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yap-6.3/CHR/chr/sbag_l.pl

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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Constraint Handling Rules version 2.2 %
% %
% (c) Copyright 1996-98 %
% LMU, Muenchen %
% %
% File: sbag_l.pl %
% Author: Christian Holzbaur christian@ai.univie.ac.at %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
% bags of suspensions
%
:- module( sbag,
[
iter_init/2,
iter_last/1,
iter_next/3,
list_to_sbag/2,
sbag_empty/1,
sbag_member/2,
sbag_union/3,
sbag_add_element/3,
sbag_del_element/3
]).
:- use_module( library(ordsets),
[
merge/3
]).
% -----------------------------------------------------------------
%
% *** MACROS ***
%
:- multifile
user:goal_expansion/3.
:- dynamic
user:goal_expansion/3.
%
user:goal_expansion( iter_init(A,A), _, true).
user:goal_expansion( iter_last([]), _, true).
user:goal_expansion( iter_next([A|B],A,B), _, true).
user:goal_expansion( list_to_sbag(A,A), _, true).
user:goal_expansion( sbag_empty(A), _, A==[]).
user:goal_expansion( sbag_add_element(A,B,C), _, C=[B|A]).
% -----------------------------------------------------------------
iter_init( A, A).
iter_last( []).
iter_next( [A|B], A, B).
list_to_sbag( L, L).
sbag_empty( B) :- B == [].
%
% here for profiling
%
sbag_member( Element, [Head|Tail]) :-
sbag_member( Element, Tail, Head).
% auxiliary to avoid choicepoint for last element
%
sbag_member( E, _, E).
sbag_member( E, [Head|Tail], _) :-
sbag_member( E, Tail, Head).
sbag_union( A, B, C) :-
sort( A, As),
sort( B, Bs),
merge( As, Bs, C).
sbag_add_element( Set1, Elem, Set2) :- Set2 = [Elem|Set1].
sbag_del_element( [], _, []).
sbag_del_element( [X|Xs], Elem, Set2) :-
( X==Elem ->
Set2 = Xs
;
Set2 = [X|Xss],
sbag_del_element( Xs, Elem, Xss)
).
end_of_file.