From e0831c1aa3c963111859278579a42dba997dc75d Mon Sep 17 00:00:00 2001
From: Yuichi Nishiwaki <yuichi.nishiwaki@gmail.com>
Date: Mon, 25 Aug 2014 17:10:25 +0900
Subject: [PATCH] change the interface of call/cc

---
 cont.c                | 34 +++++++++-------------------------
 include/picrin/cont.h |  3 +++
 2 files changed, 12 insertions(+), 25 deletions(-)

diff --git a/cont.c b/cont.c
index 30d26568..b31d54f0 100644
--- a/cont.c
+++ b/cont.c
@@ -7,7 +7,6 @@
 #include <stdarg.h>
 
 #include "picrin.h"
-#include "picrin/proc.h"
 #include "picrin/cont.h"
 #include "picrin/pair.h"
 #include "picrin/error.h"
@@ -252,23 +251,21 @@ pic_dynamic_wind(pic_state *pic, struct pic_proc *in, struct pic_proc *thunk, st
 }
 
 noreturn static pic_value
-cont_call(pic_state *pic)
+pic_cont_continue(pic_state *pic)
 {
   struct pic_proc *proc;
   size_t argc;
-  pic_value *argv;
-  struct pic_cont *cont;
+  pic_value cont, *argv;
 
   proc = pic_get_proc(pic);
-  pic_get_args(pic, "*", &argc, &argv);
+  pic_get_args(pic, "o*", &cont, &argc, &argv);
 
-  cont = (struct pic_cont *)pic_ptr(pic_attr_ref(pic, proc, "@@cont"));
-  cont->results = pic_list_by_array(pic, argc, argv);
+  pic_assert_type(pic, cont, cont);
 
   /* execute guard handlers */
-  walk_to_block(pic, pic->blk, cont->blk);
+  walk_to_block(pic, pic->blk, pic_cont_ptr(cont)->blk);
 
-  restore_cont(pic, cont);
+  restore_cont(pic, pic_cont_ptr(cont));
 }
 
 pic_value
@@ -281,14 +278,7 @@ pic_callcc(pic_state *pic, struct pic_proc *proc)
     return pic_values_by_list(pic, cont->results);
   }
   else {
-    struct pic_proc *c;
-
-    c = pic_proc_new(pic, cont_call, "<continuation-procedure>");
-
-    /* save the continuation object in proc */
-    pic_attr_set(pic, c, "@@cont", pic_obj_value(cont));
-
-    return pic_apply1(pic, proc, pic_obj_value(c));
+    return pic_apply1(pic, proc, pic_obj_value(cont));
   }
 }
 
@@ -302,14 +292,7 @@ pic_callcc_trampoline(pic_state *pic, struct pic_proc *proc)
     return pic_values_by_list(pic, cont->results);
   }
   else {
-    struct pic_proc *c;
-
-    c = pic_proc_new(pic, cont_call, "<continuation-procedure>");
-
-    /* save the continuation object in proc */
-    pic_attr_set(pic, c, "@@cont", pic_obj_value(cont));
-
-    return pic_apply_trampoline(pic, proc, pic_list1(pic, pic_obj_value(c)));
+    return pic_apply_trampoline(pic, proc, pic_list1(pic, pic_obj_value(cont)));
   }
 }
 
@@ -365,6 +348,7 @@ pic_init_cont(pic_state *pic)
 {
   pic_defun(pic, "call-with-current-continuation", pic_cont_callcc);
   pic_defun(pic, "call/cc", pic_cont_callcc);
+  pic_defun(pic, "continue", pic_cont_continue);
   pic_defun(pic, "dynamic-wind", pic_cont_dynamic_wind);
   pic_defun(pic, "values", pic_cont_values);
   pic_defun(pic, "call-with-values", pic_cont_call_with_values);
diff --git a/include/picrin/cont.h b/include/picrin/cont.h
index 0a0da9f1..6f35de38 100644
--- a/include/picrin/cont.h
+++ b/include/picrin/cont.h
@@ -43,6 +43,9 @@ struct pic_cont {
   pic_value results;
 };
 
+#define pic_cont_p(o) (pic_type(o) == PIC_TT_CONT)
+#define pic_cont_ptr(o) ((struct pic_cont *)pic_ptr(o))
+
 pic_value pic_values0(pic_state *);
 pic_value pic_values1(pic_state *, pic_value);
 pic_value pic_values2(pic_state *, pic_value, pic_value);