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    1/*  Part of SWI-Prolog
    2
    3    Author:        Jan Wielemaker
    4    E-mail:        J.Wielemaker@vu.nl
    5    WWW:           http://www.swi-prolog.org
    6    Copyright (c)  2019-2021, VU University Amsterdam
    7                              SWI-Prolog Solutions b.v.
    8    All rights reserved.
    9
   10    Redistribution and use in source and binary forms, with or without
   11    modification, are permitted provided that the following conditions
   12    are met:
   13
   14    1. Redistributions of source code must retain the above copyright
   15       notice, this list of conditions and the following disclaimer.
   16
   17    2. Redistributions in binary form must reproduce the above copyright
   18       notice, this list of conditions and the following disclaimer in
   19       the documentation and/or other materials provided with the
   20       distribution.
   21
   22    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   23    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   24    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
   25    FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
   26    COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
   27    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
   28    BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   29    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   30    CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   31    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
   32    ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   33    POSSIBILITY OF SUCH DAMAGE.
   34*/
   35
   36:- module(increval,
   37          [ incr_assert/1,                      % :Clause
   38            incr_asserta/1,                     % :Clause
   39            incr_assertz/1,                     % :Clause
   40            incr_retractall/1,                  % :Head
   41            incr_retract/1,                     % :Clause
   42
   43            is_incremental_subgoal/1,           % :Goal
   44            incr_directly_depends/2,            % :Goal1, :Goal2
   45            incr_trans_depends/2,		% :Goal1, :Goal2
   46            incr_invalid_subgoals/1,            % -List
   47            incr_is_invalid/1,                  % :Goal
   48
   49            incr_invalidate_call/1,		% :Goal
   50            incr_invalidate_calls/1,		% :Goal
   51            incr_table_update/0,
   52
   53            incr_propagate_calls/1              % :Answer
   54          ]).   55:- use_module(library(tables)).   56
   57/** <module> Incremental dynamic predicate modification
   58
   59This module emulates the XSB module   `increval`. This module serves two
   60goals: (1) provide alternatives  for   the  dynamic  clause manipulation
   61predicates that propagate into the incremental  tables and (2) query the
   62dynamically maintained _Incremental Depency Graph_ (IDG).
   63
   64The change propagation for incremental   dynamic  predicates. SWI-Prolog
   65relies in prolog_listen/2 to forward any change to dynamic predicates to
   66the table IDG  and  incr_assert/1  and   friends  thus  simply  call the
   67corresponding database update.
   68
   69@compat XSB
   70*/
   71
   72:- meta_predicate
   73    incr_assert(:),
   74    incr_asserta(:),
   75    incr_assertz(:),
   76    incr_retractall(:),
   77    incr_retract(:),
   78    is_incremental_subgoal(:),
   79    incr_directly_depends(:,:),
   80    incr_trans_depends(:, :),
   81    incr_is_invalid(:),
   82    incr_invalidate_call(:),
   83    incr_invalidate_calls(:),
   84    incr_propagate_calls(:).   85
   86incr_assert(T)     :- assertz(T).
   87incr_asserta(T)    :- asserta(T).
   88incr_assertz(T)    :- assertz(T).
   89incr_retractall(T) :- retractall(T).
   90incr_retract(T)    :- retract(T).
   91
   92%!  is_incremental_subgoal(?SubGoal) is nondet.
   93%
   94%   This   predicate   non-deterministically   unifies    Subgoal   with
   95%   incrementally tabled subgoals that are currently table entries.
   96
   97is_incremental_subgoal(SubGoal) :-
   98    '$tbl_variant_table'(VTrie),
   99    trie_gen(VTrie, SubGoal, ATrie),
  100    (   '$idg_edge'(ATrie, _Dir, _Value)
  101    ->  true
  102    ).
  103
  104%!  incr_directly_depends(:Goal1, :Goal2) is nondet.
  105%
  106%   True if Goal1 depends on Goal2 in the IDG.
  107%
  108%   @compat: In XSB, at least one of Goal 1 or Goal 2 must be bound.
  109%   This implementation may be used with both arguments unbound.
  110
  111incr_directly_depends(Goal1, Goal2) :-
  112    '$tbl_variant_table'(VTrie),
  113    (   nonvar(Goal2)
  114    ->  trie_gen(VTrie, Goal2, ATrie2),
  115        '$idg_edge'(ATrie2, affected, ATrie1),
  116        '$tbl_table_status'(ATrie1, _Status, Goal1, _Return)
  117    ;   trie_gen(VTrie, Goal1, ATrie1),
  118        '$idg_edge'(ATrie1, dependent, ATrie2),
  119        '$tbl_table_status'(ATrie2, _Status, Goal2, _Return)
  120    ).
  121
  122%!  incr_trans_depends(:Goal1, Goal2) is nondet.
  123%
  124%   True   for   each   pair    in     the    transitive    closure   of
  125%   incr_directly_depends(G1, G2).
  126
  127incr_trans_depends(Goal1, Goal2) :-
  128    '$tbl_variant_table'(VTrie),
  129    (   nonvar(Goal1)
  130    ->  trie_gen(VTrie, Goal1, ATrie1),
  131        incr_trans_depends(ATrie1, dependent, ATrie2, []),
  132        '$tbl_table_status'(ATrie2, _Status, Goal2, _Return)
  133    ;   trie_gen(VTrie, Goal2, ATrie2),
  134        incr_trans_depends(ATrie2, affected, ATrie1, []),
  135        '$tbl_table_status'(ATrie1, _Status, Goal1, _Return)
  136    ).
  137
  138incr_trans_depends(ATrie1, Dir, ATrie, Done) :-
  139    '$idg_edge'(ATrie1, Dir, ATrie2),
  140    \+ memberchk(ATrie2, Done),
  141    (   ATrie = ATrie2
  142    ;   incr_trans_depends(ATrie2, Dir, ATrie, [ATrie2|Done])
  143    ).
  144
  145%!  incr_invalid_subgoals(-List) is det.
  146%
  147%   List is a sorted list (set)  of   the  incremental subgoals that are
  148%   currently invalid.
  149
  150incr_invalid_subgoals(List) :-
  151    findall(Invalid, invalid_subgoal(Invalid, _), List0),
  152    sort(List0, List).
  153
  154invalid_subgoal(Goal, ATrie) :-
  155    '$tbl_variant_table'(VTrie),
  156    trie_gen(VTrie, Goal, ATrie),
  157    (   '$idg_edge'(ATrie, _Dir, _Value)
  158    ->  true
  159    ),
  160    '$idg_falsecount'(ATrie, Count),
  161    Count > 0,
  162    \+ '$tbl_table_status'(ATrie, dynamic, _Goal, _Return).
  163
  164%!  incr_is_invalid(:Subgoal) is semidet.
  165%
  166%   True when Subgoal's table is marked as invalid.
  167
  168incr_is_invalid(Subgoal) :-
  169    get_calls(Subgoal, Table, _Return),
  170    '$idg_falsecount'(Table, Count),
  171    Count > 0.
  172
  173%!  incr_invalidate_calls(:Goal) is det.
  174%
  175%   Invalidate all tables for subgoals of Goal   as  well as tables that
  176%   are affected by these.
  177
  178incr_invalidate_calls(Goal) :-
  179    '$tbl_variant_table'(VTable),
  180    !,
  181    forall(trie_gen(VTable, Goal, ATrie),
  182           '$idg_changed'(ATrie)).
  183incr_invalidate_calls(_).
  184
  185%!  incr_invalidate_call(:Goal) is det.
  186%
  187%   This is the XSB name, but   the  manual says incr_invalidate_calls/1
  188%   and the comment with the code suggests this is misnamed.
  189%
  190%   @deprecated Use incr_invalidate_calls/1.
  191
  192incr_invalidate_call(Goal) :-
  193    incr_invalidate_calls(Goal).
  194
  195%!  incr_table_update
  196%
  197%   Updated all invalid tables
  198
  199incr_table_update :-
  200    repeat,
  201    (   invalid_subgoal(Goal, ATrie)
  202    ->  '$tabling':reeval(ATrie, Goal, _Return),
  203        fail
  204    ;   !
  205    ).
  206
  207%!  incr_propagate_calls(:Answer) is det.
  208%
  209%   Activate the monotonic answer propagation similarly   to  when a new
  210%   fact is asserted for a monotonic  dynamic predicate. The Answer term
  211%   must match a monotonic dynamic predicate.
  212
  213incr_propagate_calls(Answer) :-
  214    setup_call_cleanup(
  215        '$tbl_propagate_start'(Old),
  216        '$tabling':incr_propagate_assert(Answer),
  217        '$tbl_propagate_end'(Old))