Ticket #508: xapian-orpositionlist.patch

xapian-core/matcher/Makefile.mk

@@ -16 +16 @@
         matcher/multimatch.h\
         matcher/multixorpostlist.h\
         matcher/nearpostlist.h\
+        matcher/orpositionlist.h\
         matcher/orpostlist.h\
         matcher/phrasepostlist.h\
         matcher/queryoptimiser.h\
@@ -54 +55 @@
         matcher/multimatch.cc\
         matcher/multixorpostlist.cc\
         matcher/nearpostlist.cc\
+        matcher/orpositionlist.cc\
         matcher/orpostlist.cc\
         matcher/phrasepostlist.cc\
         matcher/selectpostlist.cc\

new file xapian-core/matcher/orpositionlist.cc

@@ +1 @@
+/** @file orpositionlist.cc
+ * @brief Merge two PositionList objects using an OR operation.
+ */
+/* Copyright (C) 2007,2010,2016 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
+ */
+
+#include <config.h>
+
+#include "orpositionlist.h"
+
+#include "debuglog.h"
+#include "omassert.h"
+
+using namespace std;
+
+Xapian::termcount
+OrPositionList::get_size() const
+{
+    LOGCALL(EXPAND, Xapian::termcount, "OrPositionList::get_size", NO_ARGS);
+    // This is actually the upper bound, but generally there's only one term
+    // at each position, so it'll usually be correct too.
+    RETURN(left->get_size() + right->get_size());
+}
+
+Xapian::termpos
+OrPositionList::get_position() const
+{
+    LOGCALL(EXPAND, Xapian::termpos, "OrPositionList::get_position", NO_ARGS);
+    if (left_current < right_current) RETURN(left_current);
+    RETURN(right_current);
+}
+
+void
+OrPositionList::next()
+{
+    LOGCALL_VOID(EXPAND, "OrPositionList::next", NO_ARGS);
+    // If we've not started yet, both left_current and right_current will be 0,
+    // which gets handled by calling next() on both, which is what we want to
+    // do to get started.
+    if (left_current <= right_current) {
+        bool equal = (left_current == right_current);
+        if (equal && left_current == Xapian::termpos(-1)) {
+            // Both either at_end() or on the largest value and will be
+            // at_end() if we call next().
+            left = right = NULL;
+            return;
+        }
+
+        left->next();
+        if (left->at_end()) {
+            left_current = Xapian::termpos(-1);
+            left = NULL;
+        } else {
+            left_current = left->get_position();
+        }
+        if (!equal) return;
+    }
+
+    right->next();
+    if (right->at_end()) {
+        right_current = Xapian::termpos(-1);
+        right = NULL;
+    } else {
+        right_current = right->get_position();
+    }
+}
+
+void
+OrPositionList::skip_to(Xapian::termpos termpos)
+{
+    LOGCALL_VOID(EXPAND, "OrPositionList::skip_to", termpos);
+    // If we've not started yet, both left_current and right_current will be 0,
+    // which gets handled by calling next() on both, which is what we want to
+    // do to get started.
+    if (left_current <= right_current) {
+        bool equal = (left_current == right_current);
+        if (equal && left_current == Xapian::termpos(-1)) {
+            // Both either at_end() or on the largest value, so skip_to() is a
+            // no-op.
+            return;
+        }
+
+        left->skip_to(termpos);
+        if (left->at_end()) {
+            left_current = Xapian::termpos(-1);
+            left = NULL;
+        } else {
+            left_current = left->get_position();
+        }
+        if (!equal) return;
+    }
+
+    right->skip_to(termpos);
+    if (right->at_end()) {
+        right_current = Xapian::termpos(-1);
+        right = NULL;
+    } else {
+        right_current = right->get_position();
+    }
+}
+
+bool
+OrPositionList::at_end() const
+{
+    LOGCALL(EXPAND, bool, "OrPositionList::at_end", NO_ARGS);
+    RETURN(left == NULL && right == NULL);
+}

new file xapian-core/matcher/orpositionlist.h

@@ +1 @@
+/** @file orpositionlist.h
+ * @brief Merge two PositionList objects using an OR operation.
+ */
+/* Copyright (C) 2007,2010 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 XAPIAN_INCLUDED_ORPOSITIONLIST_H
+#define XAPIAN_INCLUDED_ORPOSITIONLIST_H
+
+#include "backends/positionlist.h"
+
+class OrPositionList : public PositionList {
+  protected:
+    /// The two PositionList objects we're merging.
+    PositionList *left, *right;
+
+    /// The current position for left and right respectively.
+    Xapian::termpos left_current, right_current;
+
+  public:
+    OrPositionList() { }
+
+    void init(PositionList * left_, PositionList * right_) {
+        left = left_;
+        right = right_;
+        left_current = 0;
+        right_current = 0;
+    }
+
+    Xapian::termcount get_size() const;
+
+    Xapian::termpos get_position() const;
+
+    void next();
+
+    void skip_to(Xapian::termpos termpos);
+
+    bool at_end() const;
+};
+
+#endif // XAPIAN_INCLUDED_ORPOSITIONLIST_H

xapian-core/matcher/orpostlist.cc

@@ -2 +2 @@
  *
  * Copyright 1999,2000,2001 BrightStation PLC
  * Copyright 2001,2002 Ananova Ltd
- * Copyright 2003,2004,2007,2008,2009,2010,2011,2012 Olly Betts
+ * Copyright 2003,2004,2007,2008,2009,2010,2011,2012,2016 Olly Betts
  * Copyright 2009 Lemur Consulting Ltd
  * Copyright 2010 Richard Boulton
  *
@@ -30 +30 @@
 #include "andmaybepostlist.h"
 #include "omassert.h"
 
+#include "orpositionlist.h"
+
 #include <algorithm>
 
 OrPostList::OrPostList(PostList *left_,
@@ -370 +372 @@
     RETURN(OrPostList::get_maxweight());
 }
 
+PositionList *
+OrPostList::read_position_list()
+{
+    if (lhead < rhead) return l->read_position_list();
+    if (lhead > rhead) return r->read_position_list();
+    position_list.init(l->read_position_list(), r->read_position_list());
+    return &position_list;
+}
+
 bool
 OrPostList::at_end() const
 {

xapian-core/matcher/orpostlist.h

@@ -3 +3 @@
  */
 /* Copyright 1999,2000,2001 BrightStation PLC
  * Copyright 2002 Ananova Ltd
- * Copyright 2003,2004,2009,2010,2011 Olly Betts
+ * Copyright 2003,2004,2009,2010,2011,2016 Olly Betts
  * Copyright 2009 Lemur Consulting Ltd
  * Copyright 2010 Richard Boulton
  *
@@ -27 +27 @@
 #define OM_HGUARD_ORPOSTLIST_H
 
 #include "branchpostlist.h"
+#include "orpositionlist.h"
 
 /** A postlist comprising two postlists ORed together.
  *
@@ -41 +42 @@
         bool lvalid, rvalid;
         double lmax, rmax, minmax;
         Xapian::doccount dbsize;
+        // FIXME: Do we want an OrWithPosPostList so we don't have the overhead
+        // of an OrPositionList object on every OrPostList.
+        OrPositionList position_list;
     public:
         Xapian::doccount get_termfreq_max() const;
         Xapian::doccount get_termfreq_min() const;
@@ -54 +58 @@
 
         double recalc_maxweight();
 
+        PositionList * read_position_list();
+
         PostList *next(double w_min);
         PostList *skip_to(Xapian::docid did, double w_min);
         PostList *check(Xapian::docid did, double w_min, bool &valid);