Continuations objs are pairlike for GC marking.

[scheme.forth.jl.git] / src / scheme.4th

diff --git a/src/scheme.4th b/src/scheme.4th
index d9c8aa5..9347750 100644 (file)
--- a/src/scheme.4th
+++ b/src/scheme.4th
@@ -551,11 +551,16 @@ global-env obj!
   depth 2- 2/ fixnum-type 2swap cons
 ;
 
-: make-continuation
+: make-continuation ( -- continuation true-obj )
+    \ true-obj allows calling code to detect whether
+    \ it is being called immediately following make-continuation
+    \ or by a restore-continuation.
 
   cons-param-stack
   cons-return-stack
   cons drop continuation-type
+
+  true boolean-type
 ;
 
 : continuation->pstack-list
@@ -580,7 +585,7 @@ global-env obj!
 
   R> R> 2dup cdr
   2swap
-  car drop 1- 0 swap do
+  stack-list-len 1- 0 swap do
 
       2dup car
       PSP0 object-stack-base @ + i 2* + 2 + !
@@ -592,46 +597,44 @@ global-env obj!
   2drop
 ;
 
-: list->pad ( list n -- )
+: restore-return-stack ( continuation -- )
+
+    continuation->rstack-list
+
+    2dup cdr 2swap stack-list-len ( list n )
+
+    dup RSP0 + RSP! \ expand return stack to accommodate entries
 
-    pad + 1- \ final dest addr
-    pad      \ initial dest addr
+    ( list n )
+
+    1-  \ initial offset n-1
+    0   \ final offset 0
     swap
     do
-        2dup cdr 2swap car
-        drop i !
+        2dup cdr 2swap car drop
+        RSP0 i 1+ + !
     -1 +loop
 
     2drop
 ;
 
-: restore-return-stack ( continuation -- )
-
-    continuation->rstack-list
+: restore-continuation-with-arg ( continuation obj -- )
 
-    2dup stack-list-len -rot ( n stack-list )
-    2dup cdr 2swap stack-list-len  ( n list n )
+    >R >R \ Store obj on return stack
 
-    list->pad  ( n )
+    2dup >R >R \ Store copy of continuation on return stack
 
-    dup RSP0 + RSP! \ expand return stack to accommodate entries
+    restore-param-stack
 
-    ( n )
-    0   \ initial offset
-    do
-        pad i + @ RSP0 i 1+ + !
-    loop
-;
+    R> R> \ Pop continuation from return stack
 
-: restore-continuation ( continuation -- )
-  \ TODO: replace current parameter and return stacks with
-  \ contents of continuation object.
+    R> R> \ Pop obj from return stack
 
-    2dup >R >R
+    2swap
 
-    restore-param-stack
+    false boolean-type \ Add flag signifying continuation restore
 
-    R> R>
+    2swap
 
     restore-return-stack
 ;
@@ -1779,7 +1782,22 @@ parse-idx-stack parse-idx-sp !
         endof
 
         continuation-type of
-          \ TODO: Apply continuation
+            2swap
+            nil? if
+                except-message: ." Continuations expect exactly 1 argument."
+                recoverable-exception throw
+            then
+
+            2dup cdr
+
+            nil? invert if
+                except-message: ." Continuations expect exactly 1 argument."
+                recoverable-exception throw
+            then
+
+            2drop car
+                
+            restore-continuation-with-arg
         endof
 
         except-message: ." object '" drop print ." ' not applicable." recoverable-exception throw
@@ -2083,6 +2101,7 @@ parse-idx-stack parse-idx-sp !
     symbol-type istype? if true exit then
     compound-proc-type istype? if true exit then
     port-type istype? if true exit then
+    continuation-type istype? if true exit then
 
     false
 ;
@@ -2166,9 +2185,6 @@ parse-idx-stack parse-idx-sp !
 
 \ }}}
 
-\ DEBUGGING
-xxxx
-
 \ ---- Loading files ---- {{{
 
 : load ( addr n -- finalResult )