X-Git-Url: http://nitlanguage.org

diff --git a/lib/more_collections.nit b/lib/more_collections.nit
index ac2c8d1..9fb05bb 100644
--- a/lib/more_collections.nit
+++ b/lib/more_collections.nit
@@ -13,7 +13,9 @@
 # limitations under the License.
 
 # Highly specific, but useful, collections-related classes.
-module more_collections
+module more_collections is serialize
+
+import serialization
 
 # Simple way to store an `HashMap[K, Array[V]]`
 #
@@ -61,6 +63,7 @@ end
 # assert hm2[2, "not-two"] == null
 # ~~~~
 class HashMap2[K1, K2, V]
+
 	private var level1 = new HashMap[K1, HashMap[K2, V]]
 
 	# Return the value associated to the keys `k1` and `k2`.
@@ -94,6 +97,13 @@ class HashMap2[K1, K2, V]
 		level2.keys.remove(k2)
 	end
 
+	# Is there a value at `k1, k2`?
+	fun has(k1: K1, k2: K2): Bool
+	do
+		if not level1.keys.has(k1) then return false
+		return level1[k1].keys.has(k2)
+	end
+
 	# Remove all items
 	fun clear do level1.clear
 end
@@ -108,6 +118,7 @@ end
 # assert hm3[2, "not-two", 22] == null
 # ~~~~
 class HashMap3[K1, K2, K3, V]
+
 	private var level1 = new HashMap[K1, HashMap2[K2, K3, V]]
 
 	# Return the value associated to the keys `k1`, `k2`, and `k3`.
@@ -141,6 +152,13 @@ class HashMap3[K1, K2, K3, V]
 		level2.remove_at(k2, k3)
 	end
 
+	# Is there a value at `k1, k2, k3`?
+	fun has(k1: K1, k2: K2, k3: K3): Bool
+	do
+		if not level1.keys.has(k1) then return false
+		return level1[k1].has(k2, k3)
+	end
+
 	# Remove all items
 	fun clear do level1.clear
 end