52 lines
962 B
Plaintext
52 lines
962 B
Plaintext
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:- category(point_history).
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:- info([
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version is 1.0,
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date is 1998/3/23,
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authors is 'Paulo Moura',
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comment is 'Point position history management predicates.',
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source is 'Example adopted from the SICStus Objects documentation.']).
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:- public(add_to_history/1).
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:- mode(add_to_history(+nonvar), one).
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:- public(init_history/1).
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:- mode(init_history(+list), one).
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:- public(history/1).
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:- mode(history(-list), zero_or_one).
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:- public(print_history/0).
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:- mode(print_history, zero_or_one).
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:- private(history_/1).
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:- dynamic(history_/1).
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:- mode(history_(-list), zero_or_one).
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add_to_history(Location) :-
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::retract(history_(History)),
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::assertz(history_([Location| History])).
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init_history(History) :-
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::retractall(history_(_)),
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::assertz(history_(History)).
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history(History) :-
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::history_(History).
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print_history :-
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::history_(History),
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write('location history: '),
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write(History),
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nl.
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:- end_category.
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