which included commits to RCS files with non-trunk default branches. git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@5 b08c6af1-5177-4d33-ba66-4b1c6b8b522a
		
			
				
	
	
		
			204 lines
		
	
	
		
			3.9 KiB
		
	
	
	
		
			Prolog
		
	
	
	
	
	
			
		
		
	
	
			204 lines
		
	
	
		
			3.9 KiB
		
	
	
	
		
			Prolog
		
	
	
	
	
	
% rational (finite and infinite) tree handler
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% 931119 thom fruehwirth ECRC for eclipse CHR
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% 980130, 980312 thom fruehwirth LMU for sicstus CHR, now simpler and better
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:- use_module(library(chr)).
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% need global order on variables
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:- use_module( library('chr/ordering'), [globalize/1,var_compare/3]).
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% var is smaller than any non-var term
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lt(X,Y):- (var(X),var(Y) -> globalize(X),globalize(Y),var_compare(<,X,Y) ; X@<Y).
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le(X,Y):- (var(X) -> true ; X@=<Y).
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handler tree.
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option(debug_compile,on).
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option(already_in_store, off).  
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option(already_in_heads, off).   
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option(check_guard_bindings, off).
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constraints (~)/2, ('#~')/2.
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% T1 ~ T2 means: term T1 is syntactically equal to term T2
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% T1 #~ T2 means: term T1 is syntactically different from term T2
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operator(700,xfx,(~)).
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operator(700,xfx,('#~')).
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ident @ T ~ T <=> true.
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decompose @ T1 ~ T2 <=> nonvar(T1),nonvar(T2) | 
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		same_functor(T1,T2),     
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		T1=..[F|L1],T2=..[F|L2],
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		equate(L1,L2).
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orient @ T ~ X <=> lt(X,T) | X ~ T.   
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simplify @ X ~ T1 \ X ~ T2 <=> le(T1,T2) | T1 ~ T2.
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  same_functor(T1,T2):- functor(T1,F,N),functor(T2,F,N).
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  equate([],[]).
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  equate([X|L1],[Y|L2]):- X ~ Y, equate(L1,L2).
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ident @ T #~ T <=> fail.
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decompose @ T1 #~ T2 <=> nonvar(T1),nonvar(T2) | 
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		(same_functor(T1,T2) ->
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		T1=..[F|L1],T2=..[F|L2],
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		not_equate(L1,L2)
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		;
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		true).
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orient @ T #~ X <=>  lt(X,T) | X #~ T. 
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simplify @ X ~ T1 \ X #~ T2 <=> T1 #~ T2 
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                 pragma already_in_heads.
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constraints not_equate/2, label/0.
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not_equate([],[]) <=> fail.
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not_equate([X],[Y]) <=> X #~ Y.
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not_equate([X|L1],[X|L2]) <=> fail.
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not_equate([X|L1],[Y|L2]), X~Y <=> not_equate(L1,L2).
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% not_equate([X|L1],[Y|L2]) <=> ground(X#~Y) | X #~ Y -> true ; not_equate(L1,L2).
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label, not_equate([X|L1],[Y|L2])#Id <=> true |  
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        (X #~ Y ; X ~ Y, not_equate(L1,L2)),
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	label 
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    pragma passive(Id).      
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/*
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% EXAMPLES ------------------------------------------------------------
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write(example:10), X#~a,X~b;
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write(example:11), A~B,B~C,C~D,D~A;
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write(example:12), A~B,B~C,C~D,D#~A;
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write(example:20), A~g(A),A~g(g(A));
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write(example:21), A#~g(A),A~g(g(A));
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write(example:22), A~g(A),A#~g(g(A));
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write(example:23), A~g(g(g(A))),A~g(g(A));
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write(example:24), A~g(g(g(A))),g(A)~g(g(A));
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write(example:25), A#~g(g(g(A))),A~g(g(A));
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write(example:26), A~g(g(g(A))),A#~g(g(A));
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write(example:30), X~f(T1),T2~f(T2),X~T1,X~T2;
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write(example:31), f(X)~T1,T2~f(T2),X~T1,X~T2;
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write(example:32), X~f(T1),T1~f(T2),X~T1,X~T2;
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write(example:33), f(X)~T1,f(T1)~T2,X~T1,X~T2;
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write(example:34), T1~f(T1),T2~f(T2),X~T1,X~T2;
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write(example:40), A~f(X),B~f(Y),Y~Z,Z~X,A#~B;
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write(example:41), A~X,B~Y,Y~Z,Z~X,A#~B;
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write(example:42), X~f(X,Y),X#~f(X,Y);
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write(example:43), X~f(X,Y),X#~f(Y,X);
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write(example:44), X~f(X,Y),X#~f(Y,X),label;
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write(example:45), X~f(A,B),X#~f(a,b),A~a,B~b;
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write(example:46), X~f(A,B),X#~f(a,b),A~a,B~b,label;
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write(example:50), [X|L] ~ [X,X|L], L ~ [X,X,X,X|Z];
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write(example:51), [X|L]#~[X,X|L], L ~ [X,X,X,X|Z],label;
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write(example:52), [X|L] ~ [X,X|L], L#~[X,X,X,X|Z],label;
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write(example:53), L ~ [X,X|L], L ~ [A,B,C,D];
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write(done).
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% results of current version with local already_in_heads pragma
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example:10
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X~b ? ;
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example:11
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B~A,
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A~C,
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D~C ? ;
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example:12example:20
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A~g(A) ? ;
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example:21
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A#~g(A),
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A~g(g(A)) ? ;
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example:22example:23
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A~g(A) ? ;
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example:24
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A~g(A) ? ;
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example:25
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A~g(g(A)),
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A#~g(A) ? ;
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example:26
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A~g(g(g(A))),
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A#~g(g(A)) ? ;
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example:30
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T1~X,
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X~T2,
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T2~f(T1) ? ;
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example:31
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T2~f(T2),
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T1~X,
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X~T2 ? ;
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example:32
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T1~X,
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X~T2,
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T2~f(T2) ? ;
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example:33
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T2~f(T1),
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T1~X,
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X~T2 ? ;
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example:34
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T1~X,
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X~T2,
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T2~f(T1) ? ;
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example:40example:41example:42example:43
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X~f(X,Y),
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not_equate([X,Y],[Y,X]) ? ;
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example:44
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label,
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X~f(X,Y),
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Y#~X ? ;
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example:45
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X~f(A,B),
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not_equate([A,B],[a,b]),
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A~a,
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B~b ? ;
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example:46example:50
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L~Z,
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Z~[X|Z] ? ;
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example:51
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label,
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L~[X,X,X,X|Z],
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Z#~[X|Z] ? ;
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example:52
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label,
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L~[X|L],
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Z#~L ? ;
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example:53done
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true ? 
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*/
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% end of handler tree
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