Text() string
	// File reports the source file name of the token.
	File() string
	// Base reports the position base of the token.
	Base() *src.PosBase
	// SetBase sets the position base.
	SetBase(*src.PosBase)
	// Line reports the source line number of the token.
	Line() int
	// Col reports the source column number of the token.
	Col() int
	// Close does any teardown required.
	Close()
}

}

func (s *Stack) File() string {
	return s.Base().Filename()
}

func (s *Stack) Base() *src.PosBase {
	return s.tr[len(s.tr)-1].Base()
}

func (s *Stack) SetBase(base *src.PosBase) {
	s.tr[len(s.tr)-1].SetBase(base)
}

func (s *Stack) Line() int {
	return s.tr[len(s.tr)-1].Line()
}

func (s *Stack) Col() int {
	return s.tr[len(s.tr)-1].Col()
}

func (s *Stack) Close() { // Unused.

func (s *Slice) Text() string {
	return s.tokens[s.pos].text
}

func (s *Slice) File() string {
	return s.base.Filename()
}

func (s *Slice) Base() *src.PosBase {
	return s.base
}

func (s *Slice) SetBase(base *src.PosBase) {
	// Cannot happen because we only have slices of already-scanned text,
	// but be prepared.
	s.base = base
}

func (s *Slice) Line() int {
	return s.line
}

func (s *Slice) Col() int {

		return "@>"
	}
	return t.s.TokenText()
}

func (t *Tokenizer) File() string {
	return t.base.Filename()
}

func (t *Tokenizer) Base() *src.PosBase {
	return t.base
}

func (t *Tokenizer) SetBase(base *src.PosBase) {
	t.base = base
}

func (t *Tokenizer) Line() int {
	return t.line
}

func (t *Tokenizer) Col() int {
	return t.s.Pos().Column
}

func (t *Tokenizer) Next() ScanToken {

	tok = in.Stack.Next()
	if tok != '\n' {
		in.Error("unexpected token at end of #line: ", tok)
	}
	pos := src.MakePos(in.Base(), uint(in.Line())+1, 1) // +1 because #line nnn means line nnn starts on next line
	in.Stack.SetBase(src.NewLinePragmaBase(pos, file, objabi.AbsFile(objabi.WorkingDir(), file, *flags.TrimPath), uint(line), 1))
}

// #undef processing
func (in *Input) undef() {
	name := in.macroName()
	if in.macros[name] == nil {