@humanspeak/svelte-motion/dist/utils/booleanSnapshot.svelte.js

Framer Motion for Svelte 5. Declarative motion.<tag> components with AnimatePresence exit animations, gestures (hover, tap, drag, focus, in-view), variants, FLIP layout animations, shared-layout transitions, spring physics, and scroll-linked motion values

import { SvelteSet } from 'svelte/reactivity';
/**
 * Build a `{ current, subscribe }` snapshot + an internal `set`
 * function. Centralises the dedupe + subscriber-fanout that all three
 * boolean-snapshot hooks need.
 *
 * Returns a tuple so consumers can hand the snapshot to callers while
 * keeping `set` internal (it's not on the returned state object).
 *
 * Same-value writes via `set` are no-ops — saves a fanout call and
 * means callers don't need their own change-detection guard.
 *
 * @param initial Starting value for the `current` cell.
 * @returns A `[state, set]` tuple where `state` is the publicly-shared
 *   `{ current, subscribe }` and `set` is the internal updater the hook
 *   uses to push values from its event source.
 *
 * @example
 * ```ts
 * const [state, set] = createBooleanSnapshot(media.matches)
 * media.addEventListener('change', (e) => set(e.matches))
 * return state // { current, subscribe }
 * ```
 */
export const createBooleanSnapshot = (initial) => {
    let current = $state(initial);
    const subscribers = new SvelteSet();
    const state = {
        get current() {
            return current;
        },
        subscribe(run) {
            subscribers.add(run);
            run(current);
            return () => {
                subscribers.delete(run);
            };
        }
    };
    const set = (value) => {
        if (value === current)
            return;
        current = value;
        for (const sub of subscribers)
            sub(value);
    };
    return [state, set];
};