tok := in.Stack.Next()
	if tok != scanner.Ident {
		in.expectText("expected identifier after '#'")
	}
	if !in.enabled() {
		// Can only start including again if we are at #else or #endif but also
		// need to keep track of nested #if[n]defs.
		// We let #line through because it might affect errors.
		switch in.Stack.Text() {
		case "else", "endif", "ifdef", "ifndef", "line":
			// Press on.
		default:
			return false
		}

func Fields(s []byte) [][]byte {
	// First count the fields.
	// This is an exact count if s is ASCII, otherwise it is an approximation.
	n := 0
	wasSpace := 1
	// setBits is used to track which bits are set in the bytes of s.
	setBits := uint8(0)
	for i := 0; i < len(s); i++ {
		r := s[i]
		setBits |= r
		isSpace := int(asciiSpace[r])
		n += wasSpace & ^isSpace
		wasSpace = isSpace
	}

			dst = append(dst, pre) // Only add non-empty fragments
		}
		pre.Offset = cur.endOffset()
	}
	pre.Length = size - pre.Offset // Possibly the only empty fragment
	return append(dst, pre)
}

// fileState tracks the number of logical (includes sparse holes) and physical
// (actual in tar archive) bytes remaining for the current file.
//
// Invariant: logicalRemaining >= physicalRemaining
type fileState interface {