1%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    2/*	Nan.Numerics.Prime
    3	A simple prime number library
    4	Copyright 2016 Julio P. Di Egidio
    5	<mailto:julio@diegidio.name>
    6	<http://julio.diegidio.name/Projects/Nan.Numerics.Prime/>
    7	
    8	This file is part of Nan.Numerics.Prime.
    9	
   10	Nan.Numerics.Prime is free software: you can redistribute it and/or modify
   11	it under the terms of the GNU General Public License as published by
   12	the Free Software Foundation, either version 3 of the License, or
   13	(at your option) any later version.
   14	
   15	Nan.Numerics.Prime is distributed in the hope that it will be useful,
   16	but WITHOUT ANY WARRANTY; without even the implied warranty of
   17	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   18	GNU General Public License for more details.
   19	
   20	You should have received a copy of the GNU General Public License
   21	along with Nan.Numerics.Prime.  If not, see <http://www.gnu.org/licenses/>.
   22*/

   23%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
   24
   25% (SWI-Prolog 7.3.25)
   26
   27% TODO: Use gobal variables?
   28% TODO: Implement size limits? (By recent use?)
   29
   30:- module(prime_mem, []).
   31
   32:- public
   33	gen_/2,			% ?P1:prime, ?P2:prime
   34	get_/1,			% ?P:prime
   35	get_/2,			% ?P1:prime, ?P2:prime
   36	add_/2,			% +P1:prime, +P2:prime
   37	count_/1,		% -Count:nonneg
   38	max_/1,			% -Max:prime
   39	clear_/0.		% 

   56:- initialization(clear_).
   57
   58%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

 gen_(?P1:prime, ?P2:prime) is nondet

Generates the memoized pairs (for program inspection).

   64gen_(P1, P2) :-
   65	table_(P1, P2).

 get_(+P0:prime) is semidet

 get_(+P0:prime, -P:prime) is semidet

get_(-P:prime, +P0:prime) is semidet

True if P0 exists in some memoized pair with P its consecutive (resp. for the two variants with arity 2) successor/predecessor prime.

   74get_(2) :- !.
   75get_(P) :-
   76	table_get_(P, _), !.
   77get_(P) :-
   78	table_get_(_, P).
   79
   80get_(P1, P2) :-
   81	table_get_(P1, P2).

 add_(+P1:prime, +P2:prime) is det

Memoizes the pair P1, P2.

NOTE: Does not check that P1, P2 is a pair of consecutive prime numbers and that the pair has not already been memoized.

   90add_(P1, P2) :-
   91	table_add_(P1, P2),
   92	flag_set_(count, C, C + 1),
   93	flag_set_(max, P, max(P, P2)).

 count_(-Count:nonneg) is det

Count is the number of memoized pairs.

   99count_(Count) :-
  100	flag_get_(count, Count).

 max_(-Max:prime) is det

Max is the greatest prime number that exists in any memoized pair.

Max is 2 if no memoized pair exists.

  108max_(Max) :-
  109	flag_get_(max, Max).

 clear_ is det

Clears all memoization.

  115clear_ :-
  116	clearall_,
  117	flag_set_(count, 0),
  118	flag_set_(max, 2).
  119
  120%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  121
  122%	table_(?T1:nonneg, ?T2:nonneg) is nondet.
  123
  124:- dynamic
  125	table_/2.
  126
  127%	table_get_(?T1:nonneg, ?T2:nonneg) is semidet.
  128
  129table_get_(T1, T2) :-
  130	table_(T1, T2), !.
  131
  132%	table_add_(+T1:nonneg, +T2:nonneg) is det.
  133
  134table_add_(T1, T2) :-
  135	assertz(table_(T1, T2)).
  136
  137%	flags_(?Key:atom, ?Val:nonneg) is nondet.
  138
  139:- dynamic
  140	flags_/2.
  141
  142%	flag_get_(+Key:atom, -Val:nonneg) is det.
  143
  144flag_get_(Key, Val) :-
  145	(flags_(Key, Val); Val = 0), !.
  146
  147%	flag_set_(+Key:atom, +New:arith(nonneg)) is det.
  148
  149flag_set_(Key, New) :-
  150	flag_set_(Key, _, New).
  151
  152%	flag_set_(+Key:atom, -Old:nonneg, +New:arith(nonneg)) is det.
  153
  154flag_set_(Key, Old, New) :-
  155	flag_get_(Key, Old), Val is New,
  156	ignore((
  157		Val \== Old,
  158		ignore(retract(flags_(Key, _))),
  159		assertz(flags_(Key, Val))
  160	)).
  161
  162%	clearall_ is det.
  163
  164clearall_ :-
  165	retractall(table_(_, _)),
  166	retractall(flags_(_, _)).
  167
  168%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%