松本行弘(Ruby发明者):Emacs怎样改变了我的人生

#define VALBITS 29
#define GCTYPEBITS 3
enum Lisp_Type
  {
    Lisp_Int = 0,

    /* Symbol.  XSYMBOL (object) points to a struct Lisp_Symbol.  */
    Lisp_Symbol = 2,

    /* Miscellaneous.  XMISC (object) points to a union Lisp_Misc,
       whose first member indicates the subtype.  */
    Lisp_Misc = 3,

    /* String.  XSTRING (object) points to a struct Lisp_String.
       The length of the string, and its contents, are stored therein.  */
    Lisp_String = LISP_STRING_TAG,

    /* Vector of Lisp objects, or something resembling it.
       XVECTOR (object) points to a struct Lisp_Vector, which contains
       the size and contents.  The size field also contains the type
       information, if it's not a real vector object.  */
    Lisp_Vectorlike = 5,

    /* Cons.  XCONS (object) points to a struct Lisp_Cons.  */
    Lisp_Cons = 6,

    Lisp_Float = 7,
  };

typedef union Lisp_Object
  {
    /* Used for comparing two Lisp_Objects;
       also, positive integers can be accessed fast this way.  */
    EMACS_UINT i;

    struct
      {
    EMACS_INT val  : VALBITS;
    enum Lisp_Type type : GCTYPEBITS;
      } s;
    struct
      {
    EMACS_UINT val : VALBITS;
    enum Lisp_Type type : GCTYPEBITS;
      } u;
  }
Lisp_OLisp_Stringbject;