}

	if n, err := (&Reader{}).Read(nil); n != 0 || err != io.EOF {
		t.Errorf("Read: got %d, %v; want 0, io.EOF", n, err)
	}

	if n, err := (&Reader{}).ReadAt(nil, 11); n != 0 || err != io.EOF {
		t.Errorf("ReadAt: got %d, %v; want 0, io.EOF", n, err)
	}

	if b, err := (&Reader{}).ReadByte(); b != 0 || err != io.EOF {
		t.Errorf("ReadByte: got %d, %v; want 0, io.EOF", b, err)
	}

	}
	if off >= int64(len(r.s)) {
		return 0, io.EOF
	}
	n = copy(b, r.s[off:])
	if n < len(b) {
		err = io.EOF
	}
	return
}

// ReadByte implements the [io.ByteReader] interface.
func (r *Reader) ReadByte() (byte, error) {
	r.prevRune = -1
	if r.i >= int64(len(r.s)) {
		return 0, io.EOF
	}
	b := r.s[r.i]
	r.i++
	return b, nil
}

	value, err := strconv.ParseFloat(str, 64)
	if err != nil {
		p.errorf("%s", err)
	}
	return value
}

// EOF represents the end of input.
var EOF = lex.Make(scanner.EOF, "EOF")

func (p *Parser) next() lex.Token {
	if !p.more() {
		return EOF
	}
	tok := p.input[p.inputPos]
	p.inputPos++
	return tok
}

func (p *Parser) back() {
	if p.inputPos == 0 {

			name := in.Stack.Text()
			macro := in.macros[name]
			if macro != nil {
				nesting++
				in.invokeMacro(macro)
				continue
			}
			fallthrough
		default:
			if tok == scanner.EOF && len(in.ifdefStack) > 0 {
				// We're skipping text but have run out of input with no #endif.
				in.Error("unclosed #ifdef or #ifndef")
			}
			in.beginningOfLine = tok == '\n'
			if in.enabled() {

		}
	}
	if err := tw.Close(); err != nil {
		log.Fatal(err)
	}

	// Open and iterate through the files in the archive.
	tr := tar.NewReader(&buf)
	for {
		hdr, err := tr.Next()
		if err == io.EOF {
			break // End of archive
		}
		if err != nil {
			log.Fatal(err)
		}
		fmt.Printf("Contents of %s:\n", hdr.Name)
		if _, err := io.Copy(os.Stdout, tr); err != nil {
			log.Fatal(err)
		}
		fmt.Println()

		}
	}

	// If the last fragment is a hole, then seek to 1-byte before EOF, and
	// read a single byte to ensure the file is the right size.
	if readLastByte && err == nil {
		_, err = mustReadFull(rs, []byte{0})
		sw.pos++
	}

	n = sw.pos - pos0
	switch {
	case err == io.EOF:
		return n, io.ErrUnexpectedEOF
	case err == ErrWriteTooLong:

		}
		tok := p.next()
		if test.atEOF && tok.ScanToken != scanner.EOF {
			t.Errorf("%d: %q: at EOF got %s", i, test.input, tok)
		} else if !test.atEOF && tok.ScanToken == scanner.EOF {
			t.Errorf("%d: %q: expected not EOF but at EOF", i, test.input)
		}
	}
}

type badExprTest struct {
	input string
	error string // Empty means no error.
}

func IsRegisterShift(r ScanToken) bool {
	return ROT <= r && r <= LSH // Order looks backwards because these are negative.
}

func (t ScanToken) String() string {
	switch t {
	case scanner.EOF:
		return "EOF"
	case scanner.Ident:
		return "identifier"
	case scanner.Int:
		return "integer constant"
	case scanner.Float:
		return "float constant"
	case scanner.Char:
		return "rune constant"

	return &Scanner{
		r:            r,
		split:        ScanLines,
		maxTokenSize: MaxScanTokenSize,
	}
}

// Err returns the first non-EOF error that was encountered by the [Scanner].
func (s *Scanner) Err() error {
	if s.err == io.EOF {
		return nil
	}
	return s.err
}

// Bytes returns the most recent token generated by a call to [Scanner.Scan].

}

// drain returns a single string representing the processed input tokens.
func drain(input *Input) string {
	var buf strings.Builder
	for {
		tok := input.Next()
		if tok == scanner.EOF {
			return buf.String()
		}
		if tok == '#' {
			continue
		}
		if buf.Len() > 0 {
			buf.WriteByte('.')
		}
		buf.WriteString(input.Text())
	}
}

type badLexTest struct {