File:  [gforth] / gforth / kernel / cbr.fs
Revision 1.12: download - view: text, annotated - select for diffs
Mon Dec 31 19:02:25 2007 UTC (14 years, 7 months ago) by anton
Branches: MAIN
CVS tags: v0-7-0, HEAD
updated copyright year after changing license notice

    1: \ Structural Conditionals, based on branches               12dec92py
    2: 
    3: \ Copyright (C) 1995,1996,1997,1999,2001,2003,2006,2007 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 3
   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, see http://www.gnu.org/licenses/.
   19: 
   20: : ?struc      ( flag -- )       abort" unstructured " ;
   21: : sys?        ( sys -- )        dup 0= ?struc ;
   22: : >mark       ( -- sys )        here  cell allot ;
   23: : >resolve    ( sys -- )        here swap
   24:     [ has? flash [IF] ] flash! [ [ELSE] ] ! [  [THEN] ] ;
   25: : <resolve    ( sys -- )        , ;
   26: 
   27: : BUT       sys? swap ;                      immediate restrict
   28: : YET       sys? dup ;                       immediate restrict
   29: 
   30: \ Structural Conditionals                              12dec92py
   31: 
   32: : AHEAD     postpone branch >mark ;           immediate restrict
   33: : IF        postpone ?branch >mark ;          immediate restrict
   34: : THEN      sys? ( dup @ ?struc ) >resolve ;  immediate restrict
   35: : ELSE      sys? postpone AHEAD swap postpone THEN ;
   36:                                              immediate restrict
   37: 
   38: ' THEN Alias ENDIF immediate restrict
   39: 
   40: : BEGIN     here ;                           immediate restrict
   41: : WHILE     sys? postpone IF swap ;           immediate restrict
   42: : AGAIN     sys? postpone branch  <resolve ;  immediate restrict
   43: : UNTIL     sys? postpone ?branch <resolve ;  immediate restrict
   44: : REPEAT    over 0= ?struc postpone AGAIN postpone THEN ;
   45:                                              immediate restrict
   46: 
   47: 0 CONSTANT case ( compilation  -- case-sys ; run-time  -- ) \ core-ext
   48:     immediate
   49: 
   50: : of ( compilation  -- of-sys ; run-time x1 x2 -- |x1 ) \ core-ext
   51:     \ !! the implementation does not match the stack effect
   52:     1+ >r
   53:     postpone over postpone = postpone if postpone drop
   54:     r> ; immediate
   55: 
   56: : endof ( compilation case-sys1 of-sys -- case-sys2 ; run-time  -- ) \ core-ext end-of
   57:     >r postpone else r> ; immediate
   58: 
   59: : endcase ( compilation case-sys -- ; run-time x -- ) \ core-ext end-case
   60:     postpone drop
   61:     0 ?do postpone then loop ; immediate

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