File indexing completed on 2024-05-19 04:49:56

 /****************************************************************************************
  * Copyright (c) 2008-2012 Soren Harward <stharward@gmail.com>                          *
  *                                                                                      *
  * 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 General Public License along with         *
  * this program.  If not, see <http://www.gnu.org/licenses/>.                           *
  ****************************************************************************************/
 
 #ifndef APG_GENERIC_MATCHING_CONSTRAINT
 #define APG_GENERIC_MATCHING_CONSTRAINT
 
 #include "playlistgenerator/Constraint.h"
 
 #include "core/meta/forward_declarations.h"
 
 #include <QBitArray>
 
 /* The basic ConstraintGroup logic works properly only if all the
  * constraints in the group are independent.  Constraints that work by
  * matching track attributes to fixed values need additional logic, because
  * it is possible (and even likely) that the user will create a group in
  * which two or more constraints match against the same attribute, and are
  * thus interdependent.
  *
  * For example, let's say that the user creates a "match any" group, and
  * adds two constraints: one for "genre: Rock" and the other for "genre:
  * Rap".  These two constraints are interdependent.  Without this
  * workaround, the solver algorithm will fill up the playlist with either
  * Rock tracks or Rap tracks, but not a mixture of both, because it is
  * trying to maximize the individual satisfactions and not the joint
  * satisfaction.  For "match all" groups, the solver adds tracks that
  * improve only the least-satisfied constraint, instead of adding tracks
  * that improve all constraints.
  * 
  * Interdependent constraints should have their results combined (using the
  * appropriate boolean operator) and the satisfaction value should be the
  * value of the combined results.  From a programming standpoint, it would
  * make sense just to prohibit the user from adding interdependent
  * constraints to a group.  But that approach would add a restriction to
  * constraint trees which is difficult for the user to understand, and an
  * even bigger departure from other audio player programs than the
  * constraint tree already is.  It might not even be any easier to program
  * than this logic workaround.  Thus the decision to make the code the way
  * it is.
  *
  * Thus far, the only Constraint that actually needs this workaround is
  * TagMatch.  More (like SimilarityMatch) might come later.  -- sth */
 
 namespace ConstraintTypes {
     class MatchingConstraint : public Constraint {
         public:
             virtual const QBitArray whatTracksMatch(const Meta::TrackList&) = 0;
             virtual int constraintMatchType() const = 0;
 
         protected:
             MatchingConstraint(ConstraintNode*);
     };
 }
 #endif // MATCHINGCONSTRAINT_H