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Flash-enabled Gforth EC

    1: \ Structural Conditionals, based on branches               12dec92py
    2: 
    3: \ Copyright (C) 1995,1996,1997,1999,2001,2003 Free Software Foundation, Inc.
    4: 
    5: \ This file is part of Gforth.
    6: 
    7: \ Gforth is free software; you can redistribute it and/or
    8: \ modify it under the terms of the GNU General Public License
    9: \ as published by the Free Software Foundation; either version 2
   10: \ of the License, or (at your option) any later version.
   11: 
   12: \ This program is distributed in the hope that it will be useful,
   13: \ but WITHOUT ANY WARRANTY; without even the implied warranty of
   14: \ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   15: \ GNU General Public License for more details.
   16: 
   17: \ You should have received a copy of the GNU General Public License
   18: \ along with this program; if not, write to the Free Software
   19: \ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
   20: 
   21: : ?struc      ( flag -- )       abort" unstructured " ;
   22: : sys?        ( sys -- )        dup 0= ?struc ;
   23: : >mark       ( -- sys )        here  cell allot ;
   24: : >resolve    ( sys -- )        here swap
   25:     [ has? flash [IF] ] flash! [ [ELSE] ] ! [  [THEN] ] ;
   26: : <resolve    ( sys -- )        , ;
   27: 
   28: : BUT       sys? swap ;                      immediate restrict
   29: : YET       sys? dup ;                       immediate restrict
   30: 
   31: \ Structural Conditionals                              12dec92py
   32: 
   33: : AHEAD     postpone branch >mark ;           immediate restrict
   34: : IF        postpone ?branch >mark ;          immediate restrict
   35: : THEN      sys? ( dup @ ?struc ) >resolve ;  immediate restrict
   36: : ELSE      sys? postpone AHEAD swap postpone THEN ;
   37:                                              immediate restrict
   38: 
   39: ' THEN Alias ENDIF immediate restrict
   40: 
   41: : BEGIN     here ;                           immediate restrict
   42: : WHILE     sys? postpone IF swap ;           immediate restrict
   43: : AGAIN     sys? postpone branch  <resolve ;  immediate restrict
   44: : UNTIL     sys? postpone ?branch <resolve ;  immediate restrict
   45: : REPEAT    over 0= ?struc postpone AGAIN postpone THEN ;
   46:                                              immediate restrict
   47: