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/** |
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* Tiny pub/sub store for `useSyncExternalStore`. `set` short-circuits on |
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* `equals` so `get` keeps a stable reference while unchanged. |
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* |
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* @param {*} initialState |
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* @param {Function} [equals] Default `Object.is`. |
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* @returns {{ get, set, subscribe }} |
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*/ |
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export function createPubsubStore( initialState, equals = Object.is ) { |
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let state = initialState; |
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const subscribers = new Set(); |
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return { |
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get: () => state, |
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set: ( next ) => { |
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if ( equals( state, next ) ) return; |
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state = next; |
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subscribers.forEach( ( fn ) => fn() ); |
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}, |
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subscribe: ( fn ) => { |
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subscribers.add( fn ); |
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return () => subscribers.delete( fn ); |
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}, |
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}; |
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} |
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