cons

OBJECT OBJECT -> LIST

引数の2つの値をくっつけてリストにする関数

code: alloc.c

DEFUN ("cons", Fcons, Scons, 2, 2, 0,

doc: /* Create a new cons, give it CAR and CDR as components, and return it. */)

(Lisp_Object car, Lisp_Object cdr)

{

register Lisp_Object val;

MALLOC_BLOCK_INPUT;

if (cons_free_list)

{

XSETCONS (val, cons_free_list);

cons_free_list = cons_free_list->u.s.u.chain;

}

else

{

if (cons_block_index == CONS_BLOCK_SIZE)

{

struct cons_block *new

= lisp_align_malloc (sizeof *new, MEM_TYPE_CONS);

memset (new->gcmarkbits, 0, sizeof new->gcmarkbits);

new->next = cons_block;

cons_block = new;

cons_block_index = 0;

}

cons_block_index++;

}

MALLOC_UNBLOCK_INPUT;

XSETCAR (val, car);

XSETCDR (val, cdr);

eassert (!XCONS_MARKED_P (XCONS (val)));

consing_until_gc -= sizeof (struct Lisp_Cons);

cons_cells_consed++;

return val;

}

code: example.el

(cons 1 2)

;; => (1 . 2)

(cons 1 '(2))

;; => (1 2) ;; (1 . (2 . nil)

(cons 1 ())

;; => (1) ;; (1 . nil)

(cons 1 nil)

;; => (1) ;; (1 . nil)