Add (catch-8sync) stuff

[8sync.git] / eightsync / agenda.scm

diff --git a/eightsync/agenda.scm b/eightsync/agenda.scm
index 15220d7494f0f5ec107d778e0a43754d2853a761..edade135c09499e7b08beaf86c573c01d5fb3e1e 100644 (file)
--- a/eightsync/agenda.scm
+++ b/eightsync/agenda.scm
@@ -65,6 +65,8 @@
 
             %port-request %run %run-at %run-delay
             
 
             %port-request %run %run-at %run-delay
             

+            catch-8sync catch-%8sync
+

             print-error-and-continue
 
             %current-agenda
             print-error-and-continue
 
             %current-agenda


@@ -444,8 +446,9 @@ Will produce (0 . 0) instead of a negative number, if needed."
   "Run BODY asynchronously at a prompt, passing args to make-future.
 
 Runs things asynchronously (8synchronously?)"
   "Run BODY asynchronously at a prompt, passing args to make-future.
 
 Runs things asynchronously (8synchronously?)"

-  (abort-to-prompt (current-agenda-prompt)
-                   async-request))
+  (propagate-%async-exceptions
+   (abort-to-prompt (current-agenda-prompt)
+                    async-request)))

 
 ;; Async port request and run-request meta-requests
 (define (make-async-request proc)
 
 ;; Async port request and run-request meta-requests
 (define (make-async-request proc)


@@ -466,16 +469,63 @@ return the wrong thing via (%8sync) and trip themselves up."
               "Invalid request passed back via an (%8sync) procedure."
               async-request))))
 
               "Invalid request passed back via an (%8sync) procedure."
               async-request))))
 

+(define-record-type <wrapped-exception>
+  (make-wrapped-exception key args stacks)
+  wrapped-exception?
+  (key wrapped-exception-key)
+  (args wrapped-exception-args)
+  (stacks wrapped-exception-stacks))
+
+(define-syntax-rule (propagate-%async-exceptions body)
+  (let ((body-result body))
+    (if (wrapped-exception? body-result)
+        (throw '%8sync-caught-error
+               (wrapped-exception-key body-result)
+               (wrapped-exception-args body-result)
+               (wrapped-exception-stacks body-result))
+        body-result)))
+

 (define-syntax-rule (%run body ...)
   (%run-at body ... #f))
 
 (define-syntax-rule (%run-at body ... when)
 (define-syntax-rule (%run body ...)
   (%run-at body ... #f))
 
 (define-syntax-rule (%run-at body ... when)

+  ;; Send an asynchronous request to apply a continuation to the
+  ;; following function, then handle that as a request to the agenda

   (make-async-request
    (lambda (kont)
   (make-async-request
    (lambda (kont)

+     ;; We're making a run request

      (make-run-request
      (make-run-request

+      ;; Wrapping the following execution to run...

       (wrap
       (wrap

+       ;; Once we get the result from the inner part, we'll resume
+       ;; this continuation, but first
+       ;; @@: Is this running immediately, or queueing the result
+       ;;   after evaluation for the next agenda tick?  It looks
+       ;;   like evaluating immediately.  Is that what we want?

        (kont
        (kont

-        (begin body ...)))
+        ;; Any unhandled errors are caught
+        (let ((exception-stack #f))
+          (catch #t
+            ;; Run the actual code the user requested
+            (lambda ()
+              body ...)
+            ;; If something bad happened and we didn't catch it,
+            ;; we'll wrap it up in such a way that the continuation
+            ;; can address it
+            ;; @@: For this stack to work doesn't it have to be
+            (lambda (key . args)
+              (cond
+               ((eq? key '%8sync-caught-error)
+                (match args
+                  ((orig-key orig-args orig-stacks)
+                   (make-wrapped-exception
+                    orig-key orig-args
+                    (cons exception-stack orig-stacks)))))
+               (else
+                (make-wrapped-exception key args
+                                        (list exception-stack)))))
+            (lambda _
+              (set! exception-stack (make-stack #t 1 0)))))))

       when))))
 
 (define-syntax-rule (%run-delay body ... delay-time)
       when))))
 
 (define-syntax-rule (%run-delay body ... delay-time)


@@ -495,6 +545,22 @@ return the wrong thing via (%8sync) and trip themselves up."
        (lambda ()
          body ...)))))
 
        (lambda ()
          body ...)))))
 

+(define-syntax-rule (catch-8sync exp (handler-key handler) ...)
+  (catch '%8sync-caught-error
+    (lambda ()
+      exp)
+    (lambda (_ orig-key orig-args orig-stacks)
+      (cond
+       ((or (eq? handler-key #t)
+            (eq? orig-key handler-key))
+        (apply handler orig-stacks orig-args)) ...
+       (else (raise '%8sync-caught-error
+                    orig-key orig-args orig-stacks))))))
+
+;; Alias...?
+(define-syntax-rule (catch-%8sync rest ...)
+  (catch-8sync rest ...))
+

 
 \f
 ;;; Execution of agenda, and current agenda
 
 \f
 ;;; Execution of agenda, and current agenda