47 lines
961 B
Plaintext
47 lines
961 B
Plaintext
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:- object(plan(_)).
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:- info([
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authors is 'Paulo Moura',
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version is 1.0,
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date is 2000/4/22,
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comment is 'Air-line trip planner.',
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parnames is ['Mode'],
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source is 'Example adopted from the Francis G. McCabe L&O documentation.']).
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:- public(from/3).
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:- mode(from(+atom, +atom, -list), zero_or_more).
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:- info(from/3,
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[comment is 'Plan a trip from Start to Destination.',
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argnames is ['Start', 'Destination', 'Plan']]).
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from(Start, Destination, Plan) :-
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from(Start, Destination, [], Plan).
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from(Start, Destination, _, [Step]) :-
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parameter(1, Mode),
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Mode::step(Start, Destination, Step),
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!.
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from(Start, Destination, Locations, [Step| Steps]) :-
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parameter(1, Mode),
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Mode::step(Start, City2, Step),
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not_member(City2, Locations),
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from(City2, Destination, [Start| Locations], Steps).
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not_member(_, []).
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not_member(City, [Location| Locations]) :-
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City \= Location,
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not_member(City, Locations).
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:- end_object.
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