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