import { useEffect , useState , useRef } from "react" ; import { SUSPENSE } from "../SUSPENSE" ; import { BehaviorObservable } from "../internal/BehaviorObservable" ; import { Subscription } from "rxjs" ; export const useObservable = < O > ( source$ , subscription ? ) : Exclude < O , typeof SUSPENSE > => { const [ state , setState ] = useState < [ O , BehaviorObservable < O > ] > ( ( ) => [ source$ . gV ( subscription ) , source$ , ] ) ; const prevStateRef = useRef < O | ( ( ) => O ) > ( state [ 0 ] ) ; if ( source$ !== state [ 1 ] ) { setState ( [ source$ . gV ( subscription ) , source$ ] ) ; } useEffect ( ( ) => { const suspend = ( ) => { setState ( ( ) => [ source$ . gV ( ) , source$ ] ) ; } ; const subscription = source$ . subscribe ( ( value ) => { if ( value === SUSPENSE ) { suspend ( ) ; } else { if ( ! Object . is ( prevStateRef . current , value ) ) { setState ( [ ( prevStateRef . current = value ) , source$ ] ) ; } } } , ( error ) => { setState ( ( ) => { throw error ; } ) ; } ) ; return ( ) => { subscription . unsubscribe ( ) ; } ; } , [ source$ ] ) ; return state [ 0 ] as Exclude < O , typeof SUSPENSE > ; } ;