[libgee] Fix lack of unsetting _first and _last in TreeSet on Set.clear()

[Maciej Marcin Piechotka <mpiechotka src gnome org>]

commit 679f32fac58a45d3660eb83871be2cdfd9657d3f
Author: Maciej Piechotka <uzytkownik2 gmail com>
Date:   Tue Jul 27 11:05:53 2010 +0200

    Fix lack of unsetting _first and _last in TreeSet on Set.clear()

 gee/treemap.vala          |    2 +-
 gee/treeset.vala          |    2 +-
 tests/testcollection.vala |   35 +++++++++++++++++++++++++++++++++++
 tests/testmap.vala        |   31 +++++++++++++++++++++++++++++++
 4 files changed, 68 insertions(+), 2 deletions(-)
---
diff --git a/gee/treemap.vala b/gee/treemap.vala
index f84de0f..90ddeca 100644
--- a/gee/treemap.vala
+++ b/gee/treemap.vala
@@ -357,7 +357,7 @@ public class Gee.TreeMap<K,V> : Gee.AbstractMap<K,V> {
 	 * { inheritDoc}
 	 */
 	public override void clear () {
-		root = null;
+		first = last = root = null;
 		_size = 0;
 		stamp++;
 	}
diff --git a/gee/treeset.vala b/gee/treeset.vala
index 1d7ee76..bb5d868 100644
--- a/gee/treeset.vala
+++ b/gee/treeset.vala
@@ -315,7 +315,7 @@ public class Gee.TreeSet<G> : AbstractSet<G>, SortedSet<G> {
 	 * { inheritDoc}
 	 */
 	public override void clear () {
-		root = null;
+		_first = _last = root = null;
 		_size = 0;
 		stamp++;
 	}
diff --git a/tests/testcollection.vala b/tests/testcollection.vala
index 682302d..6155f9e 100644
--- a/tests/testcollection.vala
+++ b/tests/testcollection.vala
@@ -36,6 +36,7 @@ public abstract class CollectionTests : Gee.TestCase {
 		add_test ("[Collection] contains, size and is_empty",
 		          test_contains_size_and_is_empty);
 		add_test ("[Collection] add and remove", test_add_remove);
+		add_test ("[Collection] clear", test_clear);
 		add_test ("[Collection] add_all", test_add_all);
 		add_test ("[Collection] contains_all", test_contains_all);
 		add_test ("[Collection] remove_all", test_remove_all);
@@ -368,6 +369,40 @@ public abstract class CollectionTests : Gee.TestCase {
 		assert (test_collection.size == 0);
 	}
 
+	public void test_clear () {
+		// Check the collection exists
+		assert (test_collection != null);
+
+		string[] to_add = {
+			"one", "two", "three", "four", "five", "six", "seven", "eight",
+			"nine", "ten", "eleven", "twelve", "thirteen", "fourteen",
+			"fifteen", "sixteen", "seventeen", "eighteen", "nineteen", "twenty",
+			"twenty one", "twenty two", "twenty three", "twenty four",
+			"twenty five", "twenty six", "twenty seven", "twenty eight",
+			"twenty nine", "thirty", "thirty one", "thirty two", "thirty four",
+			"thirty five", "thirty six", "thirty seven", "thirty eight",
+			"thirty nine", "fourty"
+		};
+		var expected_size = 0;
+
+		foreach (var a in to_add) {
+			assert (!test_collection.contains (a));
+			assert (test_collection.size == expected_size++);
+			assert (test_collection.add (a));
+			assert (test_collection.contains (a));
+		}
+		assert (test_collection.size == to_add.length);
+		
+		test_collection.clear ();
+		
+		assert (test_collection.size == 0);
+		
+		Iterator<string> iter = test_collection.iterator ();
+		assert (iter != null);
+		assert (!iter.has_next ());		
+		
+	}
+
 	public void test_add_all () {
 		// Check the collection exists
 		assert (test_collection != null);
diff --git a/tests/testmap.vala b/tests/testmap.vala
index 65ac245..19fc091 100644
--- a/tests/testmap.vala
+++ b/tests/testmap.vala
@@ -281,6 +281,37 @@ public abstract class MapTests : Gee.TestCase {
 		entries = test_map.entries;
 		assert (entries.size == 0);
 	}
+	
+	public void test_clear () {
+		test_map.set ("one", "value_of_one");
+		test_map.set ("two", "value_of_two");
+		test_map.set ("three", "value_of_three");
+		
+		test_map.clear ();
+		assert (test_map.size == 0);
+		
+		Set<string> keys = test_map.keys;
+		assert (keys != null);
+		Iterator<string> ikeys = keys.iterator ();
+		assert (ikeys != null);
+		assert (!ikeys.has_next ());
+		
+		Collection<string> vals = test_map.values;
+		assert (vals != null);
+		Iterator<string> ivals = vals.iterator ();
+		assert (ivals != null);
+		assert (!ivals.has_next ());
+		
+		Set<Map.Entry<string, string>> ents = test_map.entries;
+		assert (ents != null);
+		Iterator<Map.Entry<string, string>> ients = ents.iterator ();
+		assert (ients != null);
+		assert (!ients.has_next ());
+		
+		MapIterator<string, string> iter = test_map.map_iterator ();
+		assert (iter != null);
+		assert (!iter.has_next ());
+	}
 
 	public void test_set_all () {
 		var another_map = new HashMap<string,string> (str_hash,