X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?a=blobdiff_plain;f=src%2Fscheme.4th;h=9d646677e32ac788581914cb3201462bb417f51f;hb=f1f104259426dc77ec46ae1ac3bda65fcc19a034;hp=93d249650e2fdefa3cc98f31d9fa5a413963e12e;hpb=f71c5f93aefa930fd0ac175416523bc6a101e3df;p=scheme.forth.jl.git

diff --git a/src/scheme.4th b/src/scheme.4th
index 93d2496..9d64667 100644
--- a/src/scheme.4th
+++ b/src/scheme.4th
@@ -530,6 +530,8 @@ global-env obj!
   nil rsp@ 1- rsp0 do
     i 1+ @ fixnum-type 2swap cons
   loop
+
+  rsp@ 1- rsp0 - fixnum-type 2swap cons
 ;
 
 : cons-param-stack ( -- listobj )
@@ -545,13 +547,20 @@ global-env obj!
 
         2swap cons
     2 +loop
+
+  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
@@ -560,18 +569,74 @@ global-env obj!
 : continuation->rstack-list
   drop pair-type cdr ;
 
-: restore-param-stack ( continuation -- obj_stack continuation )
+: stack-list-len ( stack-list -- n )
+    car drop
+;
 
-  2dup >R >R
+: restore-param-stack ( continuation -- obj_stack )
   continuation->pstack-list
+  2dup >R >R
 
-  ( Idea: allocate stack space first using psp!,
+  ( Allocate stack space first using psp!,
     then copy objects from list. )
+
+  car drop 2*
+  object-stack-base @ psp0 + + psp!
+
+  R> R> 2dup cdr
+  2swap
+  stack-list-len 1- 0 swap do
+
+      2dup car
+      PSP0 object-stack-base @ + i 2* + 2 + !
+      PSP0 object-stack-base @ + i 2* + 1 + !
+      cdr
+
+  -1 +loop
+
+  2drop
+;
+
+: restore-return-stack ( continuation -- )
+
+    continuation->rstack-list
+
+    2dup cdr 2swap stack-list-len ( list n )
+
+    dup RSP0 + RSP! \ expand return stack to accommodate entries
+
+    ( list n )
+
+    1-  \ initial offset n-1
+    0   \ final offset 0
+    swap
+    do
+        2dup cdr 2swap car drop
+        RSP0 i 1+ + !
+    -1 +loop
+
+    2drop
 ;
 
-: restore-continuation
-  \ TODO: replace current parameter and return stacks with
-  \ contents of continuation object.
+: restore-continuation-with-arg ( continuation obj -- )
+
+    >R >R \ Store obj on return stack
+
+    2dup >R >R \ Store copy of continuation on return stack
+
+    restore-param-stack
+
+    R> R> \ Pop continuation from return stack
+
+    R> R> \ Pop obj from return stack
+
+    2swap
+
+    false boolean-type \ Add flag signifying continuation restore
+
+    2swap
+
+    restore-return-stack
 ;
 
 \ }}}
@@ -1717,7 +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? not 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