branchpostlist.h

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/* Copyright 1999,2000,2001 BrightStation PLC
 * Copyright 2002 Ananova Ltd
 * Copyright 2003,2004,2007,2011 Olly Betts
 *
 * 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, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301
 * USA
 */
 
#ifndef OM_HGUARD_BRANCHPOSTLIST_H
#define OM_HGUARD_BRANCHPOSTLIST_H
 
#include "multimatch.h"
#include "api/postlist.h"
 
class BranchPostList : public PostList {
    private:
        // Prevent copying
        BranchPostList(const BranchPostList &);
        BranchPostList & operator=(const BranchPostList &);
 
    protected:
        PostList *l;
 
        PostList *r;
 
        MultiMatch *matcher;
 
        void handle_prune(PostList *&kid, PostList *ret) {
            if (ret) {
                delete kid;
                kid = ret;
 
                // now tell matcher that maximum weights need recalculation.
                matcher->recalc_maxweight();
            }
        }
 
    public:
        BranchPostList(PostList *l_, PostList *r_, MultiMatch *matcher_)
                : l(l_), r(r_), matcher(matcher_) {}
 
        virtual ~BranchPostList();
};
 
// Helper functions - call next/skip_to on a postlist and handle any
// resulting prune
//
// Returns true iff a prune was handled, so the caller can recalculate
// weights etc if necessary
inline bool
next_handling_prune(PostList * & pl, double w_min, MultiMatch *matcher)
{
    PostList *p = pl->next(w_min);
    if (!p) return false;
    delete pl;
    pl = p;
    // now tell matcher that maximum weights need recalculation.
    if (matcher) matcher->recalc_maxweight();
    return true;
}
 
inline bool
skip_to_handling_prune(PostList * & pl, Xapian::docid did, double w_min,
                       MultiMatch *matcher)
{
    PostList *p = pl->skip_to(did, w_min);
    if (!p) return false;
    delete pl;
    pl = p;
    // now tell matcher that maximum weights need recalculation.
    if (matcher) matcher->recalc_maxweight();
    return true;
}
 
inline bool
check_handling_prune(PostList * & pl, Xapian::docid did, double w_min,
                     MultiMatch *matcher, bool & valid)
{
    PostList *p = pl->check(did, w_min, valid);
    if (!p) return false;
    delete pl;
    pl = p;
    // now tell matcher that maximum weights need recalculation.
    if (matcher) matcher->recalc_maxweight();
    return true;
}
 
#endif /* OM_HGUARD_BRANCHPOSTLIST_H */