48 lines
905 B
Prolog
48 lines
905 B
Prolog
/**
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* @file gensym.yap
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* @author VITOR SANTOS COSTA <vsc@VITORs-MBP.lan>
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* @date Tue Nov 17 18:37:13 2015
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*
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* @brief Generate a new atom.
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*
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*
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*/
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:- module(gensym, [
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init_gensym/1,
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gensym/2,
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reset_gensym/1,
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reset_gensym/0
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]).
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/**
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* @defgroup gensym Generate a new symbol.
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* @ingroup library
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*
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* Predicates to create new atoms based on the prefix _Atom_.
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* They use a counter, stored as a
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* dynamic predicate, to construct the atom's suffix.
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*
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*/
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:- dynamic gensym_key/2.
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init_gensym(Key) :-
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retractall(gensym_key(Key,_)),
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assert(gensym_key(Key,0) ).
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gensym(Key, New) :-
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retract(gensym_key(Key,Id)), !,
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atomic_concat(Key,Id,New),
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NId is Id+1,
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assert(gensym_key(Key,NId)).
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gensym(Atom, New) :-
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atomic_concat(Atom,0,New),
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assert(gensym_key(Atom,1)).
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reset_gensym(Atom) :-
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retract(gensym_key(Atom,_)).
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reset_gensym :-
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retractall(gensym_key(_,_)).
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