but not the factorial value:
atom.set(11)
// our prism _will_ recalculate, but the memoized function won't be called again:
expect(pr.getValue()).toBe(
'number is 11, num % 10 is 1 and its factorial is 1',
)
expect(spy).toHaveBeenCalledTimes(0)
unsub()
// and that's how `prism.memo()` works!
})
})
describe(`6.4 - prism.effect() and prism.state()`, () => {
// These are two more hooks that are similar to React's `useEffect()` and `useState()` hooks.
// `prism.effect()` is similar to React's `useEffect()` hook. It allows us to run side-effects when the prism is calculated.
// Note that prisms are supposed to be "virtually" pure functions. That means they either should not have side-effects (and thus, no calls for `prism.effect()`),
// or their side-effects should clean themselves up when the prism goes cold.
// `prism.state()` is similar to React's `useState()` hook. It allows us to create a stateful value that is scoped to the prism.
// We'll defer to React's documentation for [a more detailed explanation of how `useEffect()`](https://reactjs.org/docs/hooks-effect.html)
// and how [`useState()`](https://reactjs.org/docs/hooks-state.html) work.
// But here's a quick example:
test(`6.4.1 - Example: using prism.effect() and prism.state()`, () => {
jest.useFakeTimers()
const events: Array<
'effectInstalled' | 'intervalCalled' | 'effectCleanedUp'
> = []
const pr = prism(() => {
const [randomValue, setRandomValue] = prism.state('randomValue', 0)
// This is only allowed for prisms that are supposed to be hot before their first calculation.
// Otherwise it will log a warning and no effect will run.
prism.effect(
'update-random-value',
() => {
events.push('effectInstalled')
const interval = setInterval(() => {
events.push('intervalCalled')
setRandomValue(Math.random())
}, 1000)
return () => {
events.push('effectCleanedUp')
clearInterval(interval)
}
},
[],
)
return randomValue
})
// let's make our prism hot:
const unsub = pr.onStale(() => {})
// which should already have called the effect:
expect(events).toEqual(['effectInstalled'])
pr.getValue()
events.length = 0 // clear the events array
// now let's fast-forward the time by 2500ms:
jest.advanceTimersByTime(2500)
// and we should have seen the interval called twice:
expect(events).toEqual(['intervalCalled', 'intervalCalled'])
expect(pr.getValue()).toEqual(expect.any(Number))
events.length = 0 // clear the events array
// now let's unsubscribe from the prism:
unsub()
expect(events).toEqual(['effectCleanedUp'])
})
test('6.4.2 - A more useful example', () => {
// This prism holds the current mouse position and updates when the mouse moves
const mousePositionPr = 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
})
// We can't test this since our test environment doesn't have a mouse, but you get the idea :)
})
})
test(`6.5 - prism.sub()`, () => {
// `prism.sub()` is a shortcut for creating a prism inside another prism.
// It's equivalent to calling `prism.memo(key, () => prism(fn), deps).getValue()`.
// `prism.sub()` is useful when you want to divide your prism into smaller prisms, each of which
// would _only_ recalculate when _certain_ dependencies change. In other words, it's an optimization tool.
function factorial(num: number): number {
if (num === 0) return 1
return num * factorial(num - 1)
}
const events: Array<'foo-calculated' | 'bar-calculated'> = []
// example:
const state = new Atom({foo: 0, bar: 0})
const pr = prism(() => {
const resultOfFoo = prism.sub(
'foo',
() => {
events.push('foo-calculated')
const foo = val(state.pointer.foo) % 10
// Note how `prism.sub()` is more powerful than `prism.memo()` because it allows us to use `prism.memo()` and other hooks inside of it:
return prism.memo('factorial', () => factorial(foo), [foo])
},
[],
)
const resultOfBar = prism.sub(
'bar',
() => {
events.push('bar-calculated')
const bar = val(state.pointer.bar) % 10
return prism.memo('factorial', () => factorial(bar), [bar])
},
[],
)
return `result of foo is ${resultOfFoo}, result of bar is ${resultOfBar}`
})
const unsub = pr.onStale(() => {})
// on the first run, both subs should be calculated:
expect(events).toEqual(['foo-calculated', 'bar-calculated'])
events.length = 0 // clear the events array
// now if we change the value of `bar`, only `bar` should be recalculated:
state.setByPointer(state.pointer.bar, 2)
pr.getValue()
expect(events).toEqual(['bar-calculated'])
unsub()
})
test(`6.6 - prism.scope()`, () => {
// since prism hooks are keyed (as opposed to React hooks where they're identified by their order),
// it's possible to have multiple hooks with the same key in the same prism.
// To avoid this, we can use `prism.scope()` to create a "scope" for our hooks.
// Example:
const pr = prism(() => {
prism.scope('a', () => {
prism.memo('foo', () => 1, [])
})
prism.scope('b', () => {
prism.memo('foo', () => 1, [])
})
})
})
})
// What's next?
// At this point we have covered all of `@theatre/dataverse`.
// If you're planning to use Dataverse with React, have a look at [`@theatre/react`](https://github.com/theatre-js/theatre/tree/main/packages/react)
// which provides a React integration for Dataverse as well.
})

8
packages/dataverse/src/index.ts
View file

@ -4,14 +4,16 @@
* @packageDocumentation
*/
export type {PointerToPrismProvider} from './Atom'
export {default as Atom, val, pointerToPrism} from './Atom'
export type {PointerToPrismProvider} from './pointerToPrism'
export {default as Atom} from './Atom'
export {val} from './val'
export {pointerToPrism} from './pointerToPrism'
export {isPrism} from './prism/Interface'
export type {Prism} from './prism/Interface'
export {default as iterateAndCountTicks} from './prism/iterateAndCountTicks'
export {default as iterateOver} from './prism/iterateOver'
export {default as prism} from './prism/prism'
export {default as pointer, getPointerParts, isPointer} from './pointer'
export type {Pointer, PointerType} from './pointer'
export type {Pointer, PointerType, PointerMeta} from './pointer'
export {default as Ticker} from './Ticker'
export {default as PointerProxy} from './PointerProxy'

3
packages/dataverse/src/integration.test.ts
View file

@ -1,7 +1,8 @@
/*
* @jest-environment jsdom
*/
import Atom, {val} from './Atom'
import Atom from './Atom'
import {val} from './val'
import prism from './prism/prism'
import Ticker from './Ticker'

2
packages/dataverse/src/pointer.ts
View file

@ -2,7 +2,7 @@ import type {$IntentionalAny} from './types'
type PathToProp = Array<string | number>
type PointerMeta = {
export type PointerMeta = {
root: {}
path: (string | number)[]
}

58
packages/dataverse/src/pointerToPrism.ts Normal file
View file

@ -0,0 +1,58 @@
import type {Prism} from './prism/Interface'
import type {Pointer, PointerType} from './pointer'
import {getPointerMeta} from './pointer'
import type {$IntentionalAny} from './types'
const identifyPrismWeakMap = new WeakMap<{}, Prism<unknown>>()
/**
* Interface for objects that can provide a prism at a certain path.
*/
export interface PointerToPrismProvider {
/**
* @internal
* Future: We could consider using a `Symbol.for("dataverse/PointerToPrismProvider")` as a key here, similar to
* how {@link Iterable} works for `of`.
*/
readonly $$isPointerToPrismProvider: true
/**
* Returns a prism of the value at the provided pointer.
*/
pointerToPrism<P>(pointer: Pointer<P>): Prism<P>
}
export function isPointerToPrismProvider(
val: unknown,
): val is PointerToPrismProvider {
return (
typeof val === 'object' &&
val !== null &&
(val as $IntentionalAny)['$$isPointerToPrismProvider'] === true
)
}
/**
* Returns a prism of the value at the provided pointer. Prisms are
* cached per pointer.
*
* @param pointer - The pointer to return the prism at.
*/
export const pointerToPrism = <P extends PointerType<$IntentionalAny>>(
pointer: P,
): Prism<P extends PointerType<infer T> ? T : void> => {
const meta = getPointerMeta(pointer)
let prismInstance = identifyPrismWeakMap.get(meta)
if (!prismInstance) {
const root = meta.root
if (!isPointerToPrismProvider(root)) {
throw new Error(
`Cannot run pointerToPrism() on a pointer whose root is not an PointerToPrismProvider`,
)
}
prismInstance = root.pointerToPrism(pointer as $IntentionalAny)
identifyPrismWeakMap.set(meta, prismInstance)
}
return prismInstance as $IntentionalAny
}

2
packages/dataverse/src/prism/Interface.ts
View file

@ -64,5 +64,5 @@ export interface Prism<V> {
* Returns whether `d` is a prism.
*/
export function isPrism(d: any): d is Prism<unknown> {
return d && d.isPrism && d.isPrism === true
return !!(d && d.isPrism && d.isPrism === true)
}

2
packages/dataverse/src/prism/iterateAndCountTicks.ts
View file

@ -1,4 +1,4 @@
import {pointerToPrism} from '../Atom'
import {pointerToPrism} from '../pointerToPrism'
import type {Pointer} from '../pointer'
import {isPointer} from '../pointer'
import type {Prism} from './Interface'

2
packages/dataverse/src/prism/iterateOver.ts
View file

@ -1,4 +1,4 @@
import {pointerToPrism} from '../Atom'
import {pointerToPrism} from '../pointerToPrism'
import type {Pointer} from '../pointer'
import {isPointer} from '../pointer'
import Ticker from '../Ticker'

3
packages/dataverse/src/prism/prism.test.ts
View file

@ -1,7 +1,8 @@
/*
* @jest-environment jsdom
*/
import Atom, {val} from '../Atom'
import Atom from '../Atom'
import {val} from '../val'
import Ticker from '../Ticker'
import type {$FixMe, $IntentionalAny} from '../types'
import iterateAndCountTicks from './iterateAndCountTicks'

78
packages/dataverse/src/prism/prism.ts
View file

@ -541,6 +541,26 @@ type IMemo = {
cachedValue: unknown
}
/**
* Just like React's `useRef()`, `prism.ref()` allows us to create a prism that holds a reference to some value.
* The only difference is that `prism.ref()` requires a key to be passed into it, whlie `useRef()` doesn't.
* This means that we can call `prism.ref()` in any order, and we can call it multiple times with the same key.
* @param key - The key for the ref. Should be unique inside of the prism.
* @param initialValue - The initial value for the ref.
* @returns `{current: V}` - The ref object.
*
* Note that the ref object will always return its initial value if the prism is cold. It'll only record
* its current value if the prism is hot (and will forget again if the prism goes cold again).
*
* @example
* ```ts
* const pr = prism(() => {
* const ref1 = prism.ref("ref1", 0)
* console.log(ref1.current) // will print 0, and if the prism is hot, it'll print the current value
* ref1.current++ // changing the current value of the ref
* })
* ```
*/
function ref<T>(key: string, initialValue: T): IRef<T> {
const scope = hookScopeStack.peek()
if (!scope) {
@ -585,12 +605,21 @@ function depsHaveChanged(
}
/**
* Store a value to this {@link prism} stack.
* `prism.memo()` works just like React's `useMemo()` hook. It's a way to cache the result of a function call.
* The only difference is that `prism.memo()` requires a key to be passed into it, whlie `useMemo()` doesn't.
* This means that we can call `prism.memo()` in any order, and we can call it multiple times with the same key.
*
* 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 key - The key for the memo. Should be unique inside of the prism
* @param fn - The function to memoize
* @param deps - The dependency array. Provide `[]` if you want to the value to be memoized only once and never re-calculated.
* @returns The result of the function call
*
* @param deps - Passing in `undefined` will always cause a recompute
* @example
* ```ts
* const pr = prism(() => {
* const memoizedReturnValueOfExpensiveFn = prism.memo("memo1", expensiveFn, [])
* })
* ```
*/
function memo<T>(
key: string,
@ -688,6 +717,16 @@ function scope<T>(key: string, fn: () => T): T {
return ret as $IntentionalAny as T
}
/**
* Just an alias for `prism.memo(key, () => prism(fn), deps).getValue()`. It creates a new prism, memoizes it, and returns the value.
* `prism.sub()` is useful when you want to divide your prism into smaller prisms, each of which
* would _only_ recalculate when _certain_ dependencies change. In other words, it's an optimization tool.
*
* @param key - The key for the memo. Should be unique inside of the prism
* @param fn - The function to run inside the prism
* @param deps - The dependency array. Provide `[]` if you want to the value to be memoized only once and never re-calculated.
* @returns The value of the inner prism
*/
function sub<T>(
key: string,
fn: () => T,
@ -696,6 +735,9 @@ function sub<T>(
return memo(key, () => prism(fn), deps).getValue()
}
/**
* @returns true if the current function is running inside a `prism()` call.
*/
function inPrism(): boolean {
return !!hookScopeStack.peek()
}
@ -710,6 +752,34 @@ const possiblePrismToValue = <P extends Prism<$IntentionalAny> | unknown>(
}
}
/**
* `prism.source()` allow a prism to react to changes in some external source (other than other prisms).
* For example, `Atom.pointerToPrism()` uses `prism.source()` to create a prism that reacts to changes in the atom's value.
* @param subscribe - The prism will call this function as soon as the prism goes hot. This function should return an unsubscribe function function which the prism will call when it goes cold.
* @param getValue - A function that returns the current value of the external source.
* @returns The current value of the source
*
* Example:
* ```ts
* function prismFromInputElement(input: HTMLInputElement): Prism<string> {
* function listen(cb: (value: string) => void) {
* const listener = () => {
* cb(input.value)
* }
* input.addEventListener('input', listener)
* return () => {
* input.removeEventListener('input', listener)
* }
* }
*
* function get() {
* return input.value
* }
* return prism(() => prism.source(listen, get))
* }
* ```
*/
function source<V>(
subscribe: (fn: (val: V) => void) => VoidFn,
getValue: () => V,

41
packages/dataverse/src/val.ts Normal file
View file

@ -0,0 +1,41 @@
import type {Prism} from './prism/Interface'
import {isPrism} from './prism/Interface'
import type {PointerType} from './pointer'
import {isPointer} from './pointer'
import type {$IntentionalAny} from './types'
import {pointerToPrism} from './pointerToPrism'
/**
* Convenience function that returns a plain value from its argument, whether it
* is a pointer, a prism or a plain value itself.
*
* @remarks
* For pointers, the value is returned by first creating a prism, so it is
* reactive e.g. when used in a `prism`.
*
* @param input - The argument to return a value from.
*/
export const val = <
P extends
| PointerType<$IntentionalAny>
| Prism<$IntentionalAny>
| undefined
| null,
>(
input: P,
): P extends PointerType<infer T>
? T
: P extends Prism<infer T>
? T
: P extends undefined | null
? P
: unknown => {
if (isPointer(input)) {
return pointerToPrism(input).getValue() as $IntentionalAny
} else if (isPrism(input)) {
return input.getValue() as $IntentionalAny
} else {
return input as $IntentionalAny
}
}

77
packages/react/README.md
View file

@ -1,9 +1,80 @@
# @theatre/react
Utilities for using [Theatre.js](https://www.theatrejs.com) with React.
Utilities for using [Theatre.js](https://www.theatrejs.com) or [Dataverse](https://github.com/theatre-js/theatre/tree/main/packages/dataverse) with React.
## Documentation
* API Docs: [docs.theatrejs.com/api/react](https://docs.theatrejs.com/api/react.html)
* Guide: TODO
### `useVal(pointerOrPrism)`
A React hook that returns the value of the given prism or pointer.
Usage with Dataverse pointers:
```tsx
import {Atom} from '@theatre/dataverse'
import {useVal} from '@theatre/react'
const atom = new Atom({foo: 'foo'})
function Component() {
const foo = useVal(atom.pointer.foo)
return <div>{foo}</div>
}
```
Usage with Dataverse prisms:
```tsx
import {prism} from '@theatre/dataverse'
import {useVal} from '@theatre/react'
const pr = prism(() => 'some value')
function Component() {
const value = useVal(pr)
return <div>{value}</div>
}
```
Usage with Theatre.js pointers:
```tsx
import {useVal} from '@theatre/react'
import {getProject} from '@theatre/core'
const obj = getProject('my project').sheet('my sheet').object('my object', {foo: 'default value of props.foo'})
function Component() {
const value = useVal(obj.props.foo)
return <div>obj.foo is {value}</div>
}
```
_Note that `useVal()` is a React hook, so it can only be used inside a React component's render function. `val()` on the other hand, can be used either inside a `prism` (which would be reactive) or anywhere where reactive values are not needed._
### `usePrism(fn, deps)`
Creates a prism out of `fn` and subscribes the element to the value of the created prism.
```tsx
import {Atom, val, prism} from '@theatre/dataverse'
import {usePrism} from '@theatre/react'
const state = new Atom({a: 1, b: 1})
function Component(props: {which: 'a' | 'b'}) {
const value = usePrism(() => {
prism.isPrism() // true
// note that this function is running inside a prism, so all of prism's
// hooks (prism.memo(), prism.effect(), etc) are available
const num = val(props.which === 'a' ? state.pointer.a : state.pointer.b)
return doExpensiveComputation(num)
},
// since our prism reads `props.which`, we should include it in the deps array
[props.which]
)
return <div>{value}</div>
}
```
> Note that just like `useMemo(..., deps)`, it's necessary to provide a `deps` array to `usePrism()`.

3
theatre/core/src/propTypes/index.ts
View file

@ -22,8 +22,7 @@ import type {Asset} from '@theatre/shared/utils/assets'
// Notes on naming:
// As of now, prop types are either `simple` or `composite`.
// The compound type is a composite type. So is the upcoming enum type.
// Composite types are not directly sequenceable yet. Their simple sub/ancestor props are.
// We’ll provide a nice UX to manage keyframing of multiple sub-props.
// Composite types are not directly sequenceable yet. Their simple sub/descendent props are.
/**
* Validates the common options given to all prop types, such as `opts.label`