if !ok {
		b = new(bitState)
	}
	return b
}

func freeBitState(b *bitState) {
	b.inputs.clear()
	bitStatePool.Put(b)
}

// maxBitStateLen returns the maximum length of a string to search with
// the backtracker using prog.
func maxBitStateLen(prog *syntax.Prog) int {
	if !shouldBacktrack(prog) {
		return 0
	}
	return maxBacktrackVector / len(prog.Inst)
}

		longest:     longest,
		matchcap:    matchcap,
		minInputLen: minInputLen(re),
	}
	if regexp.onepass == nil {
		regexp.prefix, regexp.prefixComplete = prog.Prefix()
		regexp.maxBitStateLen = maxBitStateLen(prog)
	} else {
		regexp.prefix, regexp.prefixComplete, regexp.prefixEnd = onePassPrefix(prog)
	}
	if regexp.prefix != "" {
		// TODO(rsc): Remove this allocation by adding

	}

	if r == nil && len(b)+len(s) < re.minInputLen {
		return nil
	}

	if re.onepass != nil {
		return re.doOnePass(r, b, s, pos, ncap, dstCap)
	}
	if r == nil && len(b)+len(s) < re.maxBitStateLen {
		return re.backtrack(b, s, pos, ncap, dstCap)
	}

	m := re.get()
	i, _ := m.inputs.init(r, b, s)

	m.init(ncap)
	if !m.match(i, pos) {
		re.put(m)
		return nil
	}