//
// Buffer panics if it is called after scanning has started.
func (s *Scanner) Buffer(buf []byte, max int) {
	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.

	fmt.Println(bytes.Count([]byte("five"), []byte(""))) // before & after each rune
	// Output:
	// 3
	// 5
}

func ExampleCut() {
	show := func(s, sep string) {
		before, after, found := bytes.Cut([]byte(s), []byte(sep))
		fmt.Printf("Cut(%q, %q) = %q, %q, %v\n", s, sep, before, after, found)
	}
	show("Gopher", "Go")
	show("Gopher", "ph")
	show("Gopher", "er")

	for _, tt := range cutTests {
		if before, after, found := Cut([]byte(tt.s), []byte(tt.sep)); string(before) != tt.before || string(after) != tt.after || found != tt.found {
			t.Errorf("Cut(%q, %q) = %q, %q, %v, want %q, %q, %v", tt.s, tt.sep, before, after, found, tt.before, tt.after, tt.found)
		}
	}
}

var cutPrefixTests = []struct {
	s, sep string
	after  string
	found  bool
}{

			}
		}
		if !atEOF {
			return 0, nil, nil
		}
		// There is one final token to be delivered, which may be the empty string.
		// Returning bufio.ErrFinalToken here tells Scan there are no more tokens after this
		// but does not trigger an error to be returned from Scan itself.
		return 0, data, bufio.ErrFinalToken
	}
	scanner.Split(onComma)
	// Scan.
	for scanner.Scan() {
		fmt.Printf("%q ", scanner.Text())

	tok := in.Stack.Next()
	if tok != '\n' {
		in.expectText("expected newline after", directive)
	}
}

func (in *Input) Next() ScanToken {
	if in.peek {
		in.peek = false
		tok := in.peekToken
		in.text = in.peekText
		return tok
	}
	// If we cannot generate a token after 100 macro invocations, we're in trouble.
	// The usual case is caught by Push, below, but be safe.

func SplitN(s, sep []byte, n int) [][]byte { return genSplit(s, sep, 0, n) }

// SplitAfterN slices s into subslices after each instance of sep and
// returns a slice of those subslices.
// If sep is empty, SplitAfterN splits after each UTF-8 sequence.
// The count determines the number of subslices to return:
//
//	n > 0: at most n subslices; the last subslice will be the unsplit remainder.

	if err := b.UnreadByte(); err == nil {
		t.Fatal("UnreadByte after ReadByte at EOF: got no error")
	}

	// check not at EOF
	b.WriteString("abcdefghijklmnopqrstuvwxyz")

	// after unsuccessful read
	if n, err := b.Read(nil); n != 0 || err != nil {
		t.Fatalf("Read(nil) = %d,%v; want 0,nil", n, err)
	}
	if err := b.UnreadByte(); err == nil {
		t.Fatal("UnreadByte after Read(nil): got no error")
	}

		p.errorf("register list: expected '-' after `[%s`, found %s", loName, tok)
		return
	}
	hiName := p.next().String()
	hi, ok := p.arch.Register[hiName]
	if !ok {
		p.errorf("register list: bad high register in `[%s-%s`", loName, hiName)
		return
	}
	if tok := p.next().ScanToken; tok != ']' {
		p.errorf("register list: expected ']' after `[%s-%s`, found %s", loName, hiName, tok)
	}

// The close built-in function closes a channel, which must be either
// bidirectional or send-only. It should be executed only by the sender,
// never the receiver, and has the effect of shutting down the channel after
// the last sent value is received. After the last value has been received
// from a closed channel c, any receive from c will succeed without
// blocking, returning the zero value for the channel element. The form
//
//	x, ok := <-c
//

		lines(
			"#define A 1\\",
			"\t2\\",
			"\t3",
			"before",
			"A",
			"after",
		),
		"before.\n.1.\n.2.\n.3.\n.after.\n",
	},
	{
		"multiline macro with arguments",
		lines(
			"#define A(a, b, c) a\\",
			"\tb\\",
			"\tc",
			"before",
			"A(1, 2, 3)",
			"after",
		),
		"before.\n.1.\n.2.\n.3.\n.after.\n",
	},
	{
		"LOAD macro",
		lines(
			"#define LOAD(off, reg) \\",