Make compute-offsets public. (#1814)

Make compute-offsets public.

pkgs/base/info.rkt

@@ -12,7 +12,7 @@
 
 (define collection 'multi)
 
-(define version "6.10.1.1")
+(define version "6.10.1.2")
 
 (define deps `("racket-lib"
                ["racket" #:version ,version]))

pkgs/racket-doc/scribblings/foreign/types.scrbl

@@ -1402,6 +1402,33 @@ expects arguments for both the super fields and the new ones:
 #:changed "6.1.1.8" @elem{Added @racket[#:offset] for fields.}
 #:changed "6.3.0.13" @elem{Added @racket[#:define-unsafe].}]}
 
+@defproc[(compute-offsets [types (listof ctype?)]
+                          [alignment (or/c #f 1 2 4 8 16) #f]
+                          [declare (listof (or/c #f exact-integer?)) '()])
+         (listof exact-integer?)]{
+                                  
+ Given a list of types in a C struct type, return the offset
+ of those types.
+
+ The @racket[types] list describes a C struct type and is
+ identical to the list in @racket[make-cstruct-type].
+
+ The C struct's alignment is set with @racket[alignment]
+ The behavior is identical to @racket[make-cstruct-type].
+
+ Explicit positions can be set with @racket[declare]. If
+ provided, it is a list with the same length as as
+ @racket[types]. At each index, if a number is provided, that
+ type is at that offset. Otherwise, the type is
+ @racket[alignment] bytes after the offset.
+
+ @examples[#:eval ffi-eval
+           (compute-offsets (list _int _bool _short))
+           (compute-offsets (list _int _bool _short) 1)
+           (compute-offsets (list _int _int _int) #f (list #f 5 #f))]
+
+ @history[#:added "6.10.1.2"]}
+
 @; ------------------------------------------------------------
 
 @section{C Array Types}

pkgs/racket-test-core/tests/racket/cstruct.rktl

@@ -155,6 +155,16 @@
   
   (test #f equal? b (cast b _B-pointer _B-pointer))) ; cast forces new wrapper
 
+;; ----------------------------------------
+;; Check to ensure offsets are computed correctly
+
+(let ()
+  (test '(0 4 8) compute-offsets (list _int _bool _string))
+  (test '(0 4 5 8) compute-offsets (list _int _byte _byte _int))
+  (test '(0 4 5 6) compute-offsets (list _int _byte _byte _int) 1)
+  (test '(5 4 3 2) compute-offsets (list _int _byte _byte _int) #f (list 5 4 3 2))
+  (test '(0 5 6 8) compute-offsets (list _int _byte _byte _int) #f (list #f 5 #f #f)))
+
 ;; ----------------------------------------
 
 (report-errs)

racket/collects/ffi/unsafe.rkt

@@ -1410,10 +1410,14 @@
 ;; ----------------------------------------------------------------------------
 ;; Struct wrappers
 
-(define (compute-offsets types alignment declared)
-  (let ([alignment (if (memq alignment '(#f 1 2 4 8 16))
-                       alignment
-                       #f)])
+(define* (compute-offsets types [alignment #f] [declared '()])
+  (unless (and (list? types) (map ctype? types))
+    (raise-argument-error 'compute-offsets "(listof ctype?)" types))
+  (unless (memq alignment '(#f 1 2 4 8 16))
+    (raise-argument-error 'compute-offsets "(or/c #f 1 2 4 8 16)" alignment))
+  (unless (and (list? declared) (map (λ (v) (or (not v) (exact-integer? v))) declared))
+    (raise-argument-error 'compute-offsets "(listof (or/c exact-integer? #f))" declared))
+  (let ([declared (append declared (build-list (- (length types) (length declared)) (λ (n) #f)))])
     (let loop ([ts types] [ds declared] [cur 0] [r '()])
       (if (null? ts)
           (reverse r)

racket/src/racket/src/schvers.h

@@ -13,12 +13,12 @@
    consistently.)
 */
 
-#define MZSCHEME_VERSION "6.10.1.1"
+#define MZSCHEME_VERSION "6.10.1.2"
 
 #define MZSCHEME_VERSION_X 6
 #define MZSCHEME_VERSION_Y 10
 #define MZSCHEME_VERSION_Z 1
-#define MZSCHEME_VERSION_W 1
+#define MZSCHEME_VERSION_W 2
 
 #define MZSCHEME_VERSION_MAJOR ((MZSCHEME_VERSION_X * 100) + MZSCHEME_VERSION_Y)
 #define MZSCHEME_VERSION_MINOR ((MZSCHEME_VERSION_Z * 1000) + MZSCHEME_VERSION_W)