! Copyright (C) 2005 Chris Double.
! 
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! modification, are permitted provided that the following conditions are met:
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!
IN: coroutines
USING: kernel lists generic ;

TUPLE: coroutine resumecc exitcc ;

: cocreate ( quot - co )
  #! Create a new coroutine, which will execute the quotation
  #! when resumed. The quotation will have the coroutine
  #! on the stack and an initial value (received from coresume)
  #! when first resumed. ie. The quotation should have stack
  #! effect ( co value -- ).
  f f <coroutine> dup rot cons over set-coroutine-resumecc ;

: coresume ( v co -- result )
  #! Resume a coroutine with 'v' as the first item on the
  #! stack. The result placed on the stack is that of the 
  #! topmost argument on the stack when coyield is called
  #! within the coroutine.
  [ 
    over set-coroutine-exitcc
    coroutine-resumecc call
  ] callcc1 >r >r drop r> r> ;

: coyield ( v co -- result )
  #! Suspend a coroutine, leaving the value 'v' on the 
  #! stack when control is passed to the 'coresume' caller.
  [  
    over set-coroutine-resumecc  
    coroutine-exitcc call
  ] callcc1 >r >r drop r> r> ;

: tree-each ( [ tree ] [ quotation ] -- )
  #! Perform a preorder iteration of the tree, calling
  #! the quotation on each key.
  over [
      over cons? [
          >r uncons r> tuck >r >r tree-each r> r> tree-each
      ] [
          call
      ] ifte
  ] [
    2drop
  ] ifte ;


: test1 ( -- co )
  [ swap [ over coyield 2drop ] tree-each f swap coyield ] cocreate ; 
  
: test2 ( -- co )
  [ 1 over coyield drop 2 over coyield drop 3 over coyield ] cocreate ;

USE: prettyprint
USE: sequences

test2 f swap coresume . f swap coresume . f swap coresume . drop

: test3 ( -- co )
  [ [ 1 2 3 ] [ over coyield drop ] each ] cocreate ;

test3 f swap coresume . f swap coresume . f swap coresume . drop