112 lines
3.3 KiB
Perl
112 lines
3.3 KiB
Perl
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/*
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$Header$
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@author Nikolai van Kempen
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Following some stuff used from auxiliary.pl to display nrel types in the way
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it is done within the SecondoBDB etc.
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*/
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/*
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This is for nested relations. Like the algebra display function 4 blanks are added when the predicate runs into a arel relation.
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*/
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max_attr_length_nrel([], _, R, R).
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max_attr_length_nrel([[Name, Type] | AttrDescription], Deep, IN, OUT) :-
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( Type = [arel,[tuple,ArelDef]]
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-> (
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NewDeep is Deep + 1,
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append(IN, [0], NewIN),
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max_attr_length_nrel(ArelDef, NewDeep, NewIN, NewOut),
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OUT2=NewOut
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)
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;
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OUT2=IN
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),
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max_attr_length_nrel(AttrDescription, Deep, OUT2, M1OUT),
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% The arel attribute name is not indented.
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atom_length(Name, M2),
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% Unfortunately this is a little bit nasty, but every nested relation
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% within the deep x should be layouted at the same position.
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nth0(Deep, M1OUT, INDEND),
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M is max(INDEND, M2),
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setx(M1OUT, Deep, M, OUT).
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/*
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Create a new list where the element at position ~Index~ in the first list will be ~Element~.
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setx(+List, +Index, +Element, -NewList)
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*/
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setx([_], 0, T, [T]).
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setx([_|REST], 0, T, [T|REST]).
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setx([A|REST], Deep, T, [A|OUT]) :-
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NewDeep is Deep-1,
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setx(REST, NewDeep, T, OUT).
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/*
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For nrel types the same thing is done as by the display predicate.
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*/
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nr_pretty_print([[nrel, [tuple, AttrDescription]], Tuples]) :-
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display([[nrel, [tuple, AttrDescription]], Tuples]).
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/*
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Display predicate for nested relations.
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*/
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nr_display([Rel, [tuple, Attrs]], Tuples) :-
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Rel = nrel,
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!,
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nl,
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max_attr_length_nrel(Attrs, 0, [0], AttrLengths),
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% We should ensure this or otherwise the layout might be confusing
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% during shorter names in an inner relation.
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% max_attr_length_nrel calculates just for every deep needed lengths.
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makeIncreasingList(AttrLengths, AttrLengths2),
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displayTuplesNrel(Attrs, 0, Tuples, AttrLengths2).
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/*
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Means every element to the right is at least as high as all values to the left.
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*/
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makeIncreasingList([],[]) :- !.
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makeIncreasingList([A],[A]) :- !.
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makeIncreasingList([A,B|Rest],[A,D|Rest2]) :-
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!,
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C is max(A, B),
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makeIncreasingList([C|Rest],[D|Rest2]).
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/*
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Display function for nested relations, kept here separated, too. But if needed, this could handle the usual rel/trel case as well.
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*/
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displayTuplesNrel(_, _, [], _).
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% just avoids too much nl calls. It would result into a nasty layout.
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displayTuplesNrel(Attrs, Deep, [Tuple], AttrLength) :-
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displayTupleNrel(Attrs, Deep, Tuple, AttrLength).
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displayTuplesNrel(Attrs, Deep, [Tuple | Rest], AttrLength) :-
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displayTupleNrel(Attrs, Deep, Tuple, AttrLength),
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nl,
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displayTuplesNrel(Attrs, Deep, Rest, AttrLength).
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displayTupleNrel([], _, _, _).
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displayTupleNrel([[Name, Type] | Attrs], Deep, [Value | Values],
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[AttrNameLength|RestLength]) :-
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atom_length(Name, NLength),
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PadLength is (Deep * 4) + (AttrNameLength - NLength),
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write_spaces(PadLength),
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write(Name),
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write(' : '),
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( Type = [arel,[tuple,ArelDef]]
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-> nl,
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NewDeep is Deep + 1,
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% Note: The first element is an internal reference used by the
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% nested relation algebra.
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Value = [_|DValue],
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displayTuplesNrel(ArelDef, NewDeep, DValue, RestLength)
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;
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(display(Type, Value),nl)
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),
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displayTupleNrel(Attrs, Deep, Values, [AttrNameLength|RestLength]).
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% eof
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