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pl:prolog:pllib:skeleton [2019/06/27 15:50] (aktualna)
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 +====== Skeleton ======
 +{{tag>​misc}}
 +===== Description =====
 +Composing two enhancements of a skeleton
 +
 +**Source**: ​ The Art of Prolog
 +===== Download =====
 +Program source code: {{skeleton.pl}}
 +===== Listing =====
 +<code prolog>
 +/*
 +  compose(Program1,​Program2,​Skeleton,​FinalProgram) :-
 +     ​FinalProgram is the result of composing Program1 and
 +     ​Program2,​ which are both enhancements of Skeleton.
 +*/
 +
 + :- op(40,​xfx,​\).
 +
 +compose([Cl1|Cls1],​[Cl2|Cls2],​[ClSkel|ClsSkel],​[Cl|Cls]) :-
 +    compose_clause(Cl1,​Cl2,​ClSkel,​Cl),​
 +    compose(Cls1,​Cls2,​ClsSkel,​Cls).
 +compose([ ],[ ],[ ],[ ]).
 +
 +compose_clause((A1 :- B1),(A2 :- B2),(ASkel :- BSkel),(A :- B)) :-
 +    composition_specification(A1,​A2,​ASkel,​A),​
 +    compose_bodies(BSkel,​B1,​B2,​B\true).
 +
 +compose_bodies(SkelBody,​Body1,​Body2,​B\BRest) :-
 +    first(SkelBody,​G),​ !,
 +    align(G,​Body1,​G1,​RestBody1,​B\B1),​
 +    align(G,​Body2,​G2,​RestBody2,​B1\(Goal,​B2)),​
 +    compose_goal(G1,​G2,​Goal),​
 +    rest(SkelBody,​Gs),​
 +    compose_bodies(Gs,​RestBody1,​RestBody2,​B2\BRest).
 +compose_bodies(true,​Body1,​Body2,​B\BRest) :-
 +    rest_goals(Body1,​B\B1),​ rest_goals(Body2,​B1\BRest).
 +
 +align(Goal,​Body,​G,​RestBody,​B\B) :-
 +    first(Body,​G),​ correspond(G,​Goal),​ !, rest(Body,​RestBody).
 +align(Goal,​(G,​Body),​CorrespondingG,​RestBody,​(G,​B)\B1) :-
 +    align(Goal,​Body,​CorrespondingG,​RestBody,​B\B1).
 +
 +first((G,​Gs),​G). ​                   ​
 +first(G,G) :-   G \== (A,B), G \== true. 
 +
 +rest((G,​Gs),​Gs).
 +rest(G,​true) :-  G \== (A,B).
 +
 +correspond(G,​G).
 +correspond(G,​B) :-  map(G,B).
 +
 +compose_goal(G,​G,​G) :-  !.
 +compose_goal(A1,​A2,​A) :-
 +    !, composition_specification(A1,​A2,​ASkel,​A).
 +
 +rest_goals(true,​B\B) :-  !.
 +rest_goals(Body,​(G,​B)\BRest) :-
 +    first(Body,​G),​ !, rest(Body,​Body1),​ rest_goals(Body1,​B\BRest).
 +
 +%  Program 18.6: Composing two enhancements of a skeleton
 +</​code>​
 +===== Comments =====
  
pl/prolog/pllib/skeleton.txt · ostatnio zmienione: 2019/06/27 15:50 (edycja zewnętrzna)
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