vasille/lib/value/expression.js

The first Developer eXperience Orientated front-end framework (core library).

import { Reference } from "./reference.js";
import { IValue } from "../core/ivalue.js";
/**
 * Bind some values to one expression
 * @class Expression
 * @extends IValue
 */
export class Expression extends IValue {
    /**
     * Creates a function bounded to N values
     * @param func {Function} the function to bound
     * @param values
     * @param link {Boolean} links immediately if true
     */
    constructor(func, values) {
        super();
        /**
         * Expression will link different handler for each value of the list
         */
        this.linkedFunc = [];
        const handler = (i) => {
            /* istanbul ignore else */
            if (typeof i === "number") {
                this.valuesCache[i] = this.values[i].$;
            }
            this.sync.$ = func.apply(this, this.valuesCache);
        };
        // eslint-disable-next-line @typescript-eslint/ban-ts-comment
        // @ts-ignore
        this.valuesCache = values.map(item => item.$);
        this.sync = new Reference(func.apply(this, this.valuesCache));
        let i = 0;
        values.forEach(value => {
            const updater = handler.bind(this, Number(i++));
            this.linkedFunc.push(updater);
            value.on(updater);
        });
        this.values = values;
        this.func = handler;
    }
    get $() {
        return this.sync.$;
    }
    set $(value) {
        this.sync.$ = value;
    }
    on(handler) {
        this.sync.on(handler);
    }
    off(handler) {
        this.sync.off(handler);
    }
    destroy() {
        for (let i = 0; i < this.values.length; i++) {
            this.values[i].off(this.linkedFunc[i]);
        }
        this.values.splice(0);
        this.valuesCache.splice(0);
        this.linkedFunc.splice(0);
        super.destroy();
    }
}