Annotation of gforth/kernel/cond-old.fs, revision 1.1

1.1     ! anton       1: \ Structural Conditionals                              12dec92py
        !             2: 
        !             3: \ Copyright (C) 1995-1997 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., 675 Mass Ave, Cambridge, MA 02139, USA.
        !            20: 
        !            21: 0 constant defstart
        !            22: 
        !            23: : ?struc      ( flag -- )       abort" unstructured " ;
        !            24: : sys?        ( sys -- )        dup 0= ?struc ;
        !            25: : >mark       ( -- sys )        here  0 , ;
        !            26: : >resolve    ( sys -- )        here over - swap ! ;
        !            27: : <resolve    ( sys -- )        here - , ;
        !            28: 
        !            29: : BUT       sys? swap ;                      immediate restrict
        !            30: : YET       sys? dup ;                       immediate restrict
        !            31: 
        !            32: \ Structural Conditionals                              12dec92py
        !            33: 
        !            34: : AHEAD     compile branch >mark ;           immediate restrict
        !            35: : IF        compile ?branch >mark ;          immediate restrict
        !            36: : THEN      sys? dup @ ?struc >resolve ;     immediate restrict
        !            37: : ELSE      sys? compile AHEAD swap compile THEN ;
        !            38:                                              immediate restrict
        !            39: 
        !            40: ' THEN Alias ENDIF immediate restrict
        !            41: 
        !            42: : BEGIN     here ;                           immediate restrict
        !            43: : WHILE     sys? compile IF swap ;           immediate restrict
        !            44: : AGAIN     sys? compile branch  <resolve ;  immediate restrict
        !            45: : UNTIL     sys? compile ?branch <resolve ;  immediate restrict
        !            46: : REPEAT    over 0= ?struc compile AGAIN compile THEN ;
        !            47:                                              immediate restrict
        !            48: 
        !            49: \ Structural Conditionals                              12dec92py
        !            50: 
        !            51: Variable leavings
        !            52: 
        !            53: : (leave)   here  leavings @ ,  leavings ! ;
        !            54: : LEAVE     compile branch  (leave) ;  immediate restrict
        !            55: : ?LEAVE    compile 0= compile ?branch  (leave) ;
        !            56:                                              immediate restrict
        !            57: 
        !            58: : DONE   ( addr -- )  leavings @
        !            59:   BEGIN  2dup u<=  WHILE  dup @ swap >resolve  REPEAT
        !            60:   leavings ! drop ;                          immediate restrict
        !            61: 
        !            62: \ Structural Conditionals                              12dec92py
        !            63: 
        !            64: : DO        compile (do)   here ;            immediate restrict
        !            65: 
        !            66: : ?DO       compile (?do)  (leave) here ;
        !            67:                                              immediate restrict
        !            68: : FOR       compile (for)  here ;            immediate restrict
        !            69: 
        !            70: : loop]     dup <resolve 2 cells - compile done compile unloop ;
        !            71: 
        !            72: : LOOP      sys? compile (loop)  loop] ;     immediate restrict
        !            73: : +LOOP     sys? compile (+loop) loop] ;     immediate restrict
        !            74: : NEXT      sys? compile (next)  loop] ;     immediate restrict
        !            75: 
        !            76: : EXIT compile ;s ; immediate restrict
        !            77: : ?EXIT postpone IF postpone EXIT postpone THEN ; immediate restrict
        !            78: 

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