From 27a80dcb677705f97019f9c15eece1d326c5b5e7 Mon Sep 17 00:00:00 2001
From: djcb <djcb@djcbsoftware.nl>
Date: Tue, 25 Dec 2012 20:33:02 +0200
Subject: [PATCH] * handle the no-matches-found case correctly

---
 lib/mu-msg-iter.cc | 15 ++++++++++-----
 lib/mu-threader.c  |  2 ++
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/lib/mu-msg-iter.cc b/lib/mu-msg-iter.cc
index 9b365ba5..c2c1ebda 100644
--- a/lib/mu-msg-iter.cc
+++ b/lib/mu-msg-iter.cc
@@ -71,6 +71,11 @@ public:
 		_matches         = _enq.get_mset (0, G_MAXINT);
 
 		_matches.fetch();
+		_cursor	   = _matches.begin();
+
+		if (_matches.empty())
+			return;
+
 		_skip_dups       = false;
 		_thread_hash = mu_threader_calculate
 			(this, _matches.size(), sortfield, descending);
@@ -85,6 +90,7 @@ public:
 		 * non-scientific testing suggests. 5-10% or so */
 		if (_matches.size() <= MAX_FETCH_SIZE)
 			_matches.fetch ();
+
 	}
 
 	~_MuMsgIter () {
@@ -182,11 +188,10 @@ mu_msg_iter_new (XapianEnquire *enq, size_t maxnum,
 			      sortfield == MU_MSG_FIELD_ID_NONE,
 			      FALSE);
 	try {
-		MuMsgIter *iter;
-		iter = new MuMsgIter ((Xapian::Enquire&)*enq,
-				      maxnum,
-				      sortfield,
-				      flags);
+		MuMsgIter *iter (new MuMsgIter ((Xapian::Enquire&)*enq,
+						maxnum,
+						sortfield,
+						flags));
 		// note: we check if it's a dup even for the first message,
 		// since we need its uid in the set for checking later messages
 		if ((iter->skip_unreadable() && !is_msg_file_readable (iter)) ||
diff --git a/lib/mu-threader.c b/lib/mu-threader.c
index 79932e9f..7e832bdd 100644
--- a/lib/mu-threader.c
+++ b/lib/mu-threader.c
@@ -71,6 +71,8 @@ mu_threader_calculate (MuMsgIter *iter, size_t matchnum,
 
 	/* step 1 */
 	id_table = create_containers (iter);
+	if (matchnum == 0)
+		return id_table; /* just return an empty table */
 
 	/* step 2 -- the root_set is the list of children without parent */
 	root_set = find_root_set (id_table);