Added implementation to insert bigrams in the Posting Changes object …

…and finally send them to merge in postlist table,postlist table implementation pending

xapian-core/backends/brass/brass_inverter.cc

@@ -48,6 +48,18 @@ Inverter::flush_post_list(BrassPostListTable & table, const string & term)
     postlist_changes.erase(i);
 }
 
+void
+Inverter::flush_post_bigram_list(BrassPostListTable & table, const string & bigram)
+{
+    map<string, PostingChanges>::iterator i;
+    i = postbigram_changes.find(bigram);
+    if (i == postbigram_changes.end()) return;
+
+    // Flush buffered changes for just this term's postlist.
+    table.merge_changes(bigram, i->second);
+    postbigram_changes.erase(i);
+}
+
 void
 Inverter::flush_all_post_lists(BrassPostListTable & table)
 {
@@ -58,6 +70,16 @@ Inverter::flush_all_post_lists(BrassPostListTable & table)
     postlist_changes.clear();
 }
 
+void
+Inverter::flush_all_post_bigram_lists(BrassPostListTable & table)
+{
+    map<string, PostingChanges>::const_iterator i;
+    for (i = postbigram_changes.begin(); i != postbigram_changes.end(); ++i) {
+	table.merge_changes(i->first, i->second);
+    }
+    postbigram_changes.clear();
+}
+
 void
 Inverter::flush_post_lists(BrassPostListTable & table, const string & pfx)
 {
@@ -77,9 +99,29 @@ Inverter::flush_post_lists(BrassPostListTable & table, const string & pfx)
     postlist_changes.erase(begin, end);
 }
 
+void
+Inverter::flush_post_bigram_lists(BrassPostListTable & table, const string & pfx)
+{
+    if (pfx.empty())
+	return flush_all_post_bigram_lists(table);
+
+    map<string, PostingChanges>::iterator i, begin, end;
+    begin = postbigram_changes.lower_bound(pfx);
+    end = postbigram_changes.upper_bound(pfx);
+
+    for (i = begin; i != end; ++i) {
+	table.merge_changes(i->first, i->second);
+    }
+
+    // Erase all the entries in one go, as that's:
+    //  O(log(postlist_changes.size()) + O(number of elements removed)
+    postbigram_changes.erase(begin, end);
+}
+
 void
 Inverter::flush(BrassPostListTable & table)
 {
     flush_doclengths(table);
     flush_all_post_lists(table);
+	flush_all_post_bigram_lists(table);
 }

xapian-core/backends/brass/brass_inverter.h

@@ -107,12 +107,16 @@ class Inverter {
 
     /// Buffered changes to postlists.
     std::map<std::string, PostingChanges> postlist_changes;
+
+	/// Buffered Changes to postlists for bigrams.
+	std::map<std::string,PostingChanges> postbigram_changes;
 
   public:
     /// Buffered changes to document lengths.
     std::map<Xapian::docid, Xapian::termcount> doclen_changes;
 
   public:
+	/// Add posting for term.
     void add_posting(Xapian::docid did, const std::string & term,
 		     Xapian::doccount wdf) {
 	std::map<std::string, PostingChanges>::iterator i;
@@ -125,6 +129,20 @@ class Inverter {
 	}
     }
 
+	//// Add posting for this bigram.
+	void add_bigramposting(Xapian::docid did,const std::string & bigram,
+			Xapian::doccount wdf) {
+	std::map<std::string,PostingChanges>::iterator i;
+	i = postbigram_changes.find(bigram);
+	if (i == postbigram_changes.end()) {
+		postbigram_changes.insert(
+		std::make_pair(bigram, PostingChanges(did,wdf)));
+	} else {
+		i->second.add_posting(did,wdf);
+	}
+	}
+
+	/// Remove posting for this term.
     void remove_posting(Xapian::docid did, const std::string & term,
 			Xapian::doccount wdf) {
 	std::map<std::string, PostingChanges>::iterator i;
@@ -137,6 +155,20 @@ class Inverter {
 	}
     }
 
+	/// Remove posting for this bigram.
+	void remove_bigramposting(Xapian::docid did,const std::string & bigram,
+			Xapian::doccount wdf) {
+	std::map<std::string,PostingChanges>::iterator i;
+	i = postbigram_changes.find(bigram);
+	if (i == postbigram_changes.end()) {
+		postbigram_changes.insert(
+		std::make_pair(bigram,PostingChanges(did,wdf,false)));
+	} else {
+		i->second.remove_posting(did,wdf);
+	}
+	}
+
+	/// Update posting for this term.
     void update_posting(Xapian::docid did, const std::string & term,
 			Xapian::termcount old_wdf,
 			Xapian::termcount new_wdf) {
@@ -150,9 +182,24 @@ class Inverter {
 	}
     }
 
+	/// Updated posting for this bigram.
+	void update_bigramposting(Xapian::docid did,const std::string & bigram,
+			Xapian::termcount old_wdf,
+			Xapian::termcount new_wdf) {
+	std::map<std::string,PostingChanges>::iterator i;
+	i = postbigram_changes.find(bigram);
+	if (i == postbigram_changes.end()) {
+		postbigram_changes.insert(
+		std::make_pair(bigram,PostingChanges(did,old_wdf,new_wdf)));
+	} else {
+		i->second.update_posting(did,old_wdf,new_wdf);
+	}
+	}
+
     void clear() {
 	doclen_changes.clear();
 	postlist_changes.clear();
+	postbigram_changes.clear();
     }
 
     void set_doclength(Xapian::docid did, Xapian::termcount doclen, bool add) {
@@ -190,6 +237,15 @@ class Inverter {
     /// Flush postlist changes for all terms which start with @a pfx.
     void flush_post_lists(BrassPostListTable & table, const std::string & pfx);
 
+    /// Flush postlist changes for @a bigram.
+    void flush_post_bigram_list(BrassPostListTable & table, const std::string & bigram);
+
+    /// Flush postlist changes for all terms.
+    void flush_all_post_bigram_lists(BrassPostListTable & table);
+
+    /// Flush postlist changes for all terms which start with @a pfx.
+    void flush_post_bigram_lists(BrassPostListTable & table, const std::string & pfx);
+
     /// Flush all changes.
     void flush(BrassPostListTable & table);
 
@@ -200,6 +256,14 @@ class Inverter {
 	    return 0;
 	return i->second.get_tfdelta();
     }
+
+	Xapian::termcount_diff get_bigramtfdelta(const std::string & bigram) const {
+	std::map<std::string, PostingChanges>::const_iterator i;
+	i = postbigram_changes.find(bigram);
+	if (i == postbigram_changes.end())
+	    return 0;
+	return i->second.get_tfdelta();
+    }
 
     Xapian::termcount_diff get_cfdelta(const std::string & term) const {
 	std::map<std::string, PostingChanges>::const_iterator i;
@@ -208,6 +272,14 @@ class Inverter {
 	    return 0;
 	return i->second.get_cfdelta();
     }
+
+	Xapian::termcount_diff get_bigramcfdelta(const std::string & bigram) const {
+	std::map<std::string, PostingChanges>::const_iterator i;
+	i = postbigram_changes.find(bigram);
+	if (i == postbigram_changes.end())
+	    return 0;
+	return i->second.get_cfdelta();
+    }
 };
 
 #endif // XAPIAN_INCLUDED_BRASS_INVERTER_H