%defines
  impl(solid; on_the_fly; linked_list). 
  op(seqaccess; randaccess).
  
  relation(recommends; satisfied; unsupported).
  relation_score(satisfied, 0).
  relation_score(recommends, 1).
  relation_score(unsupported, -1).
  score(-1..1).

%domain facts:
        relation_op(seqaccess, on_the_fly, recommends).
        relation_op(randaccess, solid, recommends).
        relation_op(randaccess, on_the_fly, unsupported).
        
%dfa analysis: 
%scheme:       dfa_connection(Vto, Vfrom, proto);
%--            dfa_connection(VTo, VFrom, alias); 
%--            dfa_connection(VFormal, VActual, arg); 
%--            dfa_connection(VActual, VFormal, ret)

%compilation:
%--

%domain rules:
  %aliases:
        var_origin(VAR) :- not dfa_connection(VAR, _, alias), v(VAR).
        var_alias(VAR0, VAR_TO) :- dfa_connection(VAR_TO, VAR0, alias), var_origin(VAR0).
        var_alias(VAR0, VAR_TO2) :- dfa_connection(VAR_TO2, VAR_TO1, alias), var_alias(VAR0, VAR_TO1).
        var_alias(VAR0, VAR0):- var_origin(VAR0).
  
  %prototypes:
        var_proto(V0, Vproto) :- var_origin(V0); var_origin(Vproto); var_alias(Vproto, Vp); dfa_connection(V0, Vp, proto).

  %implementations:
        -impl_fulfill(OP, IMPL) :- relation_op(OP, IMPL, unsupported).
        impl_fulfill(OP, IMPL, SCORE):- SCORE = #sum{SCORE1, (OP, IMPL, RL): relation_op(OP, IMPL, RL),relation_score(RL, SCORE1)}
            ; op(OP); impl(IMPL); not -impl_fulfill(OP, IMPL).
            
        -var_impl_fulfill(Var0, Impl) :- var_alias(Var0, Var_Any); bind(Var_Any, op(Op)); -impl_fulfill(Op, Impl).
        var_impl_fulfill(VAR0, IMPL, Score) :- 
            Score = #sum{SCORE, (OP, IMPL, VAR_ANY): impl_fulfill(OP, IMPL, SCORE), var_alias(VAR0, VAR_ANY), bind(VAR_ANY, op(OP))}
          ; bind(VAR0, impl(IMPL)); var_origin(VAR0); not -var_impl_fulfill(VAR0, IMPL).

  %transfunction implementation:
        %bind(Vactual, op(Op)) :- var_alias(Vformal, V1); bind(V1, op(Op)); dfa_connection(Vformal, Vactual, arg); op(Op).
        
        %bind(Vactual, op(Op)) :- var_alias(VO, Vformal); var_alias(VO, V); bind(V, op(Op)); dfa_connection(Vactual,Vformal, ret); op(Op).
        % --uncomment to add possible implementations(impl) to an actual var
        %bind(Vres, op(Op)) :- var_alias(VO, VA); bind(VA, op(Op)); dfa_connection(VArg,VO, result); op(Op).
        
%optimization
%  #maximize {SCORE, (VAR0, IMPL) : var_impl_fulfill(VAR0, IMPL, SCORE)}.

#show var_alias/2.
#show var_impl_fulfill/3. 
#show proto_alias2.