Method Peek

pkg/bufio/bufio.go:128–150

Peek returns the next n bytes without advancing the reader. The bytes stop being valid at the next read call. If Peek returns fewer than n bytes, it also returns an error explaining why the read is short. The error is ErrBufferFull if n is larger than b's buffer size.

(n int)

// also returns an error explaining why the read is short. The error is
// ErrBufferFull if n is larger than b's buffer size.
func (b *Reader) Peek(n int) ([]byte, error) {
	if n < 0 {
		return nil, ErrNegativeCount
	}
	if n > len(b.buf) {
		return nil, ErrBufferFull
	}
	// 0 <= n <= len(b.buf)
	for b.w-b.r < n && b.err == nil {
		b.fill() // b.w-b.r < len(b.buf) => buffer is not full
	}

	var err error
	if avail := b.w - b.r; avail < n {
		// not enough data in buffer
		n = avail
		err = b.readErr()
		if err == nil {
			err = ErrBufferFull
		}
	}
	return b.buf[b.r : b.r+n], err
}

// Pop returns the next n bytes with advancing the reader. The bytes stop
// being valid at the next read call. If Pop returns fewer than n bytes, it