refactor exceptions to be less verbose

1 files changed, 17 insertions, 9 deletions

diff --git a/mcgoron.iterator.base.scm b/mcgoron.iterator.base.scm
index f823289..21af871 100644
--- a/mcgoron.iterator.base.scm
+++ b/mcgoron.iterator.base.scm
@@ -31,16 +31,20 @@
 
 (define-syntax define-iterator-implementation
   (syntax-rules (else)
-    ((_ (cstr cstr-args ...) ((name . formal) body ...) ...)
+    ((_ (cstr cstr-args ...) self ((name . formal) body ...) ...)
      (define (cstr cstr-args ...)
-       (make-iterator-container
-        (lambda (type args)
-          (case type
-            ((name) (apply (lambda formal body ...) args))
-            ...
-            (else (raise (not-implemented-exception type args)))))
-        '(name ...)
-        (quote cstr))))))
+       (letrec ((self
+                 (make-iterator-container
+                  (lambda (type args)
+                    (case type
+                      ((name) (apply (lambda formal body ...) args))
+                      ...
+                      (else (raise (not-implemented-exception self
+                                                              type
+                                                              args)))))
+                  '(name ...)
+                  (quote cstr))))
+         self)))))
 
 (define-invocation iterator-at-start?)
 (define-invocation iterator-at-end?)
@@ -49,3 +53,7 @@
 (define-invocation iterator-set! val)
 (define-invocation iterator->index)
 
+(define (iterator-next itr)
+  (iterator-advance itr 1))
+(define (iterator-prev itr)
+  (iterator-advance itr -1))