factor/extra/coroutines/coroutines.factor

! Copyright (C) 2005 Chris Double, 2007 Clemens Hofreither, 2008 James Cash.
! See http://factorcode.org/license.txt for BSD license.
USING: kernel hashtables namespaces make continuations quotations
accessors ;
IN: coroutines

SYMBOL: current-coro

TUPLE: coroutine resumecc exitcc originalcc ;

: cocreate ( quot -- co )
  coroutine new
  dup current-coro associate
  [ swapd , , \ bind , 
    "Coroutine has terminated illegally." , \ throw ,
  ] [ ] make
  [ >>resumecc ] [ >>originalcc ] bi ;

: coresume ( v co -- result )
  [ 
    >>exitcc
    resumecc>> call
    #! At this point, the coroutine quotation must have terminated
    #! normally (without calling coyield, coreset, or coterminate). This shouldn't happen.
    f over
  ] callcc1 2nip ;

: coresume* ( v co -- ) coresume drop ; inline
: *coresume ( co -- result ) f swap coresume ; inline

: coyield ( v -- result )
  current-coro get
  [  
    [ continue-with ] curry
    >>resumecc
    exitcc>> continue-with
  ] callcc1 2nip ;

: coyield* ( v -- ) coyield drop ; inline
: *coyield ( -- v ) f coyield ; inline

: coterminate ( v -- )
  current-coro get
  [ ] >>resumecc
  exitcc>> continue-with ;

: coreset ( v --  )
  current-coro get dup
  originalcc>> >>resumecc
  exitcc>> continue-with ;