home-assistant-js-websocket/dist/store.js

export const createStore = (state) => {
    let listeners = [];
    function unsubscribe(listener) {
        let out = [];
        for (let i = 0; i < listeners.length; i++) {
            if (listeners[i] === listener) {
                listener = null;
            }
            else {
                out.push(listeners[i]);
            }
        }
        listeners = out;
    }
    function setState(update, overwrite) {
        state = overwrite ? update : Object.assign(Object.assign({}, state), update);
        let currentListeners = listeners;
        for (let i = 0; i < currentListeners.length; i++) {
            currentListeners[i](state);
        }
    }
    /**
     * An observable state container, returned from {@link createStore}
     * @name store
     */
    return {
        get state() {
            return state;
        },
        /**
         * Create a bound copy of the given action function.
         * The bound returned function invokes action() and persists the result back to the store.
         * If the return value of `action` is a Promise, the resolved value will be used as state.
         * @param {Function} action	An action of the form `action(state, ...args) -> stateUpdate`
         * @returns {Function} boundAction()
         */
        action(action) {
            function apply(result) {
                setState(result, false);
            }
            // Note: perf tests verifying this implementation: https://esbench.com/bench/5a295e6299634800a0349500
            return function () {
                let args = [state];
                for (let i = 0; i < arguments.length; i++)
                    args.push(arguments[i]);
                // @ts-ignore
                let ret = action.apply(this, args);
                if (ret != null) {
                    if (ret.then)
                        return ret.then(apply);
                    return apply(ret);
                }
            };
        },
        /**
         * Apply a partial state object to the current state, invoking registered listeners.
         * @param {Object} update				An object with properties to be merged into state
         * @param {Boolean} [overwrite=false]	If `true`, update will replace state instead of being merged into it
         */
        setState,
        /**
         * Register a listener function to be called whenever state is changed. Returns an `unsubscribe()` function.
         * @param {Function} listener	A function to call when state changes. Gets passed the new state.
         * @returns {Function} unsubscribe()
         */
        subscribe(listener) {
            listeners.push(listener);
            return () => {
                unsubscribe(listener);
            };
        }
        // /**
        //  * Remove a previously-registered listener function.
        //  * @param {Function} listener	The callback previously passed to `subscribe()` that should be removed.
        //  * @function
        //  */
        // unsubscribe,
    };
};