Method Peek

mem/buffer_slice.go:327–345

Peek returns the next n bytes without advancing the reader. Peek appends results to the provided res slice and returns the updated slice. This pattern allows re-using the storage of res if it has sufficient capacity. The returned subslices are views into the underlying buffers and are only valid u

(n int, res [][]byte)

//
// If Peek returns fewer than n bytes, it also returns an error.
func (r *Reader) Peek(n int, res [][]byte) ([][]byte, error) {
	for i := 0; n > 0 && i < len(r.data); i++ {
		curData := r.data[i].ReadOnlyData()
		start := 0
		if i == 0 {
			start = r.bufferIdx
		}
		curSize := min(n, len(curData)-start)
		if curSize == 0 {
			continue
		}
		res = append(res, curData[start:start+curSize])
		n -= curSize
	}
	if n > 0 {
		return nil, fmt.Errorf("insufficient bytes in reader")
	}
	return res, nil
}