_getFilters(filters) {
            if(!filters) return this.filters;
            if(isArray(filters)) return filters;
            var names = filters.match(/[^\s,]+/g);
            return this.filters
                .filter(filter => names.indexOf(filter.name) !== -1);
        }
Returns array of filters
@param {Array<Function>|String} filters
@returns {Array<Function>}
@private