X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;ds=sidebyside;f=src%2Fcode%2Farray.lisp;h=266c7374f99f10286c56c0bdde1ebf8b43c4be24;hb=8eee0d3a30bf39d9f201acff28c92059fe6c3e4e;hp=7c2790ea48818db6fc31b17d4eb3c6f7458ad8b0;hpb=5758a6ab4c2d046b68b5409d13ed6b8d6199ba7c;p=sbcl.git

diff --git a/src/code/array.lisp b/src/code/array.lisp
index 7c2790e..266c737 100644
--- a/src/code/array.lisp
+++ b/src/code/array.lisp
@@ -1083,6 +1083,30 @@ of specialized arrays is supported."
       (setf (%array-dimension array 0) dimensions))
   (setf (%array-displaced-p array) displacedp)
   array)
+
+;;; User visible extension
+(declaim (ftype (function (array) (values (simple-array * (*)) &optional))
+                array-storage-vector))
+(defun array-storage-vector (array)
+  "Returns the underlying storage vector of ARRAY, which must be a non-displaced array.
+
+In SBCL, if ARRAY is a of type \(SIMPLE-ARRAY * \(*)), it is its own storage
+vector. Multidimensional arrays, arrays with fill pointers, and adjustable
+arrays have an underlying storage vector with the same ARRAY-ELEMENT-TYPE as
+ARRAY, which this function returns.
+
+Important note: the underlying vector is an implementation detail. Even though
+this function exposes it, changes in the implementation may cause this
+function to be removed without further warning."
+  ;; KLUDGE: Without TRULY-THE the system is not smart enough to figure out that
+  ;; the return value is always of the known type.
+  (truly-the (simple-array * (*))
+             (if (array-header-p array)
+                 (if (%array-displaced-p array)
+                     (error "~S cannot be used with displaced arrays. Use ~S instead."
+                            'array-storage-vector 'array-displacement)
+                     (%array-data-vector array))
+                 array)))
 
 ;;;; used by SORT