\ Structural Conditionals, branches with plugins 10May99jaw
\ Copyright (C) 1995-1997,1999,2000,2003,2007,2012 Free Software Foundation, Inc.
\ This file is part of Gforth.
\ Gforth is free software; you can redistribute it and/or
\ modify it under the terms of the GNU General Public License
\ as published by the Free Software Foundation, either version 3
\ of the License, or (at your option) any later version.
\ This program is distributed in the hope that it will be useful,
\ but WITHOUT ANY WARRANTY; without even the implied warranty of
\ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
\ GNU General Public License for more details.
\ You should have received a copy of the GNU General Public License
\ along with this program. If not, see http://www.gnu.org/licenses/.
: ?struc ( flag -- ) abort" unstructured " ;
: sys? ( sys -- ) dup 0= ?struc ;
: >mark ( -- sys ) here 0 , ;
: >resolve ( sys -- ) here over - swap ! ;
: <resolve ( sys -- ) here - , ;
: BUT sys? swap ; immediate restrict
: YET sys? dup ; immediate restrict
\ Structural Conditionals 12dec92py
: AHEAD branchmark, ; immediate restrict
: IF ?branchmark, ; immediate restrict
: THEN branchto, branchtoresolve, ; immediate restrict
: ELSE sys? compile AHEAD swap compile THEN ;
' THEN Alias ENDIF immediate restrict
: BEGIN branchtomark, ; immediate restrict
: WHILE sys? compile IF swap ; immediate restrict
: AGAIN sys? branch, ; immediate restrict
: UNTIL sys? ?branch, ; immediate restrict
: REPEAT over 0= ?struc compile AGAIN compile THEN ;