[functional tests] more work on the binary-format macro

functional-tests/binary-format.scm

@@ -1,7 +1,14 @@
 (library
   (binary-format)
-  (export binary-format)
-  (import (rnrs))
+  (export size-type binary-format le32 le64 bytes)
+  (import (rnrs)
+          (list-utils))
+
+  (define-syntax size-type
+    (syntax-rules (le32 le64 bytes)
+      ((_ le32) 4)
+      ((_ le64) 8)
+      ((_ (bytes count)) count)))
 
   (define-syntax unpack-type
     (syntax-rules (le32 le64 bytes)
@@ -16,26 +23,34 @@
         (bytevector-copy! bv offset copy 0 count)
         copy))))
 
-  (define (size-type t)
-    (syntax-case t (le32 le64 bytes)
-                 (le32 #'4)
-                 (le64 #'8)
-                 ((bytes count) #'count)))
-
-  ;;; FIXME: (bytes <count>) has to use a literal rather than a symbol.
   (define-syntax binary-format
-    (lambda (x)
-      (syntax-case x ()
-                   ((_ (name pack-name unpack-name) (field type) ...)
-                    (with-syntax ((((t o) ...)
-                                   (let f ((acc 0) (types #'(type ...)))
-                                    (if (null? types)
-                                        '()
-                                        (cons (list (car types) acc)
-                                              (f (+ (syntax->datum (size-type (car types))) acc) (cdr types)))))))
-                                 #`(begin
-                                     (define-record-type name (fields field ...))
+    (syntax-rules ()
+      ((_ (name pack-name unpack-name) (field type) ...)
+       (begin
+         (define-record-type name (fields field ...))
+
+       (define (unpack-name bv offset)
+         (let ((offset offset))
+
+          (define (inc-offset n v)
+            (set! offset (+ offset n))
+            v)
+
+          ((record-constructor (record-constructor-descriptor name))
+           (inc-offset (size-type type) (unpack-type bv offset type)) ...)))))))
+
+  ;;; since le32, le64 and bytes are used as auxiliary keywords, we must export
+  ;;; definitions of them as well.
+  ;;; FIXME: use a macro to remove duplication
+  (define-syntax le32
+    (lambda (x)
+      (syntax-violation 'le32 "misplaced auxiliary keyword" x)))
+
+  (define-syntax le64
+    (lambda (x)
+      (syntax-violation 'le64 "misplaced auxiliary keyword" x)))
+
+  (define-syntax bytes
+    (lambda (x)
+      (syntax-violation 'bytes "misplaced auxiliary keyword" x))))
 
-                                     (define (unpack-name bv offset)
-                                       ((record-constructor (record-type-descriptor name))
-                                        (unpack-type bv (+ offset o) t) ...)))))))))