if s.scanCalled {
		panic("Buffer called after Scan")
	}
	s.buf = buf[0:cap(buf)]
	s.maxTokenSize = max
}

// Split sets the split function for the [Scanner].
// The default split function is [ScanLines].
//
// Split panics if it is called after scanning has started.
func (s *Scanner) Split(split SplitFunc) {
	if s.scanCalled {
		panic("Split called after Scan")
	}
	s.split = split

	n, err := b.Read(rdbuf)
	if err != nil {
		panic(err)
	}
	fmt.Println(n)
	fmt.Println(b.String())
	fmt.Println(string(rdbuf))
	// Output:
	// 1
	// bcde
	// a
}

func ExampleBuffer_ReadByte() {
	var b bytes.Buffer
	b.Grow(64)
	b.Write([]byte("abcde"))
	c, err := b.ReadByte()
	if err != nil {
		panic(err)
	}
	fmt.Println(c)
	fmt.Println(b.String())

		copy(b.toSTAR().trailer(), trailerSTAR)
	case format.has(FormatUSTAR | FormatPAX):
		copy(b.toUSTAR().magic(), magicUSTAR)
		copy(b.toUSTAR().version(), versionUSTAR)
	default:
		panic("invalid format")
	}

	// Update checksum.
	// This field is special in that it is terminated by a NULL then space.
	var f formatter
	field := b.toV7().chksum()

func close(c chan<- Type)

// The panic built-in function stops normal execution of the current
// goroutine. When a function F calls panic, normal execution of F stops
// immediately. Any functions whose execution was deferred by F are run in
// the usual way, and then F returns to its caller. To the caller G, the
// invocation of F then behaves like a call to panic, terminating G's

func (r *Reader) WriteTo(w io.Writer) (n int64, err error) {
	r.prevRune = -1
	if r.i >= int64(len(r.s)) {
		return 0, nil
	}
	b := r.s[r.i:]
	m, err := w.Write(b)
	if m > len(b) {
		panic("bytes.Reader.WriteTo: invalid Write count")
	}
	r.i += int64(m)
	n = int64(m)
	if m != len(b) && err == nil {
		err = io.ErrShortWrite
	}
	return
}

	if count == 0 {
		return []byte{}
	}

	// Since we cannot return an error on overflow,
	// we should panic if the repeat will generate an overflow.
	// See golang.org/issue/16237.
	if count < 0 {
		panic("bytes: negative Repeat count")
	}
	if len(b) >= maxInt/count {
		panic("bytes: Repeat output length overflow")
	}
	n := len(b) * count

	if len(b) == 0 {
		return []byte{}
	}

		pkgPrefix:   pkgPrefix,
	}
}

// panicOnError is enabled when testing to abort execution on the first error
// and turn it into a recoverable panic.
var panicOnError bool

func (p *Parser) errorf(format string, args ...interface{}) {
	if panicOnError {
		panic(fmt.Errorf(format, args...))
	}
	if p.lineNum == p.errorLine {
		// Only one error per line.
		return
	}
	p.errorLine = p.lineNum
	if p.lex != nil {

			name:   name,
			args:   nil,
			tokens: Tokenize(value),
		}
	}
	return macros
}

var panicOnError bool // For testing.

func (in *Input) Error(args ...interface{}) {
	if panicOnError {
		panic(fmt.Errorf("%s:%d: %s", in.File(), in.Line(), fmt.Sprintln(args...)))
	}
	fmt.Fprintf(os.Stderr, "%s:%d: %s", in.File(), in.Line(), fmt.Sprintln(args...))
	os.Exit(1)
}

	}
}

type panicReader struct{ panic bool }

func (r panicReader) Read(p []byte) (int, error) {
	if r.panic {
		panic("oops")
	}
	return 0, io.EOF
}

// Make sure that an empty Buffer remains empty when
// it is "grown" before a Read that panics
func TestReadFromPanicReader(t *testing.T) {

	// First verify non-panic behaviour
	var buf Buffer

// Exported for testing only.
import (
	"unicode/utf8"
)

var IsSpace = isSpace

const DefaultBufSize = defaultBufSize

func (s *Scanner) MaxTokenSize(n int) {
	if n < utf8.UTFMax || n > 1e9 {
		panic("bad max token size")
	}
	if n < len(s.buf) {
		s.buf = make([]byte, n)
	}
	s.maxTokenSize = n
}

// ErrOrEOF is like Err, but returns EOF. Used to test a corner case.
func (s *Scanner) ErrOrEOF() error {