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yap-6.3/packages/chr/chr_integertable_store.pl
2015-10-13 08:17:51 +01:00

141 lines
3.6 KiB
Prolog

/* $Id$
Part of CHR (Constraint Handling Rules)
based on chr_hashtable_store (by Tom Schrijvers)
Author: Jon Sneyers
E-mail: Jon.Sneyers@cs.kuleuven.be
WWW: http://www.swi-prolog.org
Copyright (C): 2005, K.U. Leuven
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
As a special exception, if you link this library with other files,
compiled with a Free Software compiler, to produce an executable, this
library does not by itself cause the resulting executable to be covered
by the GNU General Public License. This exception does not however
invalidate any other reasons why the executable file might be covered by
the GNU General Public License.
*/
% is it safe to use nb_setarg here?
%% @addtogroup CHR_in_YAP_Programs
%
% CHR error handling
%
:- module(chr_integertable_store,
[ new_iht/1,
lookup_iht/3,
insert_iht/3,
delete_iht/3,
value_iht/2
]).
:- use_module(library(lists)).
:- use_module(library(dialect/hprolog)).
%initial_capacity(65536).
%initial_capacity(1024).
initial_capacity(8).
%initial_capacity(2).
%initial_capacity(1).
new_iht(HT) :-
initial_capacity(Capacity),
new_iht(Capacity,HT).
new_iht(Capacity,HT) :-
functor(T1,t,Capacity),
HT = ht(Capacity,Table),
Table = T1.
lookup_iht(ht(_,Table),Int,Values) :-
Index is Int + 1,
arg(Index,Table,Values),
Values \= [].
% nonvar(Values).
insert_iht(HT,Int,Value) :-
Index is Int + 1,
arg(2,HT,Table),
(arg(Index,Table,Bucket) ->
( var(Bucket) ->
Bucket = [Value]
;
setarg(Index,Table,[Value|Bucket])
)
; % index > capacity
Capacity is 1<<ceil(log(Index)/log(2)),
expand_iht(HT,Capacity),
insert_iht(HT,Int,Value)
).
delete_iht(ht(_,Table),Int,Value) :-
% arg(2,HT,Table),
Index is Int + 1,
arg(Index,Table,Bucket),
( Bucket = [_Value] ->
setarg(Index,Table,[])
;
delete_first_fail(Bucket,Value,NBucket),
setarg(Index,Table,NBucket)
).
%delete_first_fail([], Y, []).
%delete_first_fail([_], _, []) :- !.
delete_first_fail([X | Xs], Y, Xs) :-
X == Y, !.
delete_first_fail([X | Xs], Y, [X | Zs]) :-
delete_first_fail(Xs, Y, Zs).
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
value_iht(HT,Value) :-
HT = ht(Capacity,Table),
value_iht(1,Capacity,Table,Value).
value_iht(I,N,Table,Value) :-
I =< N,
arg(I,Table,Bucket),
(
nonvar(Bucket),
member(Value,Bucket)
;
J is I + 1,
value_iht(J,N,Table,Value)
).
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
expand_iht(HT,NewCapacity) :-
HT = ht(Capacity,Table),
functor(NewTable,t,NewCapacity),
setarg(1,HT,NewCapacity),
setarg(2,HT,NewTable),
expand_copy(Table,1,Capacity,NewTable,NewCapacity).
expand_copy(Table,I,N,NewTable,NewCapacity) :-
( I > N ->
true
;
arg(I,Table,Bucket),
( var(Bucket) ->
true
;
arg(I,NewTable,Bucket)
),
J is I + 1,
expand_copy(Table,J,N,NewTable,NewCapacity)
).