export function merge(...sets:string[]):string {
	if (sets.length > 1) {
		sets[0] = sets[0].slice(0, -1);
		const xl = sets.length - 1;
		for (let x = 1; x < xl; ++x) {
			sets[x] = sets[x].slice(1, -1);
		}
		sets[xl] = sets[xl].slice(1);
		return sets.join('');
	} else {
		return sets[0];
	}
}

export function subexp(str:string):string {
	return '(?:' + str + ')';
}

export function typeOf(o:any):string {
	return o === undefined ? 'undefined' : (o === null ? 'null' : Object.prototype.toString.call(o).split(' ').pop().split(']').shift().toLowerCase());
}

export function toUpperCase(str:string):string {
	return str.toUpperCase();
}

export function toArray(obj:any):any[] {
	return obj !== undefined && obj !== null ? (obj instanceof Array ? obj : (typeof obj.length !== 'number' || obj.split || obj.setInterval || obj.call ? [obj] : Array.prototype.slice.call(obj))) : [];
}


export function assign(target: object, source: any): any {
	const obj = target as any;
	if (source) {
		for (const key in source) {
			obj[key] = source[key];
		}
	}
	return obj;
}