4d94446c25
git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@1416 b08c6af1-5177-4d33-ba66-4b1c6b8b522a
195 lines
4.3 KiB
Prolog
195 lines
4.3 KiB
Prolog
:- module(hprolog,
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[ prolog_flag/3, % +Flag, -Old, +New
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append_lists/2, % +ListOfLists, -List
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nth/3, % ?Index, ?List, ?Element
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substitute/4, % +OldVal, +OldList, +NewVal, -NewList
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memberchk_eq/2, % +Val, +List
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intersect_eq/3, % +List1, +List2, -Intersection
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list_difference_eq/3, % +List, -Subtract, -Rest
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take/3, % +N, +List, -FirstElements
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max_go_list/2, % +List, -Max
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or_list/2, % +ListOfInts, -BitwiseOr
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sublist/2,
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min_list/2,
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chr_delete/3,
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strip_attributes/2,
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restore_attributes/2
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]).
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:- use_module(library(lists)).
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% prolog_flag(+Flag, -Old, +New)
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%
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% Combine ISO prolog flag reading and writing
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prolog_flag(Flag, Old, New) :-
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current_prolog_flag(Flag, Old),
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( Old == New
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-> true
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; set_prolog_flag(Flag, New)
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).
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/*******************************
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* MORE LIST OPERATIONS *
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*******************************/
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% append_lists(+ListOfLists, -List)
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%
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% Convert a one-level nested list into a flat one. E.g.
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% append_lists([[a,b], [c]], X) --> X = [a,b,c]. See also
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% flatten/3.
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append_lists([],[]).
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append_lists([X|Xs],L) :-
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append(X,T,L),
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append_lists(Xs,T).
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% nth(?Index, ?List, ?Element)
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%
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% Same as nth1/3
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nth(Index, List, Element) :-
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nth1(Index, List, Element).
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% substitute(+OldVal, +OldList, +NewVal, -NewList)
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%
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% Substitute OldVal by NewVal in OldList and unify the result
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% with NewList. JW: Shouldn't this be called substitute_eq/4?
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substitute(_, [], _, []) :- ! .
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substitute(X, [U|Us], Y, [V|Vs]) :-
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( X == U
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-> V = Y,
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substitute(X, Us, Y, Vs)
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; V = U,
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substitute(X, Us, Y, Vs)
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).
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% memberchk_eq(+Val, +List)
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%
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% Deterministic check of membership using == rather than
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% unification.
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memberchk_eq(X, [Y|Ys]) :-
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( X == Y
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-> true
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; memberchk_eq(X, Ys)
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).
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% list_difference_eq(+List, -Subtract, -Rest)
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%
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% Delete all elements of Subtract from List and unify the result
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% with Rest. Element comparision is done using ==/2.
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list_difference_eq([],_,[]).
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list_difference_eq([X|Xs],Ys,L) :-
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( memberchk_eq(X,Ys)
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-> list_difference_eq(Xs,Ys,L)
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; L = [X|T],
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list_difference_eq(Xs,Ys,T)
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).
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% intersect_eq(+List1, +List2, -Intersection)
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%
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% Determine the intersection of two lists without unifying values.
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intersect_eq([], _, []).
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intersect_eq([X|Xs], Ys, L) :-
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( memberchk_eq(X, Ys)
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-> L = [X|T],
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intersect_eq(Xs, Ys, T)
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; intersect_eq(Xs, Ys, L)
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).
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% take(+N, +List, -FirstElements)
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%
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% Take the first N elements from List and unify this with
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% FirstElements. The definition is based on the GNU-Prolog lists
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% library. Implementation by Jan Wielemaker.
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take(0, _, []) :- !.
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take(N, [H|TA], [H|TB]) :-
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N > 0,
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N2 is N - 1,
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take(N2, TA, TB).
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% max_go_list(+List, -Max)
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%
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% Return the maximum of List in the standard order of terms.
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max_go_list([H|T], Max) :-
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max_go_list(T, H, Max).
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max_go_list([], Max, Max).
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max_go_list([H|T], X, Max) :-
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( H @=< X
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-> max_go_list(T, X, Max)
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; max_go_list(T, H, Max)
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).
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% or_list(+ListOfInts, -BitwiseOr)
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%
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% Do a bitwise disjuction over all integer members of ListOfInts.
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or_list(L, Or) :-
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or_list(L, 0, Or).
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or_list([], Or, Or).
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or_list([H|T], Or0, Or) :-
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Or1 is H \/ Or0,
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or_list(T, Or1, Or).
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sublist(L, L).
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sublist(Sub, [H|T]) :-
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'$sublist1'(T, H, Sub).
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'$sublist1'(Sub, _, Sub).
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'$sublist1'([H|T], _, Sub) :-
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'$sublist1'(T, H, Sub).
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'$sublist1'([H|T], X, [X|Sub]) :-
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'$sublist1'(T, H, Sub).
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min_list([H|T], Min) :-
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'$min_list1'(T, H, Min).
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'$min_list1'([], Min, Min).
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'$min_list1'([H|T], X, Min) :-
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( H>=X ->
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'$min_list1'(T, X, Min)
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; '$min_list1'(T, H, Min)
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).
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chr_delete([], _, []).
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chr_delete([H|T], X, L) :-
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( H==X ->
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chr_delete(T, X, L)
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; L=[H|RT],
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chr_delete(T, X, RT)
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).
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strip_attributes([],[]).
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strip_attributes([V|R],[V2|R2]) :-
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( attvar(V) ->
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get_attrs(V,VAttrs),
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remove_attrs(V,VAttrs,V2)
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; V2 = []
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),
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strip_attributes(R,R2).
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remove_attrs(_V,[],[]).
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remove_attrs(V,att(X,Y,OtherAttrs),[(X,Y)|R]) :-
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del_attr(V,X),
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remove_attrs(V,OtherAttrs,R).
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restore_attributes([],[]).
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restore_attributes([_V|R],[[]|R2]) :-
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restore_attributes(R,R2).
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restore_attributes([V|R],[[(X,Y)|RVAttr]|R2]) :-
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put_attr(V,X,Y),
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restore_attributes([V|R],[RVAttr|R2]).
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