--- pl:prolog:pllib:flatten_3 [2019/06/27 15:50]
+++ pl:prolog:pllib:flatten_3 [2019/06/27 15:50] (aktualna)
@@ Linia 1: / Linia 1: @@
+====== Flatten 3 ======
+{{tag>lists operators}}
+===== Description =====
+Flattening a list using a queue
+**Source**:  The Art of Prolog
+===== Download =====
+Program source code: {{flatten_3.pl}}
+===== Listing =====
+<code prolog>
+/*
+    flatten(Xs,Ys) :-
+	Ys is a flattened list containing the elements in Xs.
+*/
+	:- op(40,xfx,\).
+	flatten(Xs,Ys) :- flatten_q(Xs,Qs\Qs,Ys).
+	flatten_q([X|Xs],Ps\[Xs|Qs],Ys) :-
+		flatten_q(X,Ps\Qs,Ys).
+	flatten_q(X,[Q|Ps]\Qs,[X|Ys]) :-
+		constant(X), X \= [], flatten_q(Q,Ps\Qs,Ys).
+	flatten_q([],Q,Ys) :-
+		non_empty(Q), dequeue(X,Q,Q1), flatten_q(X,Q1,Ys).
+	flatten_q([],[]\[],[]).
+non_empty([]\[]) :- !, fail.
+non_empty(Q).
+dequeue(X,[X|Qh]\Qt,Qh\Qt).
+%	Program 15.12:	Flattening a list using a queue
+</code>
+===== Comments =====

pl/prolog/pllib/flatten_3.txt · ostatnio zmienione: 2019/06/27 15:50 (edycja zewnętrzna)

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