406 lines
9.1 KiB
Prolog
406 lines
9.1 KiB
Prolog
/*************************************************************************
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* *
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* YAP Prolog *
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* *
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* Yap Prolog was developed at NCCUP - Universidade do Porto *
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* *
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* Copyright L.Damas, V.S.Costa and Universidade do Porto 1985-1997 *
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* *
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**************************************************************************
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* *
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* File: utils.yap *
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* Last rev: 8/2/88 *
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* mods: *
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* comments: Some utility predicates available in yap *
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* *
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*************************************************************************/
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:- system_module( '$_utils', [callable/1,
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current_op/3,
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nb_current/2,
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nth_instance/3,
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nth_instance/4,
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op/3,
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prolog/0,
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recordaifnot/3,
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recordzifnot/3,
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simple/1,
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subsumes_term/2], ['$getval_exception'/3]).
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:- use_system_module( '$_boot', ['$live'/0]).
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:- use_system_module( '$_errors', ['$do_error'/2]).
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/** @pred op(+ _P_,+ _T_,+ _A_) is iso
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Defines the operator _A_ or the list of operators _A_ with type
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_T_ (which must be one of `xfx`, `xfy`,`yfx`,
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`xf`, `yf`, `fx` or `fy`) and precedence _P_
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(see appendix iv for a list of predefined operators).
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Note that if there is a preexisting operator with the same name and
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type, this operator will be discarded. Also, `,` may not be defined
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as an operator, and it is not allowed to have the same for an infix and
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a postfix operator.
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*/
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op(P,T,V) :-
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'$check_op'(P,T,V,op(P,T,V)),
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'$op'(P, T, V).
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% just check the operator declarations for correctness.
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'$check_op'(P,T,Op,G) :-
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( var(P) ; var(T); var(Op)), !,
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'$do_error'(instantiation_error,G).
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'$check_op'(P,_,_,G) :-
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\+ integer(P), !,
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'$do_error'(type_error(integer,P),G).
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'$check_op'(P,_,_,G) :-
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P < 0, !,
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'$do_error'(domain_error(operator_priority,P),G).
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'$check_op'(P,_,_,G) :-
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P > 1200, !,
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'$do_error'(domain_error(operator_priority,P),G).
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'$check_op'(_,T,_,G) :-
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\+ atom(T), !,
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'$do_error'(type_error(atom,T),G).
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'$check_op'(_,T,_,G) :-
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\+ '$associativity'(T), !,
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'$do_error'(domain_error(operator_specifier,T),G).
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'$check_op'(P,T,V,G) :-
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'$check_module_for_op'(V, G, NV),
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'$check_top_op'(P, T, NV, G).
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'$check_top_op'(_, _, [], _) :- !.
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'$check_top_op'(P, T, [Op|NV], G) :- !,
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'$check_ops'(P, T, Op.NV, G).
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'$check_top_op'(P, T, V, G) :-
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atom(V), !,
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'$check_op_name'(P, T, V, G).
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'$check_top_op'(_P, _T, V, G) :-
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'$do_error'(type_error(atom,V),G).
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'$associativity'(xfx).
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'$associativity'(xfy).
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'$associativity'(yfx).
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'$associativity'(yfy).
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'$associativity'(xf).
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'$associativity'(yf).
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'$associativity'(fx).
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'$associativity'(fy).
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'$check_module_for_op'(MOp, G, _) :-
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var(MOp), !,
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'$do_error'(instantiation_error,G).
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'$check_module_for_op'(M:_V, G, _) :-
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var(M), !,
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'$do_error'(instantiation_error,G).
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'$check_module_for_op'(M:V, G, NV) :-
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atom(M), !,
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'$check_module_for_op'(V, G, NV).
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'$check_module_for_op'(M:_V, G, _) :- !,
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'$do_error'(type_error(atom,M),G).
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'$check_module_for_op'(V, _G, V).
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'$check_ops'(_P, _T, [], _G) :- !.
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'$check_ops'(P, T, [Op|NV], G) :- !,
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(
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var(NV)
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->
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'$do_error'(instantiation_error,G)
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;
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'$check_module_for_op'(Op, G, NOp),
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'$check_op_name'(P, T, NOp, G),
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'$check_ops'(P, T, NV, G)
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).
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'$check_ops'(_P, _T, Ops, G) :-
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'$do_error'(type_error(list,Ops),G).
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'$check_op_name'(_,_,V,G) :-
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var(V), !,
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'$do_error'(instantiation_error,G).
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'$check_op_name'(_,_,',',G) :- !,
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'$do_error'(permission_error(modify,operator,','),G).
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'$check_op_name'(_,_,'[]',G) :- T \= yf, T\= xf, !,
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'$do_error'(permission_error(create,operator,'[]'),G).
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'$check_op_name'(_,_,'{}',G) :- T \= yf, T\= xf, !,
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'$do_error'(permission_error(create,operator,'{}'),G).
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'$check_op_name'(P,T,'|',G) :-
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(
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integer(P),
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P < 1001, P > 0
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;
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atom_codes(T,[_,_])
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), !,
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'$do_error'(permission_error(create,operator,'|'),G).
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'$check_op_name'(_,_,V,_) :-
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atom(V), !.
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'$check_op_name'(_,_,A,G) :-
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'$do_error'(type_error(atom,A),G).
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'$op'(P, T, ML) :-
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strip_module(ML, M, [A|As]), !,
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'$opl'(P, T, M, [A|As]).
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'$op'(P, T, A) :-
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'$op2'(P,T,A).
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'$opl'(_P, _T, _, []).
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'$opl'(P, T, M, [A|As]) :-
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'$op2'(P, T, M:A),
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'$opl'(P, T, M, As).
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'$op2'(P,T,A) :-
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atom(A), !,
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'$opdec'(P,T,A,prolog).
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'$op2'(P,T,A) :-
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strip_module(A,M,N),
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'$opdec'(P,T,N,M).
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/** @pred current_op( _P_, _T_, _F_) is iso
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Defines the relation: _P_ is a currently defined operator of type
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_T_ and precedence _P_.
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*/
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current_op(X,Y,V) :- var(V), !,
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'$current_module'(M),
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'$do_current_op'(X,Y,V,M).
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current_op(X,Y,M:Z) :- !,
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'$current_opm'(X,Y,Z,M).
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current_op(X,Y,Z) :-
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'$current_module'(M),
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'$do_current_op'(X,Y,Z,M).
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'$current_opm'(X,Y,Z,M) :-
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nonvar(Y),
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\+ '$associativity'(Y),
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'$do_error'(domain_error(operator_specifier,Y),current_op(X,Y,M:Z)).
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'$current_opm'(X,Y,Z,M) :-
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var(Z), !,
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'$do_current_op'(X,Y,Z,M).
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'$current_opm'(X,Y,M:Z,_) :- !,
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'$current_opm'(X,Y,Z,M).
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'$current_opm'(X,Y,Z,M) :-
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'$do_current_op'(X,Y,Z,M).
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'$do_current_op'(X,Y,Z,M) :-
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nonvar(Y),
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\+ '$associativity'(Y),
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'$do_error'(domain_error(operator_specifier,Y),current_op(X,Y,M:Z)).
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'$do_current_op'(X,Y,Z,M) :-
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atom(Z), !,
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'$current_atom_op'(Z, M1, Prefix, Infix, Posfix),
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( M1 = prolog -> true ; M1 = M ),
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(
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'$get_prefix'(Prefix, X, Y)
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;
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'$get_infix'(Infix, X, Y)
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;
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'$get_posfix'(Posfix, X, Y)
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).
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'$do_current_op'(X,Y,Z,M) :-
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'$current_op'(Z, M1, Prefix, Infix, Posfix),
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( M1 = prolog -> true ; M1 = M ),
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(
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'$get_prefix'(Prefix, X, Y)
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;
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'$get_infix'(Infix, X, Y)
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;
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'$get_posfix'(Posfix, X, Y)
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).
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'$get_prefix'(Prefix, X, Y) :-
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Prefix > 0,
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X is Prefix /\ 0xfff,
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(
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0x2000 /\ Prefix =:= 0x2000
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->
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Y = fx
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;
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Y = fy
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).
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'$get_infix'(Infix, X, Y) :-
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Infix > 0,
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X is Infix /\ 0xfff,
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(
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0x3000 /\ Infix =:= 0x3000
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->
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Y = xfx
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;
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0x1000 /\ Infix =:= 0x1000
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->
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Y = xfy
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;
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Y = yfx
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).
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'$get_posfix'(Posfix, X, Y) :-
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Posfix > 0,
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X is Posfix /\ 0xfff,
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(
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0x1000 /\ Posfix =:= 0x1000
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->
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Y = xf
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;
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Y = yf
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).
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prolog :-
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'$live'.
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%%% current ....
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/** @pred recordaifnot(+ _K_, _T_,- _R_)
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If a term equal to _T_ up to variable renaming is stored under key
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_K_ fail. Otherwise, make term _T_ the first record under key
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_K_ and unify _R_ with its reference.
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*/
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recordaifnot(K,T,R) :-
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recorded(K,T,R), % force non-det binding to R.
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'$still_variant'(R,T),
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!,
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fail.
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recordaifnot(K,T,R) :-
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recorda(K,T,R).
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/** @pred recordzifnot(+ _K_, _T_,- _R_)
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If a term equal to _T_ up to variable renaming is stored under key
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_K_ fail. Otherwise, make term _T_ the first record under key
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_K_ and unify _R_ with its reference.
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This predicate is YAP specific.
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*/
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recordzifnot(K,T,R) :-
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recorded(K,T,R),
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'$still_variant'(R,T),
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!,
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fail.
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recordzifnot(K,T,R) :-
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recordz(K,T,R).
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/** @pred callable( _T_) is iso
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Checks whether _T_ is a callable term, that is, an atom or a
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compound term.
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*/
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callable(A) :-
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( var(A) -> fail ; number(A) -> fail ; true ).
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/** @pred simple( _T_)
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Checks whether _T_ is unbound, an atom, or a number.
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*/
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simple(V) :- var(V), !.
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simple(A) :- atom(A), !.
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simple(N) :- number(N).
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/** @pred nth_instance(? _Key_,? _Index_,? _R_)
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Fetches the _Index_nth entry in the internal database under the key
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_Key_. Entries are numbered from one. If the key _Key_ or the
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_Index_ are bound, a reference is unified with _R_. Otherwise,
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the reference _R_ must be given, and YAP will find
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the matching key and index.
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*/
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nth_instance(Key,Index,Ref) :-
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nonvar(Key), var(Index), var(Ref), !,
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recorded(Key,_,Ref),
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'$nth_instance'(_,Index,Ref).
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nth_instance(Key,Index,Ref) :-
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'$nth_instance'(Key,Index,Ref).
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/** @pred nth_instance(? _Key_,? _Index_, _T_,? _R_)
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Fetches the _Index_nth entry in the internal database under the key
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_Key_. Entries are numbered from one. If the key _Key_ or the
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_Index_ are bound, a reference is unified with _R_. Otherwise,
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the reference _R_ must be given, and YAP will find
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the matching key and index.
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*/
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nth_instance(Key,Index,T,Ref) :-
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nonvar(Key), var(Index), var(Ref), !,
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recorded(Key,T,Ref),
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'$nth_instance'(_,Index,Ref).
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nth_instance(Key,Index,T,Ref) :-
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'$nth_instance'(Key,Index,Ref),
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instance(Ref,T).
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/** @pred nb_current(? _Name_, ? _Value_)
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Enumerate all defined variables with their value. The order of
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enumeration is undefined.
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*/
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/** @pred nb_current(? _Name_,? _Value_)
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Enumerate all defined variables with their value. The order of
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enumeration is undefined.
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*/
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nb_current(GlobalVariable, Val) :-
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'$nb_current'(GlobalVariable),
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'$nb_getval'(GlobalVariable, Val, _).
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'$getval_exception'(GlobalVariable, _Val, Caller) :-
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user:exception(undefined_global_variable, GlobalVariable, Action),
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!,
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(
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Action == fail
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->
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fail
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;
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Action == retry
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->
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true
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;
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Action == error
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->
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'$do_error'(existence_error(variable, GlobalVariable),Caller)
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;
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'$do_error'(type_error(atom, Action),Caller)
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).
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/** @pred subsumes_term(? _Subsumer_, ? _Subsumed_)
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Succeed if _Submuser_ subsumes _Subsuned_ but does not bind any
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variable in _Subsumer_.
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*/
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subsumes_term(A,B) :-
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\+ \+ terms:subsumes(A,B).
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