array—an array.
displaced-to—an array or nil
.
displaced-index-offset—a non-negative fixnum.
If the array is a displaced array,
returns the values of the :displaced-to and :displaced-index-offset
options
for the array (see the functions make-array and adjust-array
).
If the array is not a displaced array,
nil
and 0
are returned.
If array-displacement
is called on an array
for which a non-nil object was provided as the
:displaced-to argument to make-array
or adjust-array
, it must return that object
as its first value. It is implementation-dependent
whether array-displacement
returns a non-nil
primary value for any other array.
(setq a1 (make-array 5)) → #<ARRAY 5 simple 46115576> (setq a2 (make-array 4 :displaced-to a1 :displaced-index-offset 1)) → #<ARRAY 4 indirect 46117134> (array-displacement a2) → #<ARRAY 5 simple 46115576>, 1 (setq a3 (make-array 2 :displaced-to a2 :displaced-index-offset 2)) → #<ARRAY 2 indirect 46122527> (array-displacement a3) → #<ARRAY 4 indirect 46117134>, 2
Should signal an error of type type-error
if array is not an array.