85 lines
2.4 KiB
Plaintext
85 lines
2.4 KiB
Plaintext
|
/* $Id$
|
||
|
|
|
||
|
|
Part of CHR (Constraint Handling Rules)
|
||
|
|
|
||
|
|
Author: Tom Schrijvers
|
||
|
|
E-mail: Tom.Schrijvers@cs.kuleuven.be
|
||
|
|
WWW: http://www.swi-prolog.org
|
||
|
|
Copyright (C): 2003-2004, K.U. Leuven
|
||
|
|
|
||
|
|
This program 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 2
|
||
|
|
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 Lesser General Public
|
||
|
|
License along with this library; if not, write to the Free Software
|
||
|
|
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
|
||
|
|
|
||
|
|
As a special exception, if you link this library with other files,
|
||
|
|
compiled with a Free Software compiler, to produce an executable, this
|
||
|
|
library does not by itself cause the resulting executable to be covered
|
||
|
|
by the GNU General Public License. This exception does not however
|
||
|
|
invalidate any other reasons why the executable file might be covered by
|
||
|
|
the GNU General Public License.
|
||
|
|
*/
|
||
|
|
|
||
|
|
:- module(chrdif,[chrdif/2]).
|
||
|
|
:- use_module(library(chr)).
|
||
|
|
|
||
|
|
:- constraints dif/2, dif2/3, or/2, or_seq/2, del_or/1.
|
||
|
|
|
||
|
|
chrdif(X,Y) :- dif(X,Y).
|
||
|
|
|
||
|
|
dif(X,Y) <=> compound(X), compound(Y) | dif1(X,Y).
|
||
|
|
dif(X,X) <=> fail.
|
||
|
|
dif(X,Y) <=> nonvar(X), nonvar(Y) /* X \== Y holds */ | true.
|
||
|
|
|
||
|
|
dif1(X,Y) :-
|
||
|
|
( functor(X,F,A),
|
||
|
|
functor(Y,F,A) ->
|
||
|
|
X =.. [_|XL],
|
||
|
|
Y =.. [_|YL],
|
||
|
|
dif1l(XL,YL,A)
|
||
|
|
;
|
||
|
|
true
|
||
|
|
).
|
||
|
|
|
||
|
|
dif1l(Xs,Ys,N) :-
|
||
|
|
or(Or,N),
|
||
|
|
dif1l_2(Xs,Ys,Or).
|
||
|
|
|
||
|
|
dif1l_2([],[],_).
|
||
|
|
dif1l_2([X|Xs],[Y|Ys],Or) :-
|
||
|
|
dif2(X,Y,Or),
|
||
|
|
dif1l_2(Xs,Ys,Or).
|
||
|
|
|
||
|
|
or_seq(OrP,Or) \ or(Or,0), or(OrP,N) <=> M is N - 1, or_seq(OrP,M).
|
||
|
|
or(_,0) <=> fail.
|
||
|
|
|
||
|
|
dif2(X,Y,Or) <=> compound(X), compound(Y) | dif3(X,Y,Or).
|
||
|
|
dif2(X,X,Or), or(Or,N) <=> M is N - 1, or(Or,M).
|
||
|
|
dif2(X,Y,Or) <=> nonvar(X), nonvar(Y) /* X \== Y holds */ | del_or(Or).
|
||
|
|
|
||
|
|
del_or(Or) \ or_seq(OrP,Or) <=> del_or(OrP).
|
||
|
|
del_or(Or) \ or_seq(Or,OrC) <=> del_or(OrC).
|
||
|
|
del_or(Or) \ or(Or,_) <=> true.
|
||
|
|
del_or(Or) \ dif2(_,_,Or) <=> true.
|
||
|
|
del_or(Or) <=> true.
|
||
|
|
|
||
|
|
dif3(X,Y,Or) :-
|
||
|
|
( functor(X,F,A),
|
||
|
|
functor(Y,F,A) ->
|
||
|
|
X =.. [_|XL],
|
||
|
|
Y =.. [_|YL],
|
||
|
|
or_seq(Or,Or2),
|
||
|
|
dif1l(XL,YL,A)
|
||
|
|
;
|
||
|
|
del_or(Or)
|
||
|
|
).
|